Processing of La(1.8)Sr(0.2)CuO4 and YBa2Cu3O7 superconducting thin films by dual-ion-beam sputtering

NASA Astrophysics Data System (ADS)

Madakson, P.; Cuomo, J. J.; Yee, D. S.; Roy, R. A.; Scilla, G.

1988-03-01

High-quality La(1.8)Sr(0.2)CuO4 and YBa2Cu3O7 superconducting thin films, with zero resistance at 88 K, have been made by dual-ion-beam sputtering of metal and oxide targets at elevated temperatures. The films are about 1.0 micron thick and are single phase after annealing. The substrates investigated are Nd-YAP, MgO, SrF2, Si, CaF2, ZrO2-(9 pct)Y2O3, BaF2, Al2O3, and SrTiO3. Characterization of the films was carried out using Rutherford backscattering spectroscopy, resistivity measurements, TEM, X-ray diffraction, and SIMS. Substrate/film interaction was observed in every case. This generally involves diffusion of the substrate into the film, which is accompanied by, for example, the replacement of Ba by Sr in the YBa2Cu2O7 structure, in the case of SrTiO3 substrate. The best substrates were those that did not significantly diffuse into the film and which did not react chemically with the film.

Crystal Chemical Substitutions of YBa2Cu3O7-d to Enhance Flux Pinning (Postprint)

DTIC Science & Technology

2012-02-01

ionic radii (1.42 A for 8-fold coordination), specifically including larger RE ions La, Pr, and Nd and Ca 2+ and Sr +2. Note also that Pm is normal1y...ng is especially critical for the larger RE ions or mixtures with these ions , which pre vents partial substitution of these RE io ns for Ba ...similar 123 phase can be formed with th e composition ThSr2Cu2•7Meo 30?. This 123 p hase can be formed by substituting Sr for Ba an d a small amount of

Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

NASA Astrophysics Data System (ADS)

Wang, Bo-Kun; Wu, Shao-Yi; Yuan, Zi-Yi; Liu, Zi-Xuan; Jiang, Shi-Xin; Liu, Zheng; Yao, Zi-Jian; Teng, Bao-Hua; Wu, Ming-He

2016-08-01

The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+-O2- electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Ba

Selective resputtering of bismuth in sputtered Bi-Sr-Ca-Cu-O films

NASA Astrophysics Data System (ADS)

Grace, J. M.; McDonald, D. B.; Reiten, M. T.; Olson, J.; Kampwirth, R. T.; Gray, K. E.

1991-10-01

We present studies using a dc magnetron in an on-axis configuration to sputter Bi-Sr-Ca-Cu-O films from a composite target. These studies show that bismuth can be preferentially resputtered. The influence of ozone, molecular oxygen, and total pressure on the resputtering of bismuth is investigated and discussed. Ozone, in low concentrations, can dramatically affect the degree of resputtering. By comparing the effects of molecular oxygen and ozone, some insight is gained regarding the possible mechanisms of negative ion formation in the magnetron environment. Based on our results we suggest that molecular oxygen can bring about resputtering primarily by forming O+2, which collides with the target to produce energetic negative oxygen ions. In contrast, ozone may form negative ions by electron impact in the dark space above the target, giving rise to lower-energy negative ions, which can traverse the plasma unneutralized and can be stopped with an applied bias on the sample block. With no added oxidant, negative oxygen ions from the target oxygen may dominate the background resputtering. Similarity is found between our results and those for similar studies on Y-Ba-Cu-O by other workers. Bismuth in Bi-Sr-Ca-Cu-O behaves as barium in Y-Ba-Cu-O with regards to preferential resputtering; furthermore, the response of strontium, calcium, and copper to oxygen in sputtered Bi-Sr-Ca-Cu-O is similar to what is observed for copper in Y-Ba-Cu-O.

Records of River Variation in the Shells of Freshwater Bivalves

NASA Astrophysics Data System (ADS)

Carroll, M.; Romanek, C.

2005-12-01

The skeletons of hard-shelled invertebrates such as corals and bivalves are commonly used in marine settings as archives of environmental information. They are less commonly used in freshwater settings where variability in water chemistry makes it more difficult to calibrate chemical proxies such as the Sr:Ca in a shell. Our objective is to evaluate whether trace element concentrations in freshwater bivalve shells contain information on environmental conditions. Multiple elements (Ba, Cu, Mn and Sr) were analyzed within the shells of modern bivalves from four streams on DOE's Savannah River Site in S.C. Laser Ablation ICP-MS was used to measure elemental concentrations across five aragonitic shells from each site. These elements were chosen because they are present in detectable concentrations (ppm) in the shell and they have been suggested as useful proxies for temperature, rainfall, productivity and pollution. Results were compared to historical monthly site records of water chemistry and chemical analyses of water samples collected from the streams where the clams were found. The average shell concentrations of Sr and Mn were significantly different between sites and increased proportionally to water concentration. This was not observed for Ba and Cu. For example, the Ba concentrations of shells collected at a site downstream of a lake were higher than those for shells from stream sites with significantly higher dissolved Ba concentrations. Copper was only detected at dark growth lines with the number of lines and shell material between them varying between shells within the same stream. Intrashell profiles of Ba, Sr and Mn concentrations exhibited cyclical variation. The magnitude of cyclical variation for Mn and Sr within a shell corresponds with the annual variation in monthly water sample concentrations. Again, this pattern was not observed for Ba, especially in shells from the site downstream of a lake. This supports suggestions that particulate organic matter, to which Ba preferentially partitions, plays a role in bivalve Ba uptake. Finally, variations in Ba, Cu, Mn and Sr profiles across shells are not in unison. The individual elemental responses to biological and physicochemical effects suggest that the elemental records in freshwater bivalve shells can be interpreted as environmental proxies.

Point-contact electron tunneling into the high-Tc superconductor Y-Ba-Cu-O

NASA Astrophysics Data System (ADS)

Kirk, M. D.; Smith, D. P. E.; Mitzi, D. B.; Sun, J. Z.; Webb, D. J.

1987-06-01

Results are reported from a study of electron tunneling into bulk samples of the new high-Tc superconductor Y-Ba-Cu-O using point-contact tunneling. Based on a superconductive tunneling interpretation, the results show exceptionally large energy gaps in these materials (roughly 2Delta = 100 MeV), implying 2Delta/kBTc = about 13. Similar values were found for La-Sr-Cu-O. The structure in the I-V curves is also similar to that seen in La-Sr-Cu-O. From the asymmetries observed in the I-V characteristics, it is inferred that the natural tunneling barrier on this material is of the Schottky type.

Tl sub 1-x Pr sub x Sr sub 2-y Pr sub y CuO sub 5-. delta. : First member of the family TlA sub 2 Ca sub m-1 Cu sub m O sub 2m+3 (A = Ba, Sr)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bourgault, D.; Martin, C.; Michel, C.

1989-02-01

The synthesis, structure, and superconducting properties of the first member obtained during the investigation of the Tl-Sr-Cu-O and Tl-Sr-Pr-Cu-O systems are described. In order to check out the structural model corresponding to the first member of the series, TlSr{sub 2}Ca{sub m-1}Cu{sub m}O{sub 2m+3}, structure calculations were performed from x-ray powder data of the oxide Tl{sub 0.8}Sr{sub 1.6}Pr{sub 0.6}CuO{sub 5}. Magnetic measurements show only traces of diamagnetism for Tl{sub 0.7}Pr{sub 0.3}Sr{sub 2}CuO{sub 5-{delta}} and TlSr{sub 2}CuO{sub 5-{delta}}; however, Tl{sub 0.8}Pr{sub 0.6}Sr{sub 1.6}Cu{sub 5-{delta}} exhibits diamagnetism below 40K. 21 refs., 2 figs.

Characterization of ZrO2 buffer layers for sequentially evaporated Y-Ba-CuO on Si and Al2O3 substrates

NASA Technical Reports Server (NTRS)

Valco, George J.; Rohrer, Norman J.; Pouch, John J.; Warner, Joseph D.; Bhasin, Kul B.

1988-01-01

Thin film high temperature superconductors have the potential to change the microwave technology for space communications systems. For such applications it is desirable that the films be formed on substrates such as Al2O3 which have good microwave properties. The use of ZrO2 buffer layers between Y-Ba-Cu-O and the substrate has been investigated. These superconducting films have been formed by multilayer sequential electron beam evaporation of Cu, BaF2 and Y with subsequent annealing. The three layer sequence of Y/BaF2/Cu is repeated four times for a total of twelve layers. Such a multilayer film, approximately 1 micron thick, deposited directly on SrTiO3 and annealed at 900 C for 45 min produces a film with a superconducting onset of 93 K and critical temperature of 85 K. Auger electron spectroscopy in conjunction with argon ion sputtering was used to obtain the distribution of each element as a function of depth for an unannealed film, the annealed film on SrTiO3 and annealed films on ZrO2 buffer layers. The individual layers were apparent. After annealing, the bulk of the film on SrTiO3 is observed to be fairly uniform while films on the substrates with buffer layers are less uniform. The Y-Ba-Cu-O/ZrO2 interface is broad with a long Ba tail into the ZrO2, suggesting interaction between the film and the buffer layer. The underlying ZrO2/Si interface is sharper. The detailed Auger results are presented and compared with samples annealed at different temperatures and durations.

Electron tunneling and the energy gap in Bi2Sr2CaCu2Ox

NASA Astrophysics Data System (ADS)

Lee, Mark; Mitzi, D. B.; Kapitulnik, A.; Beasley, M. R.

1989-01-01

Results of electron tunneling on single crystals of the Bi2Sr2CaCu2Ox superconductor are reported. The junctions show a gap structure with Δ~=25 meV, whose temperature dependence exhibits a qualitatively Bardeen-Cooper-Schrieffer-like behavior with a gap-closing Tc~=81-85 K. Comparisons of these tunneling spectra to those obtained on YBa2Cu3O7-x are made. Evidence that 2Δ/kTc~7 for both Ba2Sr2CaCu2Ox and YBa2Cu3O7-x is also discussed.

Homo- and heterometallic Cu(II)-M(II) (M = Ca, Sr and Ba) bis(salamo)-based complexes: Syntheses, structures and fluorescent properties.

PubMed

Zhao, Qing; Wei, Zhi-Li; Kang, Quan-Peng; Zhang, Han; Dong, Wen-Kui

2018-06-02

Four homo/heterometallic complexes [Cu 3 (L)(μ 2 -OAc) 9 (CH 3 OH) 9 ]·3CHCl 3 (1), [Cu 2 (L)Ca(μ 2 -NO 3 ) 9 ] (9), [{Cu 2 (L)Sr(μ 2 -NO 3 ) 9 } 9 ]·CH 3 CH 2 OH (11) and [Cu 2 (L)Ba(μ 2 -OAc) 9 (OAc)] (14), containing an acyclic naphthalenediol-based ligand H 4 L, were synthesized and characterized by elemental analyses, IR, UV-Vis, fluorescence spectra, TG-DTA and X-ray crystallography. The complex 1 was obtained by the reaction of H 4 L with 11 equivalents of Cu(OAc) 9 ·2H 2 O. The heterometallic complexes 9, 11, 14 were acquired by the reaction of H 4 L with 9 equivalents of Cu(OAc) 9 ·2H 2 O or Cu(NO 3 ) 9 ·2H 2 O and 1 equivalent of M(OAc) 9 (M = Ca, Sr and Ba). Owing to the different coordination cavities of the N 2 O 2 and O 6 of the completely deprotonated (L) 14- unit, the crystal structures showed the N 2 O 2 sites were occupied by Cu(II) atoms, alkaline earth metal(II) atoms occupied the O 6 site of the ligand (L) 14- unit, respectively. Furthermore, the fluorescence properties and TG-DTA analyses were discussed. Copyright © 2018 Elsevier B.V. All rights reserved.

The 1201 superconductors Hg1-y(VO4)y(Ba, Sr)2CuO4-2y+δ: evidence for VO4 tetrahedra

NASA Astrophysics Data System (ADS)

Malo, S.; Hervieu, M.; Maignan, A.; Knížek, K.; Raveau, B.; Michel, C.

1997-02-01

A series of mercury based cuprates with nominal composition Hg1-yV(y)Ba2-xSrxCuO4+2y+δ has been prepared for x = 0, 0.25, 0.5, 0.75, 1 and 1.25. The actual solid solution limit from the EDS measurement is x = 1.1, y ranges from 0.2 to 0.35. The single crystal study coupled with high resolution electron microscopy shows for the first time the presence of VO4 tetrahedra replacing partly the mercury atoms according to the formulation Hg1-y(VO4)y(Ba,Sr)2 CuO4-2y+δ. The role of vanadium for the stabilisation of the structure and as a doping agent in the superconducting properties is discussed.

Chemistry and superconductivity in thallium-based cuprates. Technical report No. 56, 1 June 1989-30 May 1990

DOE Office of Scientific and Technical Information (OSTI.GOV)

Greenblatt, M.; Li, S.; McMills, L.E.

1990-06-01

Following the discoveries of high temperature superconductivity in the rare-earth copper oxide systems at 40K bY Bednorz and Muller in 1986 and at 90K by other researchers in 1987, Sheng and Hermann, in 1988, discovered superconductivity in the thallium-alkaline-earth copper oxide systems with critical temperatures as high as 120K. All of the Tl-based compounds can be described by the general formula, TlmA2Can-1CuO2n+m+2, where m=1 or 2; n=5; A=Ba, Sr. For convenience, the names of these compounds are abbreviated as 2223 for TlBa2Ca2Cu3O10, where each number denotes the number of Tl, Ba(Sr), Ca and Cu ions per formula, respectively. The compoundsmore » with m=1 and m=2 are usually referred to as single and double T1-O layered compounds, respectively. The highest superconducting transition temperature known so far was found in Tl2BaCa2Cu3O10 at 125K.« less

Composition and Elution Behavior of Various Elements from Printed Circuit Boards, Cathode-ray Tube Glass, and Liquid-crystal Displays in Waste Consumer Electronics.

PubMed

Inaba, Kazuho; Murata, Tomoyoshi; Yamamura, Shigeki; Nagano, Masaaki; Iwasaki, Kazuhiro; Nakajima, Daisuke; Takigami, Hidetaka

2018-01-01

The contents and elution behavior of metals in consumer electronics parts were determined so as to understand their maximum environmental risk. Elements contained most in printed-circuit boards were Cu, Si, Br, Ca, Al, Sn, Pb, Sb, Ba, Fe, Ni, Ti, and Zn; in cathode-ray tube glass were Si, Pb, Ba, Sr, Zn, Zr, Ca, and Sb; in arsenic contained liquid-crystal displays were Si, Ca, Sr, Ba, As, and Fe; and in antimony contained liquid-crystal displays were Si, Ba, Ca, Sb, Sr, Fe, and Sn. The elements eluted most from printed-circuit boards were Zn, Pb, and Cu; from cathode-ray tube glass were Pb, Zn, B, Ba, and Si; and from liquid-crystal displays were B and Si, and the toxic As and Sb. The amount eluted was greatest at acidic pH. It was revealed that officially recommended 6-h-shaking with a pure water test was insufficient to understand the real environmental risk of waste electronics.

Heteroepitaxial growth of Ba1 - xSrxTiO3/YBa2Cu3O7 - x by plasma-enhanced metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Chern, C. S.; Liang, S.; Shi, Z. Q.; Yoon, S.; Safari, A.; Lu, P.; Kear, B. H.; Goodreau, B. H.; Marks, T. J.; Hou, S. Y.

1994-06-01

Epitaxial Ba1-xSrxTiO3(BST)/YBa2Cu3O7-x heterostructures with superior electrical and dielectric properties have been fabricated by plasma-enhanced metalorganic chemical vapor deposition (PE-MOCVD). Data of x-ray diffraction and high resolution transmission electron microscopy showed that <100> oriented Ba1-xSrxTiO3 layers were epitaxially deposited on epitaxial (001) YBa2Cu3O7-x layers. The leakage current density through the Ba1-xSrxTiO3 films was about 10-7 A/cm2 at 2 V (about 2×105 V/cm) operation. Moreover, the results of capacitance-temperature measurements showed that the PE-MOCVD Ba1-xSrxTiO3 films had Curie temperatures of about 30 °C and a peak dielectric constant of 600 at zero bias voltage. The Rutherford backscattering spectrometry and x-ray diffraction results showed that the BST film composition was controlled between Ba0.75Sr0.25TiO3 and Ba0.8Sr0.2TiO3. The structural and electrical properties of the Ba1-xSrxTiO3/YBa2Cu3O7-x heterostructure indicated that conductive oxide materials with close lattice to Ba1-xSrxTiO3 can be good candidates for the bottom electrode.

A new structure related to the layered cuprates: The {open_quotes}1201{angstrom} shear-like phase Tl{sub 5}Ba{sub 3}Sr{sub 5}Cu{sub 3}O{sub 19}, third member of the series (TlA{sub 2}CuO{sub 5}){sub m}{center_dot}Tl{sub 2}A{sub 2}O{sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Letouze, F.; Martin, C.; Hervieu, M.

1997-01-01

A thallium cuprate, Tl{sub 5}Ba{sub 3}Sr{sub 5}Cu{sub 3}O{sub 19}, whose structure can be derived by systematically shearing the {open_quotes}1201{close_quotes} structure has been synthesized for the first time. It crystallizes in an orthorhombic cell with a=3.7536(2) {angstrom}, b=30.631(2) {angstrom}, c=9.219(1) {angstrom}, and A-type symmetry. This new structure consists of {open_quotes}1201{close_quotes} ribbons parallel to (010) which are three CuO{sub 6} octahedra wide and are interconnected through {open_quotes}Tl{sub 2}A{sub 2}O{sub 4}{close_quotes} ribbons whose cationic configuration is that of the rock salt structure. This phase can be considered to be the m = 3 member of a new series with the generic formulation (TlA{submore » 2}CuO{sub 5}){sub m} {center_dot} Tl{sub 2}A{sub 2}O{sub 4} with A = Ba, Sr.« less

Primary fragmentation pathways of gas phase [M(uracil-H)(uracil)]+ complexes (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd , Mg, Ca, Sr, Ba, and Pb): loss of uracil versus HNCO.

PubMed

Ali, Osama Y; Randell, Nicholas M; Fridgen, Travis D

2012-04-23

Complexes formed between metal dications, the conjugate base of uracil, and uracil are investigated by sustained off-resonance irradiation collision-induced dissociation (SORI-CID) in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Positive-ion electrospray spectra show that [M(Ura-H)(Ura)](+) (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd, Mg, Ca, Sr, Ba, or Pb) is the most abundant ion even at low concentrations of uracil. SORI-CID experiments show that the main primary decomposition pathway for all [M(Ura-H)(Ura)](+) , except where M=Ca, Sr, Ba, or Pb, is the loss of HNCO. Under the same SORI-CID conditions, when M is Ca, Sr, Ba, or Pb, [M(Ura-H)(Ura)](+) are shown to lose a molecule of uracil. Similar results were observed under infrared multiple-photon dissociation excitation conditions, except that [Ca(Ura-H)(Ura)](+) was found to lose HNCO as the primary fragmentation product. The binding energies between neutral uracil and [M(Ura-H)](+) (M=Zn, Cu, Ni, Fe, Cd, Pd ,Mg, Ca, Sr Ba, or Pb) are calculated by means of electronic-structure calculations. The differences in the uracil binding energies between complexes which lose uracil and those which lose HNCO are consistent with the experimentally observed differences in fragmentation pathways. A size dependence in the binding energies suggests that the interaction between uracil and [M(Ura-H)](+) is ion-dipole complexation and the experimental evidence presented supports this. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determining baseline element composition of lichens. I. Parmelia sulcata at Theodore Roosevelt national park, North Dakota

USGS Publications Warehouse

Gough, L.P.; Severson, R.C.; Jackson, L.L.

1988-01-01

Element-concentration baselines are given for Parmelia sulcata and associated soils. Parmelia chlorochroa was found sporadically and therefore only representative concentration ranges are reported for this species. Element data include (1) for lichens; Al, As, Ba, B, Ca, Cr, Cu, Fe, Hg, Mn, Ni, P, Sr, S, Ti, V, Y, and Zn; and (2) for soils: Al, Ba, Be, Ca, Cs, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Nb, P, Pb, Sr, S, Ti, V, Y, and Zn. Very little (usually 7.2 km); thus, P sulcata is, in general, chemically similar throughout the park. This same uniformity was found for soil geochemistry. Numerous samples collected at close intervals would be required, therefore, to produce detailed element-concentration maps for P. sulcata and soils. No instances of elemental phytotoxic conditions were found; however, P. sulcata apparently possesses large concentrations of Ba, Cu, Fe, Pb, S, V, and possibly Zn.

High T(sub c) superconductors fabricated by plasma aerosol mist deposition technique

NASA Technical Reports Server (NTRS)

Wang, X. W.; Vuong, K. D.; Leone, A.; Shen, C. Q.; Williams, J.; Coy, M.

1995-01-01

We report new results on high T(sub c) superconductors fabricated by a plasma aerosol mist deposition technique, in atmospheric environment. Materials fabricated are YBaCuO, BiPbSrCaCuO, BaCaCuO precursor films for TlBaCaCuO, and other buffers such as YSZ. Depending on processing conditions, sizes of crystallites and/or particles are between dozens of nano-meters and several micrometers. Superconductive properties and other material characteristics can also be tailored.

Depth profiling of superconducting thin films using rare gas ion sputtering with laser postionization

NASA Astrophysics Data System (ADS)

Pallix, J. B.; Becker, C. H.; Missert, N.; Char, K.; Hammond, R. H.

1988-02-01

Surface analysis by laser ionization (SALI) has been used to examine a high-Tc superconducting thin film of nominal composition YBa2Cu3O7 deposited on SrTiO3 (100) by reactive magnetron sputtering. The main focus of this work was to probe the compositional uniformity and the impurity content throughout the 1800 Å thick film having critical current densities of 1 to 2×106 A/cm2. SALI depth profiles show this film to be more uniform than thicker films (˜1 μm, prepared by electron beam codeposition) which were studied previously, yet the data show that some additional (non-superconducting) phases derived from Y, Ba, Cu, and O are still present. These additional phases are studied by monitoring the atomic and diatomic-oxide photoion profiles and also the depth profiles of various clusters (e.g. Y2O2+, Y2O3+, Y3O4+, Ba2O+, Ba2O2+, BaCu+, BaCuO+, YBaO2+, YSrO2+, etc.). A variety of impurities are observed to occur throughout the film including rather large concentrations of Sr. Hydroxides, F, Cl, and COx are evident particularly in the sample's near surface region (the top ˜100 Å).

Trigonal Cu2-II-Sn-VI4 (II = Ba, Sr and VI = S, Se) quaternary compounds for earth-abundant photovoltaics.

PubMed

Hong, Feng; Lin, Wenjun; Meng, Weiwei; Yan, Yanfa

2016-02-14

We propose trigonal Cu2-II-Sn-VI4 (II = Ba, Sr and VI = S, Se) quaternary compounds for earth-abundant solar cell applications. Through density functional theory calculations, we show that these compounds exhibit similar electronic and optical properties to kesterite Cu2ZnSnS4 (CZTS): high optical absorption with band gaps suitable for efficient single-junction solar cell applications. However, the trigonal Cu2-II-Sn-VI4 compounds exhibit defect properties more suitable for photovoltaic applications than those of CZTS. In CZTS, the dominant defects are the deep acceptors, Cu substitutions on Zn sites, which cause non-radiative recombination and limit the open-circuit voltages of CZTS solar cells. On the contrary, the dominant defects in trigonal Cu2-II-Sn-VI4 are the shallow acceptors, Cu vacancies, similar to those in CuInSe2. Our results suggest that the trigonal Cu2-II-Sn-VI4 quaternary compounds could be promising candidates for efficient earth-abundant thin-film solar cell and photoeletrochemical water-splitting applications.

Fabrication and chemical composition of RF magnetron sputtered Tl-Ca-Ba-Cu-O high Tc superconducting thin films

NASA Technical Reports Server (NTRS)

Subramanyam, G.; Radpour, F.; Kapoor, V. J.; Lemon, G. H.

1990-01-01

The preparation of TlCaBaCuO superconducting thin films on (100) SrTiO3 substrates is described, and the results of their characterization are presented. Sintering and annealing the thin films in a Tl-rich ambient yielded superconductivity with a Tc of 107 K. The results of an XPS study support two possible mechanisms for the creation of holes in the TlCaBaCuO compound: (1) partial substitution of Ca(2+) for Tl(3+), resulting in hole creation, and (2) charge transfer from Tl(3+) to the CuO layers, resulting in a Tl valence between +3 and +1.

Structure and superconductivity in (Bi(0.35)Cu(0.65))Sr2YCu2O7 and related materials

NASA Technical Reports Server (NTRS)

Jennings, R. A.; Williams, S. P.; Greaves, C.

1995-01-01

The recently reported (Bi/Cu)Sr2YCu2O7 phase has been studied by time of flight powder neutron diffraction. The proposed 1212 structure has been confirmed and refinements have shown the oxygen in the (Bi/Cu)O layer is displaced by 0.78 A from the ideal (1/2,1/2,0) site (P4/mmm space group) along /100/. Bond Valence Sum calculations have suggested oxidation states of Bi(5+) and Cu(2+) for the cations in the (Bi/Cu)O layers. The material is non-superconducting and all attempts to induce superconductivity have been unsuccessful. Work on the related material (Ce/Cu)Sr2YCu2O7 has shown the ideal Ce content to be 0.5 Ce per formula unit. The introduction of Ba (10%) onto the Sr site dramatically increases phase stability and also induces superconductivity (62 K).

Structures and unimolecular chemistry of M(Pro2-H)(+) (M = Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn) by IRMPD spectroscopy, SORI-CID, and theoretical studies.

PubMed

Jami-Alahmadi, Yasaman; Fridgen, Travis D

2016-01-21

M(Pro2-H)(+) complexes were electrosprayed and isolated in an FTICR cell where their unimolecular chemistries and structures were explored using SORI-CID and IRMPD spectroscopy. These experiments were augmented by computational methods such as electronic structure, simulated annealing, and atoms in molecules (AIM) calculations. The unimolecular chemistries of the larger metal cation (Ca(2+), Sr(2+) and Ba(2+)) complexes predominantly involve loss of neutral proline whereas the complexes involving the smaller Mg(2+) and transition metal dications tend to lose small neutral molecules such as water and carbon dioxide. Interestingly, all complexes involving transition metal dications except for Cu(Pro2-H)(+) lose H2 upon collisional or IRMPD activation. IRMPD spectroscopy shows that the intact proline in the transition metal complexes and Cu(Pro2-H)(+) is predominantly canonical (charge solvated) while for the Ca(2+), Sr(2+), and Ba(2+) complexes, proline is in its zwitterionic form. The IRMPD spectra for both Mg(Pro2-H)(+) and Mn(Pro2-H)(+) are concluded to have contributions from both charge-solvated and canonical structures.

Anthropogenic metal enrichment of snow and soil in north-eastern European Russia.

PubMed

Walker, T R; Young, S D; Crittenden, P D; Zhang, H

2003-01-01

Trace metal composition of winter snowpack, snow-melt filter residues and top-soil samples were determined along three transects through industrial towns in the Usa basin, North-East Russia: Inta, Usinsk and Vorkuta. Snow was analysed for Ag, Al, As, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr and Zn using ICP-MS (Ca and K by F-AAS for Vorkuta only), pH and acidity/alkalinity. Filter residues were analysed for: Al, Ba, Ca, Cd, Cu, K, Mg, Mn, Ni, Pb, Sr and Zn using F-AAS and GF-AAS; top-soil samples were analysed for Ba, Cu, Mg, Mn, Na, Ni, Pb, Sr, Zn using F-AAS. Results indicate elevated concentrations of elements associated with alkaline combustion ash around the coal mining towns of Vorkuta and Inta. There is little evidence of deposition around the gas and oil town of Usinsk. Atmospheric deposition in the vicinity of Vorkuta, and to a lesser extent Inta, added significantly to the soil contaminant loading as a result of ash fallout. Acid deposition was associated with pristine areas whereas alkaline combustion ash near to emission sources more than compensated for the acidity caused by SO2.

Sequentially evaporated thin Y-Ba-Cu-O superconductor films: Composition and processing effects

NASA Technical Reports Server (NTRS)

Valco, George J.; Rohrer, Norman J.; Warner, Joseph D.; Bhasin, Kul B.

1988-01-01

Thin films of YBa2Cu3O(7-beta) have been grown by sequential evaporation of Cu, Y, and BaF2 on SrTiO3 and MgO substrates. The onset temperatures were as high as 93 K while T sub c was 85 K. The Ba/Y ratio was varied from 1.9 to 4.0. The Cu/Y ratio was varied from 2.8 to 3.4. The films were then annealed at various times and temperatures. The times ranged from 15 min to 3 hr, while the annealing temperatures used ranged from 850 C to 900 C. A good correlation was found between transition temperature (T sub c) and the annealing conditions; the films annealed at 900 C on SrTiO3 had the best T sub c's. There was a weaker correlation between composition and T sub c. Barium poor films exhibitied semiconducting normal state resistance behavior while barium rich films were metallic. The films were analyzed by resistance versus temperature measurements and scanning electron microscopy. The analysis of the films and the correlations are reported.

Specific Effects of Oxygen Molecule and Plasma on Thin-Film Growth of Y-Ba-Cu-O and Bi-Sr-(Ca)-Cu-O Systems

NASA Astrophysics Data System (ADS)

Endo, Tamio; Horie, Munehiro; Hirate, Naoki; Itoh, Katsutoshi; Yamada, Satoshi; Tada, Masaki; Itoh, Ken-ichi; Sugiyama, Morihiro; Sano, Shinji; Watabe, Kinji

1998-07-01

Thin films of a-oriented YBa2Cu3Ox (YBCO), Ca-doped c-oriented Bi2(Sr,Ca)2CuOx and nondoped c-oriented Bi2Sr2CuOx (Bi2201) were prepared at low temperatures by ion beam sputtering with supply of oxygen molecules or plasma. The plasma enhances crystal growth of the a-YBCO and Ca-doped Bi2201 phases. This can be interpreted in terms of their higher surface energies. The growth and quality of nondoped Bi2201 are improved with the supply of oxygen molecules. This particular result could be interpreted by the collision process between the oxygen molecules and the sputtered particles.

A -cation control of magnetoelectric quadrupole order in A (TiO)Cu 4(PO4)4(A =Ba ,Sr, and Pb)

NASA Astrophysics Data System (ADS)

Kimura, K.; Toyoda, M.; Babkevich, P.; Yamauchi, K.; Sera, M.; Nassif, V.; Rønnow, H. M.; Kimura, T.

2018-04-01

Ferroic magnetic quadrupole order exhibiting macroscopic magnetoelectric activity is discovered in the novel compound A (TiO ) Cu4(PO4)4 with A = Pb, which is in contrast with antiferroic quadrupole order observed in the isostructural compounds with A = Ba and Sr. Unlike the famous lone-pair stereochemical activity which often triggers ferroelectricity as in PbTiO3, the Pb2 + cation in Pb (TiO ) Cu4(PO4)4 is stereochemically inactive but dramatically alters specific magnetic interactions and consequently switches the quadrupole order from antiferroic to ferroic. Our first-principles calculations uncover a positive correlation between the degree of A -O bond covalency and a stability of the ferroic quadrupole order.

High Pressure Properties of a Ba-Cu-Zn-P Clathrate-I

DOE PAGES

Dolyniuk, Juli -Anna; Kovnir, Kirill

2016-08-12

Here, the high pressure properties of the novel tetrel-free clathrate, Ba 8Cu 13.1Zn 3.3P 29.6, were investigated using synchrotron powder X-ray diffraction. The pressure was applied using a diamond anvil cell. No structural transitions or decomposition were detected in the studied pressure range of 0.1–7 GPa. The calculated bulk modulus for Ba 8Cu 13.1Zn 3.3P 29.6 using a third-order Birch-Murnaghan equation of state is 65(6) GPa at 300 K. This bulk modulus is comparable to the bulk moduli of Ge- and Sn-based clathrates, like A 8Ga 16Ge 30 (A = Sr, Ba) and Sn 19.3Cu 4.7P 22I 8, but lowermore » than those for the transition metal-containing silicon-based clathrates, Ba 8 T xSi46–x, T = Ni, Cu; 3 ≤ x ≤ 5.« less

Low-temperature specific heat of single-crystal Bi2CaSr2Cu2O8 and Tl2Ca2Ba2Cu3O10

NASA Astrophysics Data System (ADS)

Urbach, J. S.; Mitzi, D. B.; Kapitulnik, A.; Wei, J. Y. T.; Morris, D. E.

1989-06-01

We report specific-heat measurements from 2 to 15 K on single crystals of Bi2CaSr2Cu2O8 and Tl2Ca2Ba2Cu3O10 We find low-temperature deviations from the Debye law that can be attributed to spin-glass behavior of a small concentration of isolated impurity copper moments. At higher temperatures, we observe contributions to the specific heat that can be attributed to a soft-phonon mode, possibly associated with the superstructure in the Bi-O and Tl-O layers. From our single-crystal data, we conclude that the thallium- and bismuth-based copper oxide superconductors show no measurable linear term in the specific heat [γ(0)<=1 mJ/mole K2].

Trace elements distribution in hawksbill turtle (Eretmochelys imbricata) and green turtle (Chelonia mydas) tissues on the northern coast of Bahia, Brazil.

PubMed

de Macêdo, Gustavo R; Tarantino, Taiana B; Barbosa, Isa S; Pires, Thaís T; Rostan, Gonzalo; Goldberg, Daphne W; Pinto, Luis Fernando B; Korn, Maria Graças A; Franke, Carlos Roberto

2015-05-15

Concentrations of elements (As, Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, Sb, Se, Sr, V, Zn) were determined in liver, kidneys and bones of Eretmochelys imbricata and Chelonia mydas specimens found stranded along the northern coast of Bahia, Brazil. Results showed that the concentrations of Cd, Cu, Ni and Zn in the liver and kidneys of juvenile C. mydas were the highest found in Brazil. We also observed a significant difference (p<0.05) on the bioaccumulation of trace elements between the two species: Al, Co, Mo, Na and Se in the liver; Al, Cr, Cu, K, Mo, Ni, Pb, Sr and V in the kidneys; and Al, Ba, Ca, Cd, Mn, Ni, Pb, Se, Sr and V in the bones. This study represents the first report on the distribution and concentration of trace elements in E. imbricata in the Brazilian coast. Copyright © 2015 Elsevier Ltd. All rights reserved.

Transport current density at temperatures up to 25 K of Cu/Ag composite sheathed 122-type tapes and wires

NASA Astrophysics Data System (ADS)

Liu, Shifa; Lin, Kaili; Yao, Chao; Zhang, Xianping; Dong, Chiheng; Wang, Dongliang; Awaji, Satoshi; Kumakura, Hiroaki; Ma, Yanwei

2017-11-01

The fabrication of iron-based superconductors with high transport critical current density (J c) and low cost is a crucial determinant of whether they can be used for practical applications. In this paper, Cu/Ag composite sheathed Sr0.6K0.4Fe2As2 (Sr122) tapes and Ba0.6K0.4Fe2As2 (Ba122) round wires were fabricated via an ex situ powder-in-tube method and heat-treated by the hot pressing and hot isostatic pressing process respectively. In order to thoroughly reveal the application potential of Cu/Ag composite sheathed ‘122’ iron pnictide superconductors, transport J c of tapes and wires in high fields at temperatures up to 25 K was measured. High transport J c of 4.4 × 104 A cm-2 at 4.2 K and 3.6 × 103 A cm-2 at 20 K in 10 T was achieved in Cu/Ag composite sheathed Sr122 tapes. Transport J c of Ba122 wires is 9.4 × 103 A cm-2 at 4.2 K and 1.9 × 103 A cm-2 at 20 K in 10 T. These results demonstrate the great potential of Cu/Ag composite sheathed ‘122’ iron pnictide superconducting tapes and wires for high-field applications at intermediate temperatures around 20 K, which can be easily obtained by using cryocoolers.

Survey on composition and bioconcentration potential of 12 metallic elements in King Bolete (Boletus edulis) mushroom that emerged at 11 spatially distant sites.

PubMed

Falandysz, Jerzy; Frankowska, Aneta; Jarzynska, Grazyna; Dryzałowska, Anna; Kojta, Anna K; Zhang, Dan

2011-01-01

This paper provides data on baseline concentrations, interrelationships and bioconcentration potential of 12 metallic elements by King Bolete collected from 11 spatially distant sites across Poland. There are significant differences in concentrations of metals (Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Sr, Zn) and their bioconcentration potential in King Bolete Boletus edulis at 11 spatially distant sites surveyed across Poland. These have resulted from significant geographical differences in trace metal concentrations in a layer (0-10 cm) of organic and mineral soil underneath to fruiting bodies and possible local bioavailabilities of macro- (Ca, K, Mg, Na) and trace metals (Al, Ba, Cd, Cu, Fe, Mn, Sr, Zn) to King Bolete. The use of highly appreciated wild-grown edible King Bolete mushroom has established a baseline measure of regional minerals status, heavy metals pollution and assessment of intake rates for wild mushroom dish fanciers against which future changes can be compared. Data on Cd, Cu and Zn from this study and from literature search can be useful to set the maximum limit of these metals in King Bolete collected from uncontaminated (background) areas. In this report also reviewed are data on Al, Ba, Ca, Cd, Cu, Fe, K, Mg, Mn, Na, Sr and Zn accumulation in King Bolete.

High Temperature Superconducting Compounds

DTIC Science & Technology

1992-11-30

broadened interest in superconductivity in both the engineering and scientific communities. Superconducting materials may be offered as a solution to a...YBa2Cu307- has been made. For yttrium, the tris( isopropoxide ) was used exclusively, while the use of both Ba(O-i-Pr)2 and Ba(OCH2Ch2OEt)2 (prepared in... solutions of Cu(acac)2, Ba(OCH2CH 2OEt)2 , and Y(O-i-Pr)3 were spin coated on SrTiO 3 (100) and fired under oxygen to give oriented (b axis normal to the

Heavy metals and metalloids in egg contents and eggshells of passerine birds from Arizona

USGS Publications Warehouse

Mora, Miguel A.

2003-01-01

Concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (Empidonax traillii extimus) from four regions in Arizona. The main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of Sr in eggshells. Seventy eggs of 11 passerine species were collected at four nesting locations during 2000. Aluminum, Ba, Cr, Cu, Mn, Se, Sr, and Zn, were detected primarily in egg contents of all bird species. Arsenic, Ni, Pb, and V were detected primarily in eggshells. A proportion of most inorganic elements accumulated in the eggshell. Concentrations of Ba, Cu, Mn, Se, Sr, and Zn in egg contents and As, Ba, Cu, and V in eggshells of yellow-breasted chats (Icteria virens) were similar among locations. However, concentrations of Mn, Ni, Sr, and Zn in eggshells were significant different among locations. Except for Cu, Mn, Se, and Zn, concentrations of inorganic elements were 2–35 times greater in eggshells than in eggs. Most concentrations of metals and metalloids in eggs and eggshells of all the bird species were below levels known to affect reproduction or that have other deleterious effects. However, I found somewhat elevated concentrations of Sr in eggshells (highest mean=1505 μg/g dw, n=3) of yellow-breasted chats and willow flycatchers, and in egg contents of yellow warblers (Dendroica petechia) and song sparrows (Melospiza melodia). Whether current observed concentrations of Sr in eggshells are affecting nesting birds in Arizona remains to be determined. Strontium and other metals could be associated with lower hatching success in some areas. This study shows that a proportion of many inorganic elements accumulates in the eggshell and that the potential effects on the proper structure and functioning of the eggshell should not be ignored.

The Effect of Oxygen Flow on the Transition Temperature of Hg0.75Pb0.25Sr2-yBayCa2Cu3O8+ δ Superconductors

NASA Astrophysics Data System (ADS)

Jasim, Kareem A.; Al-Khafaji, Raghad S.

2018-05-01

In this paper, there are three different high temperature superconductors which are Hg0.75Pb0.25Sr2-y BayCa2Cu3O8+δ with deferent weight fractions y = 0.10, 0.20 and 0.25 that have been prepared successfully by solid state reaction and the samples have been equipped with/without O2 flow. The optimum calcinations is 1073 K and the sintering process that has been achieved within 1128-1133 K. Transition temperature Tc has been found by using four probe technique through electrical resistivity measurements. The greatest Tc that has been found for Hg0.75Pb0.25Sr1.75 Ba0.25Ca2Cu3O8.31 is 115 oK. Oxygen content (O2) flow exhibits high-phased superconductors that is similar to the samples prepared without O2. Investigation of X-ray diffraction (XRD) is revealed (tetragonal structure) by the c-axis lattice parameter increasing of the samples substituted with Ba. It has been established, from the calculated results, that the Ba variation concentrations of all samples products a modification in the density (ρm), (c/a) and volume fraction (VPh(2223)).

Structure and superconductivity in (Bi{sub 0.35}Cu{sub 0.65})Sr{sub 2}YCu{sub 2}O{sub 7} and related materials

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jennings, R.A.; Williams, S.P.; Greaves, C.

1994-12-31

The recently reported (Bi/Cu)Sr{sub 2}YCu{sub 2}O{sub 7} phase has been studied by time of flight powder neutron diffraction. The proposed 1212 structure has been confirmed and refinements have shown the oxygen in the (Bi/Cu)O layer is displaced by 0.78{angstrom} from the ideal (1/2,1/2,0) site (P4/mmm space group) along (100). Bond Valence Sum calculations have suggested oxidation states of Bi{sup 5+} and Cu{sup 2+} for the cations in the (Bi/Cu)O layers. The material is non-superconducting and all attempts to induce superconductivity have been unsuccessful. Work on the related material (Ce/Cu)Sr{sub 2}YCu{sub 2}O{sub y} has shown the ideal Ce content to bemore » 0.5 Ce per formula unit. The introduction of Ba (10%) onto the Sr site dramatically increases phase stability and also induces superconductivity (62K).« less

Theoretical and experimental studies on wide-band-gap p-type conductive BaCuSeF and related compounds

NASA Astrophysics Data System (ADS)

Sakakima, Hiroshi; Nishitani, Mikihiko; Yamamoto, Koichi; Wada, Takahiro

2015-08-01

BaCuSeF and related compounds, MCuQF (M = Ba, Sr; Q = Se, S), are known to show p-type conduction. The formation energies of the Cu vacancy ΔH[VCu] in a MCuQF system were computed by first-principles calculation with a generalized gradient approximation (GGA) of the Perdew-Burke-Ernzerhof (PBE) functional as an electron exchange and correlation functional. The density of states (DOS) of BaCuSeF was calculated with the hybrid functional of Heyd-Scuseria-Ernzerhof (HSE) 06. ΔH[VCu] was found to be very small under both the Cu- and Q-rich conditions, which probably contributes to p-type conduction. The electronic structure of BaCuSeF was studied by X-ray photoelectron spectroscopy (XPS) with UV photoelectron yield spectroscopy (UVPYS) and photoemission yield spectroscopy (PYS). The determined depth of the top of the valence band relative to the vacuum level was about 4.9 eV. This value is desirable for applications in compound semiconductor thin-film tandem solar cells since the absorbers of polycrystalline thin-film solar cells, such as CdTe and Cu(In,Ga)Se2, are p-type semiconductors. The DOS of BaCuSeF calculated with the HSE06 functional was almost consistent with the XPS spectrum.

Mechanical properties of high-temperature superconducting wires. Ph.D. Thesis - Illinois Inst. of Tech.

NASA Technical Reports Server (NTRS)

Goretta, K. C.; Cluff, J. A.; Joo, J.; Lanagan, M. T.; Singh, J. P.; Vasanthamohan, N.; Xin, Y.; Wong, K. W.

1995-01-01

Bending strength, fracture toughness, and elastic modulus data were acquired for YBa2Cu3O(x), Bi2Sr2CaCu2O(x) (Bi,Pb)2Sr2Ca2Cu3O(x), and Tl2Ba2Ca2Cu3O(x) bars. These data and thermal expansion coefficients strongly suggest that the maximum possible tensile strain without fracture of bulk tapes or wires is approximately equals 0.2%. In Ag-clad conductors, residual stresses will be of limited benefit, but fractures produced by larger strains can be accommodated by shunting current through the Ag.

[Speciation Distribution and Risk Assessment of Heavy Metals in Typical Material Roof Dusts].

PubMed

Li, Dun-zhu; Guan, Yun-tao; Liu, An; Li, Si-yuan

2015-09-01

With the modified BCR sequential extraction procedure, the chemical speciation and risk for 10 heavy metals (Ba, Co, Cr, Cu, Mn, Ni, Pb, Sb, Sr and Zn) in roof dusts were investigated. The subjects of this study were collected from four typical material paved roofs (i. e., ceramic tile, concrete, metal and asphalt) in southeast China. The results indicated that the average contents of heavy metals in roof dust significantly exceeded road dust. The analysis of chemical fraction showed that the acid soluble/exchangeable fraction of Zn was much higher than other elements, the existence of Pb and Cu was mainly in oxidization fraction, while other heavy metals dominated by the residual fraction. The mobility sequence percentages for all roof dust samples decreased in the order of Pb > Zn > Cu >Mn > Co >Sr > Sb > Ni > Ba > Cr, and it should be noted that Pb, Zn, Cu, Mn and Co all have more than 50% proportion in mobility sequence. Based on environmental risk assessment, the highest values of contamination factors (Cf) and risk assessment code (RAC) consistently was observed in Zn, which indicated that Zn had relatively high ecological risk. Health risk assessment showed that the non-carcinogenic hazard indexes (HI) of heavy metals decreased in the order of Pb > Cr > Sb > Zn > Mn > Cu > Ba > Ni > Co > Sr, the HI of heavy metals for adults were lower than safe value while the HI of Pb for children was higher than safe value, suggesting that they will not harm the adult's health except Pb for children. The carcinogenic risk for Cr, Co and Ni were all below the threshold values, which indicated that there was no carcinogenic risk.

Improvement of critical current density in thallium-based (Tl,Bi)Sr(1.6)Ba(0.4)Ca2Cu3O(x) superconductors

NASA Technical Reports Server (NTRS)

Ren, Z. F.; Wang, C. A.; Wang, J. H.; Miller, D. J.; Goretta, K. C.

1995-01-01

Epitaxial (Tl,Bi)Sr(1.6)Ba(0.4)Ca2Cu3O(x) ((Tl,Bi)-1223) thin films on (100) single crystal LaAlO3 substrates were synthesized by a two-step procedure. Phase development, microstructure, and relationships between film and substrate were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Resistance versus temperature, zero-field-cooled and field cooled magnetization, and transport critical current density (J(sub c)) were measured. The zero-resistance temperature was 105-111 K. J(sub c) at 77 K and zero field was greater than 2 x 10(exp 6) A/sq cm. The films exhibited good flux pinning properties.

Geological-hydrogeochemical characteristics of a “silver spring” water source (the Lozovy ridge)

NASA Astrophysics Data System (ADS)

Ivanova, I. S.; Bragin, I. V.; Chelnokov, G. A.; Bushkareva, K. Yu; Shvagrukova, E. V.

2016-03-01

Geological and hydrogeological characteristics of the Lozovy ridge (Southern Primorye) are studied, as far as karst phenomena are widely distributed within its boundaries. Water-bearing rocks of the karst water source “Silver Spring” (“Serebryany Klyuch”), which is located near the bottom of the “Bear’s fang” (“Medvezhiy klyk”) cave, are investigated. It is found that karst rocks are presented by calcite (CaCO3), and an accessory mineral is barite (BaSO4). It is determined that among the trace elements forming the composition of carbonate water-bearing rocks the maximum concentrations are typical for Sr, Ba, Fe, Al, Za, Mn, Cu, and Ni. Also, the chemical composition of the waters taken from the “Silver Spring” water source is studied. These waters are fresh, hydrocarbonate, calcium, and weakly alkaline. Among the elements of the spring, such elements as Sr, Ba, Fe, Al, Zn, Mn, Cu, and Ni have the maximum concentration. The other elements have concentrations less than 1 µg/l.

Body distribution of trace elements in black-tailed gulls from Rishiri Island, Japan: age-dependent accumulation and transfer to feathers and eggs.

PubMed

Agusa, Tetsuro; Matsumoto, Taro; Ikemoto, Tokutaka; Anan, Yasumi; Kubota, Reiji; Yasunaga, Genta; Kunito, Takashi; Tanabe, Shinsuke; Ogi, Haruo; Shibata, Yasuyuki

2005-09-01

Body distribution and maternal transfer of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Hg, Tl, and Pb) to eggs were examined in black-tailed gulls (Larus crassirostris), which were culled in Rishiri Island, Hokkaido Prefecture, Japan. Manganese, Cu, Rb, Mo, and Cd showed the highest levels in liver and kidney, Ag, Sb, and Hg in feather, and V, Sr, and Pb in bone. Maternal transfer rates of trace elements ranged from 0.8% (Cd) to as much as 65% (Tl) of maternal body burden. Large amounts of Sr, Ba, and Tl were transferred to the eggs, though maternal transfer rates of V, Cd, Hg, and Pb were substantially low. It also was observed that Rb, Sr, Cd, Cs, and Ba hardly were excreted into feathers. Concentrations of Co in liver, Ba in liver and kidney, and Mo in liver increased significantly with age, whereas Se in bone and kidney, Hg in kidney, and Cr in feather decreased with age in the known-aged black-tailed gulls (2-20 years old). It also was suggested that feathers might be useful to estimate contamination status of trace elements in birds, especially for Hg on a population basis, although the utility is limited on an individual basis for the black-tailed gulls. To our knowledge, this is the first report on the maternal transfer rate of multielements and also on the usefulness of feathers to estimate contamination status of Hg in birds on a population basis.

Surface and interfacial chemistry of high-k dielectric and interconnect materials on silicon

NASA Astrophysics Data System (ADS)

Kirsch, Paul Daniel

Surfaces and interfaces play a critical role in the manufacture and function of silicon based integrated circuits. It is therefore reasonable to study the chemistries at these surfaces and interfaces to improve existing processes and to develop new ones. Model barium strontium titanate high-k dielectric systems have been deposited on ultrathin silicon oxynitride in ultrahigh vacuum. The resulting nanostructures are characterized with secondary ion mass spectroscopy (SIMS) and X-ray photoelectron spectroscopy (XPS). An interfacial reaction between Ba and Sr atoms and SiOxNy was found to create silicates, BaSixOy or SrSi xOy. Inclusion of N in the interfacial oxide decreased silicate formation in both Ba and Sr systems. Furthermore, inclusion of N in the interfacial oxide decreased the penetration of Ba and Sr containing species, such as silicides and silicates. Sputter deposited HfO2 was studied on nitrided and unnitrided Si(100) surfaces. XPS and SIMS were used to verify the presence of interfacial HfSixOy and estimate its relative amount on both nitrided and unnitrided samples. More HfSixOy formed without the SiNx interfacial layer. These interfacial chemistry results are then used to explain the electrical measurements obtained from metal oxide semiconductor (MOS) capacitors. MOS capacitors with interfacial SiNx exhibit reduced leakage current and increased capacitance. Lastly, surface science techniques were used to develop a processing technique for reducing thin films of copper (II) and copper (I) oxide to copper. Deuterium atoms (D*) and methyl radicals (CH3*) were shown to reduce Cu 2+ and/or Cu1+ to Cu0 within 30 min at a surface temperature of 400 K under a flux of 1 x 1015 atoms/cm2s. Temperature programmed desorption experiments suggest that oxygen leaves the surface as D2O and CO2 for the D* and CH3* treated surfaces, respectively.

Tracking Metal Pollution in Lake Chapala: Concentrations in Water, Sediments, and Fish.

PubMed

Torres, Zaria; Mora, Miguel A; Taylor, Robert J; Alvarez-Bernal, Dioselina

2016-09-01

We measured concentrations of selected metals (Al, Ba, Cu, Mn, Hg, Sr, V, and Zn) in water, sediments, and fish from Lake Chapala and a reference site to evaluate potential negative effects on wildlife, particularly fish-eating birds. Fish metal concentrations ranged from 0.05 µg/g wet weight (ww) for Al and Cu to 64.70 µg/g ww for Sr. There was a positive and significant correlation between fish length and metals particularly for Ba, Cu, Mn, and Zn in Lake Chapala (p < 0.05). However, there were no significant correlations between metal concentrations and δ(15)N values in fish indicating no biomagnification through the food web. Overall, metal concentrations in water, sediments, and fish were similar to and in some cases below those reported for Lake Chapala over the last 20 years. Also, metal concentrations were below those that could be of concern for negative effects on fish and wildlife of Lake Chapala.

Neutron-scattering evidence for a periodically modulated superconducting phase in the underdoped cuprate La 1.905Ba 0.095CuO 4

DOE PAGES

Xu, Zhijun; Stock, C.; Chi, Songxue; ...

2014-10-01

The role of antiferromagnetic spin correlations in high-temperature superconductors remains a matter of debate. We present inelastic neutron-scattering evidence that gapless spin fluctuations coexist with superconductivity in La 1.905Ba 0.095CuO 4. Furthermore, we observe that both the low-energy magnetic spectral weight and the spin incommensurability are enhanced with the onset of superconducting correlations. We propose that the coexistence occurs through intertwining of spatial modulations of the pair wave function and the antiferromagnetic correlations. This proposal is also directly relevant to sufficiently underdoped La 2-xSr xCuO 4 and YBa 2Cu 3O 6+x.

Improvement of critical current density in thallium-based (Tl,Bi)Sr{sub 1.6}Ba{sub 0.4}Ca{sub 2}Cu{sub 3}O{sub x} superconductors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ren, Z.F.; Wang, C.A.; Wang, J.H.

1994-12-31

Epitaxial (Tl,Bi)Sr{sub 1.6}Ba{sub 0.4}Ca{sub 2}Cu{sub 3}O{sub x} (Tl,Bi)-1223 thin films on (100) single crystal LaAlO{sub 3} substrates were synthesized by a two-step procedure. Phase development, microstructure, and relationships between film and substrate were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Resistance versus temperature, zero-field-cooled and field-cooled magnetization, and transport critical current density (J{sub c}) were measured. The zero-resistance temperature was 105-111 K. J{sub c} at 77 K and zero field was > 2 x 10{sup 6} A/cm{sup 2}. The films exhibited good flux pinning properties.

Optimization of the Processing Parameters of High Temperature Superconducting Glass-Ceramics: Center Director's Discretionary Fund Final Report

NASA Technical Reports Server (NTRS)

Ethridge, E. C.; Kaukler, W. F.

1993-01-01

A number of promising glass forming compositions of high Tc superconducting Ba-Sr-Ca-Cu-O (BSCCO) materials were evaluated for their glass-ceramic crystallization ability. The BSCCO ceramics belonging to the class of superconductors in the Ba-Sr-Ca-Cu-O system were the focus of this study. By first forming the superconducting material as a glass, subsequent devitrification into the crystalline (glass-ceramic) superconductor can be performed by thermal processing of the glass preform body. Glass formability and phase formation were determined by a variety of methods in another related study. This study focused on the nucleation and crystallization of the materials. Thermal analysis during rapid cooling aids in the evaluation of nucleation and crystallization behavior. Melt viscosity is used to predict glass formation ability.

Band-offsets at BaTiO3/Cu2O heterojunction and enhanced photoelectrochemical response: theory and experiment(Conference Presentation)

NASA Astrophysics Data System (ADS)

Sharma, Dipika; Satsangi, Vibha R.; Dass Kaura, Sahab; Shrivastav, Rohit; Waghmare, Umesh V.

2016-10-01

Band-offsets at BaTiO3/Cu2O heterojunction and enhanced photoelectrochemical response: theory and experiment Dipika Sharmaa, Vibha R. Satsangib, Rohit Shrivastava, Umesh V. Waghmarec, Sahab Dassa aDepartment of Chemistry, Dayalbagh Educational Institute, Agra-282 110 (India) bDepartment of Physics and Computer Sciences, Dayalbagh Educational Institute, Agra-282 110 (India) cTheoretical Sciences Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560 064 (India) * Phone: +91-9219695960. Fax: +91-562-2801226. E-mail: drsahabdas@gmail.com. Study on photoelectrochemical activity of pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction has been carried out using DFT based band offsets and charge carriers effective mass calculations and their experimental verification. The results of DFT calculations show that BaTiO3 and Cu2O have staggered type band alignment after the heterojunction formation and high mobility of electrons in Cu2O as compared to the electrons in BaTiO3. Staggered type band edges alignment and high mobility of electrons and holes improved the separation of photo-generated charge carriers in BaTiO3/Cu2O heterojunction. To validate the theoretical results experiments were carried out on pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction with varying thickness of Cu2O. All samples were characterized by X- Ray Diffractometer, SEM and UV-Vis spectrometry. Nanostructured thin films of pristine BaTiO3, Cu2O and BaTiO3/Cu2O heterojunction were used as photoelectrode in the photoelectrochemical cell for water splitting reaction. Maximum photocurrent density of 1.44 mA/cm2 at 0.90 V/SCE was exhibited by 442 nm thick BaTiO3/Cu2O heterojunction photoelectrode Increased photocurrent density and enhanced photoconversion efficiency, exhibited by the heterojunction may be attributed to improved conductivity and enhanced separation of the photogenerated carriers at the BaTiO3/Cu2O interface. The experimental results and first-principles calculations compare well, thus suggesting that such calculations have the potential to be used in screening various metal oxide heterojunction before performing the experiments thereby saving precious chemicals, time and energy. Keywords: Photoelectrochemical, Water splitting, heterojunction, Cu2O, BaTiO3 References: [1] Surbhi Choudhary, et al. Nanostructured bilayered thin films in photoelectrochemical water splitting - A review: International Journal of Hydrogen Energy, (2012). [2] Dipika Sharma, Anuradha Verma, V.R. Satsangi, Rohit shrivastav, Sahab Dass Nanostructured SrTiO3 thin films sensitized by Cu2O for Photoelectrochemical Hydrogen Generation. International journal of Hydrogen Energy;42:,4230-4241, 2014.

Electrical transport across nanometric SrTiO3 and BaTiO3 barriers in conducting/insulator/conducting junctions

NASA Astrophysics Data System (ADS)

Navarro, H.; Sirena, M.; González Sutter, J.; Troiani, H. E.; del Corro, P. G.; Granell, P.; Golmar, F.; Haberkorn, N.

2018-01-01

We report the electrical transport properties of conducting/insulator/conducting heterostructures by studying current-voltage IV curves at room temperature. The measurements were obtained on tunnel junctions with different areas (900, 400 and 100 μm2) using a conducting atomic force microscope. Trilayers with GdBa2Cu3O7 (GBCO) as the bottom electrode, SrTiO3 or BaTiO3 (thicknesses between 1.6 and 4 nm) as the insulator barrier, and GBCO or Nb as the top electrode were grown by DC sputtering on (100) SrTiO3 substrates For SrTiO3 and BaTiO3 barriers, asymmetric IV curves at positive and negative polarization can be obtained using electrodes with different work function. In addition, hysteretic IV curves are obtained for BaTiO3 barriers, which can be ascribed to a combined effect of the FE reversal switching polarization and an oxygen vacancy migration. For GBCO/BaTiO3/GBCO heterostructures, the IV curves correspond to that expected for asymmetric interfaces, which indicates that the disorder affects differently the properties at the bottom and top interfaces. Our results show the role of the interface disorder on the electrical transport of conducting/insulator/conduction heterostructures, which is relevant for different applications, going from resistive switching memories (at room temperature) to Josephson junctions (at low temperatures).

[Correlativity study of the distribution of soil magnetic susceptibility and the heavy metal contents in Xi'an City].

PubMed

Chen, Xiu-Duan; Lu, Xin-Wei; Yang, Guang

2013-03-01

The magnetic susceptibility and the concentrations of Co, Cr, Cu, Pb, Sn, Sr and Ba in topsoil samples from Xi'an City were measured to study their spatial distribution and their correlation in this study. The results show that the concentrations of all measured heavy metals are higher than their background values in Cinnamon topsoil, which is the main soil type of Xi'an City. The heavy metals concentrations and the magnetic susceptibility of the studied samples display moderate variance. Co, Cr, Cu, Pb, Sn, Sr and Ba are significantly positively correlated with low-frequency magnetic susceptibility, while are significantly negatively correlated with frequency susceptibility. The spatial distribution of low-frequency magnetic susceptibility is identical with the concentrations of Pb and Cu. However, the spatial variation of frequency magnetic susceptibility is different from the concentrations of Co, Cr and Ba. The pollution assessment results show that the heavy metal pollution in topsoil of Xi'an City is moderate. The spatial contribution of the pollution load index was significantly correlated with the magnetic susceptibility of topsoil in Xi'an City. Therefore, soil magnetic susceptibility can be used as an effective monitoring means for heavy metal pollution in urban soil.

Scaling behaviour of relaxation dependencies in metaloxide superconductors

NASA Technical Reports Server (NTRS)

Sidorenko, A. S.; Panaitov, G. I.; Gabovich, A. M.; Moiseev, D. P.; Postnikov, V. M.

1990-01-01

Superconducting glass state has been investigated in different types of metaloxide ceramics, Y-Ba-Cu-O, Bi-Sr-Ca-Cu-O, Ba-Pb-Bi-O, using the highly sensitive SQUID magnetometer. The analysis of long-time relaxation processes of thermoremanent magnetization m(sup trm) (+) = M(sub o) - Slnt displayed scaling dependence of the decay rate S = -dM/dlnt on quantity of trapped magnetic flux M(sub o): 1gs = 31g M(sub o) - observed universal dependence S is approximately M(sup 3) (sub o) seems to one of the features of superconducting glass state in metaloxide ceramics.

New 1201-type (Hg,Se)-superconducting cuprate grown by sol gel and sealed quartz tube synthesis

NASA Astrophysics Data System (ADS)

Kandyel, Elsayed; Elsabawy, Khaled M.

2008-12-01

A new mercury based superconductor (Hg1-ySey)(Sr2-xLax)CuO4+δ (y = 0.25; 0.3 ⩽ x ⩽ 0.7) with a Tc(onset) of 50 K has been synthesized using sol gel process combined with the sealed quartz tube method. X-ray diffraction shows that the (Hg0.75Se0.25)(Sr2-xLax)CuO4+δ phase crystallizes in the tetragonal symmetry (space group P4/mmm) with a ≈ ap ≈ 3.8 Å and c ≈ 8.7 Å and is isostructural with the 94 K superconductor HgBa2CuO4+δ, adopting the so-called 1201-type structure. Both Se and La are necessary for the stabilization of the 1201-type Hg/Sr cuprates. EDX analysis indicated that mercury and selenium have incorporated into the structure with Se/Hg ≈ ⅓. The new high-Tc superconductor, (Hg0.75Se0.25)(Sr1.3La0.7)CuO4+δ, exhibits a current density, Jc, of 1270 KA/cm2 at (5 K and 5 T) which is higher than the estimated Jc value for (Hg,Cr)Sr2CuO4+δ.

Fabrication Of SNS Weak Links On SOS Substrates

NASA Technical Reports Server (NTRS)

Hunt, Brian D.

1995-01-01

High-quality superconductor/normal-conductor/superconductor (SNS) devices ("weak links") containing epitaxial films of YBa(2)Cu(3)O(7-x) and SrTiO(3) fabricated on silicon-on-sapphire (SOS) substrates with help of improved multilayer buffer system. Process for fabrication of edge-defined SNS weak links described in "Edge-Geometry SNS Devices Made of Y/Ba/Cu" (NPO-18552).

Interatomic Potentials for Structure Simulation of Alkaline-Earth Cuprates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eremin, N.N.; Leonyuk, L.I.; Urusov, V.S.

2001-05-01

A specific potential model of interionic interactions was derived in which the crystal structures of alkaline-earth cuprates were satisfactorily described and some of their physical properties were predicted. It was found that a harmonic three-particle O-Cu-O potential and some Morse-type contributions to the simple Buckingham-type Cu-O repulsive potential enable one to improve essentially the results of crystal structure modeling for cuprates. The obtained potential set seems to be well transferable for different cuprates, despite the variety in linkages of the CuO{sub 4} groups. In the present work this potential set model was applied in the crystal structure modeling for Ca{submore » 2}CuO{sub 3}, CaCuO{sub 2}, SrCuO{sub 3}, (Sr{sub 1.19}Ca{sub 0.73})Cu{sub 2}O{sub 4}, and BaCuO{sub 2}. Some elastic and energetic properties of the compounds under question were predicted.« less

Magnetic studies of high Tc superconducting (La0.9Sr0.1)2CuO4-y

NASA Technical Reports Server (NTRS)

Zirngiebl, E.; Thompson, J. D.; Huang, C. Y.; Hor, P. H.; Meng, R. L.

1987-01-01

The magnetic moment of La(0.9Sr0.1)2CuO4-y was measured as a function of temperature and magnetic field, and the onset of superconductivity was found to occur at a temperature of 35 K. At 2 K, the dc magnetic susceptibility was found to reach 83 percent of perfect diamagnetism. Field studies have shown that the sample is a type-II superconductor and that the temperature dependences of the critical fiedls are anomalous. Its critical fields, kappa, and lambda(eff) are much larger than those for (La0.9Ba0.1)2CuO4-y, and their temperature dependences cannot be explained in terms of BCS theory.

High-T sub c thin films on low microwave loss alkaline-rare-earth-aluminate crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sobolewski, R.; Gierlowski, P.; Kula, W.

1991-03-01

This paper reports on the alkaline-rare-earth aluminates (K{sub 2}NiF{sub 4}-type perovskites) which are an excellent choice as the substrate material for the growth of high-T{sub c} thin films suitable for microwave and far-infrared applications. The CaNdAlO{sub 4}, and SrLaAlO{sub 4} single crystals have been grown by Czochralski pulling and fabricated into the form of (001) oriented wafers. The Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O films deposited on these substrates by a single-target magnetron sputtering exhibited very good superconducting and structural properties.

Chemical stability of high-temperature superconductors

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1992-01-01

A review of the available studies on the chemical stability of the high temperature superconductors (HTS) in various environments was made. The La(1.8)Ba(0.2)CuO4 HTS is unstable in the presence of H2O, CO2, and CO. The YBa2Cu3O(7-x) superconductor is highly susceptible to degradation in different environments, especially water. The La(2-x)Ba(x)CuO4 and Bi-Sr-Ca-Cu-O HTS are relatively less reactive than the YBa2Cu3O(7-x). Processing of YBa2Cu3O(7-x) HTS in purified oxygen, rather than in air, using high purity noncarbon containing starting materials is recommended. Exposure of this HTS to the ambient atmosphere should also be avoided at all stages during processing and storage. Devices and components made out of these oxide superconductors would have to be protected with an impermeable coating of a polymer, glass, or metal to avoid deterioration during use.

The size distribution and origin of elements bound to ambient particles: a case study of a Polish urban area.

PubMed

Rogula-Kozłowska, Wioletta; Majewski, Grzegorz; Czechowski, Piotr Oskar

2015-05-01

Ambient particulate matter (PM) was sampled in Zabrze (southern Poland) in the heating period of 2009. It was investigated for distribution of its mass and of the masses of its 18 component elements (S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Ge, As, Br, Sr, Cd, Sb, Ba, and Pb) among 13 PM size fractions. In the paper, the distribution modality of and the correlations between the ambient concentrations of these elements are discussed and interpreted in terms of the source apportionment of PM emissions. By weight, S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Ge, As, Br, Sr, Cd, Sb, Ba, and Pb were 10% of coarse and 9% of ultrafine particles. The collective mass of these elements was no more than 3.5 % of the mass of the particles with the aerodynamic diameter D p between 0.4 and 1.0 μm (PM₀.₄₋₁), whose ambient mass concentration was the highest. The PM mass size distribution for the sampling period is bimodal; it has the accumulation and coarse modes. The coarse particles were probably of the mineral/soil origin (characteristic elements: Ca, Fe, Sr, and Ba), being re-suspended polluted soil or road dust (characteristic elements: Ca, Fe, Sr, Ba, S, K, Cr, Cu, Zn, Br, Sb, Pb). The maxima of the density functions (modes) of the concentration distributions with respect to particle size of PM-bound S, Cl, K, Cu, Zn, Ge, Br, Cd, Sb, and Pb within the D p interval from 0.108 to 1.6 μm (accumulation PM particles) indicate the emissions from furnaces and road traffic. The distributions of PM-bound As, Mn, Ba, and Sr concentrations have their modes within D p ≤ 0.108 μm (nucleation PM particles), indicating the emissions from high-temperature processes (industrial sources or car engines). In this work, principal component analysis (PCA) is applied separately to each of the 13 fraction-related sets of the concentrations of the 18 PM-bound elements, and further, the fractions are grouped by their origin using cluster analysis (CA) applied to the 13 fraction-related first principal components (PC1). Four distinct groups of the PM fractions are identified: (PM₁.₆₋₂.₅, PM₂.₅₋₄.₄,), (PM₀.₀₃₋₀.₀₆, PM₀.₁₀₈₋₀.₁₇), (PM₀.₀₆₋₀.₁₀₈, PM₀.₁₇₋₀.₂₆, PM₀.₂₆₋₀.₄, PM₀.₄₋₀.₆₅, PM₀.₆₅₋₁, PM₁₋₁.₆), and (PM₄.₄₋₆.₈, PM₆.₈₋₁₀, PM>₁₀). The PM sources attributed to these groups by using PCA followed by CA are roughly the same as the sources from the apportionment done by analyzing the modality of the mass size distributions.

Chemical stabilization and high pressure synthesis of Ba-free Hg-based superconductors, (Hg,M)Sr2Ca(n-1)Cu(n)O(y)(n=1 to approximately 3)

NASA Technical Reports Server (NTRS)

Kishio, K.; Shimoyama, J.; Hahakura, S.; Kitazawa, K.; Yamaura, K.; Hiroi, Z.; Takano, M.

1995-01-01

A homologous series of new Hg-based HTSC compounds, (Hg,M)Sr2Ca(n - 1)Cu(n)P(y) with n = 1 to 3, have been synthesized. The stabilization of the pure phases have been accomplished by chemical doping of third elements such as M = Cr, Mo and Re. While the Hgl2O1(n = 1) phase was readily obtained in this way, it was necessary to simultaneously dope Y into the Ca site to stabilize the Hg1212(n = 2) phase. On the other hand, single-phase Y-free Hg1212(n = 2) and Hg1223 (n = 3) samples were synthesized only under a high pressure of 6 GPa. In sharp contrast to the Ba containing compounds, all the samples prepared in the present study have been quite stable during the synthesis and no deterioration in air has been observed after the preparation.

The occurrence and distribution of trace metals in the Mississippi River and its tributaries

USGS Publications Warehouse

Taylor, Howard E.; Garbarino, J.R.; Brinton, T.I.

1990-01-01

Quantitative and semiquantitative analyses of dissolved trace metals are reported for designated sampling sites on the Mississippi River and its main tributaries utilizing depth-integrated and width-integrated sampling technology to collect statistically representative samples. Data are reported for three sampling periods, including: July-August 1987, November-December 1987, and May-June 1988. Concentrations of Al, As, Ba, Be, Cd, Co, Cr, Cu, Fe, Li, Mn, Mo, Pb, Sr, Tl, U, V, and Zn are reported quantitatively, with the remainder of the stable metals in the periodic table reported semiquantitatively. Correlations between As and V, Ba and U, Cu and Zn, Li and Ba, and Li and U are significant at the 99% confidence level for each of the sampling trips. Comparison of the results of this study for selected metals with other published data show generally good agreement for Cr, Cu, Fe, and Zn, moderate agreement for Mo, and poor agreement for Cd and V.

Processing And Patterning Of Thin Film Superconductors Formed By Metallo-Organic Deposition

NASA Astrophysics Data System (ADS)

Micheli, Adolph L.; Mantese, Joseph V.; Hamdi, Aboud H.

1990-04-01

Thin film superconductors of Y-Ba-Cu and Yb-Ba-Cu were formed by the pyrolysis of neodecanoate solutions of Y, Yb, Ba and Cu which had been deposited onto <100> SrTiO3 substrates [1]. Rapid thermal annealing, in oxygen, of the as-deposited films produced high T films having superconducting onset temperatures above 90 K and zero resistance at 8g K. Scanning Electron Microscopy (SEM) revealed enhancements in grain growth, compared to furnace annealed films, by a factor of 4. X-ray diffraction analysis showed preferred epitaxial grain growth with the c-axis of the films oriented both perpendicular and parallel to the substrate surface. Separate Rutherford Backscattering Spectrometry (RBS) channeling experiments confirmed the formation of preferred epitaxial grain growth. Film composition was determined by RBS and Inductively Coupled Plasma Emission Spectrometry (ICPES). Selective patterning was accomplished by focused beam exposure of the metal neodecanoate films [2-4]. The exposure rendered the neodecanoate film locally insoluble in xylene, thus permitting selective area patterning prior to pyrolysis. Electron, ion and laser beams were used to pattern films on <100> SrTiO3. The finest lines, approximately 5 #m in width and 26 nm thick, were patterned using electron beams whose lines had superconducting onsets above 90 K and zero resistance at 69 K after rapid thermal annealing. Both ion beam and laser patterning had similar superconducting onsets and zero resistance. Neodecanoates of Y, Yb, Ba, and Cu were formed, as previously described [5], by reacting the metal acetates of these materials with either ammonium neodecanoate or tetramethyl ammonium neodecanoate. The carboxylates formed from these reactions were then dissolved in a solution of xylene and pyridine. The individual chemical constituents were combined to produce solutions, Ln:Ba:Cu, in the ratio 1:2:4. Here, Ln is a rare-earth element. Details of the preparation of the metal carboxylates may be found elsewhere [6]. Thin films of Y-Ba-Cu and Yb-Ba-Cu were deposited onto <100> SrTiO by flooding the substrates with the appropriate neodecanoate solutions, then spin drying them at 2000 rpm for 30 s. The substrates were heated rapidly to 500?°C for 5 min in an air oven to pyrolize the metallo organics to their oxides. This process produces thin films about 200 nm thick. The spin coating process was repeated 3-6 times if thicker films were desired. X-ray diffraction analysis of films pyrolized at 500?°C shoed the presence of only microcrystallites. Room temperature resistivities of lx10 0-cm were measured for these films. No superconducting behavior was observed. After the 500?°C pyrolysis the films were further processed by RTA in flowing oxygen. The substrates were placed upon oxidized silicon wafers, rapidly heated to 850?°C for 60 s using infrared radiation produced by a bank of quartz lamps then allowed to cool to room temperature. A second rapid annealing was then performed at 920?°C for 30 s in oxygen. Thin film superconductors formed in the manner described above were very uniform in structure and thickness across the surface of the film. The grains are approximately 1 #m wide and 2 #m long, a factor of 4 larger than the grains found in furnace annealed films formed by MOD [5].

Indication of Confirmation of Transition and Formation Boundary from Ordered to Disordered Flux Vortex Chain State in High-Tc Superconductors Y1Ba2Cu3O7- δ and Bi2Sr2Ca2Cu3O10 and New Low-Field Data Delineating Magnetic Transition in Gd1Ba2(Fe0.02Cu0.98)3O7- δ

NASA Astrophysics Data System (ADS)

Vezzoli, G. Christopher; Chen, Michaeline F.; Burke, Terence; Rosen, Carol

1996-08-01

Data are presented herein that support a phase boundary or quasi-phase-boundary delineating in Y1Ba2Cu3O7-δ and in Bi2Sr2Ca2Cu3O10 ceramic materials a transition from a vortex solid lattice to a line-flux disordered state that has been referred to as representing flux lattice melting to a flux liquid, but herein is interpreted not in terms of a liquid but in the form of a less-mobile `polymer'-like or entangled chain species. These data are derived from electrical resistance (r) versus applied magnetic field (H) measurements at various isotherms (T) corresponding to the zero resistance state of yttrium--barium--cuprate, and the mixed state foot regime of bismuth--strontium--calcium--cuprate. We interpret significant slope changes in r versus B at constant T in these materials to be indicative of the H-T conditions for a second-order or weakly first-order phase transition delineating the disordering of a flux lattice vortex solid. We believe that this technique is in ways more direct and at least as accurate as the conventional mechanical oscillator and vibrating magnetometer method to study the flux state. Additional very-low-field studies in Gd1Ba2(Fe0.02Cu0.98)3O7-δ, from 1 to 1000 mT, yield indication for what appears to be a magnetic transition at ca. 77 K at 575 mT, and possibly a second transition at 912 mT (also at ca. 77 K). These data points correspond well with the extrapolated low-field experimental magnetic phase transition boundary curve described at higher field herein (and by others using the mechanical technique), and also correspond well to theoretically predicted work regarding transition involving the vortex state.

Characterization of Hybrid Ferroelectric/HTS Thin Films for Tunable Microwave Components

NASA Technical Reports Server (NTRS)

Winters, M. D.; Mueller, C. H.; Bhasin, K. B.; Miranda, F. A.

1996-01-01

Since the discovery of High-Temperature-Superconductors (HTS) in 1986, a diversity of HTS-based microwave components has been demonstrated. Because of their low conductor losses, HTS-based components are very attractive for integration into microwave circuits for space communication systems. Recent advancements have made deposition of ferroelectric thin films onto HTS thin films possible. Due to the sensitivity of the ferroelectric's dielectric constant (epsilon(sub r)) to an externally applied electric field (E), ferroelectric/superconducting structures could be used in the fabrication of low loss, tunable microwave components. In this paper, we report on our study of Ba(0.5)Sr(0.5)TiO3/YBa2Cu3O(7-delta) and Ba(0.08)Sr(0.92)TiO3/YBa2Cu3O(7-delta) ferroelectric/superconducting thin films on lanthanum aluminate (LaAlO3) substrates. For the (Ba:Sr, 0.50:0.50) epitaxial sample, a epsilon(sub r) of 425 and a loss tangent (tan delta) of 0.040 were measured at 298 K, 1.0 MHz, and zero applied E. For the same sample, a epsilon(sub r) of 360 and tan delta of 0.036 were obtained at 77 K, 1.0 MHz, and zero applied E. Variations in epsilon(sub r) from 180 to 360 were observed over an applied E range of 0V/cm less than or equal to E less than or equal to 5.62 x 10(exp 4) V/cm with little change in tan delta. However, the range of epsilon(sub r) variation for the polycrystalline (Ba:Sr, 0.08:0.92) sample over 0V/cm less than or equal to E less than or equal to 4.00 x 10(exp 4) V/cm was only 3.6 percent while tan delta increased markedly. These results indicate that a lack of epitaxy between the ferroelectric and superconducting layers decreases tuning and increases microwave losses.

Understanding the role of A-site and B-site cations on piezoelectric instability in lead--free (1-x) BaTiO3 -- xA(Cu1/3Nb2/3)O3 (A = Sr, Ca, Ba) solid solutions

NASA Astrophysics Data System (ADS)

Maurya, Deepam; Zhou, Yuan; Priya, Shashank

2013-03-01

This study provides fundamental understanding of the enhanced piezoelectric instability in lead-free piezoelectric (1-x) BaTiO3-xA(Cu1/3Nb2/3) O3(A: Sr, Ba and Ca and x = 0.0-0.03) solid solutions. These compositions were found to exhibit large longitudinal piezoelectric constant (d33) of ~330 pC/N and electromechanical planar coupling constant (kp) ~ 46% at room temperature. The X-ray diffraction coupled with atomic pair distribution functions (PDF)s indicated increase in local polarization. Raman scattering and electron paramagnetic resonance (EPR) analysis revealed that substitutions on A and B-site both substantially perturbed the local octahedral dynamics and resulted in localized nano polar regions with lower symmetry. The presence of nano domains and local structural distortions smears the Curie peak resulting in diffuse order-disorder type phase transitions. The effect of these distortions on the variations in physical property was modeled and analyzed within the context of nanodomains and phase transitions. *spriya@vt.edu The financial support from National Science Foundation and Office of Basic Energy Science, Department of Energy (Microscopy analysis) is gratefully acknowledged. The authors would also like to acknowledge the support from KIMS (new piezoelectric)

Superconducting transition temperature in the Y(1-x)M(x)Ba2Cu3O(y) system

NASA Astrophysics Data System (ADS)

Suzuki, Takeyuki; Yamazaki, Tsutomu; Sekine, Ryuuta; Koukitsu, Akinori; Seki, Hisashi

1989-04-01

Experimental results are presented for the inclusion of compositional additives, M, to the sintered high-temperature superconductor Y(1-x)M(x)Ba2Cu3O(y); M can be the oxides of Mg, Ce, Gd, Yb, Ti, Zr, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Zn, B, Al, Ga, In, Si, Ge, Sn, Pb, Sb, Bi, and Te, as well as Li, Na, K, Ca, Sr, and La carbonates. Temperature dependence of the electrical resistance was measured down to about 80 K. Attention is given to the influence of ionic radius and the valence of the M species.

Observation of a commensurate array of flux chains in tilted flux lattices in Bi-Sr-Ca-Cu-O single crystals

NASA Astrophysics Data System (ADS)

Bolle, C. A.; Gammel, P. L.; Grier, D. G.; Murray, C. A.; Bishop, D. J.; Mitzi, D. B.; Kapitulnik, A.

1991-01-01

We report the observation of a novel flux-lattice structure, a commensurate array of flux-line chains. Our experiments consist of the magnetic decoration of the flux lattices in single crystals of Ba-Sr-Ca-Cu-O where the magnetic field is applied at an angle with respect to the conducting planes. For a narrow range of angles, the equilibrium structure is one with uniformly spaced chains with a higher line density of vortices than the background lattice. Our observations are in qualitative agreement with theories which suggest that, in strongly anisotropic materials the vortices develop an attractive interaction in tilted magnetic fields.

Evidence for filamentary superconductivity up to 220 K in oriented multiphase Y-Ba-Cu-O thin films

NASA Astrophysics Data System (ADS)

Schönberger, R.; Otto, H. H.; Brunner, B.; Renk, K. F.

1991-02-01

We report on the observation of filamentary superconductivity up to 220 K in multiphase Y-Ba-Cu-O materials that are deposited as highly oriented thin films on (110)-SrTiO 3 substrates by laser ablation from ceramic targets. The high temperature zero resistivity states are reproducible after temperature cycling down to 80 K for samples treated by a special oxygenation and ozonization process at 340 K and measured in a pure oxygen atmosphere. Our results on thin films confirm former experiments of J.T. Chen and co-workers obtained on ceramic samples with preferred crystallite orientation. A close connection between superconductivity and structural instabilities of most likely ferroic nature, which are observed more often for YBa 2Cu 3O 7 in a narrow temperature range near 220 K, is suggested.

Investigating the geometrical preferences of a flexible benzimidazolone-based linker in the synthesis of coordination polymers

PubMed Central

Jones, Corey L.; Marsden, Elizabeth A.; Nevin, Adam C.; Kariuki, Benson M.; Bhadbhade, Mohan M.; Martin, Adam D.

2017-01-01

A series of new group 2 coordination polymers, MgL ={MgL(H2O)(DMF)0.75}∞, CaL = {CaL(DMF)2}∞, SrL = {SrL(H2O)0.5}∞ and BaL = {BaL(H2O)0.5}∞, were synthesized using a flexible benzimidazolone diacetic acid linker (H2L) in which the two carboxylic acid binding sites are connected to a planar core via {–CH2–} spacers that can freely rotate in solution. In a ‘curiosity-led' diversion from group 2 metals, the first row transition metal salts Mn2+, Cu2+ and Zn2+ were also reacted with L to yield crystals of MnL = {MnL(DMF)(H2O)3.33}∞, Cu3L2 = {Cu3L2(DMF)2(CHO2)2}∞ and ZnL = {ZnL(DMF)}∞. Crystal structures were obtained for all seven materials. All structures form as two-dimensional sheets and contain six-coordinate centres, with the exception of ZnL, which displays tetrahedrally coordinated metal centres, and Cu3L2, which contains square planar coordinated metal centres and Cu paddle-wheels. In each structure, the linker adopts one of two distinct conformations, with the carboxylate groups either cis or trans with respect to the planar core. All materials were also characterized by powder X-ray diffraction and thermogravimetric analysis. PMID:29308246

Local texture and grain boundary misorientations in high H(C) oxide superconductors

NASA Astrophysics Data System (ADS)

Kroeger, D. M.; Goyal, A.; Specht, E. D.; Tkaczyk, J. E.; Sutliff, J.; Deluca, J. A.; Wang, Z. L.; Riley, G. N., Jr.

The orientations of hundreds of contiguous grains in high J(C) TlBa2Ca2Cu3O(x) deposits and (Bi, Pb)2 Sr2Ca2Cu3O(y) powder-in-tube tapes have been determined from electron back scatter diffraction patterns (EBSP). The misorientation angles and axes of rotation (angle/axis pairs) for grain boundaries connecting these grains were calculated. For both materials the population of low angle boundaries was found to be much larger than expected from calculations based on the macroscopic texture. The TlBa2Ca2Cu3O(x) deposits exhibit pronounced local texture which has been defined by EBSP and x-ray diffraction. Locally grains show significant in-plane (a-axis) alignment even though macroscopically a-axes are random, indicating the presence of colonies of grains with similar a-axis orientations. In (Bi, Pb)2 Sr2Ca2Cu3O(x) tapes no local texture was observed. In both materials the existence of connected networks of small angle grain boundaries can be inferred. Coincident site lattice (CSL) grain boundaries are also present in higher than expected numbers. Grain boundary energy thus appears to play a significant role in enhancing the population of potentially strongly-linked boundaries. We propose that long range strongly-linked conduction occurs through a percolative network small angle (and perhaps CSL) grain boundaries.

(Ba+Sr)/Ti ratio dependence of the dielectric properties for (Ba0.5Sr0.5)TiO3 thin films prepared by ion beam sputtering

NASA Astrophysics Data System (ADS)

Yamamichi, Shintaro; Yabuta, Hisato; Sakuma, Toshiyuki; Miyasaka, Yoichi

1994-03-01

(Ba0.5Sr0.5)TiO3 thin films were prepared by ion beam sputtering from powder targets with (Ba+Sr)/Ti ratios ranging from 0.80 to 1.50. All of the perovskite (Ba,Sr)TiO3 films were single phase except for the film with a (Ba+Sr)/Ti ratio of 1.41. The dielectric constant values notably depended on the (Ba+Sr)/Ti ratio for films thicker than 70 nm. The highest dielectric constant of 580 was achieved for the 5% (Ba+Sr) rich film. This (Ba+Sr)/Ti ratio dependence was diminished by the thickness dependence for thinner films. The grain sizes for the 9% (Ba+Sr) rich film and for the 6% (Ba+Sr) poor film ranged from 70 to 100 nm and from 30 to 60 nm, respectively. This grain size difference could explain why slightly A-site rich (Ba,Sr)TiO3 films have a larger dielectric constant than A-site poor films.

Metal removal from oil sands tailings pond water by indigenous micro-alga.

PubMed

Mahdavi, Hamed; Ulrich, Ania C; Liu, Yang

2012-09-01

This paper reports the removal of ten target metals of environmental concern ((53)Cr, Mn, Co, (60)Ni, (65)Cu, (66)Zn, As, (88)Sr, (95)Mo, and Ba) from oil sands tailings pond water. The organism responsible for removal was found to be an indigenous green micro-alga identified as Parachlorella kessleri by sequencing of the 23S rRNA gene. P. kessleri grew in tailings pond water samples taken from two oil sands operators (Syncrude Canada Ltd. and Albian Sands Energy Inc.), and enriched with low (0.24 mM NO(3)(-) and 0.016 mM PO(4)(-3)) and high (1.98 mM NO(3)(-) and 0.20mM PO(4)(-3)) concentrations of nutrient supplements (the most realistic scenario). The removal of (60)Ni, (65)Cu, As, (88)Sr, (95)Mo, and Ba from Syncrude tailings pond water was significantly enhanced by high concentrations of nitrogen and phosphorus, whereas the high nutrient concentrations adversely affected the removal of Co, (60)Ni, As, (88)Sr, and Mo in samples of Albian tailings pond water. Based on ANOVA two-factor analysis, higher nutrient concentration does not always result in higher metal removal, and TPW source must also be considered. Copyright © 2012. Published by Elsevier Ltd.

Design Principles of Perovskites for Thermochemical Oxygen Separation

PubMed Central

Ezbiri, Miriam; Allen, Kyle M.; Gàlvez, Maria E.; Steinfeld, Aldo

2015-01-01

Abstract Separation and concentration of O2 from gas mixtures is central to several sustainable energy technologies, such as solar‐driven synthesis of liquid hydrocarbon fuels from CO2, H2O, and concentrated sunlight. We introduce a rationale for designing metal oxide redox materials for oxygen separation through “thermochemical pumping” of O2 against a pO2 gradient with low‐grade process heat. Electronic structure calculations show that the activity of O vacancies in metal oxides pinpoints the ideal oxygen exchange capacity of perovskites. Thermogravimetric analysis and high‐temperature X‐ray diffraction for SrCoO3−δ, BaCoO3−δ and BaMnO3−δ perovskites and Ag2O and Cu2O references confirm the predicted performance of SrCoO3−δ, which surpasses the performance of state‐of‐the‐art Cu2O at these conditions with an oxygen exchange capacity of 44 mmol O 2 mol SrCoO 3−δ −1 exchanged at 12.1 μmol O 2 min−1 g−1 at 600–900 K. The redox trends are understood due to lattice expansion and electronic charge transfer. PMID:25925955

Design Principles of Perovskites for Thermochemical Oxygen Separation.

PubMed

Ezbiri, Miriam; Allen, Kyle M; Gàlvez, Maria E; Michalsky, Ronald; Steinfeld, Aldo

2015-06-08

Separation and concentration of O2 from gas mixtures is central to several sustainable energy technologies, such as solar-driven synthesis of liquid hydrocarbon fuels from CO2 , H2 O, and concentrated sunlight. We introduce a rationale for designing metal oxide redox materials for oxygen separation through "thermochemical pumping" of O2 against a pO2 gradient with low-grade process heat. Electronic structure calculations show that the activity of O vacancies in metal oxides pinpoints the ideal oxygen exchange capacity of perovskites. Thermogravimetric analysis and high-temperature X-ray diffraction for SrCoO3-δ , BaCoO3-δ and BaMnO3-δ perovskites and Ag2 O and Cu2 O references confirm the predicted performance of SrCoO3-δ , which surpasses the performance of state-of-the-art Cu2 O at these conditions with an oxygen exchange capacity of 44 mmol O 2 mol SrCoO 3-δ(-1) exchanged at 12.1 μmol O 2 min(-1)  g(-1) at 600-900 K. The redox trends are understood due to lattice expansion and electronic charge transfer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Charge transfer at the interface between ferromagnetic La0.7Sr0.3MnO3 and superconducting EuBa2Cu3O7 probed by STM/STS

NASA Astrophysics Data System (ADS)

Liu, Yinghao; Xiong, Jie

2012-02-01

La0.7Sr0.3MnO3 (LSMO) is a ferromagnetic half-metallic compound with nearly 100% spin polarization at room temperature, making it an ideal candidate for applications in spintronic devices. However, this useful functionality disappears when the thickness of LSMO film grown on SrTiO3 substrate is reduced to below 4 nm, limiting its application in nanoscale devices. Here, we show that metallic and ferromagnetic properties of ultrathin (< 4nm) LSMO film can be restored by interfacing it with a superconductor EuBa2Cu3O7- δ (EBCO). We use scanning tunneling microscopy and spectroscopy to probe the evolution of the electronic structure of LSMO film grown on EBCO as functions of LSMO layer thickness and aging of bilayer LSMO/EBCO. Our results reveal that the charge (hole) transfer at LSMO/EBCO interface is responsible for driving LSMO film (of only five-unit-cell thickness) to metallic state. The conductive behavior of aged LSMO/EBCO bilayers varies systematically with the thickness of LSMO layer, allowing us to estimate the charge-transfer depth to be 4˜5 nm on the LSMO side.

Dielectric Properties of Sol-Gel Derived Barium Strontium Titanate and Microwave Sintering of Ceramics

NASA Astrophysics Data System (ADS)

Selmi, Fathi A.

This thesis consists of two areas of research: (1) sol-gel processing of Ba_{rm 1-x}Sr_{rm x} TiO_3 ceramics and their dielectric properties measurement; and (2) microwave versus conventional sintering of ceramics such as Al_2 O_3, Ba_{ rm 1-x}Sr_{rm x}TiO_3, Sb-doped SnO _2 and YBa_2Cu _3O_7. Sol-gel powders of BaTiO_3, SrTiO_3, and their solid solutions were synthesized by the hydrolysis of titanium isopropoxide and Ba and Sr methoxyethoxides. The loss tangent and dielectric constant of both sol-gel and conventionally prepared and sintered Ba_{rm 1-x}Sr _{rm x}TiO _3 ceramics were investigated at high frequencies. The sol-gel prepared ceramics showed higher dielectric constant and lower loss compared to those prepared conventionally. Ba _{rm 1-x}Sr _{rm x}TiO_3 ceramics were tunable with applied bias, indicating the potential use of this material for phase shifter applications. Porous Ba_{0.65}Sr _{0.35}TiO_3 was also investigated to lower the dielectric constant. Microwave sintering of alpha -Al_2O_3 and SrTiO_3 was investigated using an ordinary kitchen microwave oven (2.45 GHz; 600 Watts). The use of microwaves with good insulation of alpha -Al_2O_3 and SrTiO_3 samples resulted in their rapid sintering with good final densities of 96 and 98% of the theoretical density, respectively. A comparison of grain size for conventionally and microwave sintered SrTiO_3 samples did not show a noticeable difference. However, the grain size of microwave sintered alpha-Al_2O _3 was found to be larger than that of conventionally sintered sample. These results show that rapid sintering of ceramics can be achieved by using microwave radiation. The sintering behavior of coprecipitated Sb-doped SnO_2 was investigated using microwave power absorption. With microwave power, samples were sintered at 1450^circC for 20 minutes and showed a density as high as 99.9% of theoretical. However, samples fired in a conventional electric furnace at the same temperature for 4 hours showed only 60% of theoretical density. Microwave sintering also led to improvement in terms of uniform structure and electrical properties. Ba_{0.65}Sr _{0.35}TiO_3 was sintered using the microwave power at 1300 ^circC for 10 minutes. A density of 99% was achieved with small and uniform grain size. Superconducting powders have been successfully prepared by the sol-gel process and sintered and annealed using microwave power. Sintering and densification was achieved in a shorter time with microwave heating than with conventional heating and microwave heating appears to result in refined microstructure.

Chemical stabilization and high pressure synthesis of Ba-free Hg-based superconductors, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y}(N=1{approximately}3)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kishio, K.; Shimoyama, J.; Hahakura, S.

1994-12-31

A homologous series of new Hg-based HTSC compounds, (Hg,M)Sr{sub 2}Ca{sub n-1}Cu{sub n}O{sub y} with n=1 to 3, have been synthesized. The stabilization of the pure phases have been accomplished by chemical doping of third elements such as M=Cr, Mo and Re. While the Hg1201(n=1) phase was readily obtained in this way, it was necessary to simultaneously dope Y into the Ca site to stabilize the Hg1212(n=2) phase. On the other hand, single-phase Y-free Hg1212(n=2) and Hg1223(n=3) samples were synthesized only under a high pressure of 6 GPa. In sharp contrast to the Ba-containing compounds, all the samples prepared in themore » present study have been quite stable during the synthesis and no deterioration in air has been observed after the preparation.« less

Anode materials for lithium ion batteries

DOEpatents

Abouimrane, Ali; Amine, Khalil

2017-04-11

An electrochemical device includes a composite material of general Formula (1-x)J-(x)Q wherein: J is a metal carbon alloy of formula Sn.sub.zSi.sub.z'Met.sub.wMet'.sub.w'C.sub.t; Q is a metal oxide of formula A.sub..gamma.M.sub..alpha.M'.sub..alpha.'O.sub..beta.; and wherein: A is Li, Na, or K; M and M' are individually Ge, Mo, Al, Ga, As, Sb, Te, Ti, Ta, Zr, Ca, Mg, Sr, Ba, Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Rt, Ru or Cd; Met and Met' are individually Ge, Mo, Al, Ga, As, Sb, Te, Ti, Ta, Zr, Ca, Mg, Sr, Ba, Li, Na, K, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Nb, Rt, Ru or Cd; 0

An Assessment of Binary Metallic Glasses: Correlations Between Structure, Glass Forming Ability and Stability (Preprint)

DTIC Science & Technology

2009-04-01

Cu, germanium and tellurium ," J. Mat. Sci., vol. 9, pp. 707-717, 1974. [29] A. Inoue, T. Zhang, K. Kita, and T. Masumoto, "Mechanical strengths...Toribuchi, K. Aoki, and T. Masumoto, "Formation of La-M- Cu (M=Ca, Sr or Ba) amorphous alloys and their oxidization and superconductivity," Trans. JIM...structure of Pd- Ge alloys glasses by pulsed neutron total scattering," presented at Proc. 4 th International Conference on Rapidly Quenched Metals

Methods of reforming hydrocarbon fuels using hexaaluminate catalysts

DOEpatents

Gardner, Todd H [Morgantown, WV; Berry, David A [Morgantown, WV; Shekhawat, Dushyant [Morgantown, WV

2012-03-27

A metal substituted hexaaluminate catalyst for reforming hydrocarbon fuels to synthesis gas of the general formula AB.sub.yAl.sub.12-yO.sub.19-.delta., A being selected from alkali metals, alkaline earth metals and lanthanide metals or mixtures thereof. A dopant or surface modifier selected from a transitions metal, a spinel of an oxygen-ion conductor is incorporated. The dopant may be Ca, Cs, K, La, Sr, Ba, Li, Mg, Ce, Co, Fe, Ir, Rh, Ni, Ru, Cu, Pe, Os, Pd, Cr, Mn, W, Re, Sn, Gd, V, Ti, Ag, Au, and mixtures thereof. The oxygen-ion conductor may be a perovskite selected from M'RhO.sub.3, M'PtO.sub.3, M'PdO.sub.3, M'IrO.sub.3, M'RuO.sub.3 wherein M'=Mg, Sr, Ba, La, Ca; a spinel selected from MRh.sub.2O.sub.4, MPt.sub.2O.sub.4, MPd.sub.2O.sub.4, MIr.sub.2O.sub.4, MRu.sub.2O.sub.4 wherein M=Mg, Sr, Ba, La, Ca and mixtures thereof; a florite is selected from M''O.sub.2.

Structure and magnetic properties of oxychalcogenides A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se) with Fe2O square planar layers representing an antiferromagnetic checkerboard spin lattice.

PubMed

Kabbour, Houria; Janod, Etienne; Corraze, Benoît; Danot, Michel; Lee, Changhoon; Whangbo, Myung-Hwan; Cario, Laurent

2008-07-02

The oxychalcogenides A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se), which contain Fe2O square planar layers of the anti-CuO2 type, were predicted using a modular assembly of layered secondary building units and subsequently synthesized. The physical properties of these compounds were characterized using magnetic susceptibility, electrical resistivity, specific heat, (57)Fe Mossbauer, and powder neutron diffraction measurements and also by estimating their exchange interactions on the basis of first-principles density functional theory electronic structure calculations. These compounds are magnetic semiconductors that undergo a long-range antiferromagnetic ordering below 83.6-106.2 K, and their magnetic properties are well-described by a two-dimensional Ising model. The dominant antiferromagnetic spin exchange interaction between S = 2 Fe(2+) ions occurs through corner-sharing Fe-O-Fe bridges. Moreover, the calculated spin exchange interactions show that the A2F2Fe2OQ2 (A = Sr, Ba; Q = S, Se) compounds represent a rare example of a frustrated antiferromagnetic checkerboard lattice.

Structure, stoichiometry and spectroscopy of oxide superconductors

NASA Astrophysics Data System (ADS)

Rao, C. N. R.

In the new oxide superconductors, structure and oxygen stoichiometry play the most crucial role. Thus, all the high-temperature oxide superconductors are orthorhombic perovskites with low-dimensional features. Oxygen stoichiometry in YBa2Cu3O7-δ has an important bearing on the structure as well as superconductivity. This is equally true in the La3-xBa3+xCu 6O14+δ system of which only the 123 oxide (x = 1) with the orthorhombic structure shows high Tc. Orthorhombicity though not essential, is generally found ; it is necessary for the formation of twins. The nature of oxygen and copper in the cuprates has been examined by electron spectroscopy. Copper in these cuprates is only in 1 + and 2 + states. It seems likely that oxygen holes are responsible for superconductivity of the cuprates as well as Ba(Bi, Pb)O3. High Tc superconductivity is also found in oxides of the Bi-(Ca, Sr)-Cu-O and related oxides possessing Cu-O sheets. Dans les nouveaux oxydes supraconducteurs, la structure et la stoechiométrie de l'oxygène jouent un rôle absolument crucial. Ainsi, tous les oxydes supraconducteurs à haute température critique sont des pérovskites orthorhombiques possédant des propriétés de basse dimensionnalité. La stoechiométrie de l'oxygène dans YBa2Cu3O7- δ a une influence importante tant sur la structure que sur la supraconductibilité. Ceci est également valable pour les composés du type La3 -xBa3 + xCu 6O14 + δ parmi lesquels seul l'oxyde 123 (x = 1) à structure orthorhombique présente un grand T. Bien que ce ne soit pas essentiel, cette orthorhombicité est fréquente ; elle est nécessaire à la formation de macles. La nature de l'oxygène et du cuivre a été observée par spectroscopie électronique... Dans ces cuprates, le cuivre est dans les seuls états de valence + 1 et + 2. Vraisemblablement, les trous logés sur l'oxygène sont responsables de la supraconductibilité des cuprates comme de Ba(Bi, Pb)O3. La supraconductibilité existe aussi dans les oxydes Bi- (Ca, Sr)-Cu-O et dans des oxydes parents possédant des couches de Cu-O.

Positron annihilation studies of Bi 2CaSr 2Cu 2O x and Bi 1.6Pb 0.4Ca 2Sr 2Cu 3O y in the region of the superconducting transition

NASA Astrophysics Data System (ADS)

Pujari, P. K.; Datta, T.; Manohar, S. B.; Prakash, Satya; Sastry, P. V. P. S. S.; Yakhmi, J. V.; Iyer, R. M.

1990-03-01

Doppler broadened annihilation radiation (DBAR) spectral parameters have been reported- for the first time- between 77 K and 300 K, for several Bi-based oxide superconductors, viz. A: single phase (2122) Bi 2CaSr 2Cu 2O x with Tc=85 K (R=0), B: a mixed phase lead doped sample containing both 2122 and 2223 with a nominal composition Bi 1.6Pb 0.4Ca 2Sr 2Cu 3O y, and, C: another 2122+2223 sample with same nominal composition as that of B but synthesised under a different heat-treatment schedule so as to yield a Tc=85 K (R=0). Analyses of these spectra using PAACFIT program yielded two components, of which the intensity of the narrow component, I N, and, the width of the broad component, T B, were seen to be the only temperature dependent parameters. At the onset of superconducting transition both T B and I N were seen to increase to a maximum value and decrease on further cooling. A double peak structure in T B vs temperature profile were observed in sample B and C, similar to one reported by us in Tl-Ca-Ba-Cu-O systems. In addition, presence of a magnetic field (1 KG) yielded no significant change in the DBAR spectral parameters. The results are discussed.

Electron emission and plasma generation in a modulator electron gun using ferroelectric cathode

NASA Astrophysics Data System (ADS)

Chen, Shutao; Zheng, Shuxin; Zhu, Ziqiu; Dong, Xianlin; Tang, Chuanxiang

2006-10-01

Strong electron emission and dense plasma generation have been observed in a modulator electron gun with a Ba 0.67Sr 0.33TiO 3 ferroelectric cathode. Parameter of the modulator electron gun and lifetime of the ferroelectric cathode were investigated. It was shown that electron emission from Ba 0.67Sr 0.33TiO 3 cathode with a positive triggering pulse is a sort of plasma emission. Electrons were emitted by the co-effect of surface plasma and non-compensated negative polarization charges at the surface of the ferroelectric. The element analyses of the graphite collector after emission process was performed to show the ingredient of the plasma consist of Ba, Ti and Cu heavy cations of the ceramic compound and electrode. It was demonstrated the validity of the Child-Langmuir law by introducing the decrease of vacuum gap and increase of emission area caused by the expansion of the surface plasma.

The electronic structure of the high-TC cuprates within the hidden rotating order

NASA Astrophysics Data System (ADS)

Azzouz, M.; Ramakko, B. W.; Presenza-Pitman, G.

2010-09-01

The doping dependence of the Fermi surface and energy distribution curves of the high-TC cuprate materials La2 - xSrxCuO4 and Bi2Sr2CaCu2O8 + δ are analyzed within the rotating antiferromagnetism theory. Using three different quantities; the k-dependent occupation probability, the spectral function, and the chemical potential (energy spectra), the Fermi surface is calculated and compared to experimental data for La2 - xSrxCuO4. The Fermi surface we calculate evolves from hole-like pockets in the underdoped regime to large electron-like contours in the overdoped regime. This is in agreement with recent findings by Sebastian et al for the α-pocket of Y Ba2Cu3O6 + x (2010 Phys. Rev. B 81 214524). In addition, the full width at half maximum of the energy distribution curves is found to behave linearly with their peak position in agreement with experiment for Bi2Sr2CaCu2O8 + δ. The effect of scattering on both the Fermi surface and energy distribution curves is examined.

Theoretical study of the local structures and the EPR parameters for RLNKB glasses with VO2+ and Cu2+ dopants

NASA Astrophysics Data System (ADS)

Ding, Chang-Chun; Wu, Shao-Yi; Wu, Li-Na; Zhang, Li-Juan; Peng, Li; Wu, Ming-He; Teng, Bao-Hua

2018-02-01

The electron paramagnetic resonance (EPR) parameters and local structures for impurities VO2+ and Cu2+ in RO-Li2O-Na2O-K2O-B2O3 (RLNKB; R = Zn, Mg, Sr and Ba) glasses are theoretically investigated by using the perturbation formulas of the EPR parameters for tetragonally compressed octahedral 3d1 and tetragonally elongated octahedral 3d9 clusters, respectively. The VO2+ and Cu2+ dopants are found to undergo the tetragonal compression (characterized by the negative relative distortion ratios ρ ≈ -3%, -0.98%, -1% and -0.8% for R = Zn, Mg, Sr and Ba) and elongation (characterized by the positive relative distortion ratios ρ ≈ 29%, 17%, 16% and 28%), respectively, due to the Jahn-Teller effect. Both dopants show similar overall decreasing trends of cubic field parameter Dq and covalency factor N with decreasing electronegativity of alkali earth cation R. The conventional optical basicities Λth and local optical basicities Λloc are calculated for both systems, and the local Λloc are higher for Cu2+ than for VO2+ in the same RLNKB glass, despite the opposite relationship for the conventional Λth. This point is supported by the weaker covalency or stronger ionicity for Cu2+ than VO2+ in the same RLNKB system, characterized by the larger N in the former. The above comparative analysis on the spectral and local structural properties would be helpful to understand structures and spectroscopic properties for the similar oxide glasses with transition-metal dopants of complementary electronic configurations.

U-Pb zircon, geochemical and Sr-Nd-Hf-O isotopic constraints on age and origin of the ore-bearing intrusions from the Nurkazgan porphyry Cu-Au deposit in Kazakhstan

NASA Astrophysics Data System (ADS)

Shen, Ping; Pan, Hongdi; Seitmuratova, Eleonora; Jakupova, Sholpan

2016-02-01

Nurkazgan, located in northeastern Kazakhstan, is a super-large porphyry Cu-Au deposit with 3.9 Mt metal copper and 229 tonnage gold. We report in situ zircon U-Pb age and Hf-O isotope data, whole rock geochemical and Sr-Nd isotopic data for the ore-bearing intrusions from the Nurkazgan deposit. The ore-bearing intrusions include the granodiorite porphyry, quartz diorite porphyry, quartz diorite, and diorite. Secondary ion mass spectrometry (SIMS) zircon U-Pb dating indicates that the granodiorite porphyry and quartz diorite porphyry emplaced at 440 ± 3 Ma and 437 ± 3 Ma, respectively. All host rocks have low initial 87Sr/86Sr ratios (0.70338-0.70439), high whole-rock εNd(t) values (+5.9 to +6.3) and very high zircon εHf(t) values (+13.4 to +16.5), young whole-rock Nd and zircon Hf model ages, and consistent and slightly high zircon O values (+5.7 to +6.7), indicating that the ore-bearing magmas derived from the mantle without old continental crust involvement and without marked sediment contamination during magma emplacement. The granodiorite porphyry and quartz diorite porphyry are enriched in large ion lithophile elements (LILE) and light rare earth elements (LREE) and depleted in high-field strength elements (HFSE), Eu, Ba, Nb, Sr, P and Ti. The diorite and quartz diorite have also LILE and LREE enrichment and HFSE, Nb and Ti depletion, but have not negative Eu, Ba, Sr, and P anomalies. These features suggest that the parental magma of the granodiorite porphyry and quartz diorite porphyry originated from melting of a lithospheric mantle and experienced fractional crystallization, whereas the diorite and quartz diorite has a relatively deeper lithospheric mantle source region and has not experienced strong fractional crystallization. Based on these, together with the coeval ophiolites in the area, we propose that a subduction of the Balkhash-Junggar oceanic plate took place during the Early Silurian and the ore-bearing intrusions and associated Nurkazgan porphyry Cu-Au deposit occurred in an intra-oceanic arc setting.

Preparation of Y-Ba-Cu oxide superconductor thin films using pulsed laser evaporation from high T/sub c/ bulk material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dijkkamp, D.; Venkatesan, T.; Wu, X.D.

We report the first successful preparation of thin films of Y-Ba-Cu-O superconductors using pulsed excimer laser evaporation of a single bulk material target in vacuum. Rutherford backscattering spectrometry showed the composition of these films to be close to that of the bulk material. Growth rates were typically 0.1 nm per laser shot. After an annealing treatment in oxygen the films exhibited superconductivity with an onset at 95 K and zero resistance at 85 and 75 K on SrTiO/sub 3/ and Al/sub 2/O/sub 3/ substrates, respectively. This new deposition method is relatively simple, very versatile, and does not require the usemore » of ultrahigh vacuum techniques.« less

Positron Annihilation Studies of the Electronic Structure of Selected High-Temperature Cuprate and Organic Superconductors.

NASA Astrophysics Data System (ADS)

Chan, Lie Ping

The understanding of the electronic structure of the high-T_{c} superconductors could be important for a full theoretical description of the mechanism behind superconductivity in these materials. In this thesis, we present our measurements of the positron -electron momentum distributions of the cuprate superconductors Bi_2Sr_2CaCu _2O_8, Tl _2Ba_2Ca _2Cu_3O_ {10}, and the organic superconductor kappa-(BEDT)_2Cu(NCS) _2. We use the positron Two-dimensional Angular Correlation of Annihilation Radiation technique to make the measurements on single crystals and compare our high-statistics data with band structure calculations to determine the existence and nature of the respective Fermi surfaces. The spectra from unannealed Bi _2Sr_2CaCu _2O_8 exhibit effects of the superlattice modulation in the BiO_2 layers, and a theoretical understanding of the modulation effects on the electronic band structure is required to interpret these spectra. Since the present theory does not consider the modulation, we have developed a technique to remove the modulation effects from our spectra, and the resultant data when compared with the positron -electron momentum distribution calculation, yield features consistent with the predicted CuO_2 and BiO_2 Fermi surfaces. In the data from unannealed Tl_2Ba _2Ca_2Cu_3 O_{10}, we only observe indications of the TlO Fermi surfaces, and attribute the absence of the predicted CuO_2 Fermi surfaces to the poor sample quality. In the absence of positron-electron momentum calculations for kappa-(BEDT)_2Cu(NCS) _2, we compare our data to electronic band structure calculations, and observed features suggestive of the predicted Fermi surface contributions from the BEDT cation layers. A complete positron-electron calculation for kappa-(BEDT)_2 Cu(NCS)_2 is required to understand the positron wavefunction effects in this material.

Neutron scattering studies of spin-phonon hybridization and superconducting spin gaps in the high temperature superconductor La 2-x(Sr;Ba) xCuO 4

DOE PAGES

Wagman, J. J.; Carlo, Jeremy P.; Gaudet, J.; ...

2016-03-14

We present time-of-flight neutron-scattering measurements on single crystals of La 2-xBa xCuO 4 (LBCO) with 0 ≤ x ≤ 0.095 and La 2-xSr xCuO 4 (LSCO) with x = 0.08 and 0.11. This range of dopings spans much of the phase diagram relevant to high temperature cuprate superconductivity, ranging from insulating, three dimensional commensurate long range antiferromagnetic order for x ≤ 0.02 to two dimensional (2D) incommensurate antiferromagnetism co-existing with superconductivity for x ≥ 0.05. Previous work on lightly doped LBCO with x = 0.035 showed a clear resonant enhancement of the inelastic scattering coincident with the low energy crossingsmore » of the highly dispersive spin excitations and quasi-2D optic phonons. The present work extends these measurements across the phase diagram and shows this enhancement to be a common feature to this family of layered quantum magnets. Furthermore we show that the low temperature, low energy magnetic spectral weight is substantially larger for samples with non-superconducting ground states relative to any of the samples with superconducting ground states. Lastly spin gaps, suppression of low energy magnetic spectral weight, are observed in both superconducting LBCO and LSCO samples, consistent with previous observations for superconducting LSCO« less

Two gaps make a high-temperature superconductor?

NASA Astrophysics Data System (ADS)

Hüfner, S.; Hossain, M. A.; Damascelli, A.; Sawatzky, G. A.

2008-06-01

One of the keys to the high-temperature superconductivity puzzle is the identification of the energy scales associated with the emergence of a coherent condensate of superconducting electron pairs. These might provide a measure of the pairing strength and of the coherence of the superfluid, and ultimately reveal the nature of the elusive pairing mechanism in the superconducting cuprates. To this end, a great deal of effort has been devoted to investigating the connection between the superconducting transition temperature Tc and the normal-state pseudogap crossover temperature T*. Here we present a review of a large body of experimental data which suggests a coexisting two-gap scenario, i.e. superconducting gap and pseudogap, over the whole superconducting dome. We focus on spectroscopic data from cuprate systems characterized by T_c^max\\sim 95\\,K , such as Bi2Sr2CaCu2O8+δ, YBa2Cu3O7-δ, Tl2Ba2CuO6+δ and HgBa2CuO4+δ, with particular emphasis on the Bi-compound which has been the most extensively studied with single-particle spectroscopies.

Investigation of the Influence of Selected Soil and Plant Properties from Sakarya, Turkey, on the Bioavailability of Trace Elements by Applying an In Vitro Digestion Model.

PubMed

Altundag, Huseyin; Albayrak, Sinem; Dundar, Mustafa S; Tuzen, Mustafa; Soylak, Mustafa

2015-11-01

The main aim of this study was an investigation of the influence of selected soil and plant properties on the bioaccessibility of trace elements and hence their potential impacts on human health in urban environments. Two artificial digestion models were used to determine trace element levels passing from soil and plants to man for bioavailability study. Soil and plant samples were collected from various regions of the province of Sakarya, Turkey. Digestive process is started by addition of soil and plant samples to an artificial digestion model based on human physiology. Bioavailability % values are obtained from the ratio of the amount of element passing to human digestion to element content of soil and plants. According to bioavailability % results, element levels passing from soil samples to human digestion were B = Cr = Cu = Fe = Pb = Li < Al < Ni < Co < Ba < Mn < Sr < Cd < Na < Zn < Tl, while element levels passing from plant samples to human digestion were Cu = Fe = Ni = Pb = Tl = Na = Li < Co < Al < Sr < Ba < Mn < Cd < Cr < Zn < B. It was checked whether the results obtained reached harmful levels to human health by examining the literature.

Partitioning and bioaccumulation of metals from oil sands process affected water in indigenous Parachlorella kessleri.

PubMed

Mahdavi, Hamed; Liu, Yang; Ulrich, Ania C

2013-02-01

This paper studies the partitioning and bioaccumulation of ten target metals ((53)Cr, Mn, Co, (60)Ni, (65)Cu, (66)Zn, As, (88)Sr, (95)Mo and Ba) from oil sands tailings pond water (TPW) by indigenous Parachlorella kessleri. To determine the role of extracellular and intracellular bioaccumulation in metal removal by P. kessleri, TPW samples taken from two oil sands operators (Syncrude Canada Ltd. and Albian Sands Energy Inc.) were enriched with nutrient supplements. Results indicate that intracellular bioaccumulation played the main role in metal removal from TPW; whereas extracellular bioaccumulation was only observed to some extent for Mn, Co, (60)Ni, (65)Cu, (88)Sr, (95)Mo and Ba. The FTIR scan and titration of functional groups on the cell surface indicated low metal binding capacity by indigenous P. kessleri. However, it is believed that the dissolved cations and organic ligand content in TPW (such as naphthenic acids) may interfere with metal binding on the cell surface and lower extracellular bioaccumulation. In addition, the total bioaccumulation and bioconcentration factor (BCF) varied during the cultivation period in different growth regimes. Copyright © 2012 Elsevier Ltd. All rights reserved.

Trace elements and radon in groundwater across the United States, 1992-2003

USGS Publications Warehouse

Ayotte, Joseph D.; Gronberg, Jo Ann M.; Apodaca, Lori E.

2011-01-01

Trace-element concentrations in groundwater were evaluated for samples collected between 1992 and 2003 from aquifers across the United States as part of the U.S. Geological Survey National Water-Quality Assessment Program. This study describes the first comprehensive analysis of those data by assessing occurrence (concentrations above analytical reporting levels) and by comparing concentrations to human-health benchmarks (HHBs). Data from 5,183 monitoring and drinking-water wells representing more than 40 principal and other aquifers in humid and dry regions and in various land-use settings were used in the analysis. Trace elements measured include aluminum (Al), antimony (Sb), arsenic (As), barium (Ba), beryllium (Be), boron (B), cadmium (Cd), chromium (Cr), cobalt (Co), copper (Cu), iron (Fe), lead (Pb), lithium (Li), manganese (Mn), molybdenum (Mo), nickel (Ni), selenium (Se), silver (Ag), strontium (Sr), thallium (Tl), uranium (U), vanadium (V), and zinc (Zn). Radon (Rn) gas also was measured and is included in the data analysis. Climate influenced the occurrence and distribution of trace elements in groundwater whereby more trace elements occurred and were found at greater concentrations in wells in drier regions of the United States than in humid regions. In particular, the concentrations of As, Ba, B, Cr, Cu, Mo, Ni, Se, Sr, U, V, and Zn were greater in the drier regions, where processes such as chemical evolution, ion complexation, evaporative concentration, and redox (oxidation-reduction) controls act to varying degrees to mobilize these elements. Al, Co, Fe, Pb, and Mn concentrations in groundwater were greater in humid regions of the United States than in dry regions, partly in response to lower groundwater pH and (or) more frequent anoxic conditions. In groundwater from humid regions, concentrations of Cu, Pb, Rn, and Zn were significantly greater in drinking-water wells than in monitoring wells. Samples from drinking-water wells in dry regions had greater concentrations of As, Ba, Pb, Li, Sr, V, and Zn, than samples from monitoring wells. In humid regions, however, concentrations of most trace elements were greater in monitoring wells than in drinking-water wells; the exceptions were Cu, Pb, Zn, and Rn. Cu, Pb, and Zn are common trace elements in pumps and pipes used in the construction of drinking-water wells, and contamination from these sources may have contributed to their concentrations. Al, Sb, Ba, B, Cr, Co, Fe, Mn, Mo, Ni, Se, Sr, and U concentrations were all greater in monitoring wells than in drinking-water wells in humid regions. Groundwater from wells in agricultural settings had greater concentrations of As, Mo, and U than groundwater from wells in urban settings, possibly owing to greater pH in the agricultural wells. Significantly greater concentrations of B, Cr, Se, Ag, Sr, and V also were found in agricultural wells in dry regions. Groundwater from dry-region urban wells had greater concentrations of Co, Fe, Pb, Li, Mn, and specific conductance than groundwater from agricultural wells. The geologic composition of aquifers and aquifer geochemistry are among the major factors affecting trace-element occurrence. Trace-element concentrations in groundwater were characterized in aquifers from eight major groups based on geologic material, including (1) unconsolidated sand and gravel; (2) glacial unconsolidated sand and gravel; (3) semiconsolidated sand; (4) sandstone; (5) sandstone and carbonate rock; (6) carbonate rock; (7) basaltic and other volcanic rock; and (8) crystalline rock. The majority of groundwater samples and the largest percentages of exceedences of HHBs were in the glacial and nonglacial unconsolidated sand and gravel aquifers; in these aquifers, As, Mn, and U are the most common trace elements exceeding HHBs. Overall, 19 percent of wells (962 of 5,097) exceeded an HHB for at least one trace element. The trace elements with HHBs included in this summary were Sb, As, Ba, Be, B, Cd, Cr,

PTCR characteristics and microstructure of porous (Ba,Sr)TiO3 ceramics prepared by spark plasma sintering

NASA Astrophysics Data System (ADS)

Lee, Ki-Ju; Tang, Dongxu; Park, K.; Cho, Won-Seung

2010-02-01

Porous Y-doped (Ba,Sr)TiO3 ceramics were prepared by the spark plasma sintering of (Ba,Sr)TiO3 powders with different amounts of carbon black, and by subsequently burning out the carbon black acting as a pore precursor. The microstructure, PTCR and gas-sensing characteristics for porous Y-doped (Ba,Sr)TiO3 ceramics were investigated. Spark plasma sintered (Ba,Sr)TiO3 ceramics revealed a very fine microstructure containing submicron-sized grains with a cubic phase and revealed an increased porosity after the carbon black was burned out. As a result of reoxidation treatment, the grain size of the (Ba,Sr)TiO3 ceramics increased to a few μm and the cubic phase transformed into a tetragonal phase. The phase transformation of (Ba,Sr)TiO3 ceramics was affected by grain size. The PTCR jump in the (Ba,Sr)TiO3 ceramics prepared by adding 40 vol.% carbon black showed an excellent value of 4.72 × 106, which was ten times higher than the PTCR jump in (Ba,Sr)TiO3 ceramics. The electrical resistivity of the porous (Ba,Sr)TiO3 ceramics was recovered as the atmosphere changed from a reducing gas (N2) to an oxidizing gas (O2) under consecutive heating and cooling cycles.

The influences of mole composition of strontium (x) on properties of barium strontium titanate (Ba{sub 1−x}Sr{sub x}TiO{sub 3}) prepared by solid state reaction method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sandi, Dianisa Khoirum; Supriyanto, Agus; Iriani, Yofentina, E-mail: yopen-2005@yahoo.com

2016-02-08

Barium Strontium Titanate (Ba{sub 1-x}Sr{sub x}TiO{sub 3}) or BST was prepared by solid state reaction method. Raw materials are BaCO{sub 3}, SrCO{sub 3}, and TiO{sub 2}. Those materials are mixed for 8 h, pressed, and sintered at temperature 1200°C for 2 h. Mole composition of Sr (x) was varied to study its influences on structural, morphological, and electrical properties of BST. Variation of (x) are x = 0; x = 0.1; and x = 0.5. XRD patterns showed a single phase of BST, which mean that mixture of raw materials was homogenous. Crystal structure was influenced by x. BaTiO{sub 3} and Ba{submore » 0.9}Ti{sub 0.1}TiO{sub 3} have tetragonal crystal structure, while Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} is cubic. The diffraction angle shifted to right side (angle larger) as the increases of x. Crystalline size of BaTiO{sub 3}, Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3}, and Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} are 38.13 nm; 38.62 nm; and 37.13 nm, respectively. SEM images showed that there are still of pores which were influenced by x. Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} has densest surface (pores are few and small in size). Sawyer Tower circuit showed that BaTiO{sub 3} and Ba{sub 0.9}Sr{sub 0.1} TiO{sub 3} is ferroelectric, while Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} is paraelectric. The dielectric constants of BaTiO{sub 3}, Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} and Ba{sub 0.5}Sr{sub 0.5}TiO{sub 3} at frequency of 1 KHz are 156; 196; and 83, respectively. Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} has relatively highest dielectric constant. It is considered that Ba{sub 0.9}Sr{sub 0.1}TiO{sub 3} has densest surface.« less

Ionic-Liquid-Assisted Microwave Synthesis of Solid Solutions of Sr 1–xBa xSnO 3 Perovskite for Photocatalytic Applications

DOE PAGES

Alammar, Tarek; Slowing, Igor I.; Anderegg, Jim; ...

2017-06-06

Nanocrystalline Sr 1–xBa xSnO 3 (x = 0, 0.2, 0.4, 0.8, 1) perovskite photocatalysts were prepared by microwave synthesis in an ionic liquid (IL) and subsequent heat-treatment. The influence of the Sr/Ba substitution on the structure, crystallization, morphology, and photocatalytic efficiency was investigated and the samples were fully characterized. On the basis of X-ray diffraction results, as the Ba content in the SrSnO 3 lattice increases, a symmetry increase was observed from the orthorhombic perovskite structure for SrSnO 3 to the cubic BaSnO 3 structure. The analysis of the sample morphology by SEM reveals that the Sr 1–xBa xSnO 3more » samples favor the formation of nanorods (500 nm–5 μm in diameter and several micrometers long). The photophysical properties were examined by UV/Vis diffuse reflectance spectroscopy. The band gap decreases from 3.85 to 3.19 eV with increasing Ba 2+ content. Furthermore, the photocatalytic properties were evaluated for the hydroxylation of terephthalic acid (TA). The order of the activities for TA hydroxylation was Sr 0.8Ba 0.2SnO 3 > SrSnO 3 > BaSnO 3 > Sr 0.6Ba 0.4SnO 3 > Sr 0.2Ba 0.8SnO 3. Here, the highest photocatalytic activity was observed for Sr 0.8Ba 0.2SnO 3, and this can be attributed to the synergistic impacts of the modification of the crystal structure and morphology, the relatively large surface area associated with the small crystallite size, and the suitable band gap and band-edge position.« less

High quantum yield of the Egyptian blue family of infrared phosphors (MCuSi4O10, M = Ca, Sr, Ba)

NASA Astrophysics Data System (ADS)

Berdahl, Paul; Boocock, Simon K.; Chan, George C.-Y.; Chen, Sharon S.; Levinson, Ronnen M.; Zalich, Michael A.

2018-05-01

The alkaline earth copper tetra-silicates, blue pigments, are interesting infrared phosphors. The Ca, Sr, and Ba variants fluoresce in the near-infrared (NIR) at 909, 914, and 948 nm, respectively, with spectral widths on the order of 120 nm. The highest quantum yield ϕ reported thus far is ca. 10%. We use temperature measurements in sunlight to determine this parameter. The yield depends on the pigment loading (mass per unit area) ω with values approaching 100% as ω → 0 for the Ca and Sr variants. Although maximum quantum yield occurs near ω = 0, maximum fluorescence occurs near ω = 70 g m-2, at which ϕ = 0.7. The better samples show fluorescence decay times in the range of 130 to 160 μs. The absorbing impurity CuO is often present. Good phosphor performance requires long fluorescence decay times and very low levels of parasitic absorption. The strong fluorescence enhances prospects for energy applications such as cooling of sunlit surfaces (to reduce air conditioning requirements) and luminescent solar concentrators.

Environmental exposures of trace elements assessed using keratinized matrices from patients with chronic kidney diseases of uncertain etiology (CKDu) in Sri Lanka.

PubMed

Diyabalanage, Saranga; Fonseka, Sanjeewani; Dasanayake, D M S N B; Chandrajith, Rohana

2017-01-01

An alarming increase in chronic kidney disease with unknown etiology (CKDu) has recently been reported in several provinces in Sri Lanka and chronic exposures to toxic trace elements were blamed for the etiology of this disease. Keratinized matrices such as hair and nails were investigated to determine the possible link between CKDu and toxic element exposures. Elements Li, B, Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Ba, Hg and Pb of hair and nails of patients and age that matched healthy controls were determined with Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The results showed that trace element contents in the hair of patients varies in the order of Zn>Fe>Al>Mn>Cu>Ba>Sr>Ni>Pb>Cr>B>Hg>Se>Mo>Co>As>Li>Cd while Fe>Al>Zn>Ni>Cu>Mn>Cr>Ba>Sr>B>Pb>Se>Mo>Co>Hg>Li>As>Cd in nail samples. The hair As levels of 0.007-0.165μgg -1 were found in CKDu subjects. However, no significant difference was observed between cases and controls. The total Se content in hair of CKDu subjects ranged from 0.043 to 0.513μgg -1 while it was varied from 0.031 to 1.15μgg -1 in controls. Selenium in nail samples varied from 0.037μgg -1 to 4.10μgg -1 in CKDu subjects and from 0.042μgg -1 to 2.19μgg -1 in controls. This study implies that substantial proportions of Sri Lankan population are Se deficient irrespective of gender, age and occupational exposure. Although some cutaneous manifestations were observed in patient subjects, chemical analyses of hair and nails indicated that patients were not exposed to toxic levels of arsenic or the other studied toxic elements. Therefore the early suggested causative factors such as exposure to environmental As and Cd, can be ruled out. Copyright © 2016 Elsevier GmbH. All rights reserved.

Determining Solute Sources and Water Flowpaths in a Forested Headwater Catchment: Advances With the Ca-Sr-Ba Multi-tracer

NASA Astrophysics Data System (ADS)

Bullen, T. D.; Bailey, S. W.; McGuire, K. J.; Zimmer, M. A.; Ross, D. S.

2011-12-01

Determining solute sources and water flowpaths in catchments is of critical importance to development of models that effectively describe catchment function. For solutes in soil water and stream water, simple mass balance models that compare precipitation input to catchment outlet compositions can predict average mineral weathering contributions for the catchment as a whole, but fail to provide information about either variability of contributions from different portions of the catchment and different soil depths or processes such as ion exchange and biological cycling. In order to better understand how forested headwater catchments function, we are interpreting concentration and isotope ratios of the alkaline earth elements Ca, Sr and Ba in streamwater, groundwater, the soil ion exchange pool and plants in a hydropedologic context at the 41 hectare hydrologic reference catchment (Watershed 3) at the Hubbard Brook Experimental Forest, New Hampshire, USA. This forested headwater catchment consists of a beech-birch-maple-spruce forest growing on vertically- and laterally-developed Spodosols and Inceptisols formed on granitoid glacial till that mantles Paleozoic metamorphic bedrock. Across the watershed in terms of the soil ion exchange pool, the forest floor has high Sr/Ba and Ca/Sr ratios, mineral soils have intermediate Sr/Ba and low Ca/Sr, and relatively unweathered till in the C horizon has low Sr/Ba and high Ca/Sr. Waters moving through these various compartments will obtain Sr/Ba and Ca/Sr ratios reflecting these characteristics, and thus variations of Sr/Ba and Ca/Sr of streamwater provide evidence of the depth of water flowpaths feeding the streams. 87Sr/86Sr of exchangeable Sr spans a broad range from 0.715 to 0.725, with highest values along the mid-to upper flanks of the catchment and lowest values in a broad zone along the central axis of the catchment associated with numerous groundwater seeps. Thus, variations of 87Sr/86Sr in streamwater provide evidence of the spatial distribution of water flowpaths feeding the streams. In addition, we are exploring the use of Sr and Ba stable isotope ratios (88Sr/86Sr, 138Ba/134Ba) as novel tracers of Sr and Ba sources in catchments. Initial results indicate that both Sr and Ba stable isotopes are fractionated by plants similarly to patterns observed globally for Ca stable isotopes. We hypothesize that while biologically-cycled Ca is efficiently retained in the organic soil-plant system, biologically-cycled Sr and especially Ba will be more easily leached by soil waters and delivered to the streams and thus their stable isotope ratios may provide an additional means to distinguish between shallow and deep water flowpaths in forested catchments.

Distribution, source identification, and ecological risk assessment of heavy metals in wetland soils of a river-reservoir system.

PubMed

Jiang, Xiaoliang; Xiong, Ziqian; Liu, Hui; Liu, Guihua; Liu, Wenzhi

2017-01-01

The majority of rivers in the world have been dammed, and over 45,000 large reservoirs have been constructed for multiple purposes. Riparian and reservoir shorelines are the two most important wetland types in a dammed river. To date, few studies have concerned the heavy metal pollution in wetland soils of these river-reservoir systems. In this study, we measured the concentrations of ten heavy metals (Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, and Zn) in surface soils collected from riparian and reservoir shorelines along the Han River in different seasons. Our results found that the Co, Cu, and Ni concentrations in riparian wetlands were significantly lower than those in reservoir shorelines. In riparian wetlands, only soil Sr concentration significantly increased after summer and autumn submergence. Multivariate statistical analyses demonstrated that Ba and Cd might originate from industrial and mining sources, whereas Sr and Mn predominantly originated from natural rock weathering. The ecological risk assessment analysis indicated that both riparian and reservoir shorelines along the Han River in China exhibited a moderate ecological risk in soil heavy metals. The upper Han River basin is the water resource area of China's Middle Route of the South-to-North Water Transfer Project. Therefore, to control the contamination of heavy metals in wetland soils, more efforts should be focused on reducing the discharge of mining and industrial pollutants into the riparian and reservoir shorelines.

Effects of fertilization, crop year, variety, and provenance factors on mineral concentrations in onions.

PubMed

Ariyama, Kaoru; Nishida, Tadashi; Noda, Tomoaki; Kadokura, Masashi; Yasui, Akemi

2006-05-03

Mineral concentrations of onions (Allium cepa L.) grown under various conditions, including factors (fertilization, crop year, variety, and provenance), were investigated to clarify how much each factor contributes to the variation of their concentrations. This was because the mineral concentrations might be affected by various factors. The ultimate goal of this study was to develop a technique to determine the geographic origins of onions by mineral composition. Samples were onions grown under various conditions at 52 fields in 18 farms in Hokkaido, Japan. Twenty-six elements (Li, Na, Mg, Al, P, K, Ca, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Mo, Cd, Cs, Ba, La, Ce, Nd, Gd, W, and Tl) in these samples were determined by inductively coupled plasma atomic emission spectrometry and inductively coupled plasma mass spectrometry. Fertilization conditions and crop years of onions caused variations of P, Ni, Cu, Rb, Sr, Mo, Cs, and Tl concentrations in onions; different onion varieties also showed variations in numerous element concentrations. However, the variations of mineral compositions of onions by these factors were smaller than the differences between production places with a few exceptions. Furthermore, Na, Rb, and Cs in group IA of the periodic table, Ca, Sr, and Ba in group IIA, and Zn and Cd in group IIB showed similar concentration patterns by group; this result demonstrated that elements in the same periodic groups behaved similarly in terms of their absorption in onions.

Enhancement of nitric oxide decomposition efficiency achieved with lanthanum-based perovskite-type catalyst.

PubMed

Pan, Kuan Lun; Chen, Mei Chung; Yu, Sheng Jen; Yan, Shaw Yi; Chang, Moo Been

2016-06-01

Direct decompositions of nitric oxide (NO) by La0.7Ce0.3SrNiO4, La0.4Ba0.4Ce0.2SrNiO4, and Pr0.4Ba0.4Ce0.2SrNiO4 are experimentally investigated, and the catalysts are tested with different operating parameters to evaluate their activities. Experimental results indicate that the physical and chemical properties of La0.7Ce0.3SrNiO4 are significantly improved by doping with Ba and partial substitution with Pr. NO decomposition efficiencies achieved with La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4 are 32% and 68%, respectively, at 400 °C with He as carrier gas. As the temperature is increased to 600 °C, NO decomposition efficiencies achieved with La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4, respectively, reach 100% with the inlet NO concentration of 1000 ppm while the space velocity is fixed at 8000 hr(-1). Effects of O2, H2O(g), and CO2 contents and space velocity on NO decomposition are also explored. The results indicate that NO decomposition efficiencies achieved with La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4, respectively, are slightly reduced as space velocity is increased from 8000 to 20,000 hr(-1) at 500 °C. In addition, the activities of both catalysts (La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4) for NO decomposition are slightly reduced in the presence of 5% O2, 5% CO2, or 5% H2O(g). For durability test, with the space velocity of 8000 hr(-1) and operating temperature of 600 °C, high N2 yield is maintained throughout the durability test of 60 hr, revealing the long-term stability of Pr0.4Ba0.4Ce0.2SrNiO4 for NO decomposition. Overall, Pr0.4Ba0.4Ce0.2SrNiO4 shows good catalytic activity for NO decomposition. Nitrous oxide (NO) not only causes adverse environmental effects such as acid rain, photochemical smog, and deterioration of visibility and water quality, but also harms human lungs and respiratory system. Pervoskite-type catalysts, including La0.7Ce0.3SrNiO4, La0.4Ba0.4Ce0.2SrNiO4, and Pr0.4Ba0.4Ce0.2SrNiO4, are applied for direct NO decomposition. The results show that NO decomposition can be enhanced as La0.7Ce0.3SrNiO4 is substituted with Ba and/or Pr. At 600 °C, NO decomposition efficiencies achieved with La0.4Ba0.4Ce0.2SrNiO4 and Pr0.4Ba0.4Ce0.2SrNiO4 reach 100%, demonstrating high activity and good potential for direct NO decomposition. Effects of O2, H2O(g), and CO2 contents on catalytic activities are also evaluated and discussed.

Concentrations of trace elements in marine fish and its risk assessment in Malaysia.

PubMed

Agusa, Tetsuro; Kunito, Takashi; Yasunaga, Genta; Iwata, Hisato; Subramanian, Annamalai; Ismail, Ahmad; Tanabe, Shinsuke

2005-01-01

Concentrations of trace elements (V, Cr, Mn, Co, Cu, Zn, Ga, Se, Rb, Sr, Mo, Ag, Cd, Sn, Sb, Cs, Ba, Hg, Tl, Pb and Bi) were determined in muscle and liver of 12 species of marine fish collected from coastal areas in Malaysia. Levels of V, Cr, Mn, Co, Cu, Zn, Ga, Sr, Mo, Ag, Cd, Sn, Ba and Pb in liver were higher than those in muscle, whereas Rb and Cs concentrations showed the opposite trend. Positive correlations between concentrations in liver and muscle were observed for all the trace elements except Cu and Sn. Copper, Zn, Se, Ag, Cd, Cs and Hg concentrations in bigeye scads from the east coast of the Peninsular Malaysia were higher than those from the west, whereas V showed the opposite trend. The high concentration of V in the west coast might indicate oil contamination in the Strait of Malacca. To evaluate the health risk to Malaysian population through consumption of fish, intake rates of trace elements were estimated on the basis of the concentrations of trace elements in muscle of fish and daily fish consumption. Some specimens of the marine fish had Hg levels higher than the guideline value by US Environmental Protection Agency (EPA), indicating that consumption of these fish at the present rate may be hazardous to Malaysian people. To our knowledge, this is the first study on multielemental accumulation in marine fish from the Malaysian coast.

Ion beam sputtering of in situ superconducting Y-Ba-Cu-O films

NASA Astrophysics Data System (ADS)

Klein, J. D.; Yen, A.; Clauson, S. L.

1990-05-01

Oriented superconducting YBa2Cu3O7 thin films were deposited on yttria stabilized zirconia and SrTiO3 substrates by ion-beam sputtering of a nonstoichiometric oxide target. The films exhibited zero-resistance critical temperatures as high as 83.5 K without post-deposition anneals. Both the deposition rate and the c-lattice parameter data displayed two distinct regimes of dependence on the beam power of the ion source. Low-power sputtering yielded films with large c-dimensions and low Tc. Higher-power sputtering produced a continuous decrease in the c-lattice parameter and increase in critical temperature. Films having the smaller c-lattice parameters were Cu rich. The Cu content of films deposited at beam voltages of 800 V and above increased with increasing beam power.

Epitaxial effects in thin films of high-Tc cuprates with the K2NiF4 structure

NASA Astrophysics Data System (ADS)

Naito, Michio; Sato, Hisashi; Tsukada, Akio; Yamamoto, Hideki

2018-03-01

La2-xSrxCuO4 (LSCO) and La2-xBaxCuO4 (LBCO) have been recognized as the archetype materials of "hole-doped" high-Tc superconductors. Their crystal structures are relatively simple with a small number of constituent cation elements. In addition, the doping level can be varied by the chemical substitution over a wide range enough to obtain the full spectrum of doping-dependent electronic and magnetic properties. These attractive features have dedicated many researchers to thin-film growth of LSCO and LBCO. The critical temperature (Tc) of LSCO and LBCO is sensitive to strain as manifested by a positive pressure coefficient of Tc in bulk samples. In general, films are strained if they are grown on lattice-mismatched substrates (epitaxial strain). Early attempts (before 1997) at the growth of LSCO and LBCO films resulted in depressed Tc below 30 K as they were grown on a commonly used SrTiO3 substrate (in-plane lattice parameter asub = 3.905 Å): the in-plane lattice parameters of LSCO and LBCO are ≤3.80 Å, and hence tensile epitaxial strain is introduced. The situation was changed by the use of LaSrAlO4 substrates with a slightly shorter in-plane lattice constant (asub = 3.756 Å). On LaSrAlO4 substrates, the Tc reaches 45 K in La1.85Sr0.15CuO4, 47 K in La1.85Ba0.15CuO4, and 56 K in ozone-oxidized La2CuO4+δ films, substantially higher than the Tc's of the bulk compounds. The Tc increase in La1.85Sr0.15CuO4 films on LaSrAlO4 and decrease on SrTiO3 are semi-quantitatively in accord with the phenomenological estimations based on the anisotropic strain coefficients of Tc (dTc/dεi). In this review article, we describe the growth and properties of films of cuprates having the K2NiF4 structure, mainly focusing on the increase/decrease of Tc by epitaxial strain and quasi-stable phase formation by epitaxial stabilization. We further extract the structural and/or physical parameters controlling Tc toward microscopic understanding of the variation of Tc by epitaxial strain.

Results of critical velocity experiments with barium, strontium, and calcium releases from CRRES satellite

NASA Technical Reports Server (NTRS)

Wescott, E. M.; Stenbaek-Nielsen, H. C.; Hampton, D. L.; Delamere, P. A.

1994-01-01

As part of the NASA Combined Release and Radiation Effects Satellite (CRRES) chemical release program in September 1990, two Ba and also one each Sr and Ca canisters of a boron-titanium thermite mixture, which vaporizes the element on ignition, were released near perigee after dusk in the South Pacific to study the critical velocity effect proposed by Alfven. The critical velocities of these three elements are 2.7, 3.5, and 5.4 km/s respectively, all well below the orbital velocity of 9.4 km/s. On September 10, 1990, a Sr and Ba pair (G-13, or critical ionization velocity (CIV) I) was released near Rarotonga at approximately 515 km altitude in a background electron density of 3.4 x 10(exp 6)/cu cm. On September 14, 1990, G-14 or CIV II released a Ca and Ba pair west of New Caledonia near 595 km at an electron density of 1.5 x 10(exp 6)/cu cm. Ions of all three elements were observed with low-light level imagers from two aircraft after they had transited up the magnetic field lines into the sunlight. Emissions from the spherically expanding neutral gas shells below the solar terminator, observed with cameras filtered for the Ba(+) ion line at 4554 A and also in unfiltered imagers for approximately 15 s after release, are probably due to excitation by hot electrons created in the CIV process. The ions created clearly lost much of their energy, which we now show can be explained by elastic collisions: Ba(+) + O. Inventories of the observed ions indicate yields of 0.15% and 1.84% for Ba in the first and second experiments, 0.02% for Sr and 0.27% for Ca. Ionization from all the releases continued along the satellite trajectory much longer (greater than 45 s) than expected for a CIV process. The ion production along the satellite track versus time typically shows a rapid rise to a peak in a few seconds followed by an exponential decrease to a level essentially constant rate. The characteristic distances for CIV I and II are 47 and 62 km, respectively. We interpret the early time rise and exponential fall to be due to CIV ionization, of 0.014% (CIV I) and 0.40% (CIV II) for the Ba releases. The later ions produced at a constant rate probably have origins from other such processes as stripping and associative ionization collisions with atmospheric constituents primarily O, and charge exchange with O(+), He(+), and H(+). We suggest that the much larger Ba ionization rate in CIV II than CIV I is due to the fact that the release occurred in the peak Ca density where hot electrons were already present.

Metal and metalloid accumulation in shrews (Soricomorpha, Mammalia) from two protected Mediterranean coastal sites.

PubMed

Sánchez-Chardi, Alejandro; López-Fuster, María José

2009-04-01

Although ecotoxicological data on heavy metals are abundant, information on other potentially toxic elements with attributed deficiency and/or toxic disturbances is scarce. Here we quantify zinc, copper, iron, manganese, chromium, molybdenum, strontium, barium, and boron in bones of greater white-toothed shrews, Crocidura russula, inhabiting two protected Mediterranean coastal sites: the Ebro Delta, a wetland impacted by human activities, and the Medas Islands, a reference site. Natural and anthropogenic inputs significantly increase Fe, Mn, Mo, Sr, Ba, and B in specimens from the Ebro Delta, whereas Cu and Cr were higher in Medas' shrews. Principal component analysis allowed complete separation between sites along the first two axes in particular due to B, Sr, and Cu. This study provides metal reference values in bones of insectivores, explores their variability and bioaccumulation patterns in depth, and assesses the potential environmental risk and toxicity for biota exposed to the above elements.

CuO added Pb0.92Sr0.06Ba0.02(Mg1/3Nb2/3)0.25(Ti0.53Zr0.47)0.75O3 ceramics sintered with Ag electrodes at 900 °C for multilayer piezoelectric actuator

NASA Astrophysics Data System (ADS)

Adnan Qaiser, Muhammad; Hussain, Ahmad; Xu, Yuqing; Wang, Yaojin; Wang, Yiping; Yang, Ying; Yuan, Guoliang

2017-03-01

Not Available Project supported by the National Natural Science Foundation of China (Grant Nos. 51472118, 51602156, 52177072, and 11274174) and the Fundamental Research Funds for the Central Universities, China (Grant Nos. 30916011104 and 30916011208).

Biomonitoring of 33 Elements in Blood and Urine Samples from Coastal Populations in Sanmen County of Zhejiang Province.

PubMed

Zhang, Su-jing; Luo, Ru-xin; Ma, Dong; Zhuo, Xian-yi

2016-04-01

To determine the normal reference values of 33 elements, Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Hg, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, Th, Ti, Tl, U, V, Zn and Zr, in the blood and urine samples from the general population in Sanmen County of Zhejiang province, a typical coastal area of eastern China. The 33 elements in 272 blood and 300 urine samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The normality test of data was conducted using SPSS 17.0 Statistics. The data was compared with other reports. The normal reference values of the 33 elements in the blood and urine samples from the general population in Sanmen County were obtained, which of some elements were found to be similar with other reports, such as Co, Cu, Mn and Sr, while As, Cd, Hg and Pb were generally found to be higher than those previously reported. There was a wide variation between the reports from different countries in blood Ba. The normal reference values of the 33 elements in the blood and urine samples from the general population in Sanmen County are established, and successfully applied to two poisoning cases.

Comparison of dry, wet and microwave digestion methods for the multi element determination in some dried fruit samples by ICP-OES.

PubMed

Altundag, Huseyin; Tuzen, Mustafa

2011-11-01

The aim of this study was used to investigate the level of trace metals (Ba, Pb, Cd, Mn, Cr, Co, Ni, Cu, Mn, Zn, Sr and Fe) in some dried fruits (Prunus domestica L., Ficus carica L., Morus alba L., Vitis vinifera L., Prunus armeniaca L., and Malus domestica) samples from Turkey. Trace elements were determined by ICP-OES after dry, wet and microwave digestion methods in dried fruit samples. Validation of the proposed method was carried out by using a NIST-SRM 1515-Apple Leaves certified reference material. Element concentrations in dried fruit samples were 0.33-1.77 (Ba), 0.12-0.54 (Cd), 0.25-1.03 (Co), 0.45-2.30 (Cr), 0.43-2.74 (Cu), 0.56-4.87 (Mn), 0.61-2.54 (Ni), 0.40-2.14 (Pb), 2.16-6.54 (Zn), 0.83-12.02 (Al), 11.82-40.80 (Fe) and 0.16-6.34 (Sr) μg/g. The analytical parameters show that the microwave oven digestion procedure provided best results as compared to the wet and dry digestion procedures. The results were compared with the literature values. Copyright © 2011 Elsevier Ltd. All rights reserved.

A preliminary analysis of trace-elemental signatures in statoliths of different spawning cohorts for Dosidicus gigas off EEZ waters of Chile

NASA Astrophysics Data System (ADS)

Liu, Bilin; Chen, Xinjun; Fang, Zhou; Hu, Song; Song, Qian

2015-12-01

We applied solution-based ICP-MS method to quantify the trace-elemental signatures in statoliths of jumbo flying squid, Dosidius gigas, which were collected from the waters off northern and central Chile during the scientific surveys carried out by Chinese squid jigging vessels in 2007 and 2008. The age and spawning date of the squid were back-calculated based on daily increments in statoliths. Eight elemental ratios (Sr/Ca, Ba/Ca, Mg/Ca, Mn/Ca, Na/Ca, Fe/Ca, Cu/Ca and Zn/Ca) were analyzed. It was found that Sr is the second most abundant element next to Ca, followed by Na, Fe, Mg, Zn, Cu, Ba and Mn. There was no significant relationship between element/Ca and sea surface temperature (SST) and sea surface salinity (SSS), although weak negative or positive tendency was found. MANOVA analysis showed that multivariate elemental signatures did not differ among the cohorts spawned in spring, autumn and winter, and no significant difference was found between the northern and central sampling locations. Classification results showed that all individuals of each spawned cohorts were correctly classified. This study demonstrates that the elemental signatures in D. gigas statoliths are potentially a useful tool to improve our understanding of its population structure and habitat environment.

Metals in bones of the middle-aged inhabitants of Sardinia island (Italy) to assess nutrition and environmental exposure.

PubMed

Bocca, Beatrice; Forte, Giovanni; Giuffra, Valentina; Serra, Rita Maria; Asara, Yolande; Farace, Cristiano; Milanese, Marco; Tognotti, Eugenia; Montella, Andrea; Bandiera, Pasquale; Madeddu, Roberto

2018-03-01

Metals in bones of 72 subjects lived between the twelfth and eighteenth century AC and collected in four Sardinian (Italian insular region) burial sites (Alghero, Bisarcio, Geridu, and Sassari) were determined and used as biomarkers to evaluate diet and potential social-environmental differences. Concentrations of Ba, Ca, Cd, Cu, Hg, Pb, Sr, and Zn were quantified in different types of compact bone (femur, fibula, humerus, radius, tibia, ulna) by sector field inductively coupled plasma mass spectrometry previous acidic digestion and differences among the various burial sites, centuries, types of bone, gender, and age were explored by univariate and multivariate analyses. Results indicated differences between sites in terms of diet: Bisarcio (inland village) had increased ratios of Ba/Ca and Zn/Ca due to higher incidence of vegetables, cereals, and animal foods in the diet; Geridu (coastal village) showed increased Sr/Ca ratio indicating foods of plant and marine origin that were predominant; Alghero (coastal site) and Sassari (inland site) displayed prevalently a mixed diet reflecting a higher economy and food imports. In addition, these latter sites showed increased levels of Hg/Ca (fish, drugs, cosmetics) and Pb/Ca (coins, utensils, pipeline for water). In conclusion, the elemental Ba/Ca, Sr/Ca, and Zn/Ca ratios were indicative of provenance and diet, while Hg/Ca and Pb/Ca ratios were associated to various forms of environmental exposure.

High-pressure synthesis of the cubic perovskite BaRuO3 and evolution of ferromagnetism in ARuO3 (A = Ca, Sr, Ba) ruthenates

PubMed Central

Jin, C.-Q.; Zhou, J.-S.; Goodenough, J. B.; Liu, Q. Q.; Zhao, J. G.; Yang, L. X.; Yu, Y.; Yu, R. C.; Katsura, T.; Shatskiy, A.; Ito, E.

2008-01-01

The cubic perovskite BaRuO3 has been synthesized under 18 GPa at 1,000°C. Rietveld refinement indicates that the new compound has a stretched Ru–O bond. The cubic perovskite BaRuO3 remains metallic to 4 K and exhibits a ferromagnetic transition at Tc = 60 K, which is significantly lower than the Tc ≈ 160 K for SrRuO3. The availability of cubic perovskite BaRuO3 not only makes it possible to map out the evolution of magnetism in the whole series of ARuO3 (A = Ca, Sr, Ba) as a function of the ionic size of the A-site rA, but also completes the polytypes of BaRuO3. Extension of the plot of Tc versus rA in perovskites ARuO3 (A = Ca, Sr, Ba) shows that Tc does not increase as the cubic structure is approached, but has a maximum for orthorhombic SrRuO3. Suppressing Tc by Ca and Ba doping in SrRuO3 is distinguished by sharply different magnetic susceptibilities χ(T) of the paramagnetic phase. This distinction has been interpreted in the context of a Griffiths' phase on the (Ca Sr)RuO3 side and bandwidth broadening on the (Sr,Ba)RuO3 side. PMID:18480262

Relationships between magnetic susceptibility and heavy metals in urban topsoils in the arid region of Isfahan, central Iran

NASA Astrophysics Data System (ADS)

Karimi, Rezvan; Ayoubi, Shamsollah; Jalalian, Ahmad; Sheikh-Hosseini, Ahmad Reza; Afyuni, Majid

2011-05-01

Recently methods dealing with magnetometry have been proposed as a proper proxy for assessing the heavy metal pollution of soils. A total of 113 topsoil samples were collected from public parks and green strips along the rim of roads with high-density traffic within the city of Isfahan, central Iran. The magnetic susceptibility (χ) of the collected soil samples was measured at both low and high frequency (χlf and χhf) using the Bartington MS2 dual frequency sensor. As, Cd, Cr, Ba, Cu, Mn, Pb, Zn, Sr and V concentrations were measured in the all collected soil samples. Significant correlations were found between Zn and Cu (0.85) and between Zn and Pb (0.84). The χfd value of urban topsoil varied from 0.45% to 7.7%. Low mean value of χfd indicated that the magnetic properties of the samples are predominately contributed by multi-domain grains, rather than by super-paramagnetic particles. Lead, Cu, Zn, and Ba showed positive significant correlations with magnetic susceptibility, but As, Sr, Cd, Mn, Cr and V, had no significant correlation with the magnetic susceptibility. There was a significant correlation between pollution load index (PLI) and χlf. PLI was computed to evaluate the soil environmental quality of selected heavy metals. Moreover, the results of multiple regression analysis between χlf and heavy metal concentrations indicated the LnPb, V and LnCu could explain approximately 54% of the total variability of χlf in the study area. These results indicate the potential of the magnetometric methods to evaluate the heavy metal pollution of soils.

Laser-induced voltages at room temperature in YBa{sub 2}Cu{sub 3}O{sub 7} and Pr{sub x}Y{sub 1{minus}x}Ba{sub 2}Cu{sub 3}O{sub 7} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Habermeier, H.U.; Jisrawi, N.; Jaeger-Waldau, G.

Recent reports on high transient transverse voltages at room temperature in YBa{sub 2}Cu{sub 3}O{sub 7} and Pr{sub x}Y{sub 1{minus}x}Ba{sub 2}Cu{sub 3}O{sub 7} thin films grown on SrTiO{sub 3} single crystal substrates, with a tilt angle between the [001] cubic axis and the substrate surface plane, have been interpreted by thermoelectric fields transverse to a laser-induced temperature gradient which are caused by the non-zero off diagonal elements of the Seebeck tensor. The authors have studied this effect in epitaxially grown Pr-doped, as well as undoped YBa{sub 2}Cu{sub 3}O{sub 7}, thin films and observed for a 2 mm long YBa{sub 2}Cu{sub 3}O{submore » 7} strip exposed to a UV photon fluence of 100 mJ/cm{sup 2} signals as large as 30 V. The unexpected high values for the signals and their doping dependence are discussed within the frame of a model based on a thermopile arrangement, the growth induced defect structure and the doping induced modifications of the material properties.« less

Ionic‐Liquid‐Assisted Microwave Synthesis of Solid Solutions of Sr1−xBaxSnO3 Perovskite for Photocatalytic Applications

PubMed Central

Alammar, Tarek; Slowing, Igor I.; Anderegg, Jim

2017-01-01

Abstract Nanocrystalline Sr1−xBaxSnO3 (x=0, 0.2, 0.4, 0.8, 1) perovskite photocatalysts were prepared by microwave synthesis in an ionic liquid (IL) and subsequent heat‐treatment. The influence of the Sr/Ba substitution on the structure, crystallization, morphology, and photocatalytic efficiency was investigated and the samples were fully characterized. On the basis of X‐ray diffraction results, as the Ba content in the SrSnO3 lattice increases, a symmetry increase was observed from the orthorhombic perovskite structure for SrSnO3 to the cubic BaSnO3 structure. The analysis of the sample morphology by SEM reveals that the Sr1−xBaxSnO3 samples favor the formation of nanorods (500 nm–5 μm in diameter and several micrometers long). The photophysical properties were examined by UV/Vis diffuse reflectance spectroscopy. The band gap decreases from 3.85 to 3.19 eV with increasing Ba2+ content. Furthermore, the photocatalytic properties were evaluated for the hydroxylation of terephthalic acid (TA). The order of the activities for TA hydroxylation was Sr0.8Ba0.2SnO3>SrSnO3>BaSnO3>Sr0.6Ba0.4SnO3>Sr0.2Ba0.8SnO3. The highest photocatalytic activity was observed for Sr0.8Ba0.2SnO3, and this can be attributed to the synergistic impacts of the modification of the crystal structure and morphology, the relatively large surface area associated with the small crystallite size, and the suitable band gap and band‐edge position. PMID:28589568

High-pressure synthesis of the cubic perovskite BaRuO3 and evolution of ferromagnetism in ARuO3 (A = Ca, Sr, Ba) ruthenates.

PubMed

Jin, C-Q; Zhou, J-S; Goodenough, J B; Liu, Q Q; Zhao, J G; Yang, L X; Yu, Y; Yu, R C; Katsura, T; Shatskiy, A; Ito, E

2008-05-20

The cubic perovskite BaRuO(3) has been synthesized under 18 GPa at 1,000 degrees C. Rietveld refinement indicates that the new compound has a stretched Ru-O bond. The cubic perovskite BaRuO(3) remains metallic to 4 K and exhibits a ferromagnetic transition at T(c) = 60 K, which is significantly lower than the T(c) approximately = 160 K for SrRuO(3). The availability of cubic perovskite BaRuO(3) not only makes it possible to map out the evolution of magnetism in the whole series of ARuO(3) (A = Ca, Sr, Ba) as a function of the ionic size of the A-site r(A,) but also completes the polytypes of BaRuO(3). Extension of the plot of T(c) versus r(A) in perovskites ARuO(3) (A = Ca, Sr, Ba) shows that T(c) does not increase as the cubic structure is approached, but has a maximum for orthorhombic SrRuO(3). Suppressing T(c) by Ca and Ba doping in SrRuO(3) is distinguished by sharply different magnetic susceptibilities chi(T) of the paramagnetic phase. This distinction has been interpreted in the context of a Griffiths' phase on the (Ca Sr)RuO(3) side and bandwidth broadening on the (Sr,Ba)RuO(3) side.

Microwave absorption studies on high-T sub c superconductors and related materials 7--ESR of DPPH coated on a thin BiSrCaCuO film fabricated on MgO(100) substrate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugawara, K.; Sugimoto, T.; Shiohara, Y.

1992-05-10

In this paper, ESR of DPPH coated on a Bi-Sr-Ca-Cu-O (BSCCO) film (350 {Angstrom} thick) fabricated on MgO(100) substrate by MOCVD is studied. Temperature dependence of the ESR peak-to-peak linewidth, {Delta}H{sub pp}, and the effect of applied magnetic field on {Delta}H{sub pp} are below about 100 K. The results are compared with those of ESR of DPPH coated on ceramic Y-Ba-Cu-O samples (powder and bulk) made by the MPMG method. The DPPH ESR for the BSCCO film reveals that {Delta}H{sub pp} was independent of applied magnetic field up to about 9 kG. In addition, no similarity between the temperature dependencemore » of the excess ESR linewidth of the DPPH and that of critical current density was found for the BSCCO film. These results for the BSCCO film are different from those for the MPMG YBCO samples.« less

Development of high Tc (greater than 110K) Bi, Tl and Y-based materials as superconducting circuit elements

NASA Technical Reports Server (NTRS)

Haertling, Gene; Grabert, Gregory; Gilmour, Phillip

1991-01-01

Experimental work was continued on the development and characterization of bulk and hot pressed powders and tapecast materials in the Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O systems. A process for producing warp-free, sintered, superconducting tapes of Bi composition Bi1Sr2Ca2 Cu3O(x) was established. The procedure requires a triple calcination at 830 C for 24 hours and sintering at 845 C from 20 to 200 hours. Hot pressing the triple calcined powder at 845 C for 6 hours at 5000 psi yielded a dense material, which on further heat treatment at 845 C for 24 hours, exhibited a Tc of 108.2K. The Bi compositions were found to be much less oxygen sensitive than the Y compositions. This was especially noted in the case of the hot pressed materials which were superconducting as hot pressed, a condition that could not be achieved in the Y compositions. Safire-type grounding links are in the process of being fabricated from these materials.

Uniform-large Area BaSrTiO3 Growth and Novel Material Designs to Enable Fabrication of High Quality, Affordable, and Performance Consistent Phase Shifters for OTM Phased Array Antennas

DTIC Science & Technology

2012-07-11

molar flux of each precursor entering the reactor. The molar fluxes for Ba , Sr , and Ti are measured and computed in real-time, and these measured values...allows control of the relative amounts of Ba , Sr , and Ti, and the overall total mass flow in umole/min reaching the substrate. In all, there are three...is the Ba:Sr ratio with depth (from the top of the film). The ratio of Ba to Sr was controlled from 0.87 to 0.43. The total film thickness is 130 nm

Geochemistry of the Upper Triassic black mudstones in the Qiangtang Basin, Tibet: Implications for paleoenvironment, provenance, and tectonic setting

NASA Astrophysics Data System (ADS)

Wang, Zhongwei; Wang, Jian; Fu, Xiugen; Zhan, Wangzhong; Armstrong-Altrin, John S.; Yu, Fei; Feng, Xinglei; Song, Chunyan; Zeng, Shengqiang

2018-07-01

The Qiangtang Basin is the largest Mesozoic marine basin in the Tibetan Plateau. The Upper Triassic black mudstones are among the most significant hydrocarbon source rocks in this basin. Here, we present geochemical data for the Upper Triassic black mudstones to determine their paleoenvironment conditions, provenance, and tectonic setting. To achieve these, 30 black mudstones formed in various sedimentary environments were collected from the Zangxiahe, Zana, and Bagong formations. The results show that the total REE concentrations of mudstones from these formations range from 169 to 214 ppm, 204 to 220 ppm, and 141 to 194 ppm, respectively. All samples have chondrite-normalized REE patterns with enrichment of LREE, depletion of HREE and negative Eu and Ce anomalies. Specifically, mudstones from the Bagong Formation exhibit higher negative Eu anomalies and lower REE contents than those from the Zangxiahe and Zana formations. Mudstones from the Zangxiahe and Zana formations with low Sr/Ba and Sr/Cu ratios indicate the humid climate, whereas the high Sr/Ba and Sr/Cu ratios of rocks from the Bagong Formation suggest the arid climate. The low U/Th, (Cu + Mo)/Zn, V/Cr and Ni/Co ratios of rocks from the Zangxiahe, Zana, and Bagong formations are indicators of oxidized conditions. The bivariate diagrams (TiO2 vs. Al2O3, TiO2 vs. Zr, La/Th vs. Hf, and Co/Th vs. La/Sc) reveal that mudstones from the Zangxiahe and Zana formations were potentially derived from intermediate igneous rocks, whereas mudstones from the Bagong Formation were probably sourced from felsic igneous rocks. Their source rocks are mostly deposited in the collisional setting. REE of mudstones from the Zangxiahe, Zana, and Bagong formations were possibly originated from terrigenous detritus, with minor non-terrigenous contributions into the Zana samples. The REE contents of these mudstones are controlled mainly by terrigenous detrital minerals, rather than by the paleoclimate, paleoredox conditions, or organic matter. However, calcite minerals could dilute REE. Therefore, the REE contents of the Bagong Formation mudstones are significant lower than those of the Zangxiahe and Zana formations mudstones.

Emissions and accumulation of metals in the atmosphere due to crackers and sparkles during Diwali festival in India

NASA Astrophysics Data System (ADS)

Kulshrestha, U. C.; Nageswara Rao, T.; Azhaguvel, S.; Kulshrestha, M. J.

In India, Diwali is known as one of the most famous festivals. On the occasion of this festival, people burn crackers and sparkles to express their happiness. The burning of these fireworks leads to metal pollution in air. In this study, metal concentrations in ambient air were observed to be very high as compared to background values on previous days. For some metals the concentrations were observed to be higher than reported at industrial sites. The order of concentration of metals on the day of festival was observed to be in the order—K>Al>Ba>Mg>Fe>Sr>Na>Ca>Cu>Mn>As>V>Ni>Bi. Interestingly, the concentrations of Ba, K, Al and Sr went up to 1091, 25, 18 and 15 times higher than the previous day of Diwali. This study indicated that burning of crackers and sparkles on Diwali is a very strong source of air pollution which contributes significantly high amount of metals in air.

Preparation of thin-film (Ba(0.5),Sr(0.5))TiO3 by the laser ablation technique and electrical properties

NASA Astrophysics Data System (ADS)

Yoon, Soon-Gil; Lee, Jai-Chan; Safari, A.

1994-09-01

The chemical composition and electrical properties were investigated for epitaxially crystallized (Ba(0.5),Sr(0.5))TiO3 (BST) films deposited on Pt/MgO and YBa2Cu3O(7-x) (YBCO)/MgO substrates by the laser ablation technique. Rutherford backscattering spectroscopy analysis shows that thin films on Pt/MgO have almost the same stoichiometric composition as the target material. Films deposited at 600 C exhibited an excellent epitaxial growth, a dielectric constant of 430, and a dissipation factor of 0.02 at 10 kHz frequency. They have a charge storage density of 40 fC/sq micron at an applied electric field of 0.15 MV/cm. Leakage current density of BST thin films on Pt/MgO was smaller than on YBCO/MgO. Their leakage current density is about 0.8 microA/sq cm at an applied electric field of 0.15 MV/cm.

Effect of Wood Aging on Wine Mineral Composition and 87Sr/86Sr Isotopic Ratio.

PubMed

Kaya, Ayse D; Bruno de Sousa, Raúl; Curvelo-Garcia, António S; Ricardo-da-Silva, Jorge M; Catarino, Sofia

2017-06-14

The evolution of mineral composition and wine strontium isotopic ratio 87 Sr/ 86 Sr (Sr IR) during wood aging were investigated. A red wine was aged in stainless steel tanks with French oak staves (Quercus sessiliflora Salisb.), with three industrial scale replicates. Sampling was carried out after 30, 60, and 90 days of aging, and the wines were evaluated in terms of general analysis, phenolic composition, total polysaccharides, multielement composition, and Sr IR. Li, Be, Mg, Al, Sc, Ti, V, Mn, Co, Ni, Cu, Zn, Ga, Ge, As, Rb, Sr, Y, Zr, Mo, Sb, Cs, Ba, Pr, Nd, Sm, Eu, Dy, Ho, Er, Yb, Lu, Tl, and Pb elements and 87 Sr/ 86 Sr were determined by quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) and Na, K, Ca, and Fe by flame atomic absorption spectrometry (FAAS). Two-way ANOVA was applied to assess wood aging and time effect on Sr IR and mineral composition. Wood aging resulted in significantly higher concentrations of Mg, V, Co, Ni, and Sr. At the end of the aging period, wine exhibited statistically identical Sr IR compared to control. Study suggests that wood aging does not affect 87 Sr/ 86 Sr, not precluding the use of this parameter for wine traceability purposes.

Allometric constraints on Sr/Ca and Ba/Ca partitioning in terrestrial mammalian trophic chains.

PubMed

Balter, Vincent

2004-03-01

In biological systems, strontium (Sr) and barium (Ba) are two non-essential elements, in comparison to calcium (Ca) which is essential. The Sr/Ca and Ba/Ca ratios tend to decrease in biochemical pathways which include Ca as an essential element, and these processes are termed biopurification of Ca. The quantitative pathway of the biopurification of Ca in relation to Sr and Ba between two biological reservoirs ( Rn and R(n -1)) is measured with an observed ratio (OR) expressed by the (Sr/Ca) Rn /(Sr/Ca)( Rn-1) and (Ba/Ca) Rn /(Ba/Ca)( Rn-1) ratios. For a mammalian organism, during the whole biopurification of Ca starting with the diet to the ultimate reservoir of Ca which is the bone, the mean values for ORSr and ORBa are 0.25 and 0.2, respectively. In this study, published Sr/Ca and Ba/Ca ratios are used for three sets of soils, plants, and bones of herbivorous and carnivorous mammals, each comprising a trophic chain, to illustrate the biopurification of Ca at the level of trophic chains. Calculated ORSr and ORBa of herbivore bones in relation to plants and of bones of carnivores in relation to bones of herbivores give ORSr=0.30+/-0.08 and ORBa=0.16+/-0.08, thus suggesting that trophic chains reflect the Sr/Ca and Ba/Ca fluxes that are prevalent at the level of a mammalian organism. The slopes of the three regression equations of log(Sr/Ca) vs. log(Ba/Ca) are similar, indicating that the process of biopurification of Ca with respect to Sr and Ba is due to biological processes and is independent of the geological settings. Modifications of the logarithmic expression of the Sr/Ca and Ba/Ca relationship allow a new formula of the biopurification process to be deduced, leading to the general equation ORBa=ORSr(1.79+/-0.33), where the allometric coefficient is the mean of the slopes of the three regression equations. Some recent examples are used to illustrate this new analysis of predator-prey relations between mammals. This opens up new possibilities for the utilization of Ba/Ca and Sr/Ca in addition to stable isotope ratios (delta13C and delta15N) for the determination of the relative contribution of different food sources to an animal's diet.

Properties of large area ErBa2Cu3O(7-x) thin films deposited by ionized cluster beams

NASA Technical Reports Server (NTRS)

Levenson, L. L.; Stan, Mark A.; Bhasin, Kul B.

1991-01-01

ErBa2Cu3O(7-x) films have been produced by simultaneous deposition of Er, Ba, and Cu from three ionized cluster beam (ICB) sources at acceleration voltages of 0.3 to 0.5 kV. Combining ozone oxidation with ICB deposition at 650 C eliminated any need of post annealing processing. The substrates were rotated at 10 rotations per minute during the deposition which took place at a rate of about 3 to 4 nm. Films with areas up to 70 mm in diameter have been made by ICB deposition. These films, 100 nm thick, were deposited on SrTiO3 (100) substrates at 650 C in a mixture of six percent O3 in O2 at a total pressure of 4 x 10(exp -4) Torr. They had T(sub c) ranging from 84.3 K to 86.8 K over a 70 mm diameter and J(sub c) above 10(exp 6) A/sq cm at 77 K. X ray diffraction measurements of the three samples showed preferential c-axis orientation normal to the substrate surface. Scanning electron micrographs (SEM) of the three samples also show some texture dependence on sample position. For the three samples, there is a correlation between SEM texture, full width at half-maximum of rocking curves and J(sub c) versus temperature curves.

Synthesis, Crystal and Electronic Structures of the Pnictides AE 3TrPn 3 (AE = Sr, Ba; Tr = Al, Ga; Pn = P, As)

DOE PAGES

Stoyko, Stanislav; Voss, Leonard; He, Hua; ...

2015-09-24

New ternary arsenides AE 3TrAs 3 (AE = Sr, Ba; Tr = Al, Ga) and their phosphide analogs Sr 3GaP 3 and Ba 3AlP 3 have been prepared by reactions of the respective elements at high temperatures. Single-crystal X-ray diffraction studies reveal that Sr 3AlAs 3 and Ba 3AlAs 3 adopt the Ba 3AlSb 3-type structure (Pearson symbol oC56, space group Cmce, Z = 8). This structure is also realized for Sr 3GaP 3 and Ba 3AlP 3. Likewise, the compounds Sr 3GaAs 3 and Ba 3GaAs 3 crystallize with the Ba 3GaSb 3-type structure (Pearson symbol oP56, space groupmore » Pnma, Z = 8). Both structures are made up of isolated pairs of edge-shared AlPn 4 and GaPn 4 tetrahedra (Pn = pnictogen, i.e., P or As), separated by the alkaline-earth Sr 2+ and Ba 2+ cations. In both cases, there are no homoatomic bonds, hence, regardless of the slightly different atomic arrangements, both structures can be rationalized as valence-precise [AE 2+] 3[Tr 3+][Pn 3-] 3, or rather [AE 2+] 6[Tr 2Pn 6] 12-, i.e., as Zintl phases.« less

Improvement of the field-trapping capabilities of bulk Nd Ba Cu O superconductors using Ba Cu O substrates

NASA Astrophysics Data System (ADS)

Matsui, Motohide; Nariki, Shinya; Sakai, Naomichi; Iwafuchi, Kengo; Murakami, Masato

2006-07-01

We used Ba-Cu-O substrates to fabricate bulk Nd-Ba-Cu-O superconductors using a top-seeded melt-growth method. There were several advantages for the use of Ba-Cu-O substrate compared to conventional substrate materials such as MgO, ZrO2, Al2O3, RE123 and RE211 (RE = rare earth). The Ba-Cu-O did not react with the precursor and minimized liquid loss. Accordingly, the introduction of large-sized cracks was suppressed. We also found that Tc values were high at the bottom regions, which was ascribed to the beneficial effect of Ba-Cu-O in suppressing Nd/Ba substitution. As a result, we obtained bulk Nd-Ba-Cu-O superconductors that exhibited fairly good field-trapping capabilities, even at the bottom surfaces.

Earthworm Activity and the Potential for Enhanced Leaching of Inorganic Elements in Soils

NASA Astrophysics Data System (ADS)

Gruau, G.; Ablain, F.; Cluzeau, D.

2002-12-01

The potential influence of earthworms on the mobility of soil inorganic constituents was experimentally investigated. Six 20 cm long and 15 cm i.d. columns were packed with soil (loamy material, Paris basin, France). Three earthworm specimens - Lombricus terrestris - were introduced into 3 of the 6 columns (earthworm treatment or ET), the remaing 3 being used to study changes in water composition and solute fluxes without earthworms (control treatment or CT). The 6 columns were operated for 8 weeks and were subjected to 100 ml addition of distilled water at 1, 8, 15, 22, 29, 36, 43 and 50 days. Effluents were collected weekly, filtered and analysed for their Dissolved Organic Carbon (DOC) as well as Si, Na, K, Mg, Ca, Fe, Mn, Al, Sr, Ba, Cu, Zn, Cr, Cd, REE and U concentrations. Replicates yielded extremely consistent results, with standard deviations generally lower than 10%. Effluent volumes were greatest during ET simulations (28% difference on a cumulative basis), which can be attributed to the construction by Lombricus terrestris of permanent vertical burrows into the soil columns. Different temporal chemical trends were observed depending on whether earthworms were present or not. During ET simulations, a washout phenomenon occurred for DOC, Ca, Mg, Fe, Ba, Sr, Cu and U during the startup outflow period (week 2). This washout was followed by a period of apparent equilibrium with concentrations in ET effluents remaining roughly constant for all solutes except REE, Zn and to a lesser extent Mn. No such washout nor equilibrium period was observed during CT simulations. Instead, concentrations in Ca, Mg, Fe, Ba, Sr, Cr and Cu decreased from week 2 to week 8, while those in other solutes increased from week 2 to week 5, then declining untill week 8. For many elements (not all), final (equilibrium?) concentrations (8 weeks simulation) were highest in ET effluents (e.g. 17% higher for Ca and Na; 30% higher for Zn), despite the enhanced infiltration rate (and thus the likely shorter soil-water interaction time). Although preliminary, these results suggest that earthworm activities can potentialy increase the leaching of a wide variety of inorganic elements in soils. This increase could occur through the ability of earthworms to change the biogeochemical conditions in the soil along their burrows (so-called drilosphere).

Mineralogical and geochemical characterization of weathering profiles developed on mylonites in the Fodjomekwet-Fotouni section of the Cameroon Shear Zone (CSZ), West Cameroon

NASA Astrophysics Data System (ADS)

Tematio, P.; Tchaptchet, W. T.; Nguetnkam, J. P.; Mbog, M. B.; Yongue Fouateu, R.

2017-07-01

The mineralogical and geochemical investigation of mylonitic weathering profiles in Fodjomekwet-Fotouni was done to better trace the occurrence of minerals and chemical elements in this area. Four representative soil profiles were identified in two geomorphological units (upland and lowland) differentiating three weathering products (organo-mineral, mineral and weathered materials). Weathering of these mylonites led to some minerals association such as vermiculite, kaolinite, goethite, smectite, halloysite, phlogopite and gibbsite. The minerals in a decreasing order of abundance are: quartz (24.2%-54.8%); kaolinite (8.4%-36.0%); phlogopite (5.5%-21.9%); goethite (7.8%-16.1%); vermiculite (6.7%-15.7%); smectite (10.2%-11.9%); gibbsite (9.0%-11.8%) and halloysite (5.6%-11.5%) respectively. Patterns of chemical elements allow highlighting three behaviors (enriched elements, depleted elements and elements with complex behavior), depending on the landscape position of the profiles. In the upland weathering products, K, Cr and REEs are enriched; Ca, Mg, Na, Mn, Rb, S and Sr are depleted while Si, Al, Fe, Ti, Ba, Co, Cu, Ga, Mo, Nb, Ni, Pb, Sc, V, Y, Zn and Zr portray a complex behavior. Contrarily, the lowland weathering profiles enriched elements are Fe, Ti, Co, Cr, Cu, V, Zr, Pr, Sm, Tb, Dy, Er and Yb; while depleted elements are Ca, Mg, K, Na, Mn, Ba, Ga, S, Sr, Y, Zn, La, Ce and Nd; and Si, Al, Mo, Nb, Ni, Pb, Rb, Sc evidenced complex behaviors. In all the studied weathering products, the REEs fractionation was also noticeable with a landscape-position dependency, showing light REEs (LREEs) enrichment in the upland areas and heavy REEs (HREEs) in lowland areas. SiO2, Al2O3 and Fe2O3 are positively correlated with most of the traces and REEs (Co, Cu, Nb, Ni, Mo, Pb, Sc, V, Zn, Zr, La, Ce, Sm, Tb, Dy, Er, Yb), pointing to the fact that they may be incorporated into newly formed clay minerals and oxides. Ba, Cr, Ga, Rb, S, Sr, Y, Pr and Nd behave like alkalis and alkaline earths, and are thus highly mobile during weathering.

Influences of Indium Tin Oxide Layer on the Properties of RF Magnetron-Sputtered (BaSr)TiO3 Thin Films on Indium Tin Oxide-Coated Glass Substrate

NASA Astrophysics Data System (ADS)

Kim, Tae Song; Oh, Myung Hwan; Kim, Chong Hee

1993-06-01

Nearly stoichiometric ((Ba+Sr)/Ti=1.08-1.09) and optically transparent (BaSr)TiO3 thin films were deposited on an indium tin oxide (ITO)-coated glass substrate by means of rf magnetron sputtering for their application to the insulating layer of an electroluminescent flat panel display. The influence of the ITO layer on the properties of (BaSr)TiO3 thin films deposited on the ITO-coated substrate was investigated. The ITO layer did not affect the crystallographic orientation of (BaSr)TiO3 thin film, but enhanced the grain growth. Another effect of the ITO layer on (BaSr)TiO3 thin films was the interdiffusion phenomenon, which was studied by means of secondary ion mass spectrometry (SIMS). As the substrate temperature increased, interdiffusion intensified at the interface not only between the grown film and ITO layer but also between the ITO layer and base glass substrate. The refractive index (nf) of (BaSr)TiO3 thin film deposited on a bare glass substrate was 2.138-2.286, as a function of substrate temperature.

Composition-dependent surface chemistry of colloidal Ba xSr 1-xTiO 3 perovskite nanocrystals

DOE PAGES

Margossian, Tigran; Culver, Sean P.; Larmier, Kim; ...

2016-11-01

Ba xSr 1-xTiO 3 perovskite nanocrystals, prepared by the vapor diffusion sol-gel method and characterized by state of the art surface techniques, display significantly different O-H stretching frequencies and adsorption properties towards CO 2 as a function of the alkaline earth composition (Ba vs. Sr). Lastly, the difference of properties can be associated with the more basic nature of BaO-rich than SrO-rich surfaces.

Synthesis and effect of Sr substitution on fluorescence of new Ba 2-xSr xZnS 3: Eu 2+ red phosphor: Considerable enhancement of emission intensity

NASA Astrophysics Data System (ADS)

Lee, Chi-Woo; Petrykin, Valery; Kakihana, Masato

2009-01-01

A series of 0.5 mol% Eu 2+-activated Ba 2-xSr xZnS 3 phosphor materials were synthesized using precursors prepared by the polymerizable complex method and their fluorescent properties were studied for the first time. It was found that Sr substitution for Ba leads to the considerable improvement of internal quantum efficiency and emission intensity in these materials compared to Ba 2ZnS 3, while emission peak wavelength exhibits a blue shift from 680 to 660 nm. Rietveld refinement of crystal structure of sample with x=0.7 suggests that Sr ions preferentially occupy one of two Ba sites in this compound. Such a structural re-arrangement might be responsible for the observed quantum efficiency dependence on Sr concentration.

Glass precursor approach to high-temperature superconductors

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.

1992-01-01

The available studies on the synthesis of high T sub c superconductors (HTS) via the glass precursor approach were reviewed. Melts of the Bi-Sr-Ca-Cu-O system as well as those doped with oxides of some other elements (Pb, Al, V, Te, Nb, etc.) could be quenched into glasses which, on further heat treatments under appropriate conditions, crystallized into the superconducting phase(s). The nature of the HTS phase(s) formed depends on the annealing temperature, time, atmosphere, and the cooling rate and also on the glass composition. Long term annealing was needed to obtain a large fraction of the 110 K phase. The high T sub c phase did not crystallize out directly from the glass matrix, but was preceded by the precipitation of other phases. The 110 K HTS was produced at high temperatures by reaction between the phases formed at lower temperatures resulting in multiphase material. The presence of a glass former such as B2O3 was necessary for the Y-Ba-Cu-O melt to form a glass on fast cooling. A discontinuous YBa2Cu3O(7-delta) HTS phase crystallized out on heat treatment of this glass. Attempts to prepare Tl-Ba-Ca-Cu-O system in the glassy state were not successful.

Chemical composition and some trace element contents in coals and coal ash from Tamnava-Zapadno Polje Coal Field, Serbia

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vukasinovic-Pesic, V.; Rajakovic, L.J.

2009-07-01

The chemical compositions and trace element contents (Zn, Cu, Co, Cr, Ni, Pb, Cd, As, B, Hg, Sr, Se, Be, Ba, Mn, Th, V, U) in coal and coal ash samples from Tamnava-Zapadno Polje coal field in Serbia were studied. The coal from this field belongs to lignite. This high volatility coal has high moisture and low S contents, moderate ash yield, and high calorific value. The coal ash is abundant in alumosilicates. Many trace elements such as Ni > Cd > Cr > B > As > Cu > Co > Pb > V > Zn > Mn inmore » the coal and Ni > Cr > As > B > Cu > Co = Pb > V > Zn > Mn in the coal ash are enriched in comparison with Clarke concentrations.« less

Controlling BaZrO3 nanostructure orientation in YBa2Cu3O{}_{7-\\delta } films for a three-dimensional pinning landscape

NASA Astrophysics Data System (ADS)

Wu, J. Z.; Shi, J. J.; Baca, F. J.; Emergo, R.; Wilt, J.; Haugan, T. J.

2015-12-01

The orientation phase diagram of self-assembled BaZrO3 (BZO) nanostructures in c-oriented YBa2Cu3O{}7-δ (YBCO) films on flat and vicinal SrTiO3 substrates was studied experimentally with different dopant concentrations and vicinal angles and theoretically using a micromechanical model based on the theory of elasticity. The organized BZO nanostructure configuration was found to be tunable, between c-axis to ab-plane alignment, by the dopant concentration in the YBCO film matrix strained via lattice mismatched substrates. The correlation between the local strain caused by the BZO doping and the global strain on the matrix provides a unique approach for controllable growth of dopant nanostructure landscapes. In particular, a mixed phase of the c-axis-aligned nanorods and the ab-plane-aligned planar nanostructures can be obtained, leading to a three-dimensional pinning landscape with single impurity doping and much improved J c in almost all directions of applied magnetic field.

Toxic trace elements in solid airborne particles and ecological risk assessment in the vicinity of local boiler house plants

NASA Astrophysics Data System (ADS)

Talovskaya, Anna V.; Osipova, Nina A.; Yazikov, Egor G.; Shakhova, Tatyana S.

2017-11-01

The article deals with assessment of anthropogenic pollution in vicinity of local boilers using the data on microelement composition of solid airborne particles deposited in snow. The anthropogenic feature of elevated accumulation levels of solid airborne particles deposited in snow in the vicinity of coal-fired boiler house is revealed in elevated concentrations (3-25 higher than background) of Cd, Sb, Mo, Pb, Sr, Ba, Ni, Mo, Zn and Co. In the vicinity oil-fired boiler house the specific elements as parts of solid airborne particles deposited in snow are V, Ni and Sb, as their content exceeds the background from 3 to 8 times. It is determined that the maximum shares in non-carcinogenic human health risk from chronic inhalation of trace elements to the human body in the vicinity of coal-fired boiler house belong to Al, Mn, Cu, Ba, Co, Pb, whereas in the vicinity of oil-fired boiler house - Al, Mn, Cu, Ni, V.

Influence of marine, terrestrial and anthropogenic sources on ionic and metallic composition of rainwater at a suburban site (northwest coast of Spain)

NASA Astrophysics Data System (ADS)

Moreda-Piñeiro, Jorge; Alonso-Rodríguez, Elia; Moscoso-Pérez, Carmen; Blanco-Heras, Gustavo; Turnes-Carou, Isabel; López-Mahía, Purificación; Muniategui-Lorenzo, Soledad; Prada-Rodríguez, Darío

2014-05-01

In the present research, the rainwater chemistry of soluble (SF) and non-soluble (NSF) fractions is studied over a one a half year period (from March 2011 to August 2012) at a suburban site (Oleiros, A Coruña, Spain). The monthly rainfall in this region during the studied period ranged from 10 to 137 mm, while the NSF ranged from 0.9 to 54 mg L-1. More rainfall occurs within October-January. Eighteen samples, which provide information pertaining to the monthly variation in chemistry, were analyzed. Trace metals (Al, As, Ba, Co, Cu, Cr, Fe, Mn, Ni, Pb, Sr, V, Zn) were enclosed in the study of both fractions of the rainwater. Major inorganic ions (Cl-, NO3-, SO42-, Na+, K+, Ca2+, Mg2+ and NH4+) were also enclosed in the study of the SF of the rainwater. After partition coefficients analysis, univariate and principal components analysis (PCA) and air mass back trajectories analysis, three sources were found for the ionic and metal composition of the SF of rainwater; terrestrial (Ca2+, non sea salt SO42-, Al and Fe), marine (Mg2+, Na+, Cl-) and anthropogenic (K+, NH4+, NO3-, Fe, Mn, Pb, Sr, V and Zn). Results also suggest ubiquitous sources for Ba, Co, Cu, Cr and Ni. One source (terrestrial) was found for NSF of rainwater.

Terahertz dielectric response of ferroelectric Ba(x)Sr(1-x)TiO3 thin films.

PubMed

Kang, Seung Beom; Kwak, Min Hwan; Choi, Muhan; Kim, Sungil; Kim, Taeyong; Cha, Eun Jong; Kang, Kwang Yong

2011-11-01

Terahertz time-domain spectroscopy has been used to investigate the dielectric and optical properties of ferroelectric Ba(x)Sr(1-x)TiO(3) thin films for nominal x-values of 0.4, 0.6, and 0.8 in the frequency range of 0.3 to 2.5 THz. The ferroelectric thin films were deposited at approximately 700 nm thickness on [001] MgO substrate by pulsed laser deposition. The measured complex dielectric and optical constants were compared with the Cole-Cole relaxation model. The results show that the Cole-Cole relaxation model fits well with the data throughout the frequency range and the dielectric relaxation behavior of ferroelectric Ba(x)Sr(1-x)TiO(3) thin films varies with the films compositions. Among the compositions of Ba(x)Sr(1-x)TiO(3) films with different Ba/Sr ratios, Ba(0.6)Sr(0.4)TiO(3) has the highest dielectric constants and the shortest dielectric relaxation time.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manaf, A., E-mail: azwar@ui.ac.id; Fahmi, Agam Aidil; Yustanti, Erlina

This paper describes the particle size characterization of mechanically alloyed Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} prepared with the aid of a high-power ultrasonic destruction. Analytical-grade BaCO{sub 3}, TiO{sub 2} and SrCO{sub 3} with a purity greater than 99 wt.% were used as precursors for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. The mechanically powders were respectively sintered at 1200 °C for 3 hours to form crystalline powders. This work is aimed at studying the effect of diameter ratio between reactor and transducer of a high power sonicator on the Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} andmore » Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} nanoparticles formation. The presence of a single phase of the two materials was confirmed by X-Ray Diffraction (XRD). The concentration of the particles in demineralized water was 3.0 g / 100 mL which become the object of 3 hours ultrasonic destruction subjected to the application of transducer in which the ratio between the diameter of the reactor and the transducer (D/d) was fixed at 1.4, 1.6 and 1.8 respectively. It was found that the mean particle size before the ultrasonic destruction was 538 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 480 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3}. With D/d of 1.8, the mean particle size of the two materials was found to decrease drastically to 38 nm and 24 nm, respectively. These mean particle sizes were respectively comparable with that of the crystallite size of the particles derived using the Whole Powder Pattern Modelling (WPPM) from which the mean crystallite size of 22 nm for Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and 14 nm for Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} were obtained. It is then confirmed single nanocrystallite Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Ba{sub 0.3}Sr{sub 0.7}TiO{sub 3} particles were already achieved. We can conclude that the ultrasonic destruction to mechanically milled crystalline particles would be one of an effective way to produce nanoparticles.« less

Effect of fireworks on ambient air quality in Malta

NASA Astrophysics Data System (ADS)

Camilleri, Renato; Vella, Alfred J.

2010-11-01

Religious festivals ( festas) in the densely populated Maltese archipelago (Central Mediterranean) are ubiquitous during summer when 86 of them are celebrated between June and October, each involving the burning of fireworks both in ground and aerial displays over a period of 3 days or longer per festival. We assessed the effect of fireworks on the air quality by comparing PM 10 and its content of Al, Ba, Cu, Sr and Sb which materials are used in pyrotechnic compositions. PM 10 was collected mainly from two sites, one in Malta (an urban background site) and the other in Gozo (a rural site) during July-August 2005 when 59 feasts were celebrated and September-October 2005 when only 11 feasts occurred. For both Malta and Gozo, PM 10 and metal concentration levels measured as weekly means were significantly higher during July-August compared to September-October and there exist strong correlations between PM 10 and total metal content. Additionally, for Malta dust, Al, Ba, Cu and Sr correlated strongly with each other and also with total concentration of all five metals. The same parameters measured in April 2006 in Malta were at levels similar to those found in the previous October. Ba and Sb in dust from the urban background site in Malta during July-August were at comparable or higher concentration than recently reported values in PM 10 from a heavily-trafficked London road and this suggests that these metals are locally not dominated by sources from roadside materials such as break liner wear but more likely by particulate waste from fireworks. Our findings point to the fact that festa firework displays contribute significantly and for a prolonged period every year to airborne dust in Malta where PM 10 is an intractable air quality concern. The presence in this dust of elevated levels of Ba and especially Sb, a possible carcinogen, is of concern to health.

Electrochemical performance and carbon deposition resistance of M-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ (M = Pd, Cu, Ni or NiCu) anodes for solid oxide fuel cells

PubMed Central

Li, Meng; Hua, Bin; Pu, Jian; Chi, Bo; Jian, Li

2015-01-01

Pd-, Cu-, Ni- and NiCu-BaZr0.1Ce0.7Y0.1Yb0.1O3-δ anodes, designated as M-BZCYYb, were prepared by impregnating M-containing solution into BZCYYb scaffold, and investigated in the aspects of electrocatalytic activity for the reactions of H2 and CH4 oxidation and the resistance to carbon deposition. Impregnation of Pd, Ni or NiCu significantly reduced both the ohmic (RΩ) and polarization (RP) losses of BZCYYb anode exposed to H2 or CH4, while Cu impregnation decreased only RΩ in H2 and the both in CH4. Pd-, Ni- and NiCu-BZCYYb anodes were resistant to carbon deposition in wet (3 mol. % H2O) CH4 at 750°C. Deposited carbon fibers were observed in Pd- and Ni-BZCYYb anodes exposed to dry CH4 at 750°C for 12 h, and not observed in NiCu-BZCYYb exposed to dry CH4 at 750°C for 24 h. The performance of a full cell with NiCu-BZCYYb anode, YSZ electrolyte and La0.6Sr0.4Co0.2Fe0.8O3-δ-Gd doped CeO2 (LSCF-GDC) cathode was stable at 750°C in wet CH4 for 130 h, indicating that NiCu-BZCYYb is a promising anode for direct CH4 solid oxide fuel cells (SOFCs). PMID:25563843

Synthesis of Y1Ba2Cu3O(sub x) superconducting powders by intermediate phase reaction

NASA Technical Reports Server (NTRS)

Moore, C.; Fernandez, J. F.; Recio, P.; Duran, P.

1990-01-01

One of the more striking problems for the synthesis of the Y1Ba2Cu3Ox compound is the high-temperature decomposition of the BaCO3. This compound is present as raw material or as an intermediate compound in chemical processes such as amorphous citrate, coprecipitation oxalate, sol-gel process, acetate pyrolisis, etc. This fact makes difficult the total formation reaction of the Y1Ba2Cu3Ox phase and leads to the presence of undesirable phases such as the BaCuO2 phase, the 'green phase', Y2BaCuO5 and others. Here, a new procedure to overcome this difficulty is studied. The barium cation is previously combined with yttrium and/or copper to form intermediate compounds which can react between them to give Y1Ba2Cu3Ox. BaY2O4 and BaCu2O3 react according to the equation BaY2O4+3BaCu2O3 yields 2Y1Ba2Cu3Ox. BaY2O4 is a stable compound of the Y2O3-BaO system; BaCu2O3 is an intimate mixture of BaCuO2 and uncombined CuO. The reaction kinetics of these phases have been established between 860 and 920 C. The phase evolution has been determined. The crystal structure of the Y1Ba2Cu3Ox obtained powder was studied. According to the results obtained from the kinetics study the Y1Ba2Cu3Ox the synthesis was performed at temperatures of 910 to 920 C for short treatment times (1 to 2 hours). Pure Y1Ba2Cu3Ox was prepared, which develops orthorombic type I structure despite of the cooling cycle. Superconducting transition took place at 91 K. The sintering behavior and the superconducting properties of sintered samples were studied. Density, microstructure and electrical conductivity were measured. Sintering densities higher than 95 percent D(sub th) were attained at temperatures below 940 C. Relatively fine grained microstructure was observed, and little or no-liquid phase was detected.

Improvement of electron mobility in La:BaSnO{sub 3} thin films by insertion of an atomically flat insulating (Sr,Ba)SnO{sub 3} buffer layer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shiogai, Junichi, E-mail: junichi.shiogai@imr.tohoku.ac.jp; Nishihara, Kazuki; Sato, Kazuhisa

One perovskite oxide, ASnO{sub 3} (A = Sr, Ba), is a candidate for use as a transparent conductive oxide with high electron mobility in single crystalline form. However, the electron mobility of films grown on SrTiO{sub 3} substrates does not reach the bulk value, probably because of dislocation scattering that originates from the large lattice mismatch. This study investigates the effect of insertion of bilayer BaSnO{sub 3} / (Sr,Ba)SnO{sub 3} for buffering this large lattice mismatch between La:BaSnO{sub 3} and SrTiO{sub 3} substrate. The insertion of 200-nm-thick BaSnO{sub 3} on (Sr,Ba)SnO{sub 3} bilayer buffer structures reduces the number of dislocationsmore » and improves surface smoothness of the films after annealing as proved respectively by scanning transmission electron microscopy and atomic force microscopy. A systematic investigation of BaSnO{sub 3} buffer layer thickness dependence on Hall mobility of the electron transport in La:BaSnO{sub 3} shows that the highest obtained value of mobility is 78 cm{sup 2}V{sup −1}s{sup −1} because of its fewer dislocations. High electron mobility films based on perovskite BaSnO{sub 3} can provide a good platform for transparent-conducting-oxide electronic devices and for creation of fascinating perovskite heterostructures.« less

ESR and nonresonant microwave absorption of ErBa2Cu3O(7-delta) and HoBa2Cu3O(7-delta) single crystals

NASA Astrophysics Data System (ADS)

Tagaya, Kimihito; Fukuoka, Nobuo; Nakanishi, Shigemitsu

1990-12-01

ESR measurements were performed for ErBa2Cu3O(7-delta) and HoBa2Cu3O(7-delta) single crystals from 77 K to room temperature. The ESR signals of Er2BaCuO5 and Ho2BaCuO5 were observed, and their temperature variations were investigated. Nonresonant microwave absorption was also observed below the superconducting critical temperature of 93 K. The principal values of lower critical field were determined.

Engineered Transition Metal Chalcogenides for Photovoltaic, Thermoelectric, and Magnetic Applications

NASA Astrophysics Data System (ADS)

Moroz, Nicholas Anton

This work focuses on the development of ternary and quaternary chalcogenide compounds featuring transition metal cations through careful engineering of the electronic and thermal transport as well as magnetic properties by traditional solid-state doping techniques and novel template structure synthesis methods for improvements in thermoelectric performance, diluted magnetic semiconductors, and photovoltaic conversion. Presented here is an innovative low-temperature batch synthesis that was developed to create hexagonal nanoplatelets of thermoelectrically interesting CuAgSe. This process utilized room temperature ion exchange reactions to convert cubic Cu2-xSe nanoplatelets into CuAgSe by replacing a portion of the Cu+ ions with Ag+ while maintaining the morphology of the nanoplatelet. This simple reaction process offers an energy efficient and versatile strategy to create interesting materials with superior thermoelectric performance. An investigation of the thermal and electronic transport of CuAl(S xSe1-x)2 solid solutions was also conducted. While these compounds yielded low thermal conductivity, they also exhibited low electronic conductivity. Doping with transition metals Ag, Hf, and Ti further reduced the thermal conductivity below 1 W/mK; however, most exciting was the determination that the thermal transport of the system could be modified by doping at the Al3+ site without affecting the electronic structure of the system, potentially leading to the use of CuAl(SxSe 1-x)2 as a heavily doped thermoelectric material. The effect of local carrier concentration in the diluted magnetic semiconductor FeSb2Se4 was studied by substitution of In3+ for Sb3+. Using systematic Rietveld refinement, it was determined that In3+ resides in the semiconducting layer of the structure for concentrations of x ≤ 0.1, and the magnetic layer for x > 0.1. The increase in local carrier concentration has an appreciable effect on the electronic and magnetic properties of the material in a predictable manner based on the concentration of In3+. Lastly, two new perovskite-like selenides were developed using low-pressure synthesis methods, needle-like SrHfSe3 and distorted perovskite BaHfSe3. The optical band gap of SrHfSe3 was experimentally determined to be 1.15 eV by doping of Sb3+ for Sr2+ , and 1.6 eV for BaHfSe3, both in the ideal range for visible light absorption. Thus, these new materials are intriguing candidates for thin-film photovoltaic applications.

Journal of Applied Physics. Volume 63. Number 8. Part 2B. Proceedings of the Annual conference on Magnetism and Magnetic Materials (32nd) Held in Chicago, Illinois on 9-12 November 1987

DTIC Science & Technology

1988-04-15

RBa2 Cu30 7 , compounds S. A. Shaheen, N. Jisrawi , Y. H. Lee, M. Croft, W. L. McLean, H. Zhen, L. Rebelsky, S. Horn 4190 X-ray absorption...Rev. B 36, 226 (1987). ’S. A. Shaheen, N. Jisrawi , Y. H. Lee, Y. Z. Zhang, M. Croft. W. Lvisualizing that superconductivity emerges in the relatively...Sr0 .,,Cu0 4 ,_ and Ba 2 YCu30 7 _,, thin supercon- "D. Dijkkanp, T. Venkatesan, X. D. WuS. A. Shaheen, N. Jisrawi , Y. H. ducting films may be

Les Néandertaliens étaient-ils essentiellement carnivores ? Résultats préliminaires sur les teneurs en Sr et en Ba de la paléobiocénose mammalienne de Saint-CésaireWere Neandertalians essentially carnivores? Sr and Ba preliminary results of the mammalian palaeobiocoenosis of Saint-Césaire

NASA Astrophysics Data System (ADS)

Balter, Vincent; Person, Alain; Labourdette, Nathalie; Drucker, Dorothée; Renard, Maurice; Vandermeersch, Bernard

2001-01-01

Strontium-calcium (Sr/Ca) and barium-calcium (Ba/Ca) ratios are reduced constantly between diet and bioapatite in mammal organisms. This phenomenon leads to a reduction in the Sr/Ca and Ba/Ca ratios at higher trophic level in predator-prey mammalian communities, and is applied here to the reconstruction of a castelperronian food web, which includes a Neanderthal specimen. Adapted chemical pretreatment allows to isolate bioapatite from diagenetic compounds for analysis of Ca, Sr and Ba. Sr/Ca and Ba/Ca results of the fauna are consistent with trophic predictions. Initial results for the Neandertal suggest that he was mostly carnivorous. Distribution of Ba/Ca values of bones of herbivorous taxa reveals that ruminant animals can be distinguished from non-ruminants. The biosegregation model predicts that the diet of the Neandertal was composed by about 97 % in weight of meat with a weak contribution of vegetable or fish, and that the association of fish and plant is excluded in any proportion.

Structure-Property Relationships in W Doped (Ba,Sr)TiO(3) Thin Films Deposited by Pulsed Laser Deposition on (001) MgO

DTIC Science & Technology

2003-04-03

vacancies. The lattice of an oxygen * Permanent address - Nuclear Research Center- Negev (NRCN), Beer Sheva 9001, Israel. 41 deficient perovskite film...the film were determined by analysis of x-ray diffraction pattern using Cu K,, radiation from a Rigaku rotating anode source and a powder...thank Dr. H.S Kim, Mr. R.C.Y. Auyeung, Office of Naval Research, DARPA FAME and Nuclear Research Center- Negev . REFERENCES 1. J.S. Horwitz, D.B

Effect of the Cu/Ba ratio for the YBCO deposition onto IBAD template by the MOCVD method

NASA Astrophysics Data System (ADS)

Choi, J. K.; Kim, H. J.; Jun, B. H.; Kim, C. J.

2005-10-01

YBa2Cu3O7-x (YBCO) thin films were fabricated by the metal organic chemical vapor deposition (MOCVD) using a single liquid source. The copper/barium (Cu/Ba) ratio was varied from 1.26 to 1.38 to optimize the deposition condition. The IBAD template (CeO2/YSZ/stainless steel) was used as a substrate. The growth features of the YBCO films were not significantly influenced by the Cu/Ba ratio, while the superconducting transition temperature (Tc) and critical current (Ic) depended on the Cu/Ba ratio. When Cu/Ba ratio was between 1.26 and 1.29, Tc was as low as 80 K, while as Cu/Ba ratio increased to 1.38, it increased to above 85 K. The highest Tc (89.0 K) and Ic (46.3 A/cm-width) were achieved at the Cu/Ba ratio of 1.38 (Y:Ba:Cu = 1:2.1:2.9). It indicates that the optimum Cu/Ba ratio which differs from stoichiometric balance exists for the formation of the superconducting phase with a high Tc and Ic in MOCVD method.

Luminescence properties of Eu2+ in M2MgSi2O7 (M=Ca, Sr, and Ba) phosphors

NASA Astrophysics Data System (ADS)

Kim, T.; Kim, Y.; Kang, S.

2012-03-01

The photoluminescence properties of alkali-earth magnesium silicates (M2MgSi2O7, M=Ca, Sr, and Ba) doped with Eu2+ were investigated. Solid solutions of Ba x Sr2- x Si2O7, Ca2MgSi2O7, and Sr2MgSi2O7 were prepared. Ba x Sr2- x Si2O7 retained a tetragonal crystal structure similar to the structure of the other compounds up to a stoichiometry of x=1.6, which enabled a systematic study of the common structure. Monoclinic Ba2MgSi2O7 was prepared, and the luminescence properties were compared with those of other samples. The emission and excitation spectra of tetragonal M2MgSi2O7 (M=Ca, Sr, and Ba) changed as a function of the covalency, site symmetry, and crystal field strength. The luminescence properties showed excellent agreement with theoretical predictions based on these factors. The Stokes shift differentiated the emission behaviors of the tetragonal and monoclinic structures.

Ba3CuOs2O9 and Ba3ZnOs2O9, a comparative study

NASA Astrophysics Data System (ADS)

Feng, Hai L.; Jansen, Martin

2018-02-01

Polycrystalline samples of Ba3CuOs2O9 and Ba3ZnOs2O9 were synthesized by solid-state reactions. Ba3CuOs2O9 crystallizes in Cmcm, while Ba3ZnOs2O9 adopts the hexagonal space group P63/mmc. Both the crystal structures consist of face-sharing Os-centered octahedra forming dimer-like Os2O9 units, which are interconnected by corner-sharing CuO6, or ZnO6 octahedra, respectively. In Ba3CuOs2O9, the CuO6 octahedra show a characteristic Jahn-Teller distortion. Both, Ba3CuOs2O9 and Ba3ZnOs2O9, are electrically insulating. Magnetic and specific heat measurements confirm that Ba3CuOs2O9 is antiferromagnetically ordered below 47 K. Analysis of the magnetic data indicated that its magnetic properties are dominated by Cu2+ ions. The magnetic susceptibility of Ba3ZnOs2O9 is weakly temperature-dependent with a broad maximum ≈ 280 K, indicating the presence of strong exchange interactions within the Os2O9 dimer. The residual magnetic susceptibility at low temperatures also suggests the presence of appreciable exchange coupling between the dimers.

Correlation of Structure, Tunable Colors, and Lifetimes of (Sr, Ca, Ba)Al₂O₄:Eu2+, Dy3+ Phosphors.

PubMed

Xie, Qidi; Li, Bowen; He, Xin; Zhang, Mei; Chen, Yan; Zeng, Qingguang

2017-10-18

(Sr, Ca, Ba)Al₂O₄:Eu 2+ , Dy 3+ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al₂O₄:Eu 2+ ,Dy 3+ phosphors, the different phase formation from monoclinic SrAl₂O₄ phase to hexagonal SrAl₂O₄ phase to monoclinic CaAl₂O₄ phase was observed when the Ca content increased. The emission color of SrAl₂O₄:Eu 2+ , Dy 3+ phosphors varied from green to blue. For the (Sr, Ba)Al₂O₄:Eu 2+ , Dy 3+ phosphors, different phase formation from the monoclinic SrAl₂O₄ phase to the hexagonal BaAl₂O₄ phase was observed, along with a shift of emission wavelength from 520 nm to 500 nm. More interestingly, the decay time of SrAl₂O₄:Eu 2+ , Dy 3+ changed due to the different phase formations. Lifetime can be dramatically shortened by the substitution of Sr 2+ with Ba 2+ cations, resulting in improving the performance of the alternating current light emitting diode (AC-LED). Finally, intense LEDs are successfully obtained by combining these phosphors with Ga(In)N near UV chips.

Hair chemical element contents and influence factors of reproductive-age women in the West Ujimqin Banner, Inner Mongolia, China.

PubMed

Zhou, Shanshan; Yuan, Haodong; Ma, Xiaoling; Liu, Ying

2017-01-01

Women have an increased risk for chemical element deficiencies during reproductive age, particularly due to higher chemical element requirements and poor diets. Twenty-one chemical elements (Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Se, Si, Sn, Sr, Ti, V and Zn) in hair samples, which were collected from 71 non-pregnant and 236 pregnant women living in the West Ujimqin Banner, central Inner Mongolia, China, were measured, and the environment, dietary habits and ethnic group influence factors associated with the biomarker were analyzed. The results indicated that the average values of the chemical element contents from hair were greatly different compared to those from other areas, especially the Al, Cd, Pb, Ca and Sr contents. There was no significant difference among the three ethnicities for any element except Mn and Ti in non-pregnant women. Compared to non-pregnant women, in the first trimester group, the levels of nine chemical elements (Ba, Cd, Cu, Pb, Se, Si, Sn and Ti) decreased, while the others increased, and the contents of all of the chemical elements decreased in the second trimester group, while in the third trimester, there was a slight increase. Three chemical elements (Cu, Mn and Zn) displayed a synergistic correlation between each other in the third trimester group, which may protect the placenta from some oxidant damage. The high levels of Cd and Pb in hair likely originate from house renovations and traffic pollution. This study provided basic and useful information on the levels of chemical elements in reproductive-age women, and the results of this study are helpful to control the contents and improve the health of pregnant and non-pregnant women. Copyright © 2016 Elsevier Ltd. All rights reserved.

Geochemical properties of topsoil around the coal mine and thermoelectric power plant.

PubMed

Stafilov, Trajče; Šajn, Robert; Arapčeska, Mila; Kungulovski, Ivan; Alijagić, Jasminka

2018-03-19

The results of the systematic study of the spatial distribution of trace metals in surface soil over the Bitola region, Republic of Macedonia, known for its coal mine and thermo-electrical power plant activities are reported. The investigated region (3200 km 2 ) is covered by a sparse sampling grid of 5 × 5 km, but in the urban zone and around the thermoelectric power plant the sampling grid is denser (1 × 1 km). In total, 229 soil samples from 149 locations were collected including top-soil (0-5 cm) and bottom-soil samples (20-30 cm and 0-30 cm). Inductively coupled plasma - atomic emission spectrometry (ICP-AES) was applied for the determinations of 21 elements (Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Na, Ni, P, Pb, Sr, V and Zn). Based on the results of factor analyses, three geogenic associations of elements have been defined: F1 (Fe, Ni, V, Co, Cr, Mn and Li), F2 (Zn, B, Cu, Cd, Na and K) and F3 (Ca, Sr, Mg, Ba and Al). Even typical trace metals such as As, Cd, Cu, Ni, P, Pb and Zn are not isolated into anthropogenic geochemical associations by multivariate statistical methods still show some trends of local anthropogenic enrichment. The distribution maps for each analyzed element is showing the higher content of these elements in soil samples collected around the thermoelectric power plants than their average content for the soil samples collected from the whole Bitola Region. It was found that this enrichment is a result of the pollution by fly ash from coal burning which deposited near the plant having a high content of these elements.

Trace element accumulation in hawksbill turtles (Eretmochelys imbricata) and green turtles (Chelonia mydas) from Yaeyama Islands, Japan.

PubMed

Anan, Y; Kunito, T; Watanabe, I; Sakai, H; Tanabe, S

2001-12-01

Concentrations of 18 trace elements (V, Cr, Mn, Co, Cu, Zn, Se, Rb, Sr, Zr, Mo, Ag, Cd, Sb, Ba, Hg, Tl, and Pb) were determined in the liver, kidney, and muscle of green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) from Yaeyama Islands, Okinawa, Japan. Accumulation features of trace elements in the three tissues were similar between green and hawksbill turtles. No gender differences in trace element accumulation in liver and kidney were found for most of the elements. Significant growth-dependent variations were found in concentrations of some elements in tissues of green and hawksbill turtles. Significant negative correlations (p < 0.05) were found between standard carapace length (SCL) and the concentrations of Cu, Zn, and Se in the kidney and V in muscle of green turtles and Mn in the liver, Rb and Ag in kidney, and Hg in muscle of hawksbill turtles. Concentrations of Sr, Mo, Ag, Sb, and Tl in the liver, Sb in kidney, and Sb and Ba in muscle of green turtles and Se and Hg in the liver and Co, Se, and Hg in kidney of hawksbill turtles increased with an increase in SCL (p < 0.05). Green and hawksbill turtles accumulated extremely high concentrations of Cu in the liver and Cd in kidney, whereas the levels of Hg in liver were low in comparison with those of other higher-trophic-level marine animals. High accumulation of Ag in the liver of green turtles was also observed. To evaluate the trophic transfer of trace elements, concentrations of trace elements were determined in stomach contents of green and hawksbill turtles. A remarkably high trophic transfer coefficient was found for Ag and Cd in green turtles and for Cd and Hg in hawksbill turtles.

The series Bi2Sr2Ca(n-1) Cu(n)O(2n+4) (1 less than or equal to n less than or equal to 5): Phase stability and superconducting properties

NASA Technical Reports Server (NTRS)

Deguire, Mark R.; Bansal, Narottam P.; Farrell, David E.; Finan, Valerie; Kim, Cheol J.; Hills, Bethanie J.; Allen, Christopher J.

1989-01-01

Phase relations at 850 and 870 C, melting transitions in air, oxygen, and helium were studied for Bi(2.1)Sr(1.9) CuO6 and for the Bi2Sr2Ca(n-1) Cu(n)O(2n+4) for n = 1, 2, 3, 4, 5, and infinity (CaCuO2). Up to 870 C, the n = 2 composition resides in the compatibility tetrahedron bounded by Bi(2+x)(Sr,Ca)(3-y) Cu2O8, (Sr,Ca)14 Cu24O41, Ca2CuO3, and a Bi-Sr-Ca-O phase. The n is greater than or equal to 3 compositions reside in the compatibility tetrahedron Bi(2+x)(Sr,Ca)(3-y) Cu2O8 - (Sr,Ca)14 Cu24O41 - Ca2CuO3 - CuO up to 850 C. However, Bi(2+x)Sr(4-y) Cu3O10 forms for n is greater than or equal to 3 after extended heating at 870 C. Bi(2+x)Sr(2-y) CuO6 and Bi(2+x)(Sr,Ca)(3-y) Cu2O8 melt in air at 914 C and 895 C respectively. During melting, all of the compositions studied lose 1 to 2 percent by weight of oxygen from the reduction of copper. Bi(2+x)Sr(2-y) CuO6, Bi(2+n)(Sr,Ca)(3-y) Cu2O8, and Bi(2+x)(Sr,Ca)(4-y) Cu3O10 exhibit crystallographic alignment in a magnetic field, with the c-axes orienting parallel to the field.

Analysis and Optimization of Thin Film Ferroelectric Phase Shifters

NASA Technical Reports Server (NTRS)

Romanofsky, Robert R.; VanKeuls, Fred W.; Warner, Joseph D.; Mueller, Carl H.; Alterovitz, Samuel A.; Miranda, Felix A.; Qureshi, A. Haq; Romanofsky, Robert R. (Technical Monitor)

2000-01-01

Microwave phase shifters have been fabricated from (YBa2Cu3O(7-delta) or Au)/SrTiO3 and Au/Ba(x)Sr(1-x)TiO3 films on LaAlO3 and MgO substrates. These coupled microstrip devices rival the performance of their semiconductor counter-parts parts at Ku- and K-band frequencies. Typical insertion loss for room temperature ferroelectric phase shifters at K-band is approximately equal 5 dB. An experimental and theoretical investigation of these novel devices explains the role of the ferroelectric film in overall device performance. A roadmap to the development of a 3 dB insertion loss phase shifter that would enable a new type of phased array antenna is discussed.

Evaluation methods and evaporation conditions for low-resistivity contacts on high Tc superconductors

NASA Astrophysics Data System (ADS)

Liu, Y. P.; Warner, K.; Chan, C.; Chen, K.; Markiewicz, R.

1989-12-01

Low-resistivity contacts to bulk high-Tc superconductors have been prepared by resistive evaporation with values of rho-s (ohm sq cm) as low as 10 to the -10th (77 K) for Ag/YBaCuO, 10 to the -9th (77 K) for Ag/TlPbBaCaCuO, and 10 to the 7th (60 K) for Ag/BiCaSrCuO. It was found that rho-s is improved by increasing the length of a preevaporation step. This effect has been further investigated by secondary ion-mass spectrometry analysis on several Ag/Si samples. Both three-terminal and four-terminal methods have been used to determine rho-s; the three-terminal method shows less dependency on the sample/contact geometry for measurements taken above Tc.

Atomic and electronic structures of BaHfO3-doped TFA-MOD-derived YBa2Cu3O7-δ thin films

NASA Astrophysics Data System (ADS)

Molina-Luna, Leopoldo; Duerrschnabel, Michael; Turner, Stuart; Erbe, Manuela; Martinez, Gerardo T.; Van Aert, Sandra; Holzapfel, Bernhard; Van Tendeloo, Gustaaf

2015-11-01

Tailoring the properties of oxide-based nanocomposites is of great importance for a wide range of materials relevant for energy technology. YBa2Cu3O7-δ (YBCO) superconducting thin films containing nanosized BaHfO3 (BHO) particles yield a significant improvement of the magnetic flux pinning properties and a reduced anisotropy of the critical current density. These films were prepared by chemical solution deposition (CSD) on (100) SrTiO3 (STO) substrates yielding critical current densities up to 3.6 MA cm-2 at 77 K and self-field. Transport in-field J c measurements demonstrated a high pinning force maximum of around 6 GN/m3 for a sample annealed at T = 760 °C that has a doping of 12 mol% of BHO. This sample was investigated by scanning transmission electron microscopy (STEM) in combination with electron energy-loss spectroscopy (EELS) yielding strain and spectral maps. Spherical BHO nanoparticles of 15 nm in size were found in the matrix, whereas the particles at the interface were flat. A 2 nm diffusion layer containing Ti was found at the YBCO (BHO)/STO interface. Local lattice deformation mapping at the atomic scale revealed crystal defects induced by the presence of both sorts of BHO nanoparticles, which can act as pinning centers for magnetic flux lines. Two types of local lattice defects were identified and imaged: (i) misfit edge dislocations and (ii) Ba-Cu-Cu-Ba stacking faults (Y-248 intergrowths). The local electronic structure and charge transfer were probed by high energy resolution monochromated electron energy-loss spectroscopy. This technique made it possible to distinguish superconducting from non-superconducting areas in nanocomposite samples with atomic resolution in real space, allowing the identification of local pinning sites on the order of the coherence length of YBCO (˜1.5 nm) and the determination of 0.25 nm dislocation cores.

Ternary Bismuthide SrPtBi 2: Computation and Experiment in Synergism to Explore Solid-State Materials

DOE PAGES

Gui, Xin; Zhao, Xin; Sobczak, Zuzanna; ...

2018-02-14

A combination of theoretical calculation and the experimental synthesis to explore the new ternary compound is demonstrated in the Sr–Pt–Bi system. Because Pt–Bi is considered as a new critical charge-transfer pair for superconductivity, it inspired us to investigate the Sr–Pt–Bi system. With a thorough calculation of all the known stable/metastable compounds in the Sr–Pt–Bi system and crystal structure predictions, the thermodynamic stability of hypothetical stoichiometry, SrPtBi2, is determined. Following the high-temperature synthesis and crystallographic analysis, the first ternary bismuthide in Sr–Pt–Bi, SrPtBi2 was prepared, and the stoichiometry was confirmed experimentally. SrPtBi 2 crystallizes in the space group Pnma (S.G. 62,more » Pearson Symbol oP48), which matches well with theoretical prediction using an adaptive genetic algorithm. Using first-principles calculations, we demonstrate that the orthorhombic structure has lower formation energies than other 112 structure types, such as tetragonal BaMnBi 2 (CuSmP 2) and LaAuBi 2 (CuHfSi 2) structure types. The bonding analysis indicates that the Pt–Bi interactions play a critical role in structural stability. The physical property measurements show the metallic properties at the low temperature, which agrees with the electronic structure assessment.« less

Development of high T(sub c) (greater than 110 K) Bi, Tl, and Y-based materials as superconducting circuit elements

NASA Technical Reports Server (NTRS)

Haertling, Gene H.; Grabert, Gregory; Gilmour, Phillip

1992-01-01

Experimental work has continued on the development and characterization of bulk and hot pressed powders and tapecast materials in the Bi-Sr-Ca-Cu-O and Tl-Ba-Ca-Cu-O systems. A process for producing warp-free, sintered, superconducting tapes of Bi composition Bi2Sr2Ca2Cu3O(x) with a mixed oxide process was established. This procedure required a triple calcination at 830 C for 24 hours and sintering at 845 C from 20 to 200 hours. Hot pressing the triple calcined powder at 845 C for 6 hours at 5000 psi yielded a dense material which on further heat treatment at 845 C for 24 hours exhibited a Tc of 108.2 K. A further improvement in the processing of the bismuth materials was achieved via a chemical coprecipitation process wherein the starting nitrate materials were coprecipitated with oxalic acid, thus yielding a more chemically homogeneous, more reactive powder. With the coprecipitated powders, only one calcine at 830 C for 12 hours and a final sinter at 845 C for 30 hours was sufficient to produce a bulk superconducting material with a Tc of 108.4 K. SAFIRE-type grounding links were successfully fabricated from sintered, tapecast, coprecipitated BSCCO 2223 powders. Compositional and processing investigations were continued on the Tl-based superconductors. Manganese and lithium additions and sintering temperature and time were examined to determine their influence on superconducting properties. It was found that lithium substitutions for copper enhance the transition temperatures while manganese additions produced deleterious effects on the superconducting properties. A suitable procedure for producing reproducible bulk and tapecast material of Tl composition Tl2Ba2Ca2Cu3O(x) was developed and used in fabricating uniform superconducting tapes. The highest transition temperature for Tl-based tapes was measured at 110.2 K. Thallium superconducting SAFIRE-type grounding links were fabricated from the tapes.

Temporal stability and rates of post-depositional change in geochemical signatures of brown trout Salmo trutta scales.

PubMed

Ryan, D; Shephard, S; Kelly, F L

2016-09-01

This study investigates temporal stability in the scale microchemistry of brown trout Salmo trutta in feeder streams of a large heterogeneous lake catchment and rates of change after migration into the lake. Laser-ablation inductively coupled plasma mass spectrometry was used to quantify the elemental concentrations of Na, Mg, Mn, Cu, Zn, Ba and Sr in archived (1997-2002) scales of juvenile S. trutta collected from six major feeder streams of Lough Mask, County Mayo, Ireland. Water-element Ca ratios within these streams were determined for the fish sampling period and for a later period (2013-2015). Salmo trutta scale Sr and Ba concentrations were significantly (P < 0·05) correlated with stream water sample Sr:Ca and Ba:Ca ratios respectively from both periods, indicating multi-annual stability in scale and water-elemental signatures. Discriminant analysis of scale chemistries correctly classified 91% of sampled juvenile S. trutta to their stream of origin using a cross-validated classification model. This model was used to test whether assumed post-depositional change in scale element concentrations reduced correct natal stream classification of S. trutta in successive years after migration into Lough Mask. Fish residing in the lake for 1-3 years could be reliably classified to their most likely natal stream, but the probability of correct classification diminished strongly with longer lake residence. Use of scale chemistry to identify natal streams of lake S. trutta should focus on recent migrants, but may not require contemporary water chemistry data. © 2016 The Fisheries Society of the British Isles.

The Phase Transformation and Crystal Structure Studies of Strontium Substituted Barium Monoferrite

NASA Astrophysics Data System (ADS)

Mulyawan, A.; Adi, W. A.; Mustofa, S.; Fisli, A.

2017-03-01

Unlike other AFe2O4 ferrite materials, Barium Monoferrite (BaFe2O4) have an orthorhombic structure which is very interesting to further study the crystal structure and phase formation. In this study, Strontium substituted Barium Monoferrite in the form of Ba(1-x)Sr(x)Fe2O4 has successfully been synthesized through solid state reaction method which includes BaCO3, SrCO3, and Fe2O3 as starting materials. Ba(1-x)Sr(x)Fe2O4 was made by varying the dopant composition of Strontium (Sr2+) from x = 0, 0.1, 0.3, and 0.5. Each composition was assisted by ethanol and continued to the milling process for 5 hours then followed by sintering process at 900 °C for 5 hours. The phase transformation was studied by using X-ray diffractometer (XRD) and Rietveld refinement using General Structure Analysis System (GSAS) also 3D crystal visualization using VESTA. Referring to the refinement results, a single phase of BaFe2O4 was formed in x = 0 and 0.1. The composition has orthorhombic structure, space group B b21m, and lattice parameters of a = 19.0229, b = 5.3814 c = 8.4524 Å, α = β = γ = 90° and a = 18.9978, b = 5.3802 c = 8.4385 Å, α = β = γ = 90° respectively. In the composition of x = 0.3 it was found that the phase of BaSrFe4O8 begin to form due to the overload expansion of the Sr2+ occupancy which made the distortion of the initial lattice parameters and finally in the x = 0.5 composition the single phase of BaSrFe4O8 was clearly formed. Energy Dispersive Spectroscopy (EDS) was used to confirm the change of the material structure by measuring the elemental compound composition ratio. The result of EDS spectra clearly exhibited the dominant elements were Barium (Ba), Strontium (Sr), Iron (Fe), and Oxygen (O) with the compound ratio (Atomic percentage and mass percentage) correspond to the BaFe2O4 and BaSrFe4O8 phase.

Low temperature rf sputtering deposition of (Ba, Sr) TiO3 thin film with crystallization enhancement by rf power supplied to the substrate

NASA Astrophysics Data System (ADS)

Yoshimaru, Masaki; Takehiro, Shinobu; Abe, Kazuhide; Onoda, Hiroshi

2005-05-01

The (Ba, Sr) TiO3 thin film deposited by radio frequency (rf) sputtering requires a high deposition temperature near 500 °C to realize a high relative dielectric constant over of 300. For example, the film deposited at 330 °C contains an amorphous phase and shows a low relative dielectric constant of less than 100. We found that rf power supplied not only to the (Ba, Sr) TiO3 sputtering target, but also to the substrate during the initial step of film deposition, enhanced the crystallization of the (Ba, Sr) TiO3 film drastically and realized a high dielectric constant of the film even at low deposition temperatures near 300 °C. The 50-nm-thick film with only a 10 nm initial layer deposited with the substrate rf biasing is crystallized completely and shows a high relative dielectric constant of 380 at the deposition temperature of 330 °C. The (Ba, Sr) TiO3 film deposited at higher temperatures (upwards of 400 °C) shows <110> preferred orientation, while the film deposited at 330 °C with the 10 nm initial layer shows a <111> preferred orientation on a <001>-oriented ruthenium electrode. The unit cell of (Ba, Sr) TiO3 (111) plane is similar to that of ruthenium (001) plane. We conclude that the rf power supplied to the substrate causes ion bombardments on the (Ba, Sr) TiO3 film surface, which assists the quasiepitaxial growth of (Ba, Sr) TiO3 film on the ruthenium electrode at low temperatures of less than 400 °C.

Effect of Heat Treatment on The Crystal Structur, Electrical Conductivity and Surface of Ba1.5Sr0.5Fe2O5 Composite

NASA Astrophysics Data System (ADS)

Purwanto, P.; Adi, WA; Yunasfi

2017-05-01

The Composite of Ba1,5Sr0,5Fe2O5 has been synthesized by using powder metallurgy technique. The Ba1.5Sr0.5Fe2O5 were prepared from BaCO3, SrCO3 and Fe2O3 raw materials with a specific weight ratio. The three materials were synthesized by powder metallurgy under heat treatment at 800 °C, 900 °C, and 1000 °C for 5 hours. All the three samples were characterized by using X-ray Diffraction (XRD) to determine the crystal structure and crystal size, LCR meter to determine the conductivity, and Scanning Electron Microscope (SEM) to observe the morphological of the composites. The phase analysis result showed that the composite consists of several minor phases such as BaO2, SrO2, and Fe2O3. The Crystal size of composite Ba1.5Sr0.5Fe2O5 decreased while increases the strain of crystal with increasing of sintering temperature. The crystal size of the Ba1.5Sr0.5Fe2O5 composite is 3.55 nm to 7.23 nm and value of strain is 8.47% until 3.90%. Based on the conductivity measurement, it was obtained that the conductivity of the Ba1.5Sr0.5Fe2O5 composite decreased with increasing sintering temperature. It was also noticed that the conductivity increased with increasing of frequency. The conductivity ranged from 6.619×10-7 S/cm to 65.659×10-7 S/cm. The energy dispersive spectroscopy (EDS) analysis showed that several dominant elements were a good agreement with the phase analysis.

Growth and interface engineering in thin-film Ba0.6Sr0.4TiO3 /SrMoO3 heterostructures

NASA Astrophysics Data System (ADS)

Radetinac, Aldin; Ziegler, Jürgen; Vafaee, Mehran; Alff, Lambert; Komissinskiy, Philipp

2017-04-01

Epitaxial heterostructures of ferroelectric Ba0.6Sr0.4TiO3 and highly conducting SrMoO3 were grown by pulsed laser deposition on SrTiO3 (0 0 1) substrates. Surface oxidation of the SrMoO3 film is suppressed using a thin cap interlayer of Ba0.6Sr0.4TiO3-δ grown in reduced atmosphere. As shown by X-ray photoelectron spectroscopy, the Mo4+ valence state of the SrMoO3 films is stable upon annealing of the sample in oxygen up to 600 °C. The described oxygen interface engineering enables utilization of the highly conducting material SrMoO3 in multilayer oxide ferroelectric varactors.

Preparation of porous (Ba,Sr)TiO3 by adding corn-starch

NASA Astrophysics Data System (ADS)

Kim, J.-G.; Sim, J.-H.; Cho, W.-S.

2002-11-01

A new method of preparing porous (Ba,Sr)TiO3 ceramics has been introduced, using an ordinary ceramics processing technique. The effect of corn-starch on the positive temperature coefficient of resistivity characteristics and microstructure of the porous (Ba,Sr)TiO3 ceramics has been investigated. When the corn-starch addition was 1-20 wt%, the PTCR jump was over 106 and 1-2 orders higher than that of samples without corn-starch. Also, it was found that the (Ba,Sr)TiO3 ceramics had porous microstructure by the addition of corn-starch. The porosity of the ceramics with 20 wt% corn-starch was 44%. The electrical properties of the (Ba,Sr)TiO3 ceramics have been discussed, based on the microstructure, resistivity of grain boundaries, donor concentration of grains and the electrical potential barrier of grain boundaries.

Tuning the electrocaloric effect by varying Sr concentration in ferroelectric Ba1 -xSrxTiO3

NASA Astrophysics Data System (ADS)

Lisenkov, S.; Ponomareva, I.

2018-05-01

The electrocaloric effect is investigated systematically in Ba1 -xSrxTiO3 ferroelectrics using a semiclassical direct computational approach. The data are reported for the technologically important range of Sr concentrations of 0.0-0.6, electric fields up to 1000 kV/cm, and temperatures ranging from 5 to 600 K. A detailed comparison of computational data with experimental data from the literature reveals semiquantitative agreement and suggests the origin of discrepancies. The electrocaloric change in temperature Δ T shows strong dependence on Sr concentration which offers a way to tune electrocaloric response. In particular, the maximum electrocaloric Δ T is found to decrease with the increase in Sr concentration, whereas the location of the maximum shifts towards lower temperatures following the Curie point of the ferroelectric. Surprisingly, the width of the peak in the dependence of Δ T on the initial temperature is independent of the Sr concentration but shows a strong dependence on the applied electric field. Computational data are used to propose a compositionally graded ferroelectric Ba0.70Sr0.30TiO3/Ba0.55Sr0.45TiO3/Ba0.50Sr0.50TiO3/Ba0.45Sr0.55TiO3 whose Δ T shows almost no temperature dependence in the technologically important range of temperatures and electric fields. Such a desirable feature could potentially lead to the enhancement of relative cooling power.

BariumCopperChFluorine (Ch = Sulfur, Selenium, Tellurium) p-type transparent conductors

NASA Astrophysics Data System (ADS)

Zakutayev, Andriy

BaCuChF (Ch = S, Se, Te) materials are chalcogen-based transparent conductors with wide optical band gaps (2.9 -- 3.5 eV) and a high concentration of free holes (1018 -- 1020 cm-3 ) caused by the presence of copper vacancies. Chalcogen vacancies compensate copper vacancies in these materials, setting the Fermi level close to the valence band maximum. BaCuChF thin film solid solutions prepared by pulsed laser deposition (PLD) have tunable properties, such as lattice constants, conductivity and optical band gaps. BaCuSF and BaCuSeF materials also feature room-temperature stable 3D excitons with spin-orbit-split levels. BaCuTeF has forbidden lowest-energy optical transitions which extends its transparency range. BaCuChF surfaces oxidize when exposed to air, but can be protected using Ch capping layers. Polycrystalline BaCuSeF thin films have a 4.85 eV work function, a 0.11 eV hole injection barrier into ZnPc, and 0.00 eV valence band offset with ZnTe. BaCuSeF should have s similar band offset and similar interfacial properties with CdTe and Cu(InGa)Se2, and BaCuSF should have no valence band offset with Cu2ZnSnS4, according to the transitivity rule. Therefore, BaCuSeF is suitable for applications as a p-layer in organic light-emitting diodes, p-i-n double-heterojunction and tandem chalcogenide solar cells.

Development of high Tc (greater than 110K) Bi, Tl and Y-based materials as superconducting circuit elements

NASA Technical Reports Server (NTRS)

Haertling, Gene H.; Lee, Burtrand; Grabert, Gregory; Gilmour, Phillip

1991-01-01

This report is presented in two parts. Part 1 deals primarily with Bi-based materials and a small amount of work on a Y-based composition while Part 2 covers work on Tl-based materials. In Part 1, a reliable and reproducible process for producing bulk bismuth-based superconductors has been developed. It is noted however, that a percentage of the tapecast material experiences curling and fracturing after a 30 hour sintering period and is thus in need of further examination. The Bi-Sr-Ca-Cu-O (BSCCO) material has been characterized by critical temperature data, X-ray diffraction data, and surface morphology. In the case of T sub c, it is not critical to anneal the material. It appears that the BSCCO material has the possibility of producing a better grounding strap than that of the 123 material. Attempts to reproduce near room temperature superconductors in the Y-Ba-Cu-O system were unsuccessful. In Part 2, several methods of processing the high temperature superconductor Tl2Ba2Ca2Cu3O10 were investigated; i.e., different precursor compositions were sintered at various sintering times and temperatures. The highest superconductig temperature was found to be 117.8K when fired at 900 C for three hours. Higher sintering temperatures produced a melted sample which was nonsuperconducting at liquid nitrogen temperature. Also, a preliminary study found Li2O substitutions for copper appeared to increase the transition temperature and create fluxing action upon sintering. It was suggested that lower sintering temperatures might be obtained with lithium additions to produce reliable Tl2Ba2Ca2Cu3O10 processing methods.

Correlation of Structure, Tunable Colors, and Lifetimes of (Sr, Ca, Ba)Al2O4:Eu2+, Dy3+ Phosphors

PubMed Central

Xie, Qidi; Li, Bowen; He, Xin; Zhang, Mei; Chen, Yan; Zeng, Qingguang

2017-01-01

(Sr, Ca, Ba)Al2O4:Eu2+, Dy3+ phosphors were prepared via a high temperature solid-state reaction method. The correlation of phase structure, optical properties and lifetimes of the phosphors are investigated in this work. For the (Sr, Ca)Al2O4:Eu2+, Dy3+ phosphors, the different phase formation from monoclinic SrAl2O4 phase to hexagonal SrAl2O4 phase to monoclinic CaAl2O4 phase was observed when the Ca content increased. The emission color of SrAl2O4:Eu2+, Dy3+ phosphors varied from green to blue. For the (Sr, Ba)Al2O4:Eu2+, Dy3+ phosphors, different phase formation from the monoclinic SrAl2O4 phase to the hexagonal BaAl2O4 phase was observed, along with a shift of emission wavelength from 520 nm to 500 nm. More interestingly, the decay time of SrAl2O4:Eu2+, Dy3+ changed due to the different phase formations. Lifetime can be dramatically shortened by the substitution of Sr2+ with Ba2+ cations, resulting in improving the performance of the alternating current light emitting diode (AC-LED). Finally, intense LEDs are successfully obtained by combining these phosphors with Ga(In)N near UV chips. PMID:29057839

Petrogenesis of the mafic microgranular enclaves (MMEs) and their host granodiorites from the Zijinshan intrusion along the Middle-Lower Yangtze River Valley: Implications for geodynamic setting and mineralization

NASA Astrophysics Data System (ADS)

Liu, Peng; Mao, Jingwen; Yao, Wei; Wang, Xiaoxia; Jia, Lihui; Yang, Hanwen

2017-09-01

The Zijinshan intrusion is located to the south of the Tongling ore cluster of the Middle-Lower Yangtze River Valley metallogenic belt (YRB) and even south to the Yangxing-Changzhou Fault (YCF), which separates the YRB and the Jiangnan Massif. It is an I-type high-K calc-alkaline granodiorite with abundant MMEs. Zircon LA-MC-ICP-MS U-Pb ages of 144.0 ± 1.0 Ma and 142.5 ± 1.0 Ma for the host granodiorite and MMEs indicate coeval formation. Biotites from the host granodiorites and MMEs have similar composition, with low FeOt/(FeOt + MgO) values of 0.60-0.65 and 0.60-0.65, and high MgO contents of 10.51-11.70 wt.% and 10.89-12.37 wt.%, respectively. All the biotite samples are between the NNO and the MH buffers. The host granodiorites are metaluminous (A/CNK = 0.94-0.95), enriched in Cs, Rb, U and Pb, depleted in Ba, Sr, Nb, Zr, P, and Ti, with moderate negative Eu anomalies of 0.80-0.87, (87Sr/86Sr)i of 0.70874 to 0.70887, εNd(t) of - 5.63 to - 5.36 and εHf(t) of - 8.68 to - 2.76. The MMEs have lower SiO2 and higher K2O, and they are also enriched in Cs, Rb, U, Ta and Pb, and depleted in Ba, Sr, Nb, Zr, P and Ti, with (87Sr/86Sr)i of 0.70889 to 0.70927, εNd(t) of - 5.52 to - 5.20 and εHf(t) of - 6.46 to - 3.59. All these characteristics demonstrate that partial melting of both the lower crust and an enriched lithospheric mantle metasomatized by subducted slab fluid and their subsequent mixing led to the origin of the I-type granodiorite magmas of the Zijinshan intrusion, which took place in the geodynamic context of the subduction of the Izanagi plate. Combined with the field investigations, we suggest that the Zijinshan intrusion has potential for porphyry Cu-Au mineralization and the Cu-Au metallogenic belt of the YRB may have extended to the south of the YCF.

Magnetic and magnetocaloric properties of Ba and Ti co-doped SrRuO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Babusona; Dalal, Biswajit; Dev Ashok, Vishal

2014-12-28

Temperature evolution of magnetic properties in Ba and Ti doped SrRuO{sub 3} has been investigated to observe the effects of larger ionic radius Ba at Sr site and isovalent nonmagnetic impurity Ti at Ru site. Ionic radius mismatch and different electronic configuration in comparison with Ru modify Sr(Ba)-O and Ru(Ti)-O bond lengths and Ru-O-Ru bond angle. The apical and basal Ru-O-Ru bond angles vary significantly with Ti doping. Ferromagnetic Curie temperature decreases from 161 K to 149 K monotonically with Ba (10%) and Ti (10%) substitutions at Sr and Ru sites. The zero field cooled (ZFC) magnetization reveals a prominent peak whichmore » shifts towards lower temperature with application of magnetic field. The substitution of tetravalent Ti with localized 3d{sup 0} orbitals for Ru with more delocalized 4d{sup 4} orbitals leads to a broad peak in ZFC magnetization. A spontaneous ZFC magnetization becomes negative below 160 K for all the compositions. The occurrence of both normal and inverse magnetocaloric effects in Ba and Ti co-doped SrRuO{sub 3} makes the system more interesting.« less

Distribution and Phase Association of Some Major and Trace Elements in the Arabian Gulf Sediments

NASA Astrophysics Data System (ADS)

Basaham, A. S.; El-Sayed, M. A.

1998-02-01

Twenty-four sediment samples were collected from the Arabian Gulf (ROPME Sea) and analysed for their grain size distribution and carbonate contents as well as the major elements Ca, Mg, Fe and Al and macro and trace elements Mn, Sr, Ba, Zn, Cu, Cr, V, Ni and Hg. Concentration of trace elements are found comparable to previous data published for samples taken before and after the Gulf War, and reflect the natural background level. Grain size analyses, aluminium and carbonate measurements support the presence of two major sediment types: (1) a terrigenous, fine-grained and Al rich type predominating along the Iranian side; and (2) a coarse-grained and carbonate rich type predominating along the Arabian side of the Gulf. Investigation of the correlation of the elements analysed with the sediment type indicates that they could be grouped under two distinct associations: (1) carbonate association including Ca and Sr; and (2) terrigenous association comprising Al, Fe, Mg, Ba, Mn, Zn, Cu, Cr, V, Ni and Hg. Element/Al ratios calculated for the mud non-carbonate fraction indicate that the Euphrates and Tigris rivers have minor importance as sediment sources to the Gulf. Most of the elements have exceptionally high aluminium ratios in sediments containing more than 85-90% carbonate. These sediments are restricted to the southern and south-eastern part of the area where depth is shallow and temperature and salinity are high. Both biological accumulation and chemical and biochemical coprecipitation could be responsible for this anomaly.

Sphagnum palustre clone vs native Pseudoscleropodium purum: A first trial in the field to validate the future of the moss bag technique.

PubMed

Capozzi, F; Adamo, P; Di Palma, A; Aboal, J R; Bargagli, R; Fernandez, J A; Lopez Mahia, P; Reski, R; Tretiach, M; Spagnuolo, V; Giordano, S

2017-06-01

Although a large body of literature exists on the use of transplanted mosses for biomonitoring of air pollution, no article has addressed so far the use and the accumulation performance of a cloned moss for this purpose. In this work, a direct comparison of metal accumulation between bags filled with a Sphagnum palustre L. clone or with native Pseudoscleropodium purum Hedw., one of the most used moss species in biomonitoring surveys, was investigated. The test was performed in sites with different atmospheric contamination levels selected in urban, industrial, agricultural and background areas of Italy and Spain. Among the eighteen elements investigated, S. palustre was significantly enriched in 10 elements (Al, Ba, Cr, Cu, Fe, Hg, Pb, Sr, V and Zn), while P. purum was enriched only in 6 elements (Al, Ba, Cu, Hg, Pb and Sr), and had a consistently lower uptake capacity than S. palustre. The clone proved to be more sensitive in terms of metal uptake and showed a better performance as a bioaccumulator, providing a higher accumulation signal and allowing a finer distinction among the different land uses and levels of pollution. The excellent uptake performance of the S. palustre clone compared to the native P. purum and its low and stable baseline elemental content, evidenced in this work, are key features for the improvement of the moss bag approach and its large scale application. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of Heavy Metals in Almonds and Mistletoe as a Parasite Growing on the Almond Tree Using ICP-OES or ICP-MS.

PubMed

Kamar, Veysi; Dağalp, Rukiye; Taştekin, Mustafa

2017-12-28

In this study, the elements of Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Ni, Sr, Pb, Ti, and Zn were determined in the leaves, fruits, and branches of mistletoe, (Viscum albüm L.), used as a medicinal plant, and in the leaves, branches and barks of almond tree which mistletoe grows on. The aim of the study is to investigate whether the mistletoe are more absorbent than the almond tree in terms of the heavy metal contents and the determination of the amount of the elements penetrated into the mistletoe from the almond tree. ICP-MS (inductively coupled plasma-mass spectrometry) was used for the analysis of As, Cd, Mo, and Pb, whereas ICP-OES (inductively coupled plasma optical emission spectrometry) was used for the other elements. The results obtained were statistically evaluated at 95% confidence level. Within the results obtained in this study, it was determined whether there is a significant difference between metal elements in almond tree and mistletoe, or not. As a result, it was observed that there were higher contents of B, Ba, K, Mg, and Zn in the mistletoe than in the almond tree. K was found much higher than other elements in the mistletoe. On the other hand, Al, As, Ca, Cd, Cr, Cu, Fe, Mo, Ni, Sr, Pb, and Ti contents were determined to be more in almond tree than mistletoe.

Soil pollution in Central district of Saint-Petersburg (Russia)

NASA Astrophysics Data System (ADS)

Terekhina, Natalia; Ufimtseva, Margarita

2015-04-01

Analysis of soil samples of upper horizon for the content of chemical elements (Fe, Mn, Cu, Zn, Pb, Ni, Cr, Co, Cd, Ba, Sr) was carried out by atomic emission with inductively coupled plasma. A relative indicator of soil contamination degree is a concentration coefficient, representing the ratio of metal content in tested soil samples to the local background value of the corresponding element. Total pollution index is calculated by the concentration coefficients, which are greater than 1, taking into account the hazard class of metals (1 class - Zn, Pb ,Cd; 2 - class Cr, Ni, Cu ,Со; 3 class - Fe, Mn, Sr, Ba). Analysis of trace element of urban soils demonstrated mosaic patterns of pollution for Central district. The method of correlation sets constructing and factor analysis revealed three groups of chemical elements having a strong and significant association with each other: Pb-Cu-Cd-Zn-Ba, Ni-Cr-Co, Fe-Mn. Elements of the first group are characterized by high values of concentration coefficient and are the main pollutants - their average content is 3-11 times higher than background values. Strontium does not have strong correlation with the other elements, and its lowest concentration coefficient indicates that the element can not be regarded as a pollutant. The spatial distribution of the total pollution index identified several sources of pollution, the origin of which may be different. The main reason is probably the impact of vehicle emissions, although local pollution of soil is possible (the soils, contaminated during reconstruction of lawns, dumping of construction materials, etc.). Differentiated assessment of database shows that 48% of samples refer to dangerous pollution category, 37% - to moderately dangerous category, 15% - to allowable category. Thus, almost half of the district is characterized as dangerous in terms of soil contamination. Solution of the problem of soil contamination is recommended in three ways: reducing the intensity of vehicular traffic through the historic center of the city, improving the quality of transport emissions, removal of contaminated soil layers in particularly polluted areas and the introduction of clean soil, optimization of verdurization of the urban environment, as a means of reducing the flow of atmospheric pollutants in soil.

Growth of ultrathin twin-free b-oriented YBa{sub 2}Cu{sub 3}O{sub 7} {sub –} {sub x} films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stepantsov, E. A., E-mail: stepantsov@ns.crys.ras.ru; Arpaia, R.; Lombardi, F.

2017-01-15

Twin-free b-oriented YBa{sub 2}Cu{sub 3}O{sub 7–x} films with a thickness less than 40 nm have been epitaxially grown on (100)SrLaGaO{sub 4} crystals. Based on the temperature dependence of resistance, the onset temperature of the transition to the superconducting state is found to be 90 K; the transition width is 4 K. The film growth has been performed in two stages. A (100)PrBa{sub 2}Cu{sub 3}O{sub 7–x} buffer layer was previously grown on a (100)SrLaGaO{sub 4} substrate by rf magnetron sputtering in an Ar–O{sub 2} gas mixture at a continuous and monotonic increase in temperature from 660 to 830°C. The main YBa{submore » 2}Cu{sub 3}O{sub 7–x} film was grown on the buffer layer surface by pulsed laser deposition in an oxygen medium at a fixed temperature (800°C). The above processes were implemented in different chambers, which were connected by a vacuum channel for transporting samples. Both films were grown in situ, without contacting atmosphere in all growth stages. An X-ray diffraction study has shown that the YBa{sub 2}Cu{sub 3}O{sub 7–x} films are single-crystal and free of precipitates of other phases and domains of other orientations.« less

Preparation and properties of Ba xSr 1- xCo yFe 1- yO 3- δ cathode material for intermediate temperature solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Zhao, Hailei; Shen, Wei; Zhu, Zhiming; Li, Xue; Wang, Zhifeng

Ba xSr 1- xCo yFe 1- yO 3- δ (BSCF) materials with perovskite structure were synthesized via solid-state reaction. Their structural characteristics, electrical-conduction behavior and cathode performance were investigated. Compared to A-site elements, B-site elements show a wide solid-solution range in BSCF. The electrical-conduction behavior of BSCF obeys the small polaron-hopping mechanism. An increase of Ba or Co content in the BSCF samples results in a decrease of electrical conductivity, which is mainly attributable to the preferential existence of B 3+ rather than B 4+ in Ba- or Co-rich samples. At the same time, this leads to increases in the lattice parameter a and the number of oxygen vacancies. BSCF samples with high Ba content show a high structural stability (high oxygen-loss temperature). Ba 0.6Sr 0.4Co 0.8Fe 0.2O 3- δ and Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ materials present good thermal-cycling stability of the electrical conductivity. Compared with Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3- δ, Ba 0.6Sr 0.4Co 0.8Fe 0.2O 3- δ exhibits a better cathode performance in a Ce 0.8Gd 0.2O 2- δ (GDC)-supported half cell. The cell performance can be improved by introducing a certain amount of GDC electrolyte into the BSCF cathode material.

Metallic elements and metalloids in Boletus luridus, B. magnificus and B. tomentipes mushrooms from polymetallic soils from SW China.

PubMed

Falandysz, Jerzy; Zhang, Ji; Wiejak, Anna; Barałkiewicz, Danuta; Hanć, Anetta

2017-08-01

Yunnan Province in China is known for its high biodiversity of mushrooms and a diverse geochemistry of soil bedrock and polymetallic soils, but our knowledge of mineral compositions of mushrooms from Yunnan is scarce. The metallic trace elements, Ag, Ba, Co, Cd, Cs, Cu, Cr, Hg, Li, Mn, Ni, Pb, Rb, Sr, V, Tl, U and Zn, and the metalloids, As and Sb, have been investigated using validated methods with a dynamic reactive cell by mass spectroscopy - inductive coupled plasma and cold vapour - atomic absorption spectroscopy on three popular species of Boletus mushrooms from Southwestern China. The trace mineral profiles in caps and stipes of B. luridus (24 individuals), B. magnificus (29 individuals) and B. tomentipes (38 individuals) have been evaluated. The interspecific differences in the content of several trace elements could be attributed to known differences in the geochemistry of soils in Yunnan, but for copper a difference was observed within species. The mean values of concentrations in composite samples of caps for B. luridus, B. magnificus and B. tomentipes from three to four locations were at the ranges (mgkg -1 dry biomass): Ag (1.3-3.7), As (0.79-53), Ba (4.0-12), Co (0.68-1.2), Cd (0.79-2.2), Cs (0.67-55), Cu (37-77), Cr (5.0-7.6), Hg (2.1-5.4), Li (0.15-0.61), Mn (13-28), Ni (0.86-4.6), Pb (0.59-1.8), Rb (90-120), Sb (0.014-0.088), Sr (0.63-1.6), V (1.4-2.2), Tl (0.017-0.054), U (0.029-0.065) and Zn (130-180). Caps of Boletus mushrooms were richer in Ag, Cu, Hg and Zn than stipes, while other elements were distributed roughly equally between both morphological parts. B. luridus, B. magnificus and B. tomentipes grew in certain sites in Yunnan contained Ag, As, Ba, Cr, Hg, Ni, Sr or V at elevated concentration. A specific geochemistry of the soils type (latosols, lateritic red earths, and red and yellow earths in the Circum-Pacific Mercuriferous Belt of Southwestern China) can explain occurrence of some minerals at greater or elevated amount in mushrooms in Yunnan, while number of available research and data on mineral composition of mushrooms due to geochemical anomalies of soil parent material is so far little. Copyright © 2017 Elsevier Inc. All rights reserved.

Step-by-step thermal transformations of a new porous coordination polymer [(H{sub 2}O){sub 5}CuBa(Me{sub 2}mal){sub 2}]{sub n} (Me{sub 2}mal{sup 2-}=dimethylmalonate): Thermal degradation to barium cuprate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zauzolkova, Natalya, E-mail: zauzolkova@igic.ras.ru; Dobrokhotova, Zhanna; Lermontov, Anatoly

The reactions of CuSO{sub 4}{center_dot}5H{sub 2}O, dimethylmalonic acid and Ba(OH){sub 2}{center_dot}H{sub 2}O (Cu: H{sub 2}Me{sub 2}mal: Ba=1: 2: 2) in aqueous and aqueous-ethanol solutions (H{sub 2}O: EtOH=1: 1) resulted in formation of 3D-porous coordination polymers [(H{sub 2}O){sub 3}({mu}-H{sub 2}O){sub 2}CuBa({mu}{sub 3}-Me{sub 2}mal)(Me{sub 2}mal)]{sub n} (1) and [({mu}-H{sub 2}O)CuBa({mu}{sub 3}-Me{sub 2}mal)({mu}{sub 4}-Me{sub 2}mal)]{sub n} (2), respectively. It has been shown that compound 2 was an intermediate in the thermal degradation of compound 1. Thorough studies of solid-state thermolysis of 1 and 2 allowed to detect formation of coordination polymer [CuBa({mu}{sub 4}-Me{sub 2}mal)({mu}{sub 5}-Me{sub 2}mal)]{sub n} (3), structure of which was determinedmore » by X-ray powder diffraction. It has been found that the channels in polymer 3 were accessible for guest molecules (MeOH). Theoretical estimation of methanol diffusion barrier was carried out. Complete solid-phase thermolysis of 1 and 2 leads to a mixture of BaCuO{sub 2}, BaCO{sub 3}, and CuO. Special conditions for obtaining of a crystalline phase of pure cubic BaCuO{sub 2} were determined. - Graphical abstract: Step-by-step transformation of new coordination polymer [(H{sub 2}O){sub 5}CuBa(Me{sub 2}mal){sub 2}]{sub n} to [(H{sub 2}O)CuBa(Me{sub 2}mal){sub 2}]{sub n} and [CuBa(Me{sub 2}mal){sub 2}]{sub n} were performed. Dehydration of initial compound leads to structural changes of 12-membered ring fragment. All compounds have porous structure. The final product of thermal decomposition is crystalline phase of individual cubic BaCuO{sub 2}. Highlights: Black-Right-Pointing-Pointer New 3D-polymers [(H{sub 2}O){sub 5}CuBa(Me{sub 2}mal){sub 2}]{sub n} and [(H{sub 2}O)CuBa(Me{sub 2}mal){sub 2}]{sub n} were synthesized. Black-Right-Pointing-Pointer Thermal analysis showed step-by-step transformations of [(H{sub 2}O){sub 5}CuBa(Me{sub 2}mal){sub 2}]{sub n}. Black-Right-Pointing-Pointer Crystalline phase of pure cubic BaCuO{sub 2} is the product solid-phase thermolysis.« less

Multivariate Optimization of Conditions for Digestion of Wet Feeds for Dogs and Cats Using a Closed Digester Block and Multielement Determination by ICP-OES.

PubMed

Ávila, Dayara Virgínia Lino; Souza, Sidnei Oliveira; Costa, Silvânio Silvério Lopes; Garcia, Carlos Alexandre Borges; Alves, José do Patrocínio Hora; Araujo, Rennan Geovanny Oliveira; Passos, Elisangela Andrade

2017-09-01

A full 24 factorial design was applied to find the best combination of diluted reagents (HNO3 and H2O2), time, and temperature for the digestion of samples of wet feed for dogs and cats using a closed digestion block. The residual carbon concentration (RCC) was used as the response in the factorial design. All variables and their interactions significantly influenced the digestion of the feed samples, as indicated by the RCC. The conditions established for the digestion of 0.05 g (dry mass) wet feed samples were the addition of 3.0 mol/L HNO3 and 5.0% m/m H2O2 in a final volume of 10 mL, followed by heating in a closed digestion block at a temperature of 170°C for 120 min. Analyses were performed by inductively coupled plasma (ICP) optical emission spectrometry (OES). LOQs ranged from 0.2 μg/g (Mg and Sr) to 51 μg/g (P). Accuracy of the analytical method was confirmed through the analysis of the Standard Reference Materials Tomato Leaves (NIST 1573), Apple Leaves (NIST 1515), and Peach Leaves (NIST 1547). The agreement values achieved ranged from 80.2 ± 0.3% for Ba to 113.8 ± 7.1% for Zn (n = 3). Addition and recovery tests were carried out by adding the analytes to a feed sample at two concentration levels, and the recoveries were between 84 ± 6 and 114 ± 10% for macroelements (Ca, K, Mg, and P; n = 3) and between 88 ± 3 and 113 ± 7% for microelements and trace elements (B, Cu, Fe, Sr, and Zn; n = 3). The precision values achieved for the different elements, expressed as RSDs, were better than 7.3% (Zn; n = 3) except for Cu determination, that was 14.6% (n=3). The optimized analytical method was applied to 10 commercial samples of wet feed for cats and dogs, with the concentrations of Al, B, Ba, Ca, Cu, Fe, K, Mg, Mn, P, Sr, and Zn determined by ICP-OES.

Pulsating aurora induced by upper atmospheric barium releases

NASA Technical Reports Server (NTRS)

Deehr, C.; Romick, G.

1977-01-01

The paper reports the apparent generation of pulsating aurora by explosive releases of barium vapor near 250 km altitude. This effect occurred only when the explosions were in the path of precipitating electrons associated with the visible aurora. Each explosive charge was a standard 1.5 kg thermite mixture of Ba and CuO with an excess of Ba metal which was vaporized and dispersed by the thermite explosion. Traces of Sr, Na, and Li were added to some of the charges, and monitoring was achieved by ground-based spectrophotometric observations. On March 28, 1976, an increase in emission at 5577 A and at 4278 A was observed in association with the first two bursts, these emissions pulsating with roughly a 10 sec period for approximately 60 to 100 sec after the burst.

An improved synthesis and biological evaluation of a new cage-like bifunctional chelator, 4-((8-amino-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane-1-ylamino)methyl)benzoic acid, for 64Cu radiopharmaceuticals.

PubMed

Cai, Hancheng; Li, Zibo; Huang, Chiun-Wei; Park, Ryan; Shahinian, Anthony H; Conti, Peter S

2010-01-01

Stable attachment of (64)Cu(2+) to a targeting molecule usually requires the use of a bifunctional chelator (BFC). Sarcophagine (Sar) ligands rapidly coordinate (64)Cu(2+) within the multiple macrocyclic rings comprising the cage structure under mild conditions, providing high stability in vivo. Previously, we have designed a new versatile cage-like BFC Sar ligand, 4-((8-amino-3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane-1-ylamino)methyl)benzoic acid (AmBaSar), for (64)Cu radiopharmaceuticals. Here we report the improved synthesis of AmBaSar, (64)Cu(2+) labeling conditions and its biological evaluation compared with the known BFC 1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA). The AmBaSar was synthesized in four steps starting from (1,8-diamine-Sar) cobalt(III) pentachloride ([Co(DiAmSar)]Cl(5)) using an improved synthetic method. The AmBaSar was labeled with (64)Cu(2+) in pH 5.0 ammonium acetate buffer solution at room temperature, followed by analysis and purification with HPLC. The in vitro stability of (64)Cu-AmBaSar complex was evaluated in phosphate buffered saline (PBS), fetal bovine serum and mouse blood. The microPET imaging and biodistribution studies of (64)Cu-AmBaSar were performed in Balb/c mice, and the results were compared with (64)Cu-DOTA. The AmBaSar was readily prepared and characterized by MS and (1)H NMR. The radiochemical yield of (64)Cu-AmBaSar was >or=98% after 30 min of incubation at 25 degrees C. The (64)Cu-AmBaSar complex was analyzed and purified by HPLC with a retention time of 17.9 min. The radiochemical purity of (64)Cu-AmBaSar was more than 97% after 26 h of incubation in PBS or serum. The biological evaluation of (64)Cu-AmBaSar in normal mouse demonstrated renal clearance as the primary mode of excretion, with improved stability in vivo compared to (64)Cu-DOTA. The new cage-like BFC AmBaSar was prepared using a simplified synthetic method. The (64)Cu-AmBaSar complex could be obtained rapidly with high radiochemical yield (>/=98%) under mild conditions. In vitro and in vivo evaluation of AmBaSar demonstrated its promising potential for preparation of (64)Cu radiopharmaceuticals. Copyright 2010. Published by Elsevier Inc.

Method of forming superconducting Tl-Ba-Ca-Cu-O films

DOEpatents

Wessels, Bruce W.; Marks, Tobin J.; Richeson, Darrin S.; Tonge, Lauren M.; Zhang, Jiming

1993-01-01

A method of forming a superconducting Tl-Ba-Ca-Cu-O film is disclosed, which comprises depositing a Ba-Ca-Cu-O film on a substrate by MOCVD, annealing the deposited film and heat-treating the annealed film in a closed circular vessel with TlBa.sub.2 Ca.sub.2 Cu.sub.3 O.sub.x and cooling to form said superconducting film of TlO.sub.m Ba.sub.2 Ca.sub.n-1 Cu.sub.n O.sub.2n+2, wherein m=1,2 and n=1,2,3.

The effect of drinking water quality on the health and longevity of people-A case study in Mayang, Hunan Province, China

NASA Astrophysics Data System (ADS)

Lu, J.; Yuan, F.

2017-08-01

Drinking water is an important source for trace elements intake into human body. Thus, the drinking water quality has a great impact on people’s health and longevity. This study aims to study the relationship between drinking water quality and human health and longevity. A longevity county Mayang in Hunan province, China was chosen as the study area. The drinking water and hair of local centenarians were collected and analyzed the chemical composition. The drinking water is weak alkaline and rich in the essential trace elements. The daily intakes of Ca, Cu, Fe, Se, Sr from drinking water for residents in Mayang were much higher than the national average daily intake from beverage and water. There was a positive correlation between Ni and Pb in drinking water and Ni and Pb in hair. There were significant correlations between Cu, K in drinking water and Ba, Ca, Mg, Sr in the hair at the 0.01 level. The concentrations of Mg, Sr, Se in drinking water showed extremely significant positive relation with two centenarian index 100/80% and 100/90% correlation. Essential trace elements in drinking water can be an important factor for local health and longevity.

Structure, luminescence and thermal quenching properties of Eu doped Sr{sub 2−x}Ba{sub x}Si{sub 5}N{sub 8} red phosphors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Y.H.; Chen, L.; Zhou, X.F.

Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were synthesized at 1610 ℃ for 4 h via the solid-state reaction method. The XRD results confirm that the complete solid solutions are formed. With the increase of x, the emission spectra show an obvious blue-shift from 610 nm to 585 nm under the excitation of 460 nm. The color tone can be tuned from yellow to red. The corresponding mechanism for the blue-shift of peak-wavelength is studied in detail. The results of decomposed Gaussian spectra and fluorescence lifetime show that the local coordination structure surrounding activator ions changes with increasingmore » x value. It is found that the probability of Eu occupying Sr1 and Sr2 site is dependent on Ba/Sr ratio. The variation of thermal quenching properties and the corresponding mechanism is discussed in detail. The results indicate that Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} is a promising orange red-emitting phosphor for near UV or blue light-pumped white light-emitting-diodes (wLEDs). - Graphical abstract: Eu{sup 2+} doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} solid solutions were prepared by the solid-state reaction method. The structure, luminescence and thermal quenching properties with varying Ba/Sr ratio were investigated in detail. - Highlights: • The stucture and luminescence properties of Eu doped Sr{sub 2-x}Ba{sub x}Si{sub 5}N{sub 8} phosphors were investigated. • The samples with the intermediate compositions(x=1.0,1.5) show better stability than the end members of both Sr{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+} and Ba{sub 2}Si{sub 5}N{sub 8}:Eu{sup 2+}. • The possible mechanism for the improvement of thermal quenching properties was proposed.« less

II-I2-IV-VI4 (II = Sr,Ba; I = Cu,Ag; IV = Ge,Sn; VI = S,Se): Earth-Abundant Chalcogenides for Thin Film Photovoltaics

NASA Astrophysics Data System (ADS)

Zhu, Tong; Huhn, William P.; Shin, Donghyeop; Mitzi, David B.; Blum, Volker; Saparov, Bayrammurad

Chalcogenides such as CdTe, CIGSSe, and CZTSSe are successful for thin film photovoltaics (PV) but contain elements that are rare, toxic, or prone to the formation of detrimental antisite disorder. Recently, the BaCu2SnS4-xSex system has been shown to offer a prospective path to circumvent these problems. While early prototypes show efficiencies of a few percent, many avenues remain to optimize the materials, including the underlying chemical composition. In this work, we explore 16 compounds II-I2-IV-VI4 to help identify new candidate materials for PV, with predictions based on both known experimental and computationally derived structures that belong to five different space groups. We employ hybrid density functional theory (HSE06) to explore the band gap tunability by substituting different elements, and other characteristics such as the effective mass and the absorption coefficient. Compounds containing Cu (rather than Ag) are found to have direct or nearly direct band gaps. Depending on the compound, replacing S with Se leads to a decrease of the predicted band gaps by 0.2-0.8 eV and to somewhat decreasing hole effective masses.

Changes in the superconducting properties of high-T(sub c) ceramics produced by applied electric fields

NASA Technical Reports Server (NTRS)

Smirnov, B. I.; Orlova, T. S.; Kaufmann, H.-J.

1995-01-01

Effect of an electrostatic field in the electrode-insulator-superconductor system on the current-voltage characteristics of high-T(sub c) ceramics with various composition and different preparation technology has been studied at 77 K. Ceramics of Y-Ba-Cu-O (123) and Bi-Pb-Sr-Ca-Cu-O (2223) systems and also ones doped by Ag have been used. Electric field strength has been up to 140 MV/m. It has been shown that there are reversible changes in the critical current I(sub c) and in the conductivity in electric field at the currents somewhat more than I(sub c) at T is less than T(sub c), while at T is greater than T(sub c) the noticeable electric field effect has not been found. These effects are qualitatively similar in both ceramic systems. High negative and positive gate voltages result in an increase of the conductivity. The electric field effect is modified by magnetic field H. The field effect decreases with increasing magnetic field and disappears at H is greater than 30 Oe. In Y-Ba-Cu-O/Ag (10 wt. percent) ceramics the field effect is practically absent. It may be supposed that in the ceramics the field-induced effect is consistent with weak links at grain boundaries.

Method of Synthesizing a Novel Absorbent Titanosilicate Material (UPRM-5)

NASA Technical Reports Server (NTRS)

Hernandez-Maldonado, Arturo (Inventor); Primera-Pedrozo, Jose N (Inventor)

2013-01-01

A titanium silicate variant named UPRM-5 was prepared using tetraethylammonium hydroxide as a structure-directing agent (SDA). Successful detemplation was achieved via ion exchange with NH4Cl. Effective functionalization was obtained after ion exchanging the detemplated material using SrCl2 and BaCl2. Adsorption of CO2 at 25 deg C in Sr(-) and Ba-UPRM-5 materials activated at different temperatures. For low partial pressures, the observed CO2 adsorption capacities increased as follows: NH4-UPRM-5 less than Sr-UPRM-5 less than Ba-UPRM-5. Both the Sr(-) and Ba-UPRM-5 materials exhibited outstanding selectivity for CO2 over CH4, N2 and O2.

Quantification of chemical elements in blood of patients affected by multiple sclerosis.

PubMed

Forte, Giovanni; Visconti, Andrea; Santucci, Simone; Ghazaryan, Anna; Figà-Talamanca, Lorenzo; Cannoni, Stefania; Bocca, Beatrice; Pino, Anna; Violante, Nicola; Alimonti, Alessandro; Salvetti, Marco; Ristori, Giovanni

2005-01-01

Although some studies suggested a link between exposure to trace elements and development of multiple sclerosis (MS), clear information on their role in the aetiology of MS is still lacking. In this study the concentrations of Al, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, Ni, Pb, Sb, Si, Sn, Sr, Tl, V, W, Zn and Zr were determined in the blood of 60 patients with MS and 60 controls. Quantifications were performed by inductively coupled plasma (ICP) atomic emission spectrometry and sector field ICP mass spectrometry. When the two groups were compared, an increased level of Co, Cu and Ni and a decrement of Be, Fe, Hg, Mg, Mo, Pb and Zn in blood of patients were observed. In addition, the discriminant analysis pointed out that Cu, Be, Hg, Co and Mo were able to discriminate between MS patients and controls (92.5% of cases correctly classified).

Biodistribution and Radiation Dosimetry of the Integrin Marker 64Cu-BaBaSar-RGD2 Determined from Whole-Body PET/CT in a Non-Human Primate

NASA Astrophysics Data System (ADS)

Liu, Shuanglong; Vorobyova, Ivetta; Park, Ryan; Conti, Peter S.

2017-10-01

Introduction: 64Cu-BaBaSar-RGD2 is a positron emission radiotracer taken up by integrin αvβ3, which is overexpressed in many malignancies. The aim of this study was to evaluate the biodistribution of 64Cu-BaBaSar-RGD2 in a non-human primate with positron emission tomography and to estimate the absorbed doses in major organs for human. Materials and methods: Whole-body PET imaging was done in a Siemens Biograph scanner in a male macaque monkey. After an i.v. injection of 13.1–19.7 MBq/kg of 64Cu-BaBaSar-RGD2, whole body scan was collected for a total duration of 180 min. Attenuation and scatter corrections were applied to reconstruction of the whole-body emission scan. After image reconstruction, three-dimensional volumes of interest (VOI) were hand-drawn on the PET transaxial or coronal slices of the frame where the organ was most conspicuous. Time-activity curves for each VOI were obtained, and residence time of each organ was calculated by integration of the time-activity curves. Human absorbed doses were estimated using the standard human model in OLINDA/EXM software. Results: Injection of 64Cu-BaBaSar-RGD2 was well tolerated in the macaque monkey, with no serious tracer-related adverse events observed. 64Cu-BaBaSar-RGD2 was cleared rapidly from the blood pool, with a 12.1-min biological half-time. Increased 64Cu-BaBaSar-RGD2 uptake was observed in the kidneys, and bladder, with mean percentage injected dose (ID%) values at 1 h after injection approximately 35.50 ± 6.47 and 36.89 ± 5.48, respectively. The calculated effective dose was 15.30 ± 2.21 µSv/MBq, and the kidneys had the highest absorbed dose at 108.43 ± 16.41 µGy/MBq using the non-voiding model. For an injected activity of 925 MBq 64Cu for human, the effective dose would be 14.2 ± 2.1 mSv. Discussion: Due to the limitation of the monkey number, we evaluated 64Cu-BaBaSar-RGD2 in the same monkey of three imaging sessions. Measured absorbed doses and effective doses of 64Cu-BaBaSar-RGD2 are comparable to other reported RGD-derived radiopharmaceuticals labeled with 64Cu and 18F. Therefore, 64Cu-BaBaSar-RGD2 can be safely injected into humans for studying integrin αvβ3 expression non-invasively.

Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism.

PubMed

Watanabe, Ryo; Ikushima, Maiko; Mukawa, Kei; Sumomozawa, Fumitaka; Ogo, Shuhei; Sekine, Yasushi

2013-01-01

For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH) to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1 - x SrxFe y Mn1 - y O3 - δ (0 ≤ x ≤ 1, 0.2 ≤ y ≤ 0.8), perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst with that of an industrial potassium promoted iron (Fe-K) catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst showed higher initial activity than the industrial Fe-K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe-K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ and the Fe-K catalysts in a H2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst while the Fe-K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ catalyst had higher potential for activating the steam than the Fe-K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ was superior to that of Fe-K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3 - δ perovskite oxide.

Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

NASA Astrophysics Data System (ADS)

Watanabe, Ryo; Ikushima, Maiko; Mukawa, Kei; Sumomozawa, Fumitaka; Ogo, Shuhei; Sekine, Yasushi

2013-10-01

For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH) to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1-xSrxFeyMn1-yO3-d(0 ≤ x≤ 1, 0.2 ≤ y≤ 0.8), perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst with that of an industrial potassium promoted iron (Fe-K) catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst showed higher initial activity than the industrial Fe-K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe-K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3-d and the Fe-K catalysts in aH2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst while the Fe-K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3-d catalyst had higher potential for activating the steam than the Fe-K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3-d was superior to that of Fe-K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3-d perovskite oxide.

Synthesis of barium and strontium carbonate crystals with unusual morphologies using an organic additive

NASA Astrophysics Data System (ADS)

Chen, Long; Jiang, Jizhong; Bao, Zuben; Pan, Jian; Xu, Weibing; Zhou, Lili; Wu, Zhigang; Chen, Xu

2013-12-01

In this paper, strontium carbonate (SrCO3) and barium carbonate (BaCO3) crystals were synthesized in the presence of an organic additive-hexamethylenetetramine (HMT) using two CO2 sources. Scanning electron microscopy and X-ray powder diffractometry were used to characterize the products. The results showed that the morphologies of orthorhombic strontianite SrCO3 transformed from branch-like to flower-like, and to capsicum-like at last, while the morphologies of BaCO3 change from fiber-like to branchlike, and to rod-like finally with an increase of the molar ratio HMT/Sr2+ and HMT/Ba2+ from 0.2 to 10 using ammonium carbonate as CO2 source. When using diethyl carbonate instead of ammonium carbonate as CO2 source, SrCO3 flowers aggregated by rods and BaCO3 shuttles were formed. The possible formation mechanisms of SrCO3 and BaCO3 crystals obtained in different conditions were also discussed.

Dielectric and Energy Storage Properties of Ba0.65Sr0.35TiO3 Ceramics Modified by BiNbO4

NASA Astrophysics Data System (ADS)

Zheng, Yi; Zhang, Jihua; Wei, Meng; Dong, Xiangxiang; Huang, Jiapeng; Wu, Kaituo; Chen, Hongwei

2018-02-01

(1 - x) (Ba0.65Sr0.35TiO3)-xBiNbO4 (x = 0.0-0.15) ceramic were prepared by solid-state reaction method. The phase composition, microstructure, dielectric properties, polarization-electric field, breakdown strength and energy storage behaviors for the BiNbO4-modified Ba0.65Sr0.35TiO3 ceramics were investigated. With the addition of BiNbO4, the remnant polarization and saturation polarization decreased and the nonlinearity was suppressed. When x = 0.07, the maximum recoverable energy storage achieved was 0.5 J/cm3, 1.5 times that of un-doped Ba0.65Sr0.35TiO3 ceramics, with an efficiency of 96.89% and a breakdown electric field reaching 15.3 kV/mm. Therefore, BiNbO4 doping could improve the energy storage properties of Ba0.65Sr0.35TiO3 for high-energy pulse capacitor application.

BaFe2As2/Fe Bilayers with [001]-tilt Grain Boundary on MgO and SrTiO3 Bicrystal Substrates

NASA Astrophysics Data System (ADS)

Iida, K.; Haindl, S.; Kurth, F.; Hänisch, J.; Schulz, L.; Holzapfel, B.

Co-doped BaFe2As2 (Ba-122) can be realized on both MgO and SrTiO3 bicrystal substrates with [001]-tilt grain boundary by employing Fe buffer layers. However, an additional spinel (i.e. MgAl2O4) buffer between Fe and SrTiO3 is necessary since an epitaxial, smooth surface of Fe layer can not be grown on bare SrTiO3. Both types of bicrystal films show good crystalline quality.

Structural, optoelectronic, and thermoelectric properties of AZn13 (A=Na, K, Ca, Sr, Ba) compounds

NASA Astrophysics Data System (ADS)

Basit, Abdul; Murtaza, G.; Mahmood, Asif; Yar, Abdullah; Muhammad, S.

2016-08-01

We report the structural, electronic, optical, and thermoelectric properties of the five cubic alkali-earth transition-metals AZn13 (A-Na, K, Ca, Sr, Ba) using density functional theory. Structural properties, electronic structures and optical behaviors are calculated explicitly via highly accurate contemporary full potential-linearized augmented plane wave (FP-LAPW) method. The investigated ground state data of these materials is quite close to the experimental information. The modified Becke-Johnson (mBJ) predicts the intermetallic nature of AZn13 (A-Na, K, Ca, Sr, Ba) materials. The complex dielectric function of these intermetallic compounds has been calculated and the observed noticeable peaks are examined through mBJ. With the help of complex dielectric function, the other important optical parameters like reflectivities, conductivities and refractive indices of AZn13 (A-Na, K, Ca, Sr, Ba) have been calculated as a function of energy. The optical response suggests that AZn13 (A-Na, K, Ca, Sr, Ba) compounds can be used for the optoelectronic devices. Further, the thermoelectric properties have been calculated through BoltzTraP program, the calculated values for different thermoelectric parameters recommend that these AZn13 (A-Na, K, Ca, Sr, Ba) materials are the suitable candidates for thermoelectric applications.

Cyclic catalytic upgrading of chemical species using metal oxide materials

NASA Technical Reports Server (NTRS)

White, James H. (Inventor); Schutte, Erick J. (Inventor); Rolfe, Sara L. (Inventor)

2010-01-01

Processes are disclosure which comprise alternately contacting an oxygen-carrying catalyst with a reducing substance, or a lower partial pressure of an oxidizing gas, and then with the oxidizing gas or a higher partial pressure of the oxidizing gas, whereby the catalyst is alternately reduced and then regenerated to an oxygenated state. In certain embodiments, the oxygen-carrying catalyst comprises at least one metal oxide-containing material containing a composition having one of the following formulas: (a) Ce.sub.xB.sub.yB'.sub.zB''O.sub..delta., wherein B=Ba, Sr, Ca, or Zr; B'=Mn, Co, or Fe; B''=Cu; 0.01

Cyclic catalytic upgrading of chemical species using metal oxide materials

DOEpatents

White, James H.; Schutte, Erick J.; Rolfe, Sara L.

2010-11-02

Processes are disclosure which comprise alternately contacting an oxygen-carrying catalyst with a reducing substance, or a lower partial pressure of an oxidizing gas, and then with the oxidizing gas or a higher partial pressure of the oxidizing gas, whereby the catalyst is alternately reduced and then regenerated to an oxygenated state. In certain embodiments, the oxygen-carrying catalyst comprises at least one metal oxide-containing material containing a composition having one of the following formulas: (a) Ce.sub.xB.sub.yB'.sub.zB''O.sub..delta., wherein B=Ba, Sr, Ca, or Zr; B'=Mn, Co, or Fe; B''=Cu; 0.01

Raman study of the thermal stability of HgBa 2CaCu 2O 6+δ and HgBa 2Ca 2Cu 3O 8+δ

NASA Astrophysics Data System (ADS)

Chang, H.; He, Z. H.; Meng, R. L.; Xue, Y. Y.; Chu, C. W.

1995-02-01

We studied the thermal stability of HgBa 2CaCu 2O 6+δ and HgBa 2Ca 2Cu 3O 8+δ at varying laser irradiation power. Each compound has two Raman bands around 570 and 590 cm -1 which are assigned to the vibrations of the interstitial oxygen in HgO δ layers and the apical oxygen in BaO layers, respectively. The 590 cm -1 band shifts position slightly with irradiation, and both the intensity and position of the 570 cm -1 band vary significantly with the laser power. The occupation factor of the interstitial oxygen is sensitive to the annealing temperature. At higher temperatures (550-600°C), both compounds decompose into various (Ba,Cu)-oxides such as Ba 1- xCa xCuO 2.

Imaging plates calibration to X-rays

NASA Astrophysics Data System (ADS)

Curcio, A.; Andreoli, P.; Cipriani, M.; Claps, G.; Consoli, F.; Cristofari, G.; De Angelis, R.; Giulietti, D.; Ingenito, F.; Pacella, D.

2016-05-01

The growing interest for the Imaging Plates, due to their high sensitivity range and versatility, has induced, in the last years, to detailed characterizations of their response function in different energy ranges and kind of radiation/particles. A calibration of the Imaging Plates BAS-MS, BAS-SR, BAS-TR has been performed at the ENEA-Frascati labs by exploiting the X-ray fluorescence of different targets (Ca, Cu, Pb, Mo, I, Ta) and the radioactivity of a BaCs source, in order to cover the X-ray range between few keV to 80 keV.

Skarn-mineralized porphyry adakites in the Harlik arc at Kalatage, E. Tianshan (NW China): Slab melting in the Devonian-early Carboniferous in the southern Central Asian Orogenic Belt

NASA Astrophysics Data System (ADS)

Mao, Qigui; Yu, Mingjie; Xiao, Wenjiao; Windley, Brian F.; Li, Yuechen; Wei, Xiaofeng; Zhu, Jiangjian; Lü, Xiaoqiang

2018-03-01

The geodynamic control of mineralization in the accretionary evolution of the Central Asian Orogenic Belt (CAOB) has long been controversial. Here we report new field, geochemical and geochronological data on recently defined porphyry and skarn-type ore deposits (Devonian-Early Carboniferous) in the Kalatage area in the middle of the Harlik-Dananhu arc, Eastern Tianshan, NW China in the southern CAOB, with the aim of better understanding the accretionary tectonics and genesis of porphyry and skarn-type mineralization. The Yudai porphyry Cu-(Au) deposits and the Xierqu skarn Cu-Fe-(Au) deposits are closely associated with Middle Devonian adakitic diorite porphyries (382-390 Ma), which are calc-alkaline and characterized by high Na2O/K2O ratios and Sr contents (310-1020 ppm), strong depletion of HREE (e.g., Yb = 0.80-1.44 ppm) and Y (7.68-14.50 ppm), and all enriched in Rb, Sr, Ba, K and depleted in Nb and Ti. They are characterized by distinctive Eu positive anomalies, high Na2O contents and MORB-like Sr and Nd isotope signatures (high εNd(t) = +6.1 to +7.0 and low (87Sr/86Sr)i = 0.70412-0.70462). These adakites most likely formed by melting of a young/hot subducted oceanic slab, and adakites in general are important carriers of porphyry Cu ± (Au) deposits. Early Carboniferous adakites in the Tuwu area south of Kalatage are known to have similar features. Therefore, skarn-mineralized porphyry adakites get younger from north to south, suggesting southward migration of the Harlik-Dananhu arc from 390 Ma to 322 Ma. These data indicate that partial melting of hot (and/or young) oceanic crustal slabs were an important mechanism of accretionary crustal growth and mineralization in the southern CAOB.

Eu(2+)-Activated Alkaline-Earth Halophosphates, M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) for NUV-LEDs: Site-Selective Crystal Field Effect.

PubMed

Kim, Donghyeon; Kim, Sung-Chul; Bae, Jong-Seong; Kim, Sungyun; Kim, Seung-Joo; Park, Jung-Chul

2016-09-06

Eu(2+)-activated M5(PO4)3X (M = Ca, Sr, Ba; X = F, Cl, Br) compounds providing different alkaline-earth metal and halide ions were successfully synthesized and characterized. The emission peak maxima of the M5(PO4)3Cl:Eu(2+) (M = Ca, Sr, Ba) compounds were blue-shifted from Ca to Ba (454 nm for Ca, 444 nm for Sr, and 434 nm for Ba), and those of the Sr5(PO4)3X:Eu(2+) (X = F, Cl, Br) compounds were red-shifted along the series of halides, F → Cl → Br (437 nm for F, 444 nm for Cl, and 448 nm for Br). The site selectivity and occupancy of the activator ions (Eu(2+)) in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) crystal lattices were estimated based on theoretical calculation of the 5d → 4f transition energies of Eu(2+) using LCAO. In combination with the photoluminescence measurements and theoretical calculation, it was elucidated that the Eu(2+) ions preferably enter the fully oxygen-coordinated sites in the M5(PO4)3X:Eu(2+) (M = Ca, Sr, Ba; X = F, Cl, Br) compounds. This trend can be well explained by "Pauling's rules". These compounds may provide a platform for modeling a new phosphor and application in the solid-state lighting field.

Preparation of Cu-loaded SrTiO3 nanoparticles and their photocatalytic activity for hydrogen evolution from methanol aqueous solution

NASA Astrophysics Data System (ADS)

Bui, Duc-Nguyen; Mu, Jin; Wang, Lei; Kang, Shi-Zhao; Li, Xiangqing

2013-06-01

Cu-loaded SrTiO3 nanoparticles (Cu-SrTiO3) were prepared using a simple in situ photo-deposition method and their photocatalytic activity for hydrogen evolution from methanol aqueous solution was evaluated. The results characterized with XRD, TEM, XPS and EDX indicated that the as-synthesized sample was composed of metallic Cu and cubic SrTiO3, and the metallic Cu was homogeneously loaded on the surface of SrTiO3 nanoparticles. Under UV light irradiation, Cu-SrTiO3 displayed much higher photocatalytic activity for hydrogen evolution and excellent stability in comparison with pure SrTiO3 nanoparticles. The results further confirmed that the efficient separation of photogenerated electron/hole pairs was critical for the enhanced photocatalytic activity of Cu-SrTiO3. Moreover, the rate of hydrogen evolution of 0.5 wt.% Cu-SrTiO3 is comparable with that of 0.5 wt.% Pt-SrTiO3 photocatalyst under optimum conditions, implying that the metallic Cu is an efficient alternative to Pt as a co-catalyst on SrTiO3. The high photocatalytic activity, low cost and chemical stability mean that the Cu-loaded SrTiO3 is a potential catalyst for the photocatalytic hydrogen evolution from methanol aqueous solution.

Composition and phase analysis of nanocrystalline Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 1.0; 0.6; and 0.4) by using general structure analysis system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gunanto, Y. E., E-mail: yohanes.gunanto@uph.edu; Jobiliong, E., E-mail: eric.jobiliong@uph.edu; Adi, Wisnu Ari, E-mail: dwisnuaa@batan.go.id

2016-03-11

Single phase of nanocrystalline Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 1.0; 0.6; and 0.4) was successfully synthesized by mechanical milling method and thermal process. Stoichiometric quantities of analytical-grade SrCO{sub 3}, BaCO{sub 3}, and Fe{sub 2}O{sub 3}, were mixed and milled using a high-energy milling. The mixture of all precursors was sintered at a temperature of 1000 °C for 10 hours. The refinement of x-ray diffraction trace for all samples confirmed a single phase material with a hexagonal structure. The increase of the amount of strontium content in the barium atoms in the Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} system canmore » decrease the lattice parameter which have been successfully substituted into the barium atoms. The calculation result of cationic distribution showed that the Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 0.6) and (x = 0.4) samples have nominal composition of Ba{sub 0,61}Sr{sub 0,39}Fe{sub 12}O{sub 19} and Ba{sub 0,37}Sr{sub 0,63}Fe{sub 12}O{sub 19}, respectively. Results of the mean of crystallite size evaluation for respective powder materials showed that the Ba{sub x}Sr{sub 1-x}Fe{sub 12}O{sub 19} (x = 1.0; 0.6; and 0.4) samples have the crystallite size of 22 nm, 25 nm and 34 nm, respectively. We concluded that the cationic distribution of barium atoms was successfully substituted by strontium atoms approaching the nominal stoichiometric composition.« less

Superconductivity achieved at over liquid nitrogen temperature by (mixed rare earths)-Ba-Cu oxides

NASA Astrophysics Data System (ADS)

Kishio, Kohji; Kuwahara, Kazuyuki; Kitazawa, Koichi; Fueki, Kazuo; Nakamura, Osamu

1987-05-01

Superconducting oxides were fabricated by reaction of powders of BaCO3, CuO and mixed rare earth (RE) carbonates at compositions expressed as (RE)1Ba2Cu3O(9-y). Two types of incompletely separated raw materials of mixed rare earths, namely, heavy rare earths (HRE) and medium rare earths (MRE), were examined. The zero-resistivity critical temperatures were observed at 92.5 K for the (HRE)-Ba-Cu-O and 85.0 K for the (MRE)-Ba-Cu-O systems, respectively, both of which were well above the boiling point of liquid nitrogen.

Sequentially evaporated thin Y-Ba-Co-O superconducting films on microwave substrates

NASA Technical Reports Server (NTRS)

Valco, G. J.; Rohrer, N. J.; Warner, J. D.; Bhasin, K. B.

1989-01-01

The development of high T sub c superconducting thin films on various microwave substrates is of major interest in space electronic systems. Thin films of YBa2Cu3O(7-Delta) were formed on SrTiO3, MgO, ZrO2 coated Al2O3, and LaAlO3 substrates by multi-layer sequential evaporation and subsequent annealing in oxygen. The technique allows controlled deposition of Cu, BaF2 and Y layers, as well as the ZrO buffer layers, to achieve reproducibility for microwave circuit fabrication. The three layer structure of Cu/BaF2/Y is repeated a minimum of four times. The films were annealed in an ambient of oxygen bubbled through water at temperatures between 850 C and 900 C followed by slow cooling (-2 C/minute) to 450 C, a low temperature anneal, and slow cooling to room temperature. Annealing times ranged from 15 minutes to 5 hrs. at high temperature and 0 to 6 hr. at 450 C. Silver contacts for four probe electrical measurements were formed by evaporation followed with an anneal at 500 C. The films were characterized by resistance-temperature measurements, energy dispersive X-ray spectroscopy, X-ray diffraction, and scanning electron microscopy. Critical transition temperatures ranged from 30 K to 87 K as a function of the substrate, composition of the film, thicknesses of the layers, and annealing conditions. Microwave ring resonator circuits were also patterned on these MgO and LaAlO3 substrates.

A new BaB{sub 2}Si{sub 2}O{sub 8}:Eu{sup 2+}/Eu{sup 3+}, Tb{sup 3+} phosphor - Synthesis and photoluminescence properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saradhi, M.P.; Department of Chemistry, Indian Institute of Technology Hyderabad, Yeddumailaram, Hyderabad - 502205; Laboratoire de Cristallographie et Sciences des Materiaux, ENSICAEN, Universite de Caen, CNRS, 6 Bd Marechal Juin, F-14050 Caen

2010-10-15

In the present work, we have synthesized maleevite mineral phase BaB{sub 2}Si{sub 2}O{sub 8} for the first time, which is isostructural with the pekovite mineral SrB{sub 2}Si{sub 2}O{sub 8}. In these europium doped host lattices, we observed the partial reduction of Eu{sup 3+} to Eu{sup 2+} at high temperature during the synthesis in air. Tb{sup 3+} co-doping in MB{sub 2}Si{sub 2}O{sub 8}:0.01(Eu{sup 3+}/Eu{sup 2+}) [M=Sr, Ba] improves the emission properties towards white light. The emission color varies from bluish white to greenish white under UV lamp excitation when the host cation changes from Sr to Ba. - Graphical abstract: Themore » figure shows structure refinement of both MB{sub 2}Si{sub 2}O{sub 8} [M=Sr, Ba]. The structure refinement of newly synthesized phase BaB{sub 2}Si{sub 2}O{sub 8} was carried out by taking SrB{sub 2}Si{sub 2}O{sub 8} as starting structure model. Inset in the figure shows the structure projection of BaB{sub 2}Si{sub 2}O{sub 8}. The Sr{sup 2+}/Ba{sup 2+} are embedded in polyanionic network formed by corner sharing BO{sub 4}{sup 5-} and SiO{sub 4}{sup 4-} tetrahedral that intern form interconnected layers of 4 and 8 membered rings perpendicular to b-axis.« less

Geochemical signatures in fin rays provide a nonlethal method to distinguish the natal rearing streams of endangered juvenile Chinook Salmon Oncorhynchus tshawytscha in the Wenatchee River, Washington

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linley, Timothy J.; Krogstad, Eirik J.; Nims, Megan K.

Rebuilding fish populations that have undergone a major decline is a challenging task that can be made more complicated when estimates of abundance obtained from physical tags are biased or imprecise. Abundance estimates based on natural tags where each fish in the population is marked can help address these problems, but generally requires that the samples be obtained in a nonlethal manner. We evaluated the potential of using geochemical signatures in fin rays as a nonlethal method to determine the natal tributaries of endangered juvenile spring Chinook Salmon in the Wenatchee River, Washington. Archived samples of anal fin clips collectedmore » from yearling smolt in 2009, 2010 and 2011 were analyzed for Ba/Ca, Mn/Ba, Mg/Ca, Sr/Ca, Zn/Ca and 87Sr/86Sr by inductively coupled plasma mass spectrometry. Water samples collected from these same streams in 2012 were also quantified for geochemical composition. Fin ray and water Ba/Ca, Sr/Ca, and 87Sr/86Sr were highly correlated despite the samples having been collected in different years. Fin ray Ba/Ca, Mg/Ca, Sr/Ca, Zn/Ca and 87Sr/86Sr ratios differed significantly among the natal streams, but also among years within streams. A linear discriminant model that included Ba/Ca, Mg/Ca, Sr/Ca, and 87Sr/86Sr correctly classified 95% of the salmon to their natal stream. Our results suggest that fin ray geochemistry may provide an effective, nonlethal method to identify mixtures of Wenatchee River spring Chinook Salmon for recovery efforts when these involve the capture of juvenile fish to estimate population abundance.« less

Supercritical fluid route for synthesizing crystalline Barium Strontium Titanate nanoparticles.

PubMed

Reverón, H; Elissalde, C; Aymonier, C; Bidault, O; Maglione, M; Cansell, F

2005-10-01

Pure and well-crystallized Barium Strontium Titanate (BST) nanoparticles with controlled Ba/Sr ratio have been successfully synthesized under supercritical conditions using a continuous-flow reactor in the temperature range of 150-380 degrees C at 26 MPa. To synthesize the Ba0.6Sr0.4TiO3 composition, alkoxides, ethanol and water were used. The resulting nanopowder consists of fine particles with an average particle size of 23 nm. The results show that the Ba/Sr ratio of this powder can be accurately controlled from the composition of precursor. The characterization of the as-synthesized Ba0.6Sr0.4TiO3 solid-solution and the dielectric properties of the sintered ceramics are here reported.

Paleozoic tectonic evolution of the Dananhu-Tousuquan island arc belt, Eastern Tianshan: Constraints from the magmatism of the Yuhai porphyry Cu deposit, Xinjiang, NW China

NASA Astrophysics Data System (ADS)

Wang, Yunfeng; Chen, Huayong; Han, Jinsheng; Chen, Shoubo; Huang, Baoqiang; Li, Chen; Tian, Qinglei; Wang, Chao; Wu, Jianxin; Chen, Mingxia

2018-03-01

The Yuhai intrusions (quartz diorite, granite and pyroxene diorite) are located in the eastern part of the Dananhu-Tousuquan island arc belt of the Eastern Tianshan, and associated with the early Paleozoic porphyry Cu mineralization. LA-ICP-MS zircon U-Pb dating yielded emplacement ages of 443.5 ± 4.1 Ma for the quartz diorite, 325.4 ± 2.5 Ma for the granite, and 291 ± 3.0 Ma for the pyroxene diorite. These rocks are tholeiitic to calc-alkaline and metaluminous, with A/CNK values ranging from 0.66 to 1.10. The Silurian ore-bearing Yuhai quartz diorite is rich in LREEs and LILEs (e.g., K, Ba, Pb and Sr), and depleted in HREEs and HFSEs (e.g., Nb, Ta and Ti). These rocks are MgO-rich (1.90-3.80 wt.%; Mg# = 37-72), with high Sr/Y, La/Yb and Ba/Th ratios, positive εNd(t) (6.31-6.84) and εHf(t) (13.26-16.40), low (87Sr/86Sr)i (0.7037-0.7039), and low Nb/U and Ta/U ratios. The data suggest that the quartz diorite was generated by the partial melting of subducted juvenile oceanic slab. The oxygen fugacity (ƒO2) of the quartz diorite, calculated by zircon Ce4+/Ce3+ ratios, is higher than that of the granite and pyroxene diorite, implying that the quartz diorite was more favorable to porphyry Cu mineralization. The Carboniferous Yuhai granite reveals similar geochemical features with the quartz diorite, except for the lower Mg# (27-33), and the more elevated Th/U and Th/La ratios. Furthermore, these rocks also show high εNd(t) (5.2-5.8) and εHf(t) (11.03-14.85) values, and low (87Sr/86Sr)i (0.7036-0.7037). These features indicate that the parental magma of the granite was probably derived from a juvenile lower crust with no significant mantle component involvement. Different from the Yuhai quartz diorite and granite, the early Permian Yuhai pyroxene diorite contains low SiO2 (50.76-55.74 wt.%) and high MgO (3.96-4.33 wt.%; Mg# = 40-44). The εNd(t), εHf(t) and (87Sr/86Sr)i values of the pyroxene diorite are 5.77-6.42, 7.99-12.10 and 0.7035-0.7040, respectively. The pyroxene diorite shows slight enrichments in LREEs ((La/Yb)N = 2.04-2.55), Ba, U, K and Pb, weak depletions in Nb, Ta and Ti, elevated Th/U ratios, and low Ni contents and Ce/Pb ratios. Integrating with the regional tectonic evolution, we suggest that the pyroxene diorite was likely originated from the partial melting of depleted mantle metasomatized by subducted slab-derived fluids. In addition, crustal contamination likely occurred when the pyroxene diorite magma traversed the continental crust. Integrating our new results with published works on the early Paleozoic Dananhu-Tousuquan and Bogeda-Haerlike island arc belts, we propose that the Yuhai quartz diorite may have formed in a subduction setting related to the N-dipping subduction of the North Tianshan oceanic plate. The younger Yuhai granite was likely generated by the bipolar subduction of the North Tianshan oceanic plate, which formed both of the Dananhu-Tousuquan belt to the north and the Aqishan-Yamansu belt to the south. The youngest Yuhai pyroxene diorite was likely formed under a post-collisional extension setting after the Dananhu-Tousuquan and Aqishan-Yamansu belts had collided.

Tuning the growth and strain relaxation of ferroelectric BaTiO3 thin films on SrRuO3 electrode: influence on electrical properties

NASA Astrophysics Data System (ADS)

Aidoud, Amina; Maroutian, Thomas; Matzen, Sylvia; Agnus, Guillaume; Amrani, Bouhalouane; Driss-Khodja, Kouider; Aubert, Pascal; Lecoeur, Philippe

2018-01-01

This study is focused on the link between the structural and electric properties of BaTiO3 thin films grown on SrRuO3-buffered (001) SrTiO3 substrates, SrRuO3 acting as bottom electrode. The growth regime and film structure are here tuned through the growth pressure for pulsed laser deposition in the 1-200 mTorr range. The dielectric, ferroelectric and leakage current properties are systematically measured for the different strain states of the BaTiO3 thin films on SrRuO3. The results are discussed with the help of ab initio calculations on the effects of Ba- and Ti-vacancies on BaTiO3 lattice parameters. A sharp increase of the dielectric constant is evidenced in the high pressure region, where the tetragonality of the BaTiO3 is decreasing rapidly with growth pressure. We interpret this divergence of the dielectric function as the signature of the vicinity of the phase boundary between the out-of-plane and in-plane orientations of the tetragonal BTO films.

The effect of strontium and barium doping on perovskite-structured energy materials for photovoltaic applications

NASA Astrophysics Data System (ADS)

Wu, Ming-Chung; Chen, Wei-Cheng; Chan, Shun-Hsiang; Su, Wei-Fang

2018-01-01

Perovskite solar cell is a novel photovoltaic technology with the superior progress in efficiency and the simple solution processes. Develop lead-free or lead-reduced perovskite materials is a significant concern for high-performance perovskite solar cell. Among the alkaline earth metals, the Sr2+ and Ba2+ are suitable for Pb2+ replacement in perovskite film due to fitting Goldschmidt's tolerance factor. In this study, we adopted Ba-doped and Sr-doped perovskite structured materials with different doping levels, including 1.0, 5.0, and 10.0 mol%, to prepare perovskite solar cells. Both Ba-doped and Sr-doped perovskite structured materials have a related tendency in absorption behavior and surface morphology. At 10.0 mol% doping level, the power conversion efficiency (PCE) of Sr-doped perovskite solar cells is only ∼0.5%, but the PCE of Ba-doped perovskite solar cells can be achieved to ∼9.7%. Ba-doped perovskite solar cells showed the acceptable photovoltaic characteristics than Sr-doped perovskite solar cells. Ba dopant can partially replace the amount of lead in the perovskite solar cells, and it could be a potential candidate in the field of lead-free or lead-reduced perovskite energy materials.

Grain orientation in high Tc superconductors by molten salt powder synthesis

NASA Technical Reports Server (NTRS)

Gopalakrishnan, Sudhakar; Schulze, Walter A.

1991-01-01

The molten salt or the flux method is used to fabricate a grain oriented YBa2Cu3O(7-x) (123) superconductor. Here we suggest a two-stage approach in using the 'green phase', Y2BaCuO5 (211), as seed crystals in the formation of YBa2Cu3O(7-x). The process uses Y2BaCuO5 formed by molten salt synthesis. The Y2BaCuO5 phase was observed to be stable in water and in most of the salt systems. Salt processing can form a small quantity of anisotropic particles of Y2BaCuO5. This material can form the 123 phase when tape cast and sintered in the presence of the required levels of Ba and Cu.

Ternary and quaternary oxides of Bi, Sr and Cu

NASA Technical Reports Server (NTRS)

Casais, M. T.; Millan, P.; Rasines, I.; Campa, J. A.

1991-01-01

Before the discovery of superconductivity in an oxide of Bi, Sr, and Cu, the system Bi-Sr-Cu-O had not been studied, although several solid phases had been identified in the two-component regions of the ternary system Bi2O3-Si-O-CuO. The oxides Sr2CuO3, SrCu2O2, SrCuO2, and Bi2CuO4 were then well known and characterized, and the phase diagram of the binary system Bi2O3-SrO had been established in the temperature range 620 to 1000 C. Besides nine solutions of compositions Bi(2-2x) Sr(x) O(3-2x) and different symmetries, this diagram includes three definite compounds of stoichiometries Bi(2)BrO4. Bi2Sr2O5, and Bi2Sr3O6 (x - 0.50, 0.67 and 0.75 respectively), only the second of which with known unit-cell of orthorhombic symmetry, dimensions (A) a = 14.293(2), b = 7.651(2), c = 6.172(1), and z = 4. The first superconducting oxide in the system Bi-Sr-Cu-O was initially formulated as Bi2Sr2Cu2O(7+x), with an orthorhombic unit-cell of parameters (A) a = 5.32, b = 26.6, c = 48.8. In a preliminary study the same oxide was formulated with half the copper content, Bi(2)Sr(2)CuO(6+x), and index its reflections assuming an orthorhombic unit-cell of dimensions (A) a = 5.390(2), b = 26.973(8), c = 24.69(4). Subsequent studies by diffraction techniques have confirmed the composition 2:2:1. A new family of oxygen-deficient perovskites, was characterized, after identifying by x ray diffraction the phases present in the products of thermal treatments of about 150 mixtures of analytical grade Bi2O3, Sr(OH)2-8H2O and CuO at different molar ratios. X ray diffraction data are presented for some other oxides of Bi and Sr, as well as for various quaternary oxides, among them an oxide of Bi, Sr, and Cu.

Chemical composition of modern and fossil hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

2012-11-01

This study demonstrates that alkaline earth elements in enamel of hippopotamids, in particular Ba and Sr, are tracers for water provenance and hydrochemistry in terrestrial settings. The studied specimens are permanent premolar and molar teeth found in modern and fossil lacustrine sediments of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by two orders of magnitude for Ba (120-9336 μg g-1) as well as for Sr (9-2150 μg g-1). The variations are partially induced during post-mortem alteration and during amelogenesis, but the major contribution originates ultimately from the variable water chemistry in the habitats of the hippopotamids which is controlled by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of MgO, Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.9. These elements are well correlated in single specimens, thus suggesting that their distribution is determined by a common, single process, which can be described by closed system Rayleigh crystallization of bioapatite in vivo. Enamel from most hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores. However, Ba/Sr ranges from 0.1 to 3 and varies on spatial and temporal scales. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic mantle rocks or Archean crustal rocks as the ultimate sources of Sr and Ba. This provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from 2 to 0.5. This trend can be correlated with changes in climate from humid to arid, in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that Ba mobility decreased with increasing aridification due to preferential deposition with clay and Fe-oxide-hydroxide or barite on the watershed of Lake Albert.

Selectivity in biomineralization of barium and strontium.

PubMed

Krejci, Minna R; Wasserman, Brian; Finney, Lydia; McNulty, Ian; Legnini, Daniel; Vogt, Stefan; Joester, Derk

2011-11-01

The desmid green alga Closterium moniliferum belongs to a small number of organisms that form barite (BaSO(4)) or celestite (SrSO(4)) biominerals. The ability to sequester Sr in the presence of an excess of Ca is of considerable interest for the remediation of (90)Sr from the environment and nuclear waste. While most cells dynamically regulate the concentration of the second messenger Ca(2+) in the cytosol and various organelles, transport proteins rarely discriminate strongly between Ca, Sr, and Ba. Herein, we investigate how these ions are trafficked in C. moniliferum and how precipitation of (Ba,Sr)SO(4) crystals occurs in the terminal vacuoles. Towards this goal, we simultaneously visualize intracellular dynamics of multiple elements using X-ray fluorescence microscopy (XFM) of cryo-fixed/freeze-dried samples. We correlate the resulting elemental maps with ultrastructural information gleaned from freeze-fracture cryo-SEM of frozen-hydrated cells and use micro X-ray absorption near edge structure (micro-XANES) to determine sulfur speciation. We find that the kinetics of Sr uptake and efflux depend on external Ca concentrations, and Sr, Ba, and Ca show similar intracellular localization. A highly ion-selective cross-membrane transport step is not evident. Based on elevated levels of sulfate detected in the terminal vacuoles, we propose a "sulfate trap" model, where the presence of dissolved barium leads to preferential precipitation of (Ba,Sr)SO(4) due to its low solubility relative to SrSO(4) and CaSO(4). Engineering the sulfate concentration in the vacuole may thus be the most direct way to increase the Sr sequestered per cell, an important consideration in using desmids for phytoremediation of (90)Sr. Copyright © 2011 Elsevier Inc. All rights reserved.

Low-resistance noble metal contacts to high-temperature superconductors

NASA Technical Reports Server (NTRS)

Selim, R.; Caton, R.; Buoncristiani, A. M.; Byvik, C. E.; Edahl, R. A., Jr.

1990-01-01

Low-resistance contacts were made to both YBa2Cu3O(7-x) and Bi2BaSr2Cu2O8, and to related superconducting compounds by melting gold or silver pads onto the samples before the final oxygen treatment. Scanning electron microscope studies show that both gold and silver do not diffuse far from the contact area. The surface contact resistivity of the best contacts made by the melting technique has an upper limit value in the 10 to the -8th ohm sq cm range at 77 K. This contact resistivity shows no significant change in its value over a period of 17 months. Furthermore, an electron radiation dose of 5.7 x 10 to the 17th electron/sq cm only doubled the contact resistivity.

Structure refinement of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-d} as cathode materials for intermediate temperature solid oxide fuel cells (IT-SOFC)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zakaria, Nurhamidah, E-mail: nurhamidahzakaria@yahoo.com; Idris, Mohd Sobri, E-mail: sobri@unimap.edu.my; Osman, Rozana A. M., E-mail: rozana@unimap.edu.my

2016-07-19

Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} was successfully prepared using modified solid-state synthesis routes. The lowest temperature to obtained single phase of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} is about 900°C for 15 hours. Longer period of time are required compared to only 5 hours at 950°C as established in literatures. The X-ray Diffraction (XRD) data confirmed that Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} is formed a cubic perovskite with the space group of Pm-3m. The lattice parameters of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} are a = 3.990 (1) Å and unit cell volume is V = 63.5 (1)more » Å{sup 3}. The Rietveld refinement of XRD data revealed that the crystal structure of Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-δ} slightly changes as a function of temperature.« less

Multielemental analysis of 20 mushroom species growing near a heavily trafficked road in Poland.

PubMed

Mleczek, M; Niedzielski, P; Kalač, P; Budka, A; Siwulski, M; Gąsecka, M; Rzymski, P; Magdziak, Z; Sobieralski, K

2016-08-01

The aim of this work was to compare 10 mostly edible aboveground and 10 wood-growing mushroom species collected near a heavily trafficked road (approximately 28,000 vehicles per 24 h) in Poland with regard to their capacity to accumulate 26 trace elements (Ag, Al, As, Au, B, Ba, Bi, Cd, Co, Cr, Cu, Fe, Ga, Ge, In, Li, Mn, Ni, Pb, Re, Sb, Se, Sr, Te, Tl, and Zn) in their fruit bodies in order to illustrate mushroom diversity in element accumulation. All analyses were performed using an inductively coupled plasma optical emission spectrometry (ICP-OES) spectrometer in synchronous dual view mode. The aboveground species had significantly higher levels of 12 elements, including Ag, As, Pb, and Se, compared to the wood-growing species. An opposite relationship was observed only for Au, Ba, and Sr. The results of principal component analysis (PCA) and hierarchical cluster analysis (HCA) implied some new relationships among the analyzed species and elements. Of the analyzed mushroom species, lead content in Macrolepiota procera would seem to pose a health risk; however, at present knowledge regarding lead bioaccessibility from mushrooms is quite limited.

Improvement of a sample preparation procedure for multi-elemental determination in Brazil nuts by ICP-OES.

PubMed

Welna, Maja; Szymczycha-Madeja, Anna

2014-04-01

Various sample preparation procedures, such as common wet digestions and alternatives based on solubilisation in aqua regia or tetramethyl ammonium hydroxide, were compared for the determination of the total Ba, Ca, Cr, Cd, Cu, Fe, Mg, Mn, Ni, P, Pb, Se, Sr and Zn contents in Brazil nuts using inductively coupled plasma optical emission spectrometry (ICP-OES). For measurement of Se, a hydride generation technique was used. The performance of these procedures was measured in terms of precision, accuracy and limits of detection of the elements. It was found that solubilisation in aqua regia gave the best results, i.e. limits of detection from 0.60 to 41.9 ng ml(-1), precision of 1.0-3.9% and accuracy better than 5%. External calibration with simple standard solutions could be applied for the analysis. The proposed procedure is simple, reduces sample handling, and minimises the time and reagent consumption. Thus, this can be a vital alternative to traditional sample treatment approaches based on the total digestion with concentrated reagents. A phenomenon resulting from levels of Ba, Se and Sr in Brazil nuts was also discussed.

Metal concentrations in aquatic environments of Puebla River basin, Mexico: natural and industrial influences.

PubMed

Morales-García, S S; Rodríguez-Espinosa, P F; Shruti, V C; Jonathan, M P; Martínez-Tavera, E

2017-01-01

The rapid urban expansion and presence of volcanoes in the premises of Puebla River basin in central Mexico exert significant influences over its aquatic environments. Twenty surface sediment samples from Puebla River basin consisting of R. Alseseca, R. Atoyac, and Valsequillo dam were collected during September 2009 and analyzed for major (Al, Fe, Mg, Ba, Ca, and K) and trace elements (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, V, and Zn) in order to identify the metal concentrations and their enrichment. R. Atoyac sediments presented higher concentrations of Ba (1193.8 μg g -1 ) and Pb (27.1 μg g -1 ) in comparison with the local reference sample values. All the metal concentrations except Sr for R. Alseseca sediments were within the range of local reference sample values indicating no significant external influence, whereas Valsequillo dam sediments had elevated concentrations of all the metals suggesting both natural and external influences in the study region. The magnitude of metal contamination was assessed using several indices such as geoaccumulation index (I geo ), enrichment factor (EF), degree of contamination (C d ), and pollution load index (PLI). The results suggest that As, Pb, and Zn were predominantly enriched in the Puebla River basin sediments. Comparing with sediment quality guidelines and ecotoxicological values, it is revealed that Cd, Cr, Cu, and Ni have possible harmful effects on the biological community. The present study provides an outlook of metal enrichment in Puebla River basin sediments, highlighting the necessity to conserve this river ecosystem for the near future.

Lanthanoid-free perovskite oxide catalyst for dehydrogenation of ethylbenzene working with redox mechanism

PubMed Central

Watanabe, Ryo; Ikushima, Maiko; Mukawa, Kei; Sumomozawa, Fumitaka; Ogo, Shuhei; Sekine, Yasushi

2013-01-01

For the development of highly active and robust catalysts for dehydrogenation of ethylbenzene (EBDH) to produce styrene; an important monomer for polystyrene production, perovskite-type oxides were applied to the reaction. Controlling the mobility of lattice oxygen by changing the structure of Ba1 − xSrxFeyMn1 − yO3 − δ (0 ≤ x ≤ 1, 0.2 ≤ y ≤ 0.8), perovskite catalyst showed higher activity and stability on EBDH. The optimized Ba/Sr and Fe/Mn molar ratios were 0.4/0.6 and 0.6/0.4, respectively. Comparison of the dehydrogenation activity of Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst with that of an industrial potassium promoted iron (Fe–K) catalyst revealed that the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst showed higher initial activity than the industrial Fe–K oxide catalyst. Additionally, the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst showed high activity and stability under severe conditions, even at temperatures as low as 783 K, or at the low steam/EB ratio of 2, while, the Fe–K catalyst showed low activity in such conditions. Comparing reduction profiles of the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ and the Fe–K catalysts in a H2O/H2 atmosphere, reduction was suppressed by the presence of H2O over the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst while the Fe–K catalyst was reduced. In other words, Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ catalyst had higher potential for activating the steam than the Fe–K catalyst. The lattice oxygen in perovskite-structure was consumed by H2, subsequently the consumed lattice oxygen was regenerated by H2O. So the catalytic performance of Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ was superior to that of Fe–K catalyst thanks to the high redox property of the Ba0.4Sr0.6Fe0.6Mn0.4O3 − δ perovskite oxide. PMID:24790949

High pressure synthesis and magnetic studies of quasi one dimensional systems Sr(n-1)Cu(n+1)O(2n) (n=3,5)

NASA Technical Reports Server (NTRS)

Azuma, M.; Hiroi, Z.; Takano, M.; Ishida, K.; Kitaoka, Y.

1995-01-01

SrCu2O3 and Sr2Cu3O5 containing two-leg and three-leg S = 1/2 ladders made of antiferromagnetic Cu-O-Cu linear bonds, respectively, were synthesized at high pressure, and their crystallographic and magnetic properties were investigated. Both susceptibility and T(1) data of NMR (nuclear magnetic resonance) revealed the existence of a large spin gap only for SrCu2O3. Superconductivity, which had been predicted theoretically for carrier-doped SrCu2O3 could not be realized although partial substitution of La(3+) for Sr(2+) seemed to be carried out successfully. Electron carriers injected seems to remain localized.

Fabrication of single domain GdBCO bulk superconductors by a new modified TSIG technique

NASA Astrophysics Data System (ADS)

Yang, W. M.; Zhi, X.; Chen, S. L.; Wang, M.; Li, J. W.; Ma, J.; Chao, X. X.

2014-01-01

Single domain GdBCO bulk superconductors have been fabricated with new and traditional solid phases by a top seeded infiltration and growth (TSIG) process technique. In the conventional TSIG process, three types of powders, such as Gd2BaCuO5, GdBa2Cu3O7-x and Ba3Cu5O8, must be prepared, but in our new modified TSIG technique, only BaCuO2 powders are required during the fabrication of the single domain GdBCO bulk superconductors. The solid phase used in the conventional process is Gd2BaCuO5 instead of the solid phase (Gd2O3 + BaCuO2) utilized in the new process. The liquid phase used in the conventional process is a mixture of (GdBa2Cu3O7-x + Ba3Cu5O8), and the liquid phase in the new process is a mixture of (Gd2O3 + 10BaCuO2 + 6CuO). Single domain GdBCO bulk superconductors have been fabricated with the new solid and liquid phases. The levitation force of the GdBCO bulk samples fabricated by the new solid phase is 28 N, which is slightly higher than that of the samples fabricated using the conventional solid phases (26 N). The microstructure and the levitation force of the samples indicate that this new method can greatly simplify the fabrication process, introduce nanometer-sized flux centers, improve the levitation force and working efficiency, and greatly reduce the cost of fabrication of single domain GdBCO bulk superconductors by the TSIG process.

Crystallographic Study of Mixture CeBa1.8Pb0.2Cu3Oy in the Range of 860°C to 940 °C

NASA Astrophysics Data System (ADS)

Stergiou, A.; Yilmaz, S.; Stergiou, C.

2007-04-01

A powder mixture with chemical formula CeBa1.8Pb0.2Cu3Oy was prepared. The mixture was heated in free atmosphere, at temperatures 860°C to 940°C, for 24 to 72h. The samples were measured by X-Ray powder diffraction with CuKa radiation. Each sample was characterized with the help of the PDF and refined, using the Rietveld's ``Powder Profile Analysis''. The first sample (860°C) was identified with the phases: Ba2CeBiO6, CuO and BaCuO2, while all the remaining samples (870°C-940°C) with the phases Ba2CePbO6, CuO and CeO2. The phases Ba2CeBiO6 and Ba2CePbO6 are the main phases with analogous chemical types, but different symmetry. The phase CuO is common in all the samples, while from the remaining phases the BaCuO2 appears only in the first sample and the CeO2 in all, except the first one. The quantity 0.2 of Pb is distributed in the Ba positions, substituting a part of these. The percentages of phases are about 82%, 10% and 8% for the first sample and for all the remaining about 85%, 8% and 7%, respectively with above serious.

A first principles study on newly proposed (Ca/Sr/Ba)Fe2Bi2 compounds with their parent compounds

NASA Astrophysics Data System (ADS)

Sundareswari, M.; Jayalakshmi, D. S.; Viswanathan, E.

2016-02-01

The structural, electronic, bonding and magnetic properties of newly proposed iron-based compounds viz., CaFe2Bi2, SrFe2Bi2, BaFe2Bi2 with their Fermi surface topology are reported here for the first time by means of first principles calculation. All these properties of newly proposed compounds are compared and analysed along with their respective parent compounds namely (Ca,Sr,Ba)Fe2As2.

Aluminum/alkaline earth metal composites and method for producing

DOEpatents

Russell, Alan M; Anderson, Iver E; Kim, Hyong J; Freichs, Andrew E

2014-02-11

A composite is provided having an electrically conducting Al matrix and elongated filaments comprising Ca and/or Sr and/or Ba disposed in the matrix and extending along a longitudinal axis of the composite. The filaments initially comprise Ca and/or Sr and/or Ba metal or allow and then may be reacted with the Al matrix to form a strengthening intermetallic compound comprising Al and Ca and/or Sr and/or Ba. The composite is useful as a long-distance, high voltage power transmission conductor.

Yttrium enrichment and improved magnetic properties in partially melted Y-Ba-Cu-O materials

NASA Technical Reports Server (NTRS)

Alterescu, Sidney; Hojaji, Hamid; Barkatt, Aaron; Michael, Karen A.; Hu, Shouxiang

1990-01-01

The yttrium-rich compositions in the Y-Ba-Cu-O system were mapped out in a systematic manner to quantify their magnetic properties and to correlate them with the microstructure and phase composition as determined by scanning electron microscopy and X-ray diffraction analysis. It is found that the microstructure of Y-Ba-Cu-O compositions is a sensitive function of both their composition and processing conditions. Measurements of magnetic susceptibility and maximum (low-field) and remanent magnetization for the system Y:Ba:Cu = x:2:3 show highest values for x = 2. The corresponding structures involve numerous small crystals of Y2BaCuO5 (211) embedded in highly ordered assemblages of continous YBa2Cu3O(7-y) (123) layers.

Investigations of Ba{sub x}Sr{sub 1−x}TiO{sub 3} ceramics and powders prepared by direct current arc discharge technique

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Shuangbin; Wang, Xiaohan; University of Chinese Academy of Sciences, Beijing 100049

2014-09-01

Ba{sub x}Sr{sub 1−x}TiO{sub 3} ceramics with x ranging from 0 to 1 were prepared by direct current arc discharge technique and studied by means of x-ray diffraction (XRD) and Raman spectroscopy. The cubic-tetragonal ferroelectric phase transition in Ba{sub x}Sr{sub 1−x}TiO{sub 3} ceramics was found to occur at x ≈ 0.75. XRD investigation of as-grown BaTiO{sub 3} ceramics revealed co-existence of tetragonal and hexagonal modifications with a small amount of impurity phase BaTi{sub 4}O{sub 9}. No evidences of hexagonal phase were observed in Raman spectra of as-grown BaTiO{sub 3} ceramics, while Raman peaks related to hexagonal phase were clearly observed in the spectrummore » of fine-grain powders prepared from the same ceramics. A core-shell model for BaTiO{sub 3} ceramics prepared by direct current arc discharge technique is proposed. Absence of the hexagonal phase in any Ba{sub x}Sr{sub 1−x}TiO{sub 3} solid solution with x < 1 is discussed in the frame of specific atomic arrangement.« less

Antiferromagnetism in semiconducting SrMn2Sb2 and BaMn2Sb2 single crystals

NASA Astrophysics Data System (ADS)

Sangeetha, N. S.; Smetana, V.; Mudring, A.-V.; Johnston, D. C.

2018-01-01

Crystals of SrMn2Sb2 and BaMn2Sb2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ , heat capacity Cp, and magnetic susceptibility χ measurements versus temperature T , and magnetization versus field M (H ) isotherm measurements. SrMn2Sb2 adopts the trigonal CaAl2Si2 -type structure, whereas BaMn2Sb2 crystallizes in the tetragonal ThCr2Si2 -type structure. The ρ (T ) data indicate semiconducting behaviors for both compounds with activation energies of ≳0.35 eV for SrMn2Sb2 and 0.16 eV for BaMn2Sb2 . The χ (T ) and Cp(T ) data reveal antiferromagnetic (AFM) ordering at TN = 110 K for SrMn2Sb2 and 450 K for BaMn2Sb2 . The anisotropic χ (T ≤TN) data also show that the ordered moments in SrMn2Sb2 are aligned in the hexagonal a b plane, whereas the ordered moments in BaMn2Sb2 are aligned collinearly along the tetragonal c axis. The a b -plane M (H ) data for SrMn2Sb2 exhibit a continuous metamagnetic transition at low fields 0

Assessment of trace metal levels in size-resolved particulate matter in the area of Leipzig

NASA Astrophysics Data System (ADS)

Fomba, Khanneh Wadinga; van Pinxteren, Dominik; Müller, Konrad; Spindler, Gerald; Herrmann, Hartmut

2018-03-01

Size-resolved trace metal concentrations at four sites in Leipzig (Germany) and its surrounding were assessed between the winter of 2013 and the summer of 2015. The measurements were performed in parallel at; traffic dominated (Leipzig - Mitte, LMI), traffic and residential dominated (Eisenbahnstrasse, EIB), urban background (TROPOS, TRO) and regional background (Melpitz, MEL) sites. In total, 19 trace metals, i.e. K, Ca, Ti, Mn, Fe, Cu, Zn, As, Se, Ba, V, Pb, Ni, Cr, Sr, Sn, Sb, Co and Rb were analysed using total reflection x-ray fluorescence (TXRF). The major metals were Fe, K and Ca with concentrations ranging between; 31-440 ng/m3, 42-153 ng/m3 and 24-322 ng/m3, respectively, while the trace metals with the lowest concentrations were Co, Rb and Se with concentrations of; < 0.3 ng/m3, <0.5 ng/m3 and 0.5-0.7 ng/m3, respectively. PM10 trace metal concentrations during easterly air mass inflow especially at the background sites were in average 70% higher in the winter and 30% higher in the summer in comparison to westerly air mass inflow. Traffic at LMI contributed to about 75% of Cr, Ba, Cu, Sb, Sn, Ca, Co, Mn, Fe and Ti concentrations while regional activities contributed to more than 70% of K, Rb, Pb, Se, As and V concentrations. Traffic dominated trace metals were often observed in the coarse mode while the regional background dominated trace metals were often observed in the fine mode. Trace metal sources were related to crustal matter and road dust re-suspension for metals such as Ca, Fe, Co, Sr, and Ti, brake and tire wear (Cu, Sb, Ba, Fe, Zn, Pb), biomass burning (K, Rb), oil and coal combustion (V, Zn, As, Pb). Crustal matter contributed 5-12% in winter and 8-19% in summer of the PM10 mass. Using Cu and Zn as markers for brake and tire wear, respectively, the estimated brake and tire wear contributions to the PM10 mass were 0.1-0.8% and 1.7-2.9%, respectively. The higher contributions were observed at the traffic sites while the lower contributions were observed at the regional background site. In total, non-exhaust emissions could account for about 10-22% of the PM10 mass in the summer and about 7-15% of the PM10 mass in the winter.

Partial-melting of fertile metasedimentary rocks controlling the ore formation in the Jiangnan porphyry-skarn tungsten belt, south China: A case study at the giant Zhuxi W-Cu skarn deposit

NASA Astrophysics Data System (ADS)

Song, Shiwei; Mao, Jingwen; Zhu, Yongfeng; Yao, Zaiyu; Chen, Guohua; Rao, Jianfeng; Ouyang, Yongpeng

2018-04-01

The Zhuxi W-Cu deposit, located in the Jiangnan porphyry-skarn W belt, is a world-class W deposit. We studied three coeval mineralization-related intrusions composed of biotite monzogranite, fine-grained granite, and granite porphyry in the Zhuxi mine. These rocks contain peritectic garnet and K-feldspar. The LA-ICP-MS U-Pb dating of zircon from the biotite monzogranite, fine-grained granite, and granite porphyry yields average ages of 149.38 ± 0.86 Ma, 149.0 ± 1.0 Ma, and 148.30 ± 1.4 Ma, respectively. The Zhuxi granites are enriched in Cs, Rb, and U and depleted in Ba, Sr, and Ti, with ASI [molar Al2O3 / (CaO + Na2O + K2O)] values of 1.03-2.15. The fine-grained granite exhibits initial 87Sr/86Sr values of 0.716-0.717 and εNd(t) values ranging from -9.61 to -9.21. The εHf(t) values of the biotite monzogranite and fine-grained granite range from -8.83 to -6.30 and from -9.86 to -7.62, respectively. The Sr-Nd-Hf isotopic compositions of these rocks are similar to those of the fertile Neoproterozoic metasedimentary rocks in the Jiangnan W belt. The Zhuxi granites are S-type granites based on their mineral assemblages and geochemical characteristics. The Hf isotopic compositions, Sr-Nd isotopic characteristics, and trace element modelling suggest that the studied granites formed from the dehydration melting of fertile Neoproterozoic metasedimentary rocks caused by the Late Jurassic underplating of OIB-like basaltic magma.

Spatial Variations and Sources of Trace Elements in Recent Snow from Glaciers at the Tibetan Plateau

NASA Astrophysics Data System (ADS)

Huang, J.; Li, Y.; Li, Z.; Cozzi, G.; Turetta, C.; Barbante, C.; Xiong, L.

2017-12-01

Various trace element (TEs) could be long-range transported through the atmosphere and deposited onto the snow surface. Recently, with the development of economy of China and the surrounding countries, TEs such as Pb, Cd, Mo and Sb in several glaciers from the Tibetan Plateau (TP) have been gradually affected by anthropogenic activities. This study presents the acid leached concentrations of TEs (e.g., Al, As, Ba, Co, Cr, Cs, Cu, Fe, Li, Mn, Mo, Pb, Rb, Sb, Sr, Ti, Tl, U, V) and dust content sampled from Qiumianleike (QMLK), Meikuang (MK), Yuzhufeng (YZF), Xiaodongkemadi (XDKMD), Gurenhekou (GRHK) glaciers on the TP from April to May of 2013. The different concentrations of TEs in the surface snow and snow pit samples over the five glaciers show that TEs were influenced both by surrounding environment of glaciers and seasonal variations of atmospheric impurity loading. Comparison of TEs concentrations with data of other sites, elevated concentrations of As, Cu, Mo, Pb and Sb were observed in glaciers of TP, showing significant atmospheric TEs pollution. Enrichment factor(EF) analysis indicates that Rb, V, U, Cr, Ba, Cs, Li, As, Co, Mn, Tl, Sr and Cu mainly originated from crustal dust, while anthropogenic inputs such as nonferrous metals melting, coal combustion and traffic emission made an important contribution to the Mo, Pb and Sb. Evidences from air mass back trajectories show the air masses arrived at QMLK mostly came from the Taklimakan desert, the TEs from the Taklimakan desert and the western TP could be transported to the MK and YZF glaciers . The air masses derived from the western TP and the southwestern TP affected the environment of the XDKMD and GRHK glaciers. Futhermore, the air masses passed through some big cities with developed industry and large population such as Urumqi, Bishkek, Dushanbe and some countries such as Pakistan and India could also bring pollutants to the studied glaciers.

[Distribution Characteristics and Source Analysis of Dustfall Trace Elements During Winter in Beijing].

PubMed

Xiong, Qiu-lin; Zhao, Wen-ji; Guo, Xiao-yu; Chen, Fan-tao; Shu, Tong-tong; Zheng, Xiao-xia; Zhao, Wen-hui

2015-08-01

The dustfall content is one of the evaluation indexes of atmospheric pollution. Trace elements especially heavy metals in dustfall can lead to risks to ecological environment and human health. In order to study the distribution characteristics of trace elements, heavy metals pollution and their sources in winter atmospheric dust, 49 dustfall samples were collected in Beijing City and nearby during November 2013 to March 2014. Then the contents (mass percentages) of 40 trace elements were measured by Elan DRC It type inductively coupled plasma mass (ICP-MS). Test results showed that more than half of the trace elements in the dust were less than 10 mg x kg(-1); about a quarter were between 10-100 mg x kg-1); while 7 elements (Pb, Zr, Cr, Cu, Zn, Sr and Ba) were more than 100 mg x kg(-1). The contents of Pb, Cu, Zn, Bi, Cd and Mo of winter dustfall in Beijing city.were respectively 4.18, 4.66, 5.35, 6.31, 6.62, and 8.62 times as high as those of corresponding elements in the surface soil in the same period, which went beyond the soil background values by more than 300% . The contribution of human activities to dustfall trace heavy metals content in Beijing city was larger than that in the surrounding region. Then sources analysis of dustfall and its 20 main trace elements (Cd, Mo, Nb, Ga, Co, Y, Nd, Li, La, Ni, Rb, V, Ce, Pb, Zr, Cr, Cu, Zn, Sr, Ba) was conducted through a multi-method analysis, including Pearson correlation analysis, Kendall correlation coefficient analysis and principal component analysis. Research results indicated that sources of winter dustfall in Beijing city were mainly composed of the earth's crust sources (including road dust, construction dust and remote transmission of dust) and the burning of fossil fuels (vehicle emissions, coal combustion, biomass combustion and industrial processes).

Operation of a 400MHz NMR magnet using a (RE:Rare Earth)Ba2Cu3O7-x high-temperature superconducting coil: Towards an ultra-compact super-high field NMR spectrometer operated beyond 1GHz.

PubMed

Yanagisawa, Y; Piao, R; Iguchi, S; Nakagome, H; Takao, T; Kominato, K; Hamada, M; Matsumoto, S; Suematsu, H; Jin, X; Takahashi, M; Yamazaki, T; Maeda, H

2014-12-01

High-temperature superconductors (HTS) are the key technology to achieve super-high magnetic field nuclear magnetic resonance (NMR) spectrometers with an operating frequency far beyond 1GHz (23.5T). (RE)Ba 2 Cu 3 O 7- x (REBCO, RE: rare earth) conductors have an advantage over Bi 2 Sr 2 Ca 2 Cu 3 O 10- x (Bi-2223) and Bi 2 Sr 2 CaCu 2 O 8- x (Bi-2212) conductors in that they have very high tensile strengths and tolerate strong electromagnetic hoop stress, thereby having the potential to act as an ultra-compact super-high field NMR magnet. As a first step, we developed the world's first NMR magnet comprising an inner REBCO coil and outer low-temperature superconducting (LTS) coils. The magnet was successfully charged without degradation and mainly operated at 400MHz (9.39T). Technical problems for the NMR magnet due to screening current in the REBCO coil were clarified and solved as follows: (i) A remarkable temporal drift of the central magnetic field was suppressed by a current sweep reversal method utilizing ∼10% of the peak current. (ii) A Z2 field error harmonic of the main coil cannot be compensated by an outer correction coil and therefore an additional ferromagnetic shim was used. (iii) Large tesseral harmonics emerged that could not be corrected by cryoshim coils. Due to those harmonics, the resolution and sensitivity of NMR spectra are ten-fold lower than those for a conventional LTS NMR magnet. As a result, a HSQC spectrum could be achieved for a protein sample, while a NOESY spectrum could not be obtained. An ultra-compact 1.2GHz NMR magnet could be realized if we effectively take advantage of REBCO conductors, although this will require further research to suppress the effect of the screening current. Copyright © 2014 Elsevier Inc. All rights reserved.

Synthesis and Characterization of an Earth-Abundant Cu2BaSn(S,Se)4 Chalcogenide for Photoelectrochemical Cell Application.

PubMed

Shin, Donghyeop; Ngaboyamahina, Edgard; Zhou, Yihao; Glass, Jeffrey T; Mitzi, David B

2016-11-17

Cu 2 BaSnS 4-x Se x films consisting of earth-abundant metals have been examined for photocathode application. Films with different Se contents (i.e., Cu 2 BaSnS 4-x Se x with x ≤ 2.4) were synthesized using a cosputter system with post-deposition sulfurization/selenization annealing treatments. Each film adopts a trigonal P3 1 crystal structure, with progressively larger lattice constants and with band gaps shifting from 2.0 to 1.6 eV, as more Se substitutes for S in the parent compound Cu 2 BaSnS 4 . Given the suitable bandgap and earth-abundant elements, the Cu 2 BaSnS 4-x Se x films were studied as prospective photocathodes for water splitting. Greater than 6 mA/cm 2 was obtained under illumination at -0.4 V versus reversible hydrogen electrode for Pt/Cu 2 BaSnS 4-x Se x films with ∼60% Se content (i.e., x = 2.4), whereas a bare Cu 2 BaSnS 4-x Se x (x = 2.4) film yielded ∼3 mA/cm 2 at -0.4 V/RHE.

Concentrations of strontium, barium, cadmium, copper, zinc, manganese, chromium, antimony, selenium, and lead in the liver and kidneys of dogs according to age, gender, and the occurrence of chronic kidney disease

PubMed Central

Mainzer, Barbara; Lahrssen-Wiederholt, Monika; Schafft, Helmut; Palavinskas, Richard; Breithaupt, Angele; Zentek, Jürgen

2015-01-01

This study was conducted to measure the concentrations of strontium (Sr), barium (Ba), cadmium (Cd), copper (Cu), zinc (Zn), manganese (Mn), chromium (Cr), antimony (Sb), selenium (Se), and lead (Pb) in canine liver, renal cortex, and renal medulla, and the association of these concentrations with age, gender, and occurrence of chronic kidney disease (CKD). Tissues from 50 dogs were analyzed using inductively coupled plasma mass spectrometry. Cu, Zn, and Mn levels were highest in the liver followed by the renal cortex and renal medulla. The highest Sr, Cd, and Se concentrations were measured in the renal cortex while lower levels were found in the renal medulla and liver. Female dogs had higher tissue concentrations of Sr (liver and renal medulla), Cd (liver), Zn (liver and renal cortex), Cr (liver, renal cortex, and renal medulla), and Pb (liver) than male animals. Except for Mn and Sb, age-dependent variations were observed for all element concentrations in the canine tissues. Hepatic Cd and Cr concentrations were higher in dogs with CKD. In conclusion, the present results provide new knowledge about the storage of specific elements in canine liver and kidneys, and can be considered important reference data for diagnostic methods and further investigations. PMID:25234328

Phase Equilibria and Crystal Chemistry in Portions of the System SrO-CaO-Bi2O3-CuO, Part II—The System SrO-Bi2O3-CuO

PubMed Central

Roth, R. S.; Rawn, C. J.; Burton, B. P.; Beech, F.

1990-01-01

New data are presented on the phase equilibria and crystal chemistry of the binary systems Sr0-Bi203 and SrO-CuO and the ternary system SrO-Bi2O3-CuO. Symmetry data and unit cell dimensions based on single crystal and powder x-ray diffraction measurements are reported for all the binary SrO-Bi2O3 phases, including a new phase identified as Sr6Bi2O9. The ternary system contains at least four ternary phases which can be formed in air at ~900 °C. These are identified as Sr2Bi2CuO6, Sr8Bi4Cu5O19+x, Sr3Bi2Cu2O8 and a solid solution (the Raveau phase) which, for equilibrium conditions at ~900 °C, corresponds approximately to the formula Sr1.8−xBi2.2+xCu1±x/2Oz.(0.0⩽x⩽~0.15). Superconductivity in this phase apparently occurs only in compositions that correspond to negative values of x. Compositions that lie outside the equilibrium Raveau-phase field often form nearly homogeneous Raveau-phase products. Typically this occurs after relatively brief heat treatments, or in crystallization of a quenched melt. PMID:28179779

Implications for food safety of the uptake by tomato of 25 trace-elements from a phosphogypsum amended soil from SW Spain.

PubMed

Enamorado, Santiago; Abril, José M; Delgado, Antonio; Más, José L; Polvillo, Oliva; Quintero, José M

2014-02-15

Phosphogypsum (PG) has been usually applied as Ca-amendment to reclaim sodic soils such as those in the marshland area of Lebrija (SW Spain). This work aimed at the effects of PG amendments on the uptake of trace-elements by tomato and its implications for food safety. A completely randomized experiment was performed using a representative soil from Lebrija in a greenhouse involving six replicates and four PG treatments equivalent to 0, 20, 60, and 200 Mg ha(-1). Soil-to-plant transfer factors (TFs) were determined for Be, B, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Ag, Cd, Sb, Cs, Ba, Tl, Pb, Th and U. The highest TF in shoots was observed for Cd (4.0; 1.5 in fruits), its concentration being increased with increasing PG doses due to its content in this metal (2.1 mg Cd kg(-1)PG). Phosphogypsum applying decreased the concentrations of Mn, Co and Cu in shoots; and of B, Cu, Sb, Cs, Ba, Tl and Th in fruits, however enhanced the accumulation of Se in fruits. Although Cd concentrations in tomato were below the maximum allowed levels in control pots (0 Mg PG ha(-1)), PG amendments above 60 Mg ha(-1) exceeded such limits. Copyright © 2013 Elsevier B.V. All rights reserved.

Tungsten-doped thin film materials

DOEpatents

Xiang, Xiao-Dong; Chang, Hauyee; Gao, Chen; Takeuchi, Ichiro; Schultz, Peter G.

2003-12-09

A dielectric thin film material for high frequency use, including use as a capacitor, and having a low dielectric loss factor is provided, the film comprising a composition of tungsten-doped barium strontium titanate of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3, where X is between about 0.5 and about 1.0. Also provided is a method for making a dielectric thin film of the general formula (Ba.sub.x Sr.sub.1-x)TiO.sub.3 and doped with W, where X is between about 0.5 and about 1.0, a substrate is provided, TiO.sub.2, the W dopant, Ba, and optionally Sr are deposited on the substrate, and the substrate containing TiO.sub.2, the W dopant, Ba, and optionally Sr is heated to form a low loss dielectric thin film.

Dielectric properties of Ba0.6Sr0.4TiO3-La(B0.5Ti0.5)O3 (B=Mg, Zn) ceramics.

PubMed

Xu, Yebin; Liu, Ting; He, Yanyan; Yuan, Xiao

2009-11-01

Ba(0.6)Sr(0.4)TiO(3)-La(B(0.5)Ti(0.5))O(3) (B = Mg, Zn) ceramics were prepared by a solid-state reaction method, and their microwave dielectric characteristics and tunability were investigated. The ferroelectric-dielectric solid solutions with cubic perovskite structures were obtained for compositions of 10 to 60 mol% La(Mg(0.5)Ti(0.5))O(3) and 10 to 50 mol% La(Zn(0.5)Ti(0.5))O(3). With the increase of linear oxide dielectric content, the dielectric constant and tunability were decreased and Qf was increased. Ba(0.6)Sr(0.4)TiO(3)-La(Mg(0.5)Ti(0.5))O(3) has better dielectric properties than Ba(0.6)Sr(0.4)TiO(3)-La(Zn(0.5)Ti(0.5))O(3). 0.9Ba(0.6)Sr(0.4)TiO(3)-0.1La(Mg(0.5)Ti(0.5))O(3) has a dielectric constant epsilon = 338.2, Qf = 979 GHz and a tunability of was 3.7% at 100 kHz under 1.67 kV/mm. The Qf value of 0.5Ba(0.6)Sr(0.4)TiO(3)- 0.5La(Mg(0.5)Ti(0.5))O(3) reached 9367 GHz, but the tunable properties were lost.

Pressure-induced photoluminescence in Mn2+-doped BaF2 and SrF2 fluorites

NASA Astrophysics Data System (ADS)

Hernández, Ignacio; Rodríguez, Fernando

2003-01-01

This work reports an effective way for inducing room temperature photoluminescence (PL) in Mn2+-doped BaF2 and SrF2 using high-pressure techniques. The aim is to understand the surprising PL behavior exhibited by Mn2+ at the cubal site of the fluorite structure. While Mn2+-doped CaF2 shows a green PL with quantum yield close to 1 at room temperature, Mn2+-doped MF2 (M=Ba,Sr) is not PL either at room temperature (SrF2) or at any temperature (BaF2) at ambient pressure. We associate the loss of Mn2+ PL on passing from CaF2 to SrF2 or BaF2 with nonradiative multiphonon relaxation whose thermal activation energy decreases along the series CaF2→SrF2→BaF2. A salient feature of this work deals with the increase of activation energy induced by pressure. It leads to a quantum yield enhancement, which favors PL recovery. Furthermore, the activation energy mainly depends on the crystal volume per molecule irrespective of the crystal structure or the local symmetry around the impurity. In this way, the relevance of the fluorite-to-cotunnite phase transition is analyzed in connection with the PL properties of the investigated compounds. The PL spectrum and the corresponding lifetime are reported for both structural phases as a function of pressure.

Dissolved metals and associated constituents in abandoned coal-mine discharges, Pennsylvania, USA. Part 2: Geochemical controls on constituent concentrations

USGS Publications Warehouse

Cravotta, C.A.

2008-01-01

Water-quality data for discharges from 140 abandoned mines in the Anthracite and Bituminous Coalfields of Pennsylvania reveal complex relations among the pH and dissolved solute concentrations that can be explained with geochemical equilibrium models. Observed values of pH ranged from 2.7 to 7.3 in the coal-mine discharges (CMD). Generally, flow rates were smaller and solute concentrations were greater for low-pH CMD samples; pH typically increased with flow rate. Although the frequency distribution of pH was similar for the anthracite and bituminous discharges, the bituminous discharges had smaller median flow rates; greater concentrations of SO4, Fe, Al, As, Cd, Cu, Ni and Sr; comparable concentrations of Mn, Cd, Zn and Se; and smaller concentrations of Ba and Pb than anthracite discharges with the same pH values. The observed relations between the pH and constituent concentrations can be attributed to (1) dilution of acidic water by near-neutral or alkaline ground water; (2) solubility control of Al, Fe, Mn, Ba and Sr by hydroxide, sulfate, and/or carbonate minerals; and (3) aqueous SO4-complexation and surface-complexation (adsorption) reactions. The formation of AlSO4+ and AlHSO42 + complexes adds to the total dissolved Al concentration at equilibrium with Al(OH)3 and/or Al hydroxysulfate phases and can account for 10-20 times greater concentrations of dissolved Al in SO4-laden bituminous discharges compared to anthracite discharges at pH of 5. Sulfate complexation can also account for 10-30 times greater concentrations of dissolved FeIII concentrations at equilibrium with Fe(OH)3 and/or schwertmannite (Fe8O8(OH)4.5(SO4)1.75) at pH of 3-5. In contrast, lower Ba concentrations in bituminous discharges indicate that elevated SO4 concentrations in these CMD sources could limit Ba concentrations by the precipitation of barite (BaSO4). Coprecipitation of Sr with barite could limit concentrations of this element. However, concentrations of dissolved Pb, Cu, Cd, Zn, and most other trace cations in CMD samples were orders of magnitude less than equilibrium with sulfate, carbonate, and/or hydroxide minerals. Surface complexation (adsorption) by hydrous ferric oxides (HFO) could account for the decreased concentrations of these divalent cations with increased pH. In contrast, increased concentrations of As and, to a lesser extent, Se with increased pH could result from the adsorption of these oxyanions by HFO at low pH and desorption at near-neutral pH. Hence, the solute concentrations in CMD and the purity of associated "ochres" formed in CMD settings are expected to vary with pH and aqueous SO4 concentration, with potential for elevated SO4, As and Se in ochres formed at low pH and elevated Cu, Cd, Pb and Zn in ochres formed at near-neutral pH. Elevated SO4 content of ochres could enhance the adsorption of cations at low pH, but decrease the adsorption of anions such as As. Such information on environmental processes that control element concentrations in aqueous samples and associated precipitates could be useful in the design of systems to reduce dissolved contaminant concentrations and/or to recover potentially valuable constituents in mine effluents.

The effect of rare earth ions on structural, morphological and thermoelectric properties of nanostructured tin oxide based perovskite materials

NASA Astrophysics Data System (ADS)

Rajasekaran, P.; Alagar Nedunchezhian, A. S.; Yalini Devi, N.; Sidharth, D.; Arivanandhan, M.; Jayavel, R.

2017-11-01

Metal oxide based materials are promising for thermoelectric applications especially at elevated temperature due to their high thermal stability. Recently, perovskite based oxide materials have been focused as a novel thermoelectric material due to their tunable electrical conductivity. Thermoelectric properties of BaSnO3 has been extensively investigated. However, the effect of various rare earth doping on the thermoelectric properties of BaSnO3 is not studied in detail. In the present work, Ba1-x RE x SnO3 (RE  =  La and Sr) materials with x  =  0.05 were prepared by polymerization complex (PC) method in order to study the effect of RE incorporation on the structural, morphological and thermoelectric characteristics of BaSnO3. The structural and morphological properties of the synthesized materials were studied by XRD and TEM analysis. XRD analysis confirmed the mixed phases of the synthesized samples. The TEM images of Ba1-x Sr x SnO3 shows hexagonal and cubic morphology while, Ba1-x La x SnO3 exhibit rod like morphology. Various functional groups of the perovskite material were identified using FTIR analysis. Formation of the perovskite material was further confirmed by XPS analysis. The Seebeck coefficient of Ba0.95La0.05SnO3 was relatively higher than that of Ba0.95Sr0.05SnO3, especially at high temperature. The rod like morphology of Ba0.95La0.05SnO3 may facilitate fast electron transport which results high thermal power compared to Ba0.95Sr0.05SnO3 despite of its poor crystalline nature. The substitution of La3+ on the Ba2+ site could vary the carrier density which results high Seebeck coefficient of Ba0.95La0.05SnO3 compared to Ba0.95Sr0.05SnO3. From the experimental results, it is obvious that Ba0.95La0.05SnO3 could be a promising thermoelectric material for high temperature application.

Chemical composition of modern and fossil Hippopotamid teeth and implications for paleoenvironmental reconstructions and enamel formation - Part 2: Alkaline earth elements as tracers of watershed hydrochemistry and provenance

NASA Astrophysics Data System (ADS)

Brügmann, G.; Krause, J.; Brachert, T. C.; Stoll, B.; Weis, U.; Kullmer, O.; Ssemmanda, I.; Mertz, D. F.

2012-03-01

For reconstructing environmental change in terrestrial realms the geochemistry of fossil bioapatite in bones and teeth is among the most promising applications. This study demonstrates that alkaline earth elements in enamel of Hippopotamids, in particular Ba and Sr are tracers for water provenance and hydrochemistry. The studied specimens are molar teeth from Hippopotamids found in modern and fossil lacustrine settings of the Western Branch of the East African Rift system (Lake Kikorongo, Lake Albert, and Lake Malawi) and from modern fluvial environments of the Nile River. Concentrations in enamel vary by ca. two orders of magnitude for Ba (120-9336 μg g-1) as well as for Sr (9-2150 μg g-1). Concentration variations in enamel are partly induced during post-mortem alteration and during amelogenesis, but the major contribution originates from the variable water chemistry in the habitats of the Hippopotamids which is dominated by the lithologies and weathering processes in the watershed areas. Amelogenesis causes a distinct distribution of Ba and Sr in modern and fossil enamel, in that element concentrations increase along profiles from the outer rim towards the enamel-dentin junction by a factor of 1.3-1.5. These elements are well correlated with MgO and Na2O in single specimens, thus suggesting that their distribution is determined by a common, single process. Presuming that the shape of the tooth is established at the end of the secretion process and apatite composition is in equilibrium with the enamel fluid, the maturation process can be modeled by closed system Rayleigh crystallization. Enamel from many Hippopotamid specimens has Sr/Ca and Ba/Ca which are typical for herbivores, but the compositions extend well into the levels of plants and carnivores. Within enamel from single specimens these element ratios covary and provide a specific fingerprint of the Hippopotamid habitat. All specimens together, however, define subparallel trends with different Ba/Sr ranging from 0.1 to 3. This ratio varies on spatial and temporal scales and traces provenance signals as well as the fractionation of the elements in the hydrological cycle. Thus, Sr concentrations and Ba/Sr in enamel differentiate between habitats having basaltic or Archean crustal rocks as the ultimate sources of Sr and Ba. The provenance signal is modulated by climate change. In Miocene to Pleistocene enamel from the Lake Albert region, Ba/Sr decreases systematically with time from about 2 to 0.5. This trend can be correlated with changes in climate from humid to arid in vegetation from C3 to C4 biomass as well as with increasing evaporation of the lake water. The most plausible explanation is that with time, Ba mobility decreased relative to that of Sr. This can arise if preferential adsorption of Ba to clay and Fe-oxide-hydroxide is related to increasing aridification. Additionally, weathering solutions and lake water can become increasingly alkaline and barite becomes stable. In this case, Ba will be preferentially deposited on the watershed of Lake Albert and rivers with low Ba/Sr will feed the habitats of the Hippopotamids.

Capturing anharmonicity in a lattice thermal conductivity model for high-throughput predictions

DOE PAGES

Miller, Samuel A.; Gorai, Prashun; Ortiz, Brenden R.; ...

2017-01-06

High-throughput, low-cost, and accurate predictions of thermal properties of new materials would be beneficial in fields ranging from thermal barrier coatings and thermoelectrics to integrated circuits. To date, computational efforts for predicting lattice thermal conductivity (κ L) have been hampered by the complexity associated with computing multiple phonon interactions. In this work, we develop and validate a semiempirical model for κ L by fitting density functional theory calculations to experimental data. Experimental values for κ L come from new measurements on SrIn 2O 4, Ba 2SnO 4, Cu 2ZnSiTe 4, MoTe 2, Ba 3In 2O 6, Cu 3TaTe 4, SnO,more » and InI as well as 55 compounds from across the published literature. Here, to capture the anharmonicity in phonon interactions, we incorporate a structural parameter that allows the model to predict κ L within a factor of 1.5 of the experimental value across 4 orders of magnitude in κ L values and over a diverse chemical and structural phase space, with accuracy similar to or better than that of computationally more expensive models.« less

Aspects of forming metal-clad melt-processed Y-Ba-Cu-O tapes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kozlowski, G.; Oberly, C.E.; Ho, J.

1991-03-01

This paper reports on melt-processing of Y-Ba-Cu-O superconductor in a usable form for magnet winding which requires the development of a cladding with demanding properties. Numerous recent efforts in cold forming Bi-based superconductor tapes have been successful because a silver tube can be used to constrain the ceramic material, which is sintered at much lower temperature than the Y-Ba-Cu-O. Typical high temperature metals which can be used to encase Y-Ba-Cu-O during sintering do not permit ready diffusion of oxygen as silver does. Recently, the full or partial recovery of superconductivity has been achieved in transition-metal- doped Y-Ba-Cu-O due to themore » partial-melt processing.« less

High pressure synthesis and magnetic studies of quasi one dimensional systems Sr{sub n-1} Cu{sub n+1} O{sub 2n} (n=3,5)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Azuma, M.; Hiroi, Z.; Takano, M.

1994-12-31

SrCu{sub 2}O{sub 3} and Sr{sub 2}Cu{sub 3}O{sub 5} containing two-leg and three-leg S=1/2 ladders made of antiferromagnetic Cu-O-Cu linear bonds, respectively, were synthesized at high pressure, and their crystallographic and magnetic properties were investigated. Both susceptibility and T{sub 1} data of NMR revealed the existence of a large spin gap only for SrCu{sub 2}O{sub 3}. Superconductivity, which had been predicted theoretically for carrier-doped SrCu{sub 2}O{sub 3} could not be realized although partial substitution of La{sup 3+} for Sr{sup 2+} seemed to be carried out successfully. Electron carriers injected seems to remain localized.

Removal of barium and strontium from aqueous solution using zeolite 4A.

PubMed

Araissi, Manel; Ayed, Imen; Elaloui, Elimame; Moussaoui, Younes

2016-01-01

The adsorption efficiency of Sr(2+) and Ba(2+) from aqueous solutions by zeolite 4A was investigated. Adsorption studies were carried out both in single and binary component systems. The single ion equilibrium adsorption data were fitted to three isotherm models: Langmuir, Freundlich and Dubinin-Radushkevich. The Langmuir model represents the equilibrium data better than the Freundlich model in the studied initial metal concentration (0.3-25 mmol L(-1)) in both the single and binary component systems. The obtained RL (separation factor or Langmuir parameter) values were in the range of 0-1 indicating that Sr(2+) and Ba(2+) sorption were favorable. The obtained mean free energy value for adsorption of Ba(2+) and Sr(2+) was 8.45 kJ mol(-1) and 9.12 kJ mol(-1), respectively, indicating that both ions were uptaken through an ion exchange process. The maximum adsorption capacities (Qmax) were 2.25 mmol g(-1) and 2.34 mmol g(-1) for Ba(2+) and Sr(2+) ions, respectively. Also, the study of the competitive sorption of ions in the binary system showed that zeolite 4A preferentially adsorbs cations in the following order: Ba(2+) < Sr(2+).

Electronic Structure of I-M8Ga16Sn30 (M = Ba, Sr, Yb) by First-Principles Calculation

NASA Astrophysics Data System (ADS)

Wang, Jin-song; Liu, Hong-xia; Deng, Shuping; Li, De-cong; Shen, Lan-xian; Cheng, Feng; Deng, Shu-kang

2017-05-01

Sn-based clathrates possess excellent thermoelectric properties ascribed to their higher Seebeck coefficient and lower thermal conductivity. Guest atoms significantly modulate the thermoelectric properties of Sn-based calculates because of their diverse atomic radius and interactions with framework atoms. Thus, we explored the electronic structure of I-M8Ga16Sn30 (M = Ba, Sr, Yb) by first-principles calculation. Results revealed significant differences between Yb8Ga16Sn30 and M8Ga16Sn30 (M = Ba, Sr,). In particular, the Yb-filled compound substitution possesses lowest formation energy and the off-center distance of the Yb atom is the largest compared with the other structures. I-M8Ga16Sn30 (M = Ba, Sr, Yb) is an indirect band gap semiconductor, and the enhanced hybridization effect between the guest and framework atoms' orbits exists because the Yb f orbit results in a decrease in band gap. Ba- and Sr-filled clathrates have similar valence bands but slightly different conduction bands; however, Yb8Ga16Sn30 possess the spiculate density of states near the Fermi level that reveals excellent thermoelectric properties.

Optimization of single crystals of solid electrolytes with tysonite-type structure (LaF3) for conductivity at 293 K: 2. Nonstoichiometric phases R 1- y M y F3- y ( R = La-Lu, Y; M = Sr, Ba)

NASA Astrophysics Data System (ADS)

Sorokin, N. I.; Sobolev, B. P.; Krivandina, E. A.; Zhmurova, Z. I.

2015-01-01

Single crystals of fluorine-conducting solid electrolytes R 1 - y Sr y F3 - y and R 1 - y Ba y F3 - y ( R = La-Lu, Y) with a tysonite-type structure (LaF3) have been optimized for room-temperature conductivity σ293 K. The optimization is based on high-temperature measurements of σ( T) in two-component nonstoichiometric phases R 1 - y M y F3 - y ( M = Sr, Ba) as a function of the MF2 content. Optimization for thermal stability is based on studying the phase diagrams of MF2- RF3 systems ( M = Sr, Ba) and the behavior of nonstoichiometric crystals upon heating when measuring temperature dependences σ( T). Single crystals of many studied R 1 - y Sr y F3 - y and R 1 - y Ba y F3 - y phases have σ293 K values large enough to use these materials in solid-state electrochemical devices (chemical sensors, fluorine-ion batteries, accumulators, etc.) operating at room temperature.

Crystal structure, oxidation state and magnetism of Sr{sub x}La{sub 2−x}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} (x=1, 1.5)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, Minfeng, E-mail: m.f.lv@ciac.jl.cn; Deng, Xiaolong; Waerenborgh, João C.

2014-03-15

Sr{sub x}La{sub 2−x}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} (x=1, 1.5) oxides with K{sub 2}NiF{sub 4}-type structure were prepared by solid state reaction and characterized by powder X-ray diffraction, X-ray photoelectron spectroscopy, magnetic and electrical resistivity measurements. The SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} phase was obtained for the first time with a negligible amount of impurities. The octahedral Cu/RuO{sub 6} units are more elongated in SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} than in Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} indicating a greater extent of static Jahn–Teller distortion. XPS suggests that mixed ion pairs Ru{sup 5+}/Ru{sup 4+}↔Cu{sup +}/Cu{sup 2+} are present in SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4}, whilemore » Ru remains as Ru{sup 5+} and Cu as Cu{sup 2+} in Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4}. Both samples show spin-glass behavior, which can be explained by competition between ferromagnetic and antiferromagnetic superexchange interactions. The negative Weiss temperature estimated for SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4}, −318 K, is significantly lower than −11.5 K deduced for Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} which may be related to the higher static Jahn–Teller distortion in the former oxide. -- Graphical abstract: SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} with K{sub 2}NiF{sub 4}-type structure show a larger static Jahn–Teller distortion than Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4}, which may be related to stronger antiferromagnetic superexchange interactions. Highlights: • SrLaCu{sub 0.5}Ru{sub 0.5}O{sub 4} (I) larger Jahn–Teller (J–T) distortion than Sr{sub 1.5}La{sub 0.5}Cu{sub 0.5}Ru{sub 0.5}O{sub 4} (II). • Octahedral Cu/RuO{sub 6} units are more elongated in I than in II. • Mixed ion pairs Ru{sup 5+}/Ru{sup 4+}↔Cu{sup +}/Cu{sup 2+} are present in I, while Ru remains as Ru{sup 5+} and Cu as Cu{sup 2+} in II. • Negative Weiss temperature of I significantly lower, consistent with higher J–T distortion.« less

Magmatic evolution of lunar highland rocks estimated from trace elements in plagioclase: A new bulk silicate Moon model with sub-chondritic Ti/Ba, Sr/Ba, and Sr/Al ratios

NASA Astrophysics Data System (ADS)

Togashi, Shigeko; Kita, Noriko T.; Tomiya, Akihiko; Morishita, Yuichi

2017-08-01

The compositions of host magmas of ferroan anorthosites (FAN-host magmas) were estimated from secondary ion mass spectrometry analyses of plagioclase in lunar highland rocks. The evolution of the magmas was investigated by considering phase relations based on the MELTS algorithm and by re-examining partition coefficients for trace elements between plagioclase and melts. Data little affected by post-magmatic processes were selected by using plagioclase with relatively primitive Sc and Co contents. The FAN-host magma contained 90-174 ppm Sr, 40-119 ppm Ba and 0.5-1.3% TiO2, and had sub-chondritic Sr/Ba and Ti/Ba ratios. It is difficult to account for the formation of FAN-host magma on the basis of magma evolution processes of previously proposed bulk silicate Moon models with chondritic ratios for refractory elements at global scale. Therefore, the source of the FAN-host magma must have had primordial sub-chondritic Sr/Ba and Ti/Ba ratios. The FAN-host magmas were consistent in refractory elements with the estimated host mafic magma for feldspathic crust based on lunar meteorites, and some very-low-Ti mare rocks from lunar meteorites. Here, we propose an alternative bulk silicate Moon model (the cBSM model), which is enriched in crustal components of proto-bodies relative to the present whole Earth-Moon system.

Trace element concentrations in livers of polar bears from two populations in Northern and Western Alaska.

PubMed

Kannan, Kurunthachalam; Agusa, Tetsuro; Evans, Thomas J; Tanabe, Shinsuke

2007-10-01

Concentrations of 20 trace elements (V, Cr, Mn, Co, Cu, Zn, Rb, Sr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, Hg, Tl, Pb, and Bi) were measured in livers of polar bears (Ursus maritimus) collected from Northern and Western Alaska from 1993 to 2002 to examine differences in the profiles of trace metals between the Beaufort Sea (Northern Alaska) and the Chukchi Sea (Western Alaska) subpopulations in Alaska. Among the trace elements analyzed, concentrations of Cu (50-290 microg/g, dry wt) in polar bear livers were in the higher range of values that have been reported for marine mammals. Concentrations of Hg in polar bears varied widely, from 3.5 to 99 microg/g dry wt, and the mean concentrations in polar bears were comparable to concentrations reported previously for several other species of marine mammals. Mean concentrations of Pb and Cd were 0.67 and 1.0 microg/g dry wt, respectively; these concentrations were lower than levels reported elsewhere for polar bears from Greenland and Canada. Age- and gender-related variations in the concentrations of trace elements in our polar bears were minimal. Concentrations of Hg decreased slowly in samples collected during 1993-2002, whereas Cd and Pb concentrations were found to be stable or slowly increasing, in the livers of Alaskan polar bears. Concentrations of Ag, Bi, Ba, Cu, and Sn were significantly higher in the Chukchi Sea subpopulation than in the Beaufort Sea subpopulation. Concentrations of Hg were significantly higher in the Beaufort Sea subpopulation than in the Chukchi Sea subpopulation. Differences in the profiles and concentrations of Hg, Ag, Bi, Ba, Cu, and Sn suggest that the sources of exposure to these trace elements between Western and Northern Alaskan polar bears are different, in agreement with findings reported earlier for several organic contaminants.

Influence of La content on magnetic properties of Cu doped M-type strontium hexaferrite: Structural, magnetic, and Mossbauer spectroscopy study

NASA Astrophysics Data System (ADS)

Ghimire, M.; Yoon, S.; Wang, L.; Neupane, D.; Alam, J.; Mishra, S. R.

2018-05-01

The present study investigates the influence of Cu2+ and La3+-Cu2+ doping on the magnetic properties of Sr1-xLaxFe12-xCuxO19 (x = 0.0-0.5) hexaferrite (SrM) compounds. The samples were prepared via facile autocombustion technique followed by sintering. X-ray powder diffraction patterns show the formation of the pure phase of M-type hexaferrite for all x. Invariance in lattice parameters was observed with only Cu2+ substitution while lattice contraction along c-axis was observed with co-doping La3+-Cu2+ in SrM. The magnetic property of these compounds is explained based on Cu2+ occupancy in the absence and presence of La3+ in SrM magnetoplumbite structure. The Cu2+ doped SrFe12-xCuxO19 sample showed a monotonic decrease in Ms value while La3+-Cu2+ showed a noticeable increase in Ms value with x. Furthermore, while coercivity of Cu2+ doped SrM reduced with x, the coercivity of La3+-Cu2+ doped SrM showed a marked 12% increase in coercivity at x = 0.1 (Hc = 4391 Oe) from that of x = 0.0 (3918 Oe). Interestingly, Cu2+ doped SrM displayed invariance in Tc ∼ 458.6 °C with x, while La3+-Cu2+ doping reduced Tc by 5% from its x = 0 (Tc = 451.9 °C) to 429.6 °C. The room temperature Mossbauer spectral analysis confirmed a Cu2+ preference for the 12k site and its occupancy is observed to be influenced by the presence of La3+ ion at the Sr2+ site.

Microstructure and dielectric parameters of epitaxial SrRuO3/BaTiO3/SrRuO3 heterostructures

NASA Astrophysics Data System (ADS)

Boikov, Yu. A.; Claeson, T.

2001-05-01

Epitaxial films of ferroelectric barium titanate are desirable in a number of applications but their properties are inferior to those of bulk material. Relations between microstructure and dielectric properties may give better understanding of limitations. Trilayer heterostructures SrRuO3/BaTiO3/SrRuO3 were grown by laser ablation on (100)LaAlO3 and (100)MgO substrates. The BaTiO3 layer was granular in structure. When grown on (100)SrRuO3/(100)LaAlO3, it was preferentially a-axis oriented due to tensile mechanical stress. Using (100)MgO as a substrate, on the other hand, produced a mixture of about equal value of a-axis and c-axis oriented grains of BaTiO3. The dielectric permittivity, ɛ, of the BaTiO3 layer was almost twice as large, at T>200 K and f=100 kHz, for the LaAlO3 substrate as compared to the MgO one. Its maximum value (ɛ/ɛ0≈6200) depended on temperature of growth, grain size, and electric field and compares well with optimal values commonly used for ceramic material. The maximum in the ɛ(T) shifted from about 370 to 320 K when the grain size in the BaTiO3 film decreased from 100 to 40 nm. At T<300 K, hysteresis loops in polarization versus electric field were roughly symmetric. The BaTiO3 films grown on (100)SrRuO3/(100)MgO exhibit the largest remnant polarizations and coercive fields in the temperature range 100-380 K.

[Application of ICP-MS to Identify the Botanic Source of Characteristic Honey in South Yunnan].

PubMed

Wei, Yue; Chen, Fang; Wang, Yong; Chen, Lan-zhen; Zhang, Xue-wen; Wang, Yan-hui; Wu, Li-ming; Zhou, Qun

2016-01-01

By adopting inductively coupled plasma mass spectrometry (ICP-MS) combined with chemometric analysis technology, 23 kinds of minerals in four kinds of characteristic honey derived from Yunnan province were analyzed. The result showed that 21 kinds of mineral elements, namely Na, Mg, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Mo, Cd, Sb, Ba, Tl and Pb, have significant differences among different varieties of honey. The results of principal component analysis (PCA) showed that the cumulative variance contribution rate of the first four main components reached 77.74%, seven kinds of elements (Mg, Ca, Mn, Co, Sr, Cd, Ba) from the first main component contained most of the honey information. Through the stepwise discriminant analysis, seven kinds of elements (Mg, K, Ca, Cr, Mn, Sr, Pb) were filtered. out and used to establish the discriminant function model, and the correct classification rates of the proposed model reached 90% and 86.7%, respectively, which showed elements contents could be effectively indicators to discriminate the four kinds characteristic honey in southern Yunnan Province. In view of all the honey samples were harvested from apiaries located at south Yunnan Province where have similar climate, soil and other environment conditions, the differences of the mineral elements contents for the honey samples mainly due to their corresponding nectariferous plant. Therefore, it is feasible to identify honey botanical source through the differences of mineral elements.

Chemical Synthesis of Next Generation High Energy Product Hybrid SmCo Permanent Magnets for High Temperature Applications

DTIC Science & Technology

2010-08-01

among CoxC, AINiCo and Ba / Sr ferrite magnets. AINiCo is shown to exhibit high (BH)max, 35 kJmŗ, but a low intrinsic coercivity, mostly ə kOe...whereas Ba / Sr ferrite features high intrinsic coercivity, 3-4.5 kOe, but typical values of (BH)max below 25 kJm-3. However, the multiple...coercivity of cobalt carbide nanoparticles is compared with free powders of AINiCo and ceramic magnets of the Ba / Sr hexaferrite type. Curie temperatures near

Alkyl complexes of strontium and barium: synthesis and structural characterization of [(Me3Si)2(MeOMe2Si)C]2Sr(THF) and [(Me3Si)2(MeOMe2Si)C]2Ba(MeOCH2CH2OMe).

PubMed

Izod, Keith; Liddle, Stephen T; Clegg, William

2003-06-25

Metathesis between either SrI2 or BaI2 and 2 equiv of {(Me3Si)2(MeOMe2Si)C}K in THF yields the novel heavier alkali metal dialkyls {(Me3Si)2(MeOMe2Si)C}2M(L) [M(L) = Sr(THF) (2), Ba(DME) (3) (DME = 1,2-dimethoxyethane)] after recrystallization.

Critical current density in (YBa2Cu3O7-δ)1-x-(PrBa2Cu3O7-δ)x melt-textured composites

NASA Astrophysics Data System (ADS)

Opata, Yuri Aparecido; Monteiro, João Frederico Haas Leandro; Jurelo, Alcione Roberto; Siqueira, Ezequiel Costa

2018-06-01

Melt textured (YBa2Cu3O7-δ)1-x-(PrBa2Cu3O7-δ)x composites (x = 0.00 and x = 0.05) were grown using the top seeding method. The effect of the PrBa2Cu3O7-δ phase on the growth process and the modification of the microstructure as well as on the physical properties was analyzed. X-ray analyses indicated that both pure and Pr-doped samples present an orthorhombic superconducting phase. From resistivity measurements for YBa2Cu3O7-δ and (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 samples, the Tcab did not change and was around 90.5 K. However, from magnetic measurements, the superconductivity was observed in critical temperatures TC = 92.9 K and 92.4 K for YBa2Cu3O7-δ and (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 samples, respectively. The YBa2Cu3O7-δ sample showed higher critical current densities than those shown by the (YBa2Cu3O7-δ)0.95-(PrBa2Cu3O7-δ)0.05 sample, with values of JC = 5.85 × 105 A/cm2 and 4.72 × 105 A/cm2, respectively. This paper also discusses the importance of Pr substitution on nano- and micro-meter scales to enhance JC(H).

Multifunctional Oxide Films for Advanced Multifunction RF Systems

DTIC Science & Technology

2007-09-14

during the epitaxy runs. Effusion cells (SVT) provide perovskite and rocksalt matrix elements (Ti, Ba , Sr , Mg). An e-gun evaporator (MDC):can be used to...sample that best matched the targeted stoichiometry. 10 5 MgO Ba 0 . Sr 1.4 TiO3/MgO 10 000 BS I 102 3~) ;101 0~ 0 (a) RHiEED of BST rowthonM 0 105O... Ba 0. Sr .. iO3 /SrMO. 5 200 1Is V STO10 -STO 3 -10 _ 10 2 30S 15 10 100 10 20 30 40 50 60 70 80 90 20 (b) RHEED of BST growth on STO (c) XRD scan of

Synthesis and Structure of A New Perovskite, SrCuO 2.5

NASA Astrophysics Data System (ADS)

Chen, Bai-Hao; Walker, Dave; Scott, Bruce A.; Mitzi, David B.

1996-02-01

A new oxygen-deficient perovskite, SrCuO2.5, was prepared at 950°C and 100 kbar pressure in a multianvil apparatus. Rietveld profile analysis, using X-ray powder diffraction data, was employed for the structural determination. SrCuO2.5is orthorhombic,Pbam(No. 55),Z= 4,a= 5.424(2) Â,b= 10.837(4) Â, andc= 3.731(1) Â, which is related to the perovskite subcell by root{2}ap× 2root{2}ap×ap, whereapis the simple cubic perovskite lattice parameter. It consists of corner-shared CuO5square pyramids with oxygen vacancy ordering in the CuO2layers. The ordered oxygen vacancies create parallel pseudo-hexagonal tunnels where the Sr atoms reside, forming SrO10polyhedra. Structural features with respect to oxygen vacancies, superstructures, and distortions are analogous to the type of ordering observed in Sr2CuO3+δ. Superconductivity was not observed in SrCuO2.5down to 5 K.

Radionuclide transfer to reptiles.

PubMed

Wood, Michael D; Beresford, Nicholas A; Semenov, Dmitry V; Yankovich, Tamara L; Copplestone, David

2010-11-01

Reptiles are an important, and often protected, component of many ecosystems but have rarely been fully considered within ecological risk assessments (ERA) due to a paucity of data on contaminant uptake and effects. This paper presents a meta-analysis of literature-derived environmental media (soil and water) to whole-body concentration ratios (CRs) for predicting the transfer of 35 elements (Am, As, B, Ba, Ca, Cd, Ce, Cm, Co, Cr, Cs, Cu, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Po, Pu, Ra, Rb, Sb, Se, Sr, Th, U, V, Y, Zn, Zr) to reptiles in freshwater ecosystems and 15 elements (Am, C, Cs, Cu, K, Mn, Ni, Pb, Po, Pu, Sr, Tc, Th, U, Zn) to reptiles in terrestrial ecosystems. These reptile CRs are compared with CRs for other vertebrate groups. Tissue distribution data are also presented along with data on the fractional mass of bone, kidney, liver and muscle in reptiles. Although the data were originally collected for use in radiation dose assessments, many of the CR data presented in this paper will also be useful for chemical ERA and for the assessments of dietary transfer in humans for whom reptiles constitute an important component of the diet, such as in Australian aboriginal communities.

The Universality of the Rapid Neutron-capture Process Revealed by a Possible Disrupted Dwarf Galaxy Star

NASA Astrophysics Data System (ADS)

Casey, Andrew R.; Schlaufman, Kevin C.

2017-12-01

The rapid neutron-capture or r-process is thought to produce the majority of the heavy elements (Z> 30) in extremely metal-poor stars. The same process is also responsible for a significant fraction of the heavy elements in the Sun. This universality of the r-process is one of its characteristic features, as well as one of the most important clues to its astrophysical origin. We report the discovery of an extremely metal-poor field giant with [{Sr},{Ba}/{{H}}]≈ -6.0 and [{Sr},{Ba}/{Fe}]≈ -3.0, the lowest abundances of strontium and barium relative to iron ever observed. Despite its low abundances, the star 2MASS J151113.24-213003.0 has [{Sr}/{Ba}]=-0.11+/- 0.14, therefore its neutron-capture abundances are consistent with the main solar r-process pattern that has [{Sr}/{Ba}]=-0.25. It has been suggested that extremely low neutron-capture abundances are a characteristic of dwarf galaxies, and we find that this star is on a highly eccentric orbit with an apocenter ≳100 kpc that lies in the disk of satellites in the halo of the Milky Way. We show that other extremely metal-poor stars with low [Sr, Ba/H] and [Sr, Ba/Fe] plus solar [Sr/Ba] tend to have orbits with large apocenters, consistent with a dwarf galaxy origin for this class of object. The nucleosynthesis event that produced the neutron-capture elements in 2MASS J151113.24-213003.0 must produce both strontium and barium together in the solar ratio. We exclude contributions from the s-process in intermediate-mass asymptotic giant branch or fast-rotating massive metal-poor stars, pair-instability supernovae, the weak r-process, and neutron-star mergers. We argue that the event was a Pop III or extreme Pop II core-collapse supernova explosion. This paper includes data gathered with the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile.

The influence of seafloor hydrothermal activity on major and trace elements of the sediments from the South Mid-Atlantic Ridge

NASA Astrophysics Data System (ADS)

Huang, Xin; Chen, Shuai; Zeng, Zhigang; Pu, Xiaoqiang; Hou, Qinghua

2017-10-01

Sediment samples obtained from the South Mid-Atlantic Ridge were analyzed for the major and trace elements by inductively coupled plasma atomic emission spectroscopy and inductively coupled plasma mass spectrometry. Results revealed that the contents of elements (e.g., Fe, Mn, Cu, Zn, V, Co) were high in samples 22V-TVG10 and 26V-TVG05 from the sites near the hydrothermal areas, and low in sample 22V-TVG14, which was collected far from the hydrothermal areas. The contents of Ca, Sr and Ba in the samples showed opposite trends. A positive correlation between the concentrations of metallic elements (Cu, Zn, Co, Ni, Pb, V) and Fe in the samples were observed. These results are consistent with chemical evolution of the dispersing hydrothermal plume.

Acoustic identification of the elastic properties of porous and nonporous superconducting materials DyBa2-XSrXCu3O7-δ

NASA Astrophysics Data System (ADS)

Sayoud, N.; Lazri, H.; Ogam, E.; Boumaiza, Y.; Boudour, A.

2018-05-01

This work involves the development of a method using the principle of acoustic microscopy to determine the elastic properties of high-temperature superconducting materials, the method is applied to analyse the variation of the elastic properties of the superconducting alloy DyBa 2-x Sr x Cu 3 O 7‑δ for different variations of the concentration parameters (x = 0, x = 0.3 and x = 0.6), porosity and temperature. The method is based on the reconstruction of the reflection coefficient calculated from the acoustic signature of the signal received by the microscope during the exploration of the superconducting material for different concentrations. This permitted the determination of the velocities of the surface and volume waves from the modelled reflection coefficient. On the other hand, the elastic parameters of the material such as Young’s, shear and bulk moduli were also deduced.

Novel natural super-lattice materials with low thermal conductivity for thermoelectric applications: A first principles study

NASA Astrophysics Data System (ADS)

Sreeparvathy, P. C.; Kanchana, V.

2017-12-01

A systematic study which reveals the low thermal conductivity and high thermopower on a series of natural superlattice structures in the form BaXFCh (X: Cu, Ag, Ch: S, Se, Te), LaXSO (X: Cu, Ag) and SrCuTeF are presented. Low thermal conductivity is predicted by combining elastic constants and few well established models. The electronic properties reveal the highly two dimensional nature of band structure in the valence band, and this is confirmed through effective mass calculations. The huge difference in effective mass along different crystallographic directions in valence band introduces anisotropy in the transport properties for hole doping, and 'a' axis is found to be more favourable. In addition to these, the parameter A (S2σ/τT/κe /τ), which can decouple the relaxation time is also calculated, and it reveals the possibility of good thermoelectric properties in these compounds. Our results are comparable with prototype thermoelectric materials, and show better values than traditional TE materials.

Microstructures and properties of superconducting Y-ErBaCuO thin films obtained from disordered Y-ErBaF2Cu films

NASA Technical Reports Server (NTRS)

Cikmach, P.; Diociaiuti, M.; Fontana, A.; Giovannella, C.; Iannuzzi, M.; Lucchini, C.; Merlo, V.; Messi, R.; Paoluzi, L.; Scopa, L.

1991-01-01

The preparation procedure used to obtain superconducting thin films by radio frequency magnetron sputtering of a single mosaic target is described in detail. The single mosaic target is composed of (Y-Er), BaF2, and Cu.

Synthesis of barium-strontium titanate hollow tubes using Kirkendall effect

NASA Astrophysics Data System (ADS)

Chen, Xuncai; Im, SangHyuk; Kim, Jinsoo; Kim, Woo-Sik

2018-02-01

(BaSr)TiO3 hexagonal hollow tubes was fabricated by a solid-state interfacial reaction including a Kirkendall diffusion. Using a co-precipitation and sol-gel process, a core@shell structure of (BaSr)CO3@TiO2 rods were prepared, and then converted to (BaSr)TiO3 hollow tubes at 750 °C. This was a first achievement of single-phase crystal hollow tube. Here, the inner diameter and wall thickness of hollow tube were about 700 nm and 130 nm, respectively. The fabrication of (BaSr)TiO3 hollow tubes was monitored with scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), transmission electron microscopy (TEM), and X-ray diffraction (XRD) to investigate their formation mechanism. The present synthetic approach would provide a new insight into the design and fabrication of hollow architectures of many perovskite oxides.

Elemental fractionation and magnetic properties of melt-based Y1Ba2Cu3Oz containing excess Tb or Pt

NASA Technical Reports Server (NTRS)

Hojaji, Hamid; Barkatt, Aaron; Hu, Shouxiang; Michael, Karen A.; Thorpe, Arthur N.; Talmy, Inna G.; Haught, Debbie A.; Alterescu, Sidney

1990-01-01

Scanning electron microscopy of certain partially melted Y-Ba-Cu-O materials containing minority metal oxide species (Y:Tb:Ba:Cu = 1:0.1:2:3 or Y:Ba:Cu with Pt impurities), accompanied by both EDX and EMP analysis, indicates that the minority species (Tb or Pt) is quantitatively concentrated in a relatively small number of 123-type grains. High magnetic susceptibility and magnetization observed for these materials indicate that such elemental distribution is not detrimental to superconducting behavior.

Sr{sub 7}Ge{sub 6}, Ba{sub 7}Ge{sub 6} and Ba{sub 3}Sn{sub 2} -Three new binary compounds containing dumbbells and four-membered chains of tetrel atoms with considerable Ge-Ge {pi}-bonding character

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siggelkow, Lisa; Hlukhyy, Viktor; Faessler, Thomas F., E-mail: thomas.faessler@lrz.tum.de

2012-07-15

The germanides Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} as well as the stannide Ba{sub 3}Sn{sub 2} were prepared by arc melting and annealing in welded tantalum ampoules using induction as well as resistance furnaces. The compounds were investigated by powder and single crystal X-ray diffraction. Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} crystallize in the Ca{sub 7}Sn{sub 6} structure type (space group Pmna, Z=4: a=7.777(2) A, b=23.595(4) A, c=8.563(2) A, wR{sub 2}=0.081 (all data), 2175 independent reflections, 64 variable parameters for Sr{sub 7}Ge{sub 6} and a=8.0853(6) A, b=24.545(2) A, c=8.9782(8) A, wR{sub 2}=0.085 (all data), 2307 independent reflections, 64more » variable parameters for Ba{sub 7}Ge{sub 6}). Ba{sub 3}Sn{sub 2} crystallizes in an own structure type with the space group P4{sub 3}2{sub 1}2, Z=4, a=6.6854(2) A, c=17.842(2) A, wR{sub 2}=0.037 (all data), 1163 independent reflections, 25 variable parameters. In Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} the Ge atoms are arranged as Ge{sub 2} dumbbells and Ge{sub 4} four-membered atom chains. Their crystal structures cannot be rationalized according to the (8-N) rule. In contrast, Ba{sub 3}Sn{sub 2} presents Sn{sub 2} dumbbells as a main structural motif and thereby can be described as an electron precise Zintl phase. The chemical bonding situation in these structures is discussed on the basis of partial and total Density Of States (DOS) curves, band structures including fatbands, topological analysis of the Electron Localization Function (ELF) as well as Bader analysis of the bond critical points using the programs TB-LMTO-ASA and WIEN2K. While Ba{sub 3}Sn{sub 2} reveals semiconducting behaviour, all germanides Ae{sub 7}Ge{sub 6} (Ae=Ca, Sr, and Ba) show metallic properties and a considerable {pi}-bonding character between the Ge atoms of the four-membered chains and the dumbbells. The {pi}-bonding character of the germanides is best reflected by the resonance hybrid structures {l_brace}[Ge-Ge]{sup 6-}/[Ge-{sup ....}Ge-{sup ....}Ge-{sup ....}Ge]{sup 8-}{r_brace}{r_reversible}{l_brace}[Ge=Ge]{sup 4-}/[Ge-Ge-Ge-Ge]{sup 10-}{r_brace}. - Graphical abstract: The structure of Ba{sub 3}Sn{sub 2} contains Sn{sub 2} dumbbells as a main structural motif and thereby can be described as an electron precise Zintl phase. Ge{sub 2} dumbbells and Ge{sub 4} four-membered atom chains are the predominant features in Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6}. Their crystal structures cannot be rationalized according to the (8-N) rule. While Ba{sub 3}Sn{sub 2} reveals semiconducting behaviour, the germanides Ae{sub 7}Ge{sub 6} (Ae=Ca, Sr, and Ba) show metallic properties and a considerable {pi}-bonding character between the Ge atoms of the four-membered chains and the dumbbells. Highlights: Black-Right-Pointing-Pointer The germanides Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} as well as the stannide Ba{sub 3}Sn{sub 2} have been synthesized. Black-Right-Pointing-Pointer In Sr{sub 7}Ge{sub 6} and Ba{sub 7}Ge{sub 6} the Ge atoms are arranged as dumbbells and four-membered atom chains. Black-Right-Pointing-Pointer Ba{sub 3}Sn{sub 2} presents Sn{sub 2} dumbbells as a main structural motif. Black-Right-Pointing-Pointer The chemical bonding situation within these structures is discussed.« less

STABILIZATION OF SPIDER CRAB NERVE MEMBRANES BY ALKALINE EARTHS, AS MANIFESTED IN RESTING POTENTIAL MEASUREMENTS

PubMed Central

Guttman, Rita

1940-01-01

1. The alkaline earths, Ba, Sr, Ca, and Mg, in isotonic solutions of their chlorides, have, in general, no effect upon the resting potential of non-medullated spider crab nerve. 2. Ba, Sr, and Ca can, however, prevent the depressing action of K upon the resting potential. The order of effectiveness of these ions in this regard is the following: Ba > Sr > Ca. 3. Ba, Sr, Ca, and Mg oppose the depressing action of veratrine sulfate upon the resting potential. The order of effectiveness is Ba > Sr > Ca > Mg. The relation between drop in potential caused by veratrine sulfate and the logarithm of the veratrine sulfate concentration is a linear one. 4. The action of various other organic ions and molecules which depress the resting potential: saponin, amyl urethane, chloral hydrate, and Na salicylate is neutralized by Ba. 5. Hypertonic sea water solutions do not affect the resting potential. Also, preliminary experiments indicate that the nerves do not shrink in hypertonic solutions although they swell in hypotonic sea water. 6. The alkaline earths depress excitability reversibly. The various organic agents which depress the resting potential also depress excitability, in most cases, reversibly, but the concentrations necessary to depress excitability are much smaller than those necessary to depress the resting potential. 7. The relation of these findings to theories put forward as possible explanations of resting potential phenomena is considered. PMID:19873160

Concentrations and ratios of Sr, Ba and Ca along an estuarine river to the Gulf of Mexico - implication for sea level rise effects on trace metal distribution

NASA Astrophysics Data System (ADS)

He, S.; Xu, Y. J.

2015-11-01

Strontium and barium to calcium ratios are often used as proxies for tracking animal movement across salinity gradients. As sea level rise continues, many estuarine rivers in the world face saltwater intrusion, which may cause changes in mobility and distribution of these metals upstream. Despite intensive research on metal adsorption and desorption in marine systems, knowledge of the spatiotemporal distribution of these elements along estuarine rivers is still limited. In this study, we conducted an intensive monitoring of Sr and Ba dynamics along an 88 km long estuary, the Calcasieu River in South Louisiana, USA, which has been strongly affected by saltwater intrusion. Over the period from May 2013 to August 2015, we collected monthly water samples and performed in-situ water quality measurements at six sites from the upstream to the river mouth, with a salinity range from 0.02 to 29.50 ppt. Water samples were analyzed for Sr, Ba, and Ca concentrations. In-situ measurements were made on salinity, pH, water temperature, dissolved oxygen concentration, and specific conductance. We found that the Sr and Ca concentrations and the Sr / Ca ratio all increased significantly with increasing salinity. The average Sr concentration at the site closest to the Gulf of Mexico (site 6) was 46.21 μmol L-1, which was about 130 times higher than that of the site furthest upstream (site 1, 0.35 μmol L-1). The average Ca concentration at site 6 was 8.19 mmol L-1, which was about 60 times higher than that of site 1 (0.13 mmol L-1). The average Sr / Ca ratio at site 6 (8.41 mmol mol-1) was about 3 times the average Sr / Ca ratio at site 1 (2.89 mmol mol-1). However, the spatial variation in Ba concentration was marginal, varying from 0.36 μmol L-1 at site 6 to 0.47 at site 5. The average Ba / Ca ratio at site 1 (4.82 mmol mol-1) was about 54 times the average Ba / Ca ratio at site 6 (0.09 mmol mol-1), showing a clear negative relation between the Ba / Ca ratio and increasing salinity. All the elemental concentrations and ratios had considerable seasonal variations, with significant differences among sampling months for the Sr, Ba concentrations and the Ba / Ca ratio (p < 0.01). The results from this study suggest that concentrations of Sr and Ca in the world's estuaries will very likely increase in the future as sea level rise continues. For low-gradient estuarine rivers such as the Calcasieu River in South Louisiana, USA, water chemistry upstream would experience substantial Sr and Ca enrichment, which could affect aquatic environments and biological communities.

Ba(1-x)Sr(x)Zn2Si2O7--A new family of materials with negative and very high thermal expansion.

PubMed

Thieme, Christian; Görls, Helmar; Rüssel, Christian

2015-12-15

The compound BaZn2Si2O7 shows a high coefficient of thermal expansion up to a temperature of 280 °C, then a transition to a high temperature phase is observed. This high temperature phase exhibits negative thermal expansion. If Ba(2+) is successively replaced by Sr(2+), a new phase with a structure, similar to that of the high temperature phase of BaZn2Si2O7, forms. At the composition Ba0.8Sr0.2Zn2Si2O7, this new phase is completely stabilized. The crystal structure was determined with single crystal X-ray diffraction using the composition Ba0.6Sr0.4Zn2Si2O7, which crystallizes in the orthorhombic space group Cmcm. The negative thermal expansion is a result of motions and distortions inside the crystal lattice, especially inside the chains of ZnO4 tetrahedra. Dilatometry and high temperature X-ray powder diffraction were used to verify the negative thermal expansion. Coefficients of thermal expansion partially smaller than -10·10(-6) K(-1) were measured.

Thermoluminescence dosimetry features of DY and Cu doped SrF2 nanoparticles under gamma irradiation.

PubMed

Zahedifar, M; Sadeghi, E; Kashefi Biroon, M; Harooni, S; Almasifard, F

2015-11-01

Dy and Cu-doped SrF2 nanoparticles (NPs) were synthesized by using co-precipitation method and their possible application to solid state dosimetry were studied and compared to that of pure SrF2 NPs. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) were used for sample characterization. The highest thermoluminescence (TL) response of SrF2:Dy and SrF2:Cu NPs were found respectively at 0.5 and 0.7mol% of Dy and Cu impurities. Seven overlapping glow peaks at 384, 406, 421, 449, 569, 495, 508K and three component glow peaks at 381, 421 and 467K were identified respectively for SrF2:Dy and SrF2:Cu NPs employing Tm-Tstop and computerized glow curve deconvolution (CGCD) methods. The TL sensitivity of SrF2:Dy is approximately the same as that of LiF:Mg,Ti (TLD-100) cheeps. Linear dose response were observed for the SrF2:Dy and SrF2:Cu NPs up to the absorbed doses of 1kGy and 10kGy correspondingly. Regarding other dosimetry characteristics of the produced NPs such as fading, reproducibility and thermal treatment, Dy and Cu doped SrF2 NPs recommend for high dose TL dosimetry applications. Copyright © 2015 Elsevier Ltd. All rights reserved.

A simplified soil extraction sequence to monitor the main and trace element speciation in soil after compost and mineral fertilizer additions upon the composition of wheat grains

NASA Astrophysics Data System (ADS)

Sager, Manfred; Erhart, Eva

2016-04-01

High quality biological waste treatment aims at producing compost in order to maintain a clean environment and to sustain soil organic carbon levels. Fertilization with compost as a source of organic carbon, nutrients, and accessory elements, as well as fertilization with mineral N- and PK fertilizer have been tested in a field experiment on a calcaric Fluvisol in the Danube wetlands, at 4 levels each. Yields of wheat were recorded, and grains and soils were sampled from each treatment, and analyzed for main and trace element composition. The corresponding soils were characterized by mobile phases, obtained by leaching with 0,16M acetic acid to cover exchangeables plus carbonates, and subsequently by 0,1M oxalate buffer pH 3 to dissolve the pedogenic oxides. Total amounts were obtained from digests with perchloric- nitric-hydrofluoric acid. For quasi-total amounts, aqua regia was replaced by pressure decomposition with KClO3 in dilute nitric acid. The proposed extraction sequence permits to analyze and interpret soil for main elements, trace elements, nutrients and anions simultaneously. Factor analyses of soil extracts obtained from dilute acetic acid revealed Ba-Be-Cd-Cu-Li-S (traces), Ca-Mg-Mn (main carbonates), Al-Fe-B, Y, and P-K (nutrients) as chemically feasible principal components. Subsequent soil extracts from oxalate contained Al-B-Co-K-Na-Pb-Si-V-S (maybe acid silicate weathering), Cr-Li-Ni-Sr-Ti (maybe basic silicate weathering), Be-Cu-Fe-P, Co-Mg-Mn-Zn (Mn-oxides) and Ba-Sc as principal components. Factor analyses of total element data distinguished the principal components Ce-La-Li-Sc-Y-P (rare earths), Al-Ca-Fe-K-Mg-Na-P (main elements), Cd-Co-Cr-Cu-Ni-Zn (trace elements), As-Pb (contaminants), Ba-Mn-Sr, and Ti, which looks chemically feasible also. Factor analyses of those soil fractions which presumably form the main fractions of exchangeables, carbonates, pedogenic oxides and silicates, showed no cross connections, except for P. Oxalate-soluble Fe together with P and S was independent from oxalate-soluble Al-Mn-Si. In the crops, all element levels were within a non-contaminated and non-deficient range, therefore correlations with concentrations as well as loads in the wheat grains where largely not pronounced. Maximum correlations between plant and soil data were obtained with Li and Be. The load data (concentration times yield, given in g/ha) were much more intercorrelated than the concentrations. Regarding the same element, correlation coefficients between loads and respective concentrations were larger than 0,800 for Al, Ba, Cd, Co, Cr, Li, Mo, Na, Ni, Se, and Sr, which means the transfer remained independent from the load. In case of Ca, Mg, P, S, Zn, however, correlation coefficients between loads and concentrations were < 0,500, thus the transfer was not constant because of obvious metabolic influences. The proposed method of soil characterization was applied at a field trial here for the first time, and offers new possibilities of intercorrelations between plant uptake and geochemical soil fractions.

Strontium, barium, and manganese metabolism in isolated presynaptic nerve terminals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rasgado-Flores, H.; Sanchez-Armass, S.; Blaustein, M.P.

1987-06-01

To gain insight into the mechanisms by which the divalent cations Sr, Ba, and Mn affect neurotransmitter release from presynaptic nerve terminals, the authors examined the sequestration of these cations, ion comparison to Ca, by mitochondrial and nonmitochondrial organelles and the extrusion of these cations from isolated nerve terminals. Sequestration was studied in synaptosomes made leaky to small ions by treatment with saponin; efflux was examined in intact synaptosomes that were preloaded with the divalent cations by incubation in depolarizing (K rich) media. The selectivity sequence for ATP-dependent mitochondrial uptake that they observed was Mn>>Ca>Sr>>Ba, whereas that for the SERmore » was Ca greater than or equal to Mn>Sr>>Ba. When synaptosomes that were preloaded with divalent cations were incubated in Na- and Ca-free media, there was little efflux of /sup 45/Ca, /sup 133/Ba, /sup 85/Sr, or /sup 54/Mn. When the incubation was carried out in media containing Na without Ca, there was substantial stimulation of Ca and Sr efflux, but only slight stimulation of Ba or Mn efflux. In Na-free media, the addition of 1 mM Ca promoted the efflux of all four divalent cations, probably via Ca-divalent cation exchange. In summary, the sequestration and extrusion data suggest that, with equal loads, Mn will be buffered to the greatest extent, whereas Ba will be least well buffered. These results may help to explain why Mn has a very long-lasting effect on transmitter release, while the effect of Sr is much briefer.« less

Magnetic-field-induced vortex-lattice transition in HgBa 2 CuO 4 + δ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Jeongseop A.; Xin, Yizhou; Stolt, I.

Measurements of the 17O nuclear magnetic resonance (NMR) quadrupolar spectrum of apical oxygen in HgBa 2CuO 4+δ were performed over a range of magnetic fields from 6.4–30 T in the superconducting state. Oxygen-isotope-exchanged single crystals were investigated with doping corresponding to superconducting transition temperatures from 74 K underdoped, to 78 K overdoped. The apical oxygen site was chosen since its NMR spectrum has narrow quadrupolar satellites that are well separated from any other resonance. Nonvortex contributions to the spectra can be deconvolved in the time domain to determine the local magnetic field distribution from the vortices. Numerical analysis using Brandt'smore » Ginzburg-Landau theory was used to find structural parameters of the vortex lattice, penetration depth, and coherence length as a function of magnetic field in the vortex solid phase. From this analysis we report a vortex structural transition near 15 T from an oblique lattice with an opening angle of 73° at low magnetic fields to a triangular lattice with 60° stabilized at high field. The temperature for onset of vortex dynamics has been identified from spin-spin relaxation. This is independent of the magnetic field at sufficiently high magnetic field similar to that reported for YBa 2Cu 3O 7 and Bi 2Sr 2CaCu 2O 8+δ and is correlated with mass anisotropy of the material. Here, this behavior is accounted for theoretically only in the limit of very high anisotropy.« less

Antiferromagnetism in semiconducting SrMn 2 Sb 2 and BaMn 2 Sb 2 single crystals

DOE PAGES

Sangeetha, N. S.; Smetana, V.; Mudring, A. -V.; ...

2018-01-03

Here, crystals of SrMn 2Sb 2 and BaMn 2Sb 2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ, heat capacity C p, and magnetic susceptibility χ measurements versus temperature T, and magnetization versus field M(H) isotherm measurements. SrMn 2Sb 2 adopts the trigonal CaAl 2Si 2-type structure, whereas BaMn 2Sb 2 crystallizes in the tetragonal ThCr 2Si 2-type structure. The ρ(T) data indicate semiconducting behaviors for both compounds with activation energies of ≳0.35 eV for SrMn 2Sb 2 and 0.16 eV for BaMn 2Sb 2. The χ(T) andmore » C p(T) data reveal antiferromagnetic (AFM) ordering at T N = 110 K for SrMn 2Sb 2 and 450 K for BaMn 2Sb 2. The anisotropic χ(T≤T N) data also show that the ordered moments in SrMn 2Sb 2 are aligned in the hexagonal ab plane, whereas the ordered moments in BaMn 2Sb 2 are aligned collinearly along the tetragonal c axis. The ab-plane M(H) data for SrMn 2Sb 2 exhibit a continuous metamagnetic transition at low fields 02Sb 2 exhibits no metamagnetic transitions up to 5.5 T. The χ(T) and C p(T) data for both SrMn 2Sb 2 and BaMn 2Sb 2 indicate strong dynamic short-range AFM correlations above their respective T N up to at least 900 K within a local-moment picture, corresponding to quasi-two-dimensional magnetic behavior. The present results and a survey of the literature for Mn pnictides with the CaAl 2Si 2 and ThCr 2Si 2 crystal structures show that the T N values for the CaAl 2Si 2-type compounds are much smaller than those for the ThCr 2Si 2-type materials.« less

Double-perovskites A 2FeMoO 6- δ (A = Ca, Sr, Ba) as anodes for solid oxide fuel cells

NASA Astrophysics Data System (ADS)

Zhang, Leilei; Zhou, Qingjun; He, Qiang; He, Tianmin

Double-perovskites A 2FeMoO 6- δ (A = Ca, Sr, Ba) have been investigated as potential anode materials for solid oxide fuel cells (SOFCs). At room temperature, A 2FeMoO 6- δ compounds crystallize in monoclinic, tetragonal, and cubic structures for A = Ca, Sr, and Ba, respectively. A weak peak observed at around 880 cm -1 in the Raman spectra can be attributed to traces of AMoO 4. XPS has confirmed the coexistence of Fe 2+-Mo 6+ and Fe 3+-Mo 5+ electronic configurations. Moreover, a systematic shift from Fe 2+/3+-Mo 6+/5+ to Fe 2+-Mo 6+ configuration is seen with increasing A-site cation size. A 2FeMoO 6- δ samples display distinct electrical properties in H 2, which can be attributed to different degrees of degeneracy of the Fe 2+-Mo 6+ and Fe 3+-Mo 5+ configurations. Ca 2FeMoO 6- δ is unstable in a nitrogen atmosphere, while Sr 2FeMoO 6- δ and Ba 2FeMoO 6- δ are stable up to 1200 °C. The thermal expansion coefficients of Sr 2FeMoO 6- δ and Ba 2FeMoO 6- δ are very close to that of La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ (LSGM). The performances of cells with 300 μm thick LSGM electrolyte, double-perovskite SmBaCo 2O 5+ x cathodes, and A 2FeMoO 6- δ anodes follow the sequence Ca 2FeMoO 6- δ < Ba 2FeMoO 6- δ < Sr 2FeMoO 6- δ. The maximum power densities of a cell with an Sr 2FeMoO 6- δ anode reach 831 mW cm -2 in dry H 2 and 735 mW cm -2 in commercial city gas at 850 °C, respectively.

c-Axis oriented epitaxial Ba 0.25Sr 0.75TiO 3 films display Curie-Weiss behavior

NASA Astrophysics Data System (ADS)

Boikov, Yu. A.; Claeson, T.

2002-02-01

Thin films of ferroelectrics have inferior dielectric properties, including microwave losses, compared to bulk material and generally do not display a proper Curie-Weiss behavior. This study shows that the film properties can be improved considerably, with a Curie-Weiss behavior, by choosing lattice matched electrodes and proper stoichiometry. A 700 nm thick Ba 0.25Sr 0.75TiO 3 layer was inserted, by laser ablation, between two epitaxial metallic oxide (200 nm) SrRuO 3 electrodes. Because of compressive stress in the plane of the substrate, the c-axis of the unit cell in the Ba 0.25Sr 0.75TiO 3 layer was normal to the substrate plane. Grains were of the order of 100-200 nm (with small misorientation angles in a× b plane) as determined by X-rays and AFM. The positions of pronounced maxima in the temperature dependence of the permittivity depended on external bias voltage applied between the SrRuO 3 electrodes to the dielectric film. The measured ε( T) curves agreed well with existing theoretical models at temperatures below and above the ferroelectric phase transition point. At T≈200 K, ε/ ε0 for the Ba 0.25Sr 0.75TiO 3 layer was suppressed up to 85% (from 4400 down to 560) when ±2.5 V bias voltage was applied to the metallic oxide electrodes. Well saturated polarization-vs.-voltage hysteresis loops were measured for the Ba 0.25Sr 0.75TiO 3 layer in the temperature interval 4.2-200 K. Because of depolarization effects, the polarization of the Ba 0.25Sr 0.75TiO 3 layer was suppressed at positive voltage applied between the electrodes, as compared with a negative one.

DEPENDENCE OF THE Sr-TO-Ba AND Sr-TO-Eu RATIO ON THE NUCLEAR EQUATION OF STATE IN METAL-POOR HALO STARS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Famiano, M. A.; Kajino, T.; Aoki, W.

A model is proposed in which the dependence on the equation of state (EOS) of the scatter of [Sr/Ba] in metal-poor stars is studied. Light r-process element enrichment in these stars has been explained via a truncated r-process, or “tr-process.” The truncation of the r-process from a generic core-collapse event followed by a collapse into an accretion-induced black hole is examined in the framework of a galactic chemical evolution model. The constraints on this model imposed by observations of extremely metal-poor stars are explained, and the upper limits in the [Sr/Ba] distributions are found to be related to the nuclearmore » EOS in a collapse scenario. The scatter in [Sr/Ba] and [Sr/Eu] as a function of metallicity has been found to be consistent with turbulent ejection in core-collapse supernovae. Adaptations of this model are evaluated to account for the scatter in isotopic observables. This is done by assuming mixing in ejecta in a supernova event. Stiff EOS are eliminated by this model.« less

Generation of spin currents from one-dimensional quantum spin liquid

NASA Astrophysics Data System (ADS)

Hirobe, Daichi; Kawamata, Takayuki; Oyanagi, Koichi; Koike, Yoji; Saitoh, Eiji

2018-03-01

Spin-Seebeck effects (SSEs) in a one-dimensional quantum spin liquid (QSL) system have been investigated in a Sr2CuO3/Pt hybrid structure. Sr2CuO3 contains one-dimensional spin- /1 2 chains in which typical spinons in QSL have been confirmed. Heat-induced voltage measured in a clean Pt/Sr2CuO3 exhibits anomalous sign reversal with decreasing temperature, the negative component of which can be attributed to the spinon-induced SSE. However, the SSE was found to be critically decreased upon the exposure of Sr2CuO3 to air, which can be associated with the chemical degradation of the interface of Sr2CuO3. Despite the drastic change in the SSE signals, properties of the one-dimensional QSL are little changed in the spin susceptibility as well as the thermal conductivity of Sr2CuO3. The SSE signal is also sensitive to the purity of Sr2CuO3; it is suppressed with a decrease in the purity of the primary compounds of the Sr2CuO3. The result indicates that the spinon-induced SSE in Sr2CuO3 is sensitive to the bulk condition due to the one-dimensional atomic channel for spin transport in Sr2CuO3. In a carefully prepared Sr2CuO3/Pt sample, we found that the spinon-induced SSE signal is tolerant to magnetic fields; it increases linearly with the field even up to 9 T. In contrast, SSEs are suppressed under such a high field in ferrimagnetic insulators Y3Fe5O12 or paramagnetic insulators Gd3Ga5O12, which is caused by the Zeeman gap in the spin-wave or paramagnetic spin excitations. The robustness of the spinon-induced SSE is consistent with the Tomonaga-Luttinger liquid theories.

Ca, Sr and Ba stable isotopes reveal the fate of soil nutrients along a tropical climosequence

USGS Publications Warehouse

Bullen, Thomas D.; Chadwick, Oliver A.

2016-01-01

Nutrient biolifting is an important pedogenic process in which plant roots obtain inorganic nutrients such as phosphorus (P) and calcium (Ca) from minerals at depth and concentrate those nutrients at the surface. Here we use soil chemistry and stable isotopes of the alkaline earth elements Ca, strontium (Sr) and barium (Ba) to test the hypothesis that biolifting of P has been an important pedogenic process across a soil climosequence developed on volcanic deposits at Kohala Mountain, Hawaii. The geochemical linkage between these elements is revealed as generally positive site-specific relationships in soil mass gains and losses, particularly for P, Ba and Ca, using the ratio of immobile elements titanium and niobium (Ti/Nb) to link individual soil samples to a restricted compositional range of the chemically and isotopically diverse volcanic parent materials. At sites where P is enriched in surface soils relative to abundances in deeper soils, the isotope compositions of exchangeable Ca, Sr and Ba in the shallowest soil horizons (< 10 cm depth) are lighter than those of the volcanic parent materials and trend toward those of plants growing on fresh volcanic deposits. In contrast the isotope composition of exchangeable Ba in deeper soil horizons (> 10 cm depth) at those sites is consistently heavier than the volcanic parent materials. The isotope compositions of exchangeable Ca and Sr trend toward heavier compositions with depth more gradually, reflecting increasing leakiness from these soils in the order Ba < Sr < Ca and downward transfer of light biocycled Ca and Sr to deeper exchange sites. Given the long-term stability of ecosystem properties at the sites where P is enriched in surface soils, a simple box model demonstrates that persistence of isotopically light exchangeable Ca, Sr and Ba in the shallowest soil horizons requires that the uptake flux to plants from those near-surface layers is less than the recycling flux returned to the surface as litterfall. This observation implicates an uptake flux from an additional source which we attribute to biolifting. We view the heavy exchangeable Ba relative to soil parent values in deeper soils at sites where P is enriched in surface soils, and indeed at all but the wettest site across the climosequence, to represent the complement of an isotopically light Ba fraction removed from these soils by plant roots consistent with the biolifting hypothesis. We further suggest that decreasing heaviness of depth-integrated exchangeable Ba in deeper soils with increasing median annual precipitation across the climosequence reflects greater reliance on shallow nutrient sources as site water balance increases. While the Ca, Sr and Ba isotopes considered together were useful in confirming an important role for nutrient biolifting across the climosequence, the Ba isotopes provided the most robust tracer of biolifting and have the greatest potential to find application as an isotopic proxy for P dynamics in soils.

Synthesis and characterization of high-Tc superconductors in the Tl-Ca-Ba-Cu-O system

NASA Technical Reports Server (NTRS)

Bansal, Narottam P.; Farrell, D. E.

1989-01-01

Both Tl2Ca2Ba2Cu3O10 and TlCa3BaCu3O8.5 are investigated for superconductivity as a function of the sintering temperature, time, atmosphere, and quench rate in an effort to synthesize the high-Tc superconducting phase in the thallium system. The samples are characterized by electrical resistivity measurements, X-ray diffraction, and scanning electron microscopy. Samples of starting composition Tl2Ca2Ba2Cu3O10 fired in air at 860-900 C and rapidly quenched show a Tc of 96-107 K. In contrast, specimens of starting composition TlCa3BaCu3O8.5 when baked at 900 C and slowly cooled in oxygen superconduct at 116 K and above and consist of Tl2Ca2Ba2Cu3O(10+x) as the dominant phase. The results also show that, in contrast to the case of YBa2Cu3O(7-x), doping with a small concentration of fluorine sharpens the resistive transition and produces a large Tc increase in thallium-based superconductors.

Major, minor, trace and rare earth elements in sediments of the Bijagós archipelago, Guinea-Bissau.

PubMed

Carvalho, Lina; Figueira, Paula; Monteiro, Rui; Reis, Ana Teresa; Almeida, Joana; Catry, Teresa; Lourenço, Pedro Miguel; Catry, Paulo; Barbosa, Castro; Catry, Inês; Pereira, Eduarda; Granadeiro, José Pedro; Vale, Carlos

2018-04-01

Sixty sediment samples from four sites in the Bijagós archipelago were characterized for fine fraction, loss on ignition, major, minor and trace elemental composition (Al, Fe, Ca, Mg, Ti, P, Zr, Mn, Cr, Sr, Ba, B, V, Li, Zn, Ni, Pb, As, Co, U, Cu, Cs and Cd), and the elements of the La-Lu series. Element concentrations were largely explained by the Al content and the proportion of fine fraction content, with the exception of Ca and Sr. Sediments showed enhanced Ti, U, Cr, As and Cd concentrations with respect to estimated upper crust values, most likely mirroring a regional signature. Rare earth elements were in deficit relatively to the North American Shale Composite (NASC), mainly in coarser material. No pronounced Ce-anomaly was observed, while Eu-anomalies were positive in most analyzed sediments. Copyright © 2017 Elsevier Ltd. All rights reserved.

Metals detected by ICP/MS in wound tissue of war injuries without fragments in Gaza

PubMed Central

2010-01-01

Background The amount and identity of metals incorporated into "weapons without fragments" remain undisclosed to health personnel. This poses a long-term risk of assumption and contributes to additional hazards for victims because of increased difficulties with clinical management. We assessed if there was evidence that metals are embedded in "wounds without fragments" of victims of the Israeli military operations in Gaza in 2006 and 2009. Methods Biopsies of "wounds without fragments" from clinically classified injuries, amputation (A), charred (C), burns (B), multiple piercing wounds by White Phosphorus (WP) (M), were analyzed by ICP/MS for content in 32 metals. Results Toxic and carcinogenic metals were detected in folds over control tissues in wound tissues from all injuries: in A and C wounds (Al, Ti, Cu, Sr, Ba, Co, Hg, V, Cs and Sn), in M wounds (Al, Ti, Cu, Sr, Ba, Co and Hg) and in B wounds (Co, Hg, Cs, and Sn); Pb and U in wounds of all classes; B, As, Mn, Rb, Cd, Cr, Zn in wounds of all classes, but M; Ni was in wounds of class A. Kind and amounts of metals correlate with clinical classification of injuries, exposing a specific metal signature, similar for 2006 and 2009 samples. Conclusions The presence of toxic and carcinogenic metals in wound tissue is indicative of the presence in weapon inducing the injury. Metal contamination of wounds carries unknown long term risks for survivors, and can imply effects on populations from environmental contamination. We discuss remediation strategies, and believe that these data suggest the need for epidemiological and environmental surveys. PMID:20579349

Spatial and ontogenetic variability in the chemical composition of juvenile common sole ( Solea solea) otoliths

NASA Astrophysics Data System (ADS)

Tanner, S. E.; Vasconcelos, R. P.; Reis-Santos, P.; Cabral, H. N.; Thorrold, S. R.

2011-01-01

A description of variations in the chemical composition of fish otoliths at different spatial scales and life history stages is a prerequisite for their use as natural tags in fish population connectivity and migration studies. Otolith geochemistry of juvenile common sole ( Solea solea), a marine migrant species collected in six Portuguese estuaries was examined. Elemental ratios (Mg:Ca, Mn:Ca, Cu:Ca, Sr:Ca, Ba:Ca, Pb:Ca) were analysed in two zones of the right otolith (corresponding to late larval and juvenile stages) using laser ablation inductively coupled plasma mass spectrometry (ICP-MS). Stable carbon and oxygen isotopes (δ 13C and δ 18O) were determined in left otoliths using isotopic ratio monitoring mass spectrometry (irm-MS). Significant differences in otolith geochemical signatures were found among estuaries, among sites within estuaries and between otolith zones. Several elemental ratios (Mg:Ca, Mn:Ca, Cu:Ca and Sr:Ca) showed consistent patterns between otolith zones and were likely influenced by environmental factors and ontogenetic effects associated with physiological changes during metamorphosis. Assignment of individuals to their collection estuary based on the otolith geochemical signatures was more accurate at the site level (81%) than among estuaries (69%). Site temperature was not correlated with any of the elemental or isotope ratios, but salinity was significantly correlated with Ba:Ca, δ 13C and δ 18O. Observed spatial variations among estuaries and sites within estuaries indicate that geochemical signatures in otoliths are accurate natural tags of estuarine habitat in common sole. Nevertheless, the significant variations observed between otolith zones should be taken into account in the design of population connectivity studies.

Effects of glyphosate on the mineral content of glyphosate-resistant soybeans (Glycine max).

PubMed

Duke, Stephen O; Reddy, Krishna N; Bu, Kaixuan; Cizdziel, James V

2012-07-11

There are conflicting claims as to whether treatment with glyphosate adversely affects mineral nutrition of glyphosate-resistant (GR) crops. Those who have made claims of adverse effects have argued links between reduced Mn and diseases in these crops. This article describes experiments designed to determine the effects of a recommended rate (0.86 kg ha(-1)) of glyphosate applied once or twice on the mineral content of young and mature leaves, as well as in seeds produced by GR soybeans (Glycine max) in both the greenhouse and field using inductively coupled plasma mass spectrometry (ICP-MS). In the greenhouse, there were no effects of either one application (at 3 weeks after planting, WAP) or two applications (at 3 and 6 WAP) of glyphosate on Ca, Mg, Mn, Zn, Fe, Cu, Sr, Ba, Al, Cd, Cr, Co, or Ni content of young or old leaves sampled at 6, 9, and 12 WAP and in harvested seed. Se concentrations were too low for accurate detection in leaves, but there was also no effect of glyphosate applications on Se in the seeds. In the field study, there were no effects of two applications (at 3 and 6 WAP) of glyphosate on Ca, Mg, Mn, Zn, Fe, Cu, Sr, Ba, Al, Cd, Cr, Co, or Ni content of young or old leaves at either 9 or 12 WAP. There was also no effect on Se in the seeds. There was no difference in yield between control and glyphosate-treated GR soybeans in the field. The results indicate that glyphosate does not influence mineral nutrition of GR soybean at recommended rates for weed management in the field. Furthermore, the field studies confirm the results of greenhouse studies.

Impact of Ficoll density gradient centrifugation on major and trace element concentrations in erythrocytes and blood plasma.

PubMed

Lu, Ying; Ahmed, Sultan; Harari, Florencia; Vahter, Marie

2015-01-01

Ficoll density gradient centrifugation is widely used to separate cellular components of human blood. We evaluated the suitability to use erythrocytes and blood plasma obtained from Ficoll centrifugation for assessment of elemental concentrations. We determined 22 elements (from Li to U) in erythrocytes and blood plasma separated by direct or Ficoll density gradient centrifugation, using inductively coupled plasma mass spectrometry. Compared with erythrocytes and blood plasma separated by direct centrifugation, those separated by Ficoll had highly elevated iodine and Ba concentration, due to the contamination from the Ficoll-Paque medium, and about twice as high concentrations of Sr and Mo in erythrocytes. On the other hand, the concentrations of Ca in erythrocytes and plasma were markedly reduced by the Ficoll separation, to some extent also Li, Co, Cu, and U. The reduced concentrations were probably due to EDTA, a chelator present in the Ficoll medium. Arsenic concentrations seemed to be lowered by Ficoll, probably in a species-specific manner. The concentrations of Mg, P, S, K, Fe, Zn, Se, Rb, and Cs were not affected in the erythrocytes, but decreased in plasma. Concentrations of Mn, Cd, and Pb were not affected in erythrocytes, but in plasma affected by EDTA and/or pre-analytical contamination. Ficoll separation changed the concentrations of Li, Ca, Co, Cu, As, Mo, I, Ba, and U in erythrocytes and blood plasma, Sr in erythrocytes, and Mg, P, S, K, Fe, Zn, Se, Rb and Cs in blood plasma, to an extent that will invalidate evaluation of deficiencies or excess intakes. Copyright © 2014 Elsevier GmbH. All rights reserved.

Efficient degradation of Methylene Blue dye over highly reactive Cu doped strontium titanate (SrTiO3) nanoparticles photocatalyst under visible light.

PubMed

Rahman, Qazi Inamur; Ahmad, Musheer; Misra, Sunil Kumar; Lohani, Minaxi

2012-09-01

Visible light induced photocatalysts of Cu doped SrTiO3 (Cu/SrTiO3) nanoparticles with the size -60-75 nm were prepared via facile sol-gel method. The morphological, optical, crystalline properties and compositions of synthesized Cu/SrTiO3 nanoparticles were thoroughly characterized by field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), ultra violet-visible spectroscopy (UV-Vis) and energy dispersive X-ray (EDX). A significant red shift in the UV-diffused reflectance spectrum was observed and the absorption edge shifted to visible region by the Cu doping. Surprisingly, the band gap of SrTiO3 was changed from 3.2 eV drop to 2.96 eV. The photocatalytic activity of the synthesized Cu/SrTiO3 nanoparticles was demonstrated for the degradation of Methylene Blue dye under visible light irradiation. The formation of new acceptor region in Cu/SrTiO3 was responsible for high photocatalytic activity of Cu/SrTiO3 nanoparticles. The results showed that the Methylene Blue dye was degraded by -66% within time span of 2 h over the Cu/SrTiO3 nanoparticles. This dye degradation reaction followed the Langmuir-Hinshelwood kinetics and also exhibited first order reaction rate. The calculated rate constant for the degradation reaction following first order kinetics was k = 0.0016 min(-1).

Cooperative oscillations of electron-copper-oxygen interaction: Possible relevance for superconduction theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tributsch, H.

1989-01-01

Interfaces of copper containing crystallized materials (Cu/sub 5/FeS/sub 4/, CuFeS/sub 2/, Cu/sub 2/S, CuS, CuInS/sub 2/, and CuInSe/sub 2/), exposed to oxidation by H/sub 2/O/sub 2/, undergo sustained electrochemical oscillations. They involve electronic (Cu/sup +/), (Cu/sup 2 +/), and (Cu/sup 3 +/) interactions with chemically bound oxygen similar as in superconducting YBa/sub 2/Cu/sub 3/O/sub 7/ or (La,Sr)/sub 2/CuO/sub 4/ and may be a phenomenon of irreversible thermodynamics which is related to the kind of cooperative electron-copper-oxygen interactions which also give rise to high-temperature superconduction. The relevance of the model system is supported by the formation of the H/sub 2/O/sub 2/more » species on the surface of high-temperature superconducting materials in contact with ambiental humidity. It is shown how, by a simple modification of the interaction mechanism, an oscillatory phenomenon such as that observed with oxidized copper sulfide interfaces, which follows a limiting cycle, can be converted into a triple-state phenomenon. Such a cooperative mechanism that involves a lowest steady state which is unable to turn over energy may be the background for the pairing of electrons or a related cooperative interaction process in superconduction. As a possible support, no interfacial oscillations could yet be induced with Ba/sub 2/Cu/sub 3/Y/sub 7/.« less

Core-shell-shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) with remarkably enhanced upconversion luminescence.

PubMed

Su, Yue; Liu, Xiuling; Lei, Pengpeng; Xu, Xia; Dong, Lile; Guo, Xianmin; Yan, Xingxu; Wang, Peng; Song, Shuyan; Feng, Jing; Zhang, Hongjie

2016-07-05

Core-shell-shell heterostructures of α-NaLuF4:Yb/Er@NaLuF4:Yb@MF2 (M = Ca, Sr, Ba) have been successfully fabricated via the thermal decomposition method. Upconversion nanoparticles (UCNPs) were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), upconversion luminescence (UCL) spectroscopy, etc. Under 980 nm excitation, the emission intensities of the UCNPs are remarkably enhanced after coating the MF2 (M = Ca, Sr, and Ba) shell. Among these samples, CaF2 coated UCNPs show the strongest overall emission, while BaF2 coated UCNPs exhibit the longest lifetime. These results demonstrate that alkaline earth metal fluorides are ideal materials to improve the UCL properties. Meanwhile, although the lattice mismatch between the ternary NaREF4 core and the binary MF2 (M = Sr and Ba) shell is relatively large, the successfully synthesized NaLuF4:Yb/Er@NaLuF4:Yb@MF2 indicates a new outlook on the fabrication of heterostructural core-shell UCNPs.

Structural studies of the rhombohedral and orthorhombic monouranates: CaUO{sub 4}, α-SrUO{sub 4}, β-SrUO{sub 4} and BaUO{sub 4}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Murphy, Gabriel; Kennedy, Brendan J., E-mail: kennedyb@chem.usyd.edu.au; Johannessen, Bernt

The structures of some AUO{sub 4} (A=Ca, Sr, or Ba) oxides have been determined using a combination of neutron and synchrotron X-ray diffraction, supported by X-ray absorption spectroscopic measurements at the U L{sub 3}-edge. The smaller Ca cation favours a rhombohedral AUO{sub 4} structure with 8-coordinate UO{sub 8} moieties whilst an orthorhombic structure based on UO{sub 6} groups is found for BaUO{sub 4}. Both the rhombohedral and orthorhombic structures can be stabilised for SrUO{sub 4}. The structural studies suggest that the bonding requirements of the A site cation play a significant role in determining which structure is favoured. In themore » rhombohedral structure, Bond Valence Sums demonstrate the A site is invariably overbonded, which, in the case of rhombohedral α-SrUO{sub 4}, is compensated for by the formation of vacancies in the oxygen sub-lattice. The uranium cation, with its flexible oxidation state, is able to accommodate this by inducing vacancies along its equatorial coordination site as demonstrated by neutron powder diffraction. - Graphical abstract: Diffraction studies of AUO{sub 4} (A = Ca, Sr, or Ba) oxides reveal the importance of the bonding requirements of the A site cation in determining whether the structure is rhombohedral or orthorhombic. - Highlights: • Structures of AUO{sub 4} ( A = Ca Sr, Ba) refined against X-ray and Neutron diffraction. • The alkali cations size has a dramatic effect on the crystal structure. • Smaller cations favouring a rhombohedral structure. • Oxygen vacancies to stabilise the rhombohedral structure in SrUO{sub 4}.« less

Crystal structure and optical property of complex perovskite oxynitrides ALi0.2Nb0.8O2.8N0.2, ANa0.2Nb0.8O2.8N0.2, and AMg0.2Nb0.8O2.6N0.4 (A = Sr, Ba)

NASA Astrophysics Data System (ADS)

Moon, Keon Ho; Avdeev, Maxim; Kim, Young-Il

2017-10-01

Oxynitride type complex perovskites AM0.2Nb0.8O3-xNx (A = Sr, Ba; M = Li, Na, Mg) were newly synthesized by the solid state diffusion of Li+, Na+, or Mg2+ into the layered oxide, A5Nb4O15, with concurrent O/N substitution. Neutron and synchrotron X-ray Rietveld refinement showed that SrLi0.2Nb0.8O2.8N0.2, SrNa0.2Nb0.8O2.8N0.2, and SrMg0.2Nb0.8O2.6N0.4 had body-centered tetragonal symmetry (I4/mcm), while those with A = Ba had simple cubic symmetry (Pm 3 ̅ m). In the tetragonal Sr-compounds, the nitrogen atoms were localized on the c-axial 4a site. However, the octahedral cations, M/Nb (M = Li, Na, Mg) were distributed randomly in all six compounds. The lattice volume of AM0.2Nb0.8O3-xNx was dependent on various factors including the type of A and the electronegativity of M. Compared to the simple perovskites, ANbO2N (A = Sr, Ba), AM0.2Nb0.8O3-xNx had wider band gaps (1.76-2.15 eV for A = Sr and 1.65-2.10 eV for A = Ba), but significantly lower sub-gap absorption.

Structural evolution of atomically precise thiolated bimetallic [Au(12+n)Cu₃₂(SR)(30+n)]⁴⁻ (n = 0, 2, 4, 6) nanoclusters.

PubMed

Yang, Huayan; Wang, Yu; Yan, Juanzhu; Chen, Xi; Zhang, Xin; Häkkinen, Hannu; Zheng, Nanfeng

2014-05-21

A series of all-thiol stabilized bimetallic Au-Cu nanoclusters, [Au(12+n)Cu32(SR)(30+n)](4-) (n = 0, 2, 4, 6 and SR = SPhCF3), are successfully synthesized and characterized by X-ray single-crystal analysis and density functional theory (DFT) calculations. Each cluster consists of a Keplerate two-shell Au12@Cu20 core protected by (6 - n) units of Cu2(SR)5 and n units of Cu2Au(SR)6 (n = 0, 2, 4, 6) motifs on its surface. The size and structural evolution of the clusters is atomically controlled by the Au precursors and countercations used in the syntheses. The clusters exhibit similar optical absorption properties that are not dependent on the number of surface Cu2Au(SR)6 units. Although DFT suggests an electronic structure with an 18-electron superatom shell closure, the clusters display different thermal stabilities. [Au(12+n)Cu32(SR)(30+n)](4-) clusters with n = 0 and 2 are more stable than those with n = 4 and 6. Moreover, an oxidation product of the clusters, [Au13Cu12(SR)20](4-), is structurally identified to gain insight into how the clusters are oxidized.

Interplay between magnetism and relativistic fermions in Eu doped (Sr/Ba)MnSb2

NASA Astrophysics Data System (ADS)

Liu, Jinyu; Hu, Jin; Zhu, Yanglin; Chuang, Alyssa; Graf, David; Jaime, Marcelo; Balakirev, Fedor; Weickert, Franziska; Zhang, Qiang; Ditusa, John; Wu, Yan; Cao, Huibo; Mao, Zhiqiang

Layered compounds AMnBi2 (A =Ca, Sr, Ba, Eu, and Yb) have been established as Dirac materials with fascinating properties. In our previous work, we have demonstrated that Sr1-y Mn1-z Sb2 (y, z <0.1), isostructural to AMnBi2, not only host relativistic fermions, but also exhibit ferromagnetic properties, with its ferromagnetism being coupled to the relativistic fermions' transport. To gain further insight into the relativistic fermion-magnetism coupling, we have synthesized a series of Eu doped (Sr/Ba)MnSb2 single crystals and found Eu moments order antiferromagnetically. Through neutron scattering experiments, we determined the magnetic structures for Sr1-xEuxMnSb2 with x = 0.2, 0.5, and 0.8. From magnetotransport measurements, we find the Eu antiferromagnetism is also coupled to relativistic fermion transport. More importantly, we observed a novel quantum phase with saturated magnetoresistivity near the quantum limit for the 10% Eu doped BaMnSb2 sample. We will discuss possible mechanisms for this novel phase.

Functionalized inorganic membranes for gas separation

DOEpatents

Ku, Anthony Yu-Chung [Rexford, NY; Ruud, James Anthony [Delmar, NY; Molaison, Jennifer Lynn [Marietta, GA; Schick, Louis Andrew ,; Ramaswamy, Vidya [Niskayuna, NY

2008-07-08

A porous membrane for separation of carbon dioxide from a fluid stream at a temperature higher than about 200.degree. C. with selectivity higher than Knudsen diffusion selectivity. The porous membrane comprises a porous support layer comprising alumina, silica, zirconia or stabilized zirconia; a porous separation layer comprising alumina, silica, zirconia or stabilized zirconia, and a functional layer comprising a ceramic oxide contactable with the fluid stream to preferentially transport carbon dioxide. In particular, the functional layer may be MgO, CaO, SrO, BaO, La.sub.2O.sub.3, CeO.sub.2, ATiO.sub.3, AZrO.sub.3, AAl.sub.2O.sub.4, A.sup.1FeO.sub.3, A.sup.1MnO.sub.3, A.sup.1CoO.sub.3, A.sup.1NiO.sub.3, A.sup.2HfO.sub.3, A.sup.3CeO.sub.3, Li.sub.2ZrO.sub.3, Li.sub.2SiO.sub.3, Li.sub.2TiO.sub.3 or a mixture thereof; wherein A is Mg, Ca, Sr or Ba; A.sup.1 is La, Ca, Sr or Ba; A.sup.2 is Ca, Sr or Ba; and A.sup.3 is Sr or Ba.

Physical and magnetic properties of (Ba/Sr) substituted magnesium nano ferrites

NASA Astrophysics Data System (ADS)

Ateia, Ebtesam E.; Takla, E.; Mohamed, Amira T.

2017-10-01

In the presented paper, strontium (Sr) and barium (Ba) nano ferrites were synthesized by citrate auto combustion method. The investigated samples are characterized by X-ray diffraction technique (XRD), field emission scanning electron microscopy, high resolution transmission electron microscopy and energy dispersive X-ray spectroscopy. The structural properties of the obtained samples were examined by XRD analysis showing that the synthesized nanoparticles are in cubic spinel structure. The average crystallite sizes are in the range of 22.66 and 21.95 nm for Mg0.7Ba0.3Fe2O4 and Mg0.7 Sr0.3Fe2O4 respectively. The VSM analysis confirms the existence of ferromagnetic nature of Sr2+/Ba2+ substituted magnesium nano particles. Exchange interaction between hard (Sr/Ba) and soft (Mg) magnetic phases improves the structural and magnetic properties of nano ferrite particles. Rigidity modulus, longitudinal and shear wave velocities are predicted theoretically from Raman spectroscopy and structural data of the investigated spinel ferrite. The magnetic and structural properties of magnesium are enhanced by doping with barium and strontium nano particles. The saturation magnetization, remanent magnetization and coercivity reported on vibrating sample magnetometer curve illustrate the promising industrial and magnetic recording applications of the prepared samples.

Trace element partitioning between coexisting biotite and muscovite from metamorphic rocks, western Labrador: Structural, compositional and thermal controls

NASA Astrophysics Data System (ADS)

Yang, Panseok; Rivers, Toby

2000-04-01

Coexisting biotite and muscovite in ten metapelitic and quartzofeldspathic rocks from western Labrador have been analyzed by electron microprobe for major and minor elements and by a laser ablation microprobe coupled to ICP-MS (LAM-ICP-MS) for selected trace elements - Li, Sc, V, Cr, Mn, Co, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Cs, Ba, REE, Hf and Ta. The samples have experienced a single prograde Grenvillian metamorphism ranging from 490 to 680°C and from 7 to 12 kbar. The trace element compositions of coexisting micas in the metamorphic rocks are used to assess the effects of crystal structure, major element composition and temperature on the partitioning of each element between biotite and muscovite. Overall, trace element distributions are systematic across the range of metamorphic grade and bulk composition, suggesting that chemical equilibrium was approached. Most distribution coefficients (biotite/muscovite) show good agreement with published data. However, distribution coefficients for Co and Sr are significantly different from previous determinations, probably because of contamination associated with older data obtained by bulk analysis techniques. The sequence of distribution coefficients is governed mainly by the ionic radii and charges of substituting cations compared to the optimum ionic radius of each crystallographic site in the micas. In particular, distribution coefficients exhibit the sequence Cr 3+ (0.615 Å) > V 3+ (0.64 Å) > Sc 3+ (0.745 Å) in VI-sites, and Ba 2+ (1.61 Å) > Sr 2+ (1.44 Å) and Cs + (1.88 Å) > K + (1.64 Å) > Rb + (1.72 Å) > Na + (1.39 Å) in XII-sites. The distributions of Li, Sc, Sr and Ba appear to be thermally sensitive but are also controlled by major element compositions of micas. V and Zr partitioning is dependent on T and may be used to cross-check thermometry calculations where the latter suffer from retrograde re-equilibration and/or high concentrations of Fe 3+. The ranges and dependence of distribution coefficients on major element compositions provide important constraints on the values that can be used in geochemical modeling.

Metal ferrite oxygen carriers for chemical looping combustion of solid fuels

DOEpatents

Siriwardane, Ranjani V.; Fan, Yueying

2017-01-31

The disclosure provides a metal ferrite oxygen carrier for the chemical looping combustion of solid carbonaceous fuels, such as coal, coke, coal and biomass char, and the like. The metal ferrite oxygen carrier comprises MFe.sub.xO.sub.y on an inert support, where MFe.sub.xO.sub.y is a chemical composition and M is one of Mg, Ca, Sr, Ba, Co, Mn, and combinations thereof. For example, MFe.sub.xO.sub.y may be one of MgFe.sub.2O.sub.4, CaFe.sub.2O.sub.4, SrFe.sub.2O.sub.4, BaFe.sub.2O.sub.4, CoFe.sub.2O.sub.4, MnFeO.sub.3, and combinations thereof. The MFe.sub.xO.sub.y is supported on an inert support. The inert support disperses the MFe.sub.xO.sub.y oxides to avoid agglomeration and improve performance stability. In an embodiment, the inert support comprises from about 5 wt. % to about 60 wt. % of the metal ferrite oxygen carrier and the MFe.sub.xO.sub.y comprises at least 30 wt. % of the metal ferrite oxygen carrier. The metal ferrite oxygen carriers disclosed display improved reduction rates over Fe.sub.2O.sub.3, and improved oxidation rates over CuO.

High-efficiency thermoelectric Ba8Cu14Ge6P26: bridging the gap between tetrel-based and tetrel-free clathrates† †Electronic supplementary information (ESI) available: Calculated and experimental powder XRD patterns; tables with crystallographic information; SEM and EDS results; additional DSC, thermal conductivities, and ZT figures. CCDC 1568106. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c7sc03482b

PubMed Central

Wang, Jian; Lebedev, Oleg I.; Lee, Kathleen; Dolyniuk, Juli-Anna; Klavins, Peter; Bux, Sabah

2017-01-01

A new type-I clathrate, Ba8Cu14Ge6P26, was synthesized by solid-state methods as a polycrystalline powder and grown as a cm-sized single crystal via the vertical Bridgman method. Single-crystal and powder X-ray diffraction show that Ba8Cu14Ge6P26 crystallizes in the cubic space group Pm3n (no. 223). Ba8Cu14Ge6P26 is the first representative of anionic clathrates whose framework is composed of three atom types of very different chemical natures: a transition metal, tetrel element, and pnicogen. Uniform distribution of the Cu, Ge, and P atoms over the framework sites and the absence of any superstructural or local ordering in Ba8Cu14Ge6P26 were confirmed by synchrotron X-ray diffraction, electron diffraction and high-angle annular dark field scanning transmission electron microscopy, and neutron and X-ray pair distribution function analyses. Characterization of the transport properties demonstrate that Ba8Cu14Ge6P26 is a p-type semiconductor with an intrinsically low thermal conductivity of 0.72 W m–1 K–1 at 812 K. The thermoelectric figure of merit, ZT, for a slice of the Bridgman-grown crystal of Ba8Cu14Ge6P26 approaches 0.63 at 812 K due to a high power factor of 5.62 μW cm–1 K–2. The thermoelectric efficiency of Ba8Cu14Ge6P26 is on par with the best optimized p-type Ge-based clathrates and outperforms the majority of clathrates in the 700–850 K temperature region, including all tetrel-free clathrates. Ba8Cu14Ge6P26 expands clathrate chemistry by bridging conventional tetrel-based and tetrel-free clathrates. Advanced transport properties, in combination with earth-abundant framework elements and congruent melting make Ba8Cu14Ge6P26 a strong candidate as a novel and efficient thermoelectric material. PMID:29568451

Interactive Cumulative Burden Assessment: Engaging Stakeholders in an Adaptive, Participatory and Transdisciplinary Approach

PubMed Central

Shrestha, Rehana; van Maarseveen, Martin

2018-01-01

Cumulative burden assessment (CuBA) has the potential to inform planning and decision-making on health disparities related to multiple environmental burdens. However, scholars have raised concerns about the social complexity to be dealt with while conducting CuBA, suggesting that it should be addressed in an adaptive, participatory and transdisciplinary (APT) approach. APT calls for deliberation among stakeholders by engaging them in a process of social learning and knowledge co-production. We propose an interactive stakeholder-based approach that facilitates a science-based stakeholder dialogue as an interface for combining different knowledge domains and engendering social learning in CuBA processes. Our approach allows participants to interact with each other using a flexible and auditable CuBA model implemented within a shared workspace. In two workshops we explored the usefulness and practicality of the approach. Results show that stakeholders were enabled to deliberate on cumulative burdens collaboratively, to learn about the technical uncertainties and social challenges associated with CuBA, and to co-produce knowledge in a realm of both technical and societal challenges. The paper identifies potential benefits relevant for responding to social complexity in the CuBA and further recommends exploration of how our approach can enable or constraint social learning and knowledge co-production in CuBA processes under various institutional, social and political contexts. PMID:29401676

Raman spectroscopy of DNA-metal complexes. I. Interactions and conformational effects of the divalent cations: Mg, Ca, Sr, Ba, Mn, Co, Ni, Cu, Pd, and Cd.

PubMed

Duguid, J; Bloomfield, V A; Benevides, J; Thomas, G J

1993-11-01

Interactions of divalent metal cations (Mg2+, Ca2+, Ba2+, Sr2+, Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) with DNA have been investigated by laser Raman spectroscopy. Both genomic calf-thymus DNA (> 23 kilobase pairs) and mononucleosomal fragments (160 base pairs) were employed as targets of metal interaction in solutions containing 5 weight-% DNA and metal:phosphate molar ratios of 0.6:1. Raman difference spectra reveal that transition metal cations (Mn2+, Co2+, Ni2+, Cu2+, Pd2+, and Cd2+) induce the greatest structural changes in B-DNA. The Raman (vibrational) band differences are extensive and indicate partial disordering of the B-form backbone, reduction in base stacking, reduction in base pairing, and specific metal interaction with acceptor sites on the purine (N7) and pyrimidine (N3) rings. Many of the observed spectral changes parallel those accompanying thermal denaturation of B-DNA and suggest that the metals link the bases of denatured DNA. While exocyclic carbonyls of dT, dG, and dC may stabilize metal ligation, correlation plots show that perturbations of the carbonyls are mainly a consequence of metal-induced denaturation of the double helix. Transition metal interactions with the DNA phosphates are weak in comparison to interactions with the bases, except in the case of Cu2+, which strongly perturbs both base and phosphate group vibrations. On the other hand, the Raman signature of B-DNA is largely unperturbed by Mg2+, Ca2+, Sr2+, and Ba2+, suggesting much weaker interactions of the alkaline earth metals with both base and phosphate sites. A notable exception is a moderate perturbation by alkaline earths of purine N7 sites in 160-base pair DNA, with Ca2+ causing the greatest effect. Correlation plots demonstrate a strong interrelationship between perturbations of Raman bands assigned to ring vibrations of the bases and those of bands assigned to exocyclic carbonyls and backbone phosphodiester groups. However, strong correlations do not occur between the Raman phosphodioxy band (centered near 1092 cm-1) and other Raman bands, suggesting that the former is not highly sensitive to the structural changes induced by divalent metal cations. The structural perturbations induced by divalent cations are much greater for > 23-kilobase pair DNA than for 160-base pair DNA, as evidenced by both the Raman difference spectra and the tendency toward the formation of insoluble aggregates. In the presence of transition metals, aggregation of high-molecular-weight DNA is evident at temperatures as low as 11 degrees C. A relationship between DNA melting and aggregation is proposed in which initial metal binding at major groove sites locally destabilizes the B-DNA double helix, causing displacement of the bases away from one another and exposing additional metal binding sites. Metal cation linkage of two displaced bases would allow separate DNA strands to crosslink. Aggregation is proposed to result from the formation of an extended network of these crosslinks.

Experimentally Determined Phase Diagram for the Barium Sulfide-Copper(I) Sulfide System Above 873 K (600 °C)

NASA Astrophysics Data System (ADS)

Stinn, Caspar; Nose, Katsuhiro; Okabe, Toru; Allanore, Antoine

2017-12-01

The phase diagram of the barium sulfide-copper(I) sulfide system was investigated above 873 K (600 °C) using a custom-built differential thermal analysis (DTA) apparatus. The melting point of barium sulfide was determined utilizing a floating zone furnace. Four new compounds, Ba2Cu14S9, Ba2Cu2S3, Ba5Cu4S7, and Ba9Cu2S10, were identified through quench experiments analyzed with wavelength dispersive X-ray spectroscopy (WDS) and energy dispersive X-ray analysis (EDS). A miscibility gap was observed between 72 and 92 mol pct BaS using both DTA experiments and in situ melts observation in a floating zone furnace. A monotectic was observed at 94.5 mol pct BaS and 1288 K (1015 °C).

Effect of divalent Ba cation substitution with Sr on coupled ‘multiglass’ state in the magnetoelectric multiferroic compound Ba3NbFe3Si2O14

PubMed Central

Rathore, Satyapal Singh; Vitta, Satish

2015-01-01

(Ba/Sr)3NbFe3Si2O14 is a magneto-electric multiferroic with an incommensurate antiferromagnetic spiral magnetic structure which induces electric polarization at 26 K. Structural studies show that both the compounds have similar crystal structure down to 6 K. They exhibit a transition, TN at 26 K and 25 K respectively, as indicated by heat capacity and magnetization, into an antiferromagnetic state. Although Ba and Sr are isovalent, they exhibit very different static and dynamic magnetic behaviors. The Ba-compound exhibits a glassy behavior with critical slowing dynamics with a freezing temperature of ~35 K and a critical exponent of 3.9, a value close to the 3-D Ising model above TN, in addition to the invariant transition into an antiferromagnetic state. The Sr-compound however does not exhibit any dispersive behavior except for the invariant transition at TN. The dielectric constant reflects magnetic behavior of the two compounds: the Ba-compound has two distinct dispersive peaks while the Sr-compound has a single dispersive peak. Thus the compounds exhibit coupled ‘multiglass’ behavior. The difference in magnetic properties between the two compounds is found to be due to modifications to super exchange path angle and length as well as anti-site defects which stabilize either ferromagnetic or antiferromagnetic interactions. PMID:25988657

Electronic structure of clean and Ag-covered single-crystalline Bi2Sr2CuO6

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Shen, Z.-X.; Wells, B. O.; Mitzi, D. B.; Lindau, I.; Spicer, W. E.; Kapitulnik, A.

1989-11-01

Photoemission studies of single-crystalline samples of Bi2Sr2CuO6 show clear resemblance to the corresponding data for single crystals of Bi2Sr2CaCu2O8. In particular, a sharp Fermi-level cutoff, giving evidence of metallic conductivity at room temperature, as well as single-component O 1s emission and Cu 2p satellites with a strength amounting to about 50% of that of the main Cu 2p line, are observed. An analysis of the relative core-level photoemission intensities shows that the preferential cleavage plane of single-crystalline Bi2Sr2CuO6 is between adjacent Bi-O layers. Deposition of Ag adatoms causes only weak reaction with the Bi and O ions of the Bi2Sr2CuO6 substrate, while the Cu states rapidly react with the Ag adatoms, as monitored by a continuous reduction of the Cu 2p satellite intensity as the Ag overlayer becomes thicker.

Investigations on the local structures of Cu2+ at various BaO concentrations in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO glasses

NASA Astrophysics Data System (ADS)

Jin, Jia-Rui; Wu, Shao-Yi; Hong, Jian; Liu, Shi-Nan; Song, Min-Xian; Teng, Bao-Hua; Wu, Ming-He

2017-11-01

The local structures and electron paramagnetic resonance (EPR) parameters for Cu2+ in 59B2O3-10K2O-(30-x)ZnO-xBaO-1CuO (BKZBC) glasses are theoretically investigated with distinct modifier BaO concentrations x (= 0, 6, 12, 18, 24 and 30 mol %). The ? clusters are found to undergo the relative tetragonal elongations of about 13.5 and 5.0% at zero and higher BaO concentrations. The concentration dependences of the measured d-d transition bands, g factors and A// are suitably reproduced from the Fourier type functions or sign functions of the relevant quantities with x by using only six adjustable parameters. The features of the EPR parameters and the local structures of Cu2+ are analysed in a consistent way by considering the differences in the local ligand field strength and electronic cloud admixtures around Cu2+ under addition of Ba2+ with the highest ionicity and polarisability. The present theoretical studies would be helpful to the researches on the structures, optical and EPR properties for the similar potassium barium zinc borate glasses containing copper with variation concentration of modifier BaO.

Defect Chemistry of " BaCuO2" I. Oxygen Non -Stoichiometry, Cation Molecularity and X-ray Diffraction Determinations

NASA Astrophysics Data System (ADS)

Spinolo, G.; Anselmi-Tamburini, U.; Arimondi, M.; Ghigna, P.; Flor, G.

1995-11-01

"BaCuO2" is the key intermediate in the synthesis of the Ba2YCu3O7-δ superconductor. Its very complex crystal structure is able to accommodate a large change in oxygen content. Oxygen non-stoichiometry of "BaCuO2" materials with 1:1 and 88:90 (Ba :Cu) molecularity has been investigated by polythermal X-ray powder diffraction coupled with isobaric-isothermal gravimetry determinations under different temperature and oxygen partial pressure conditions [300≤ T≤ 820 °C, 1 ≥ P(O2) ≥ 3 • 10-3 atm]. The 1:1 composition does not give well reproducible results, thus suggesting its polyphasic nature, at least in part of the investigated range. The results for the 88:90 ≅ 0.98 (Ba :Cu) composi­ tion are well reproducible and show that the material is single phase. Ba0.98CuO1.98 + δ is oxygen over-stoichiometric in the whole investigated [T, P(O2)] range, with a maximum value δ˜0.21. A Rietveld X-ray profile fitting is in agreement with previous single-crystal data. The trend of δ vs. P(O2) is consistent with the presence of oxygen interstitial defects on (possibly different) crystallographic sites.

Structural trends for celestite (SrSO[subscript 4]), anglesite (PbSO[subscript 4]), and barite (BaSO[subscript 4]): Confirmation of expected variations within the SO[subscript 4] groups

DOE Office of Scientific and Technical Information (OSTI.GOV)

Antao, Sytle M.

2012-05-10

The crystal structures of the isostructural orthorhombic sulfates celestite (SrSO{sub 4}), anglesite (PbSO{sub 4}), and barite (BaSO{sub 4}) were refined by Rietveld methods using synchrotron high-resolution powder X-ray diffraction (HRPXRD) data. Their structural model was refined in space group Pbnm. The unit-cell parameters are a = 6.87032(3), b = 8.36030(5), c = 5.34732(1) {angstrom}, and V = 307.139(3) {angstrom}{sup 3} for SrSO{sub 4}; a = 6.95802(1), b = 8.48024(3), c = 5.39754(1) {angstrom}, and V = 318.486(1) {angstrom}{sup 3} for PbSO{sub 4}; and a = 7.15505(1), b = 8.88101(3), c = 5.45447(1) {angstrom}, and V = 346.599(1) {angstrom}{sup 3} formore » BaSO{sub 4}. The average [12] distances are 2.827(1), 2.865(1), and 2.953(1) {angstrom} for SrSO{sub 4}, PbSO{sub 4}, and BaSO{sub 4}, respectively, and their corresponding average [4] distances are 1.480(1), 1.477(3), and 1.471(1) {angstrom}. The geometrical features of the SO{sub 4} and MO{sub 12} polyhedra become more symmetrical from SrSO{sub 4} to BaSO{sub 4}. Across the series, the a, b, and c parameters vary non-linearly with increasing V. The radii of the M{sup 2+} cations, rM, [12], and [4] distances vary linearly with V. These structural trends arise from the effective size of the M{sup 2+} cation (rM: Sr < Pb < Ba) that is coordinated to 12 O atoms.« less

Dissolved Strontium and Barium in Fresh and Saltwater: a 2-year Study in the Calcasieu River to the Gulf of Mexico

NASA Astrophysics Data System (ADS)

He, S.; Xu, Y. J.

2016-02-01

Strontium and barium to calcium ratios are often used as proxies for tracking animal movement across salinity gradients. As sea level rise continues, many estuarine rivers face saltwater intrusion, which may cause changes in mobility and distribution of these metals upstream. Despite intensive research on metal adsorption and desorption in marine systems, knowledge of the spatiotemporal distribution of these elements along estuarine rivers is still limited. In this study, we conducted an intensive monitoring of Sr and Ba dynamics along an 88-km long estuary, the Calcasieu River, which has been strongly affected by saltwater intrusion. Over the period from May 2013 to July 2015, we collected monthly water samples and performed in-situ water quality measurements at six sites from the upstream to the river mouth. Water samples were analyzed for dissolved Sr, Ba, and Ca concentrations. In-situ measurements of salinity, pH, water temperature, dissolved oxygen concentration, and specific conductance were taken. Our preliminary data showed that the Sr and Ca concentrations and the Sr/Ca ratio all increased significantly with decreasing distance to the Gulf of Mexico, while the Ba/Ca ratio decreased with decreasing distance to the Gulf. The spatial variation in Ba concentration was marginal. The Sr and Ca concentrations and ratios were positively related to salinity, while Ba/Ca was negatively related to salinity. All the elemental concentrations and ratios had considerable seasonal and interannual variations. There were significant differences among sampling months for all the elemental concentrations and ratios (p<0.05), and there were significant differences among sampling years for the Sr and Ca concentrations and the Ba/Ca ratio (p<0.05).

Chemical abundances of primary stars in the Sirius-like binary systems

NASA Astrophysics Data System (ADS)

Kong, X. M.; Zhao, G.; Zhao, J. K.; Shi, J. R.; Kumar, Y. Bharat; Wang, L.; Zhang, J. B.; Wang, Y.; Zhou, Y. T.

2018-05-01

Study of primary stars lying in Sirius-like systems with various masses of white dwarf (WD) companions and orbital separations is one of the key aspects to understand the origin and nature of barium (Ba) stars. In this paper, based on high-resolution and high-S/N spectra, we present systematic analysis of photospheric abundances for 18 FGK primary stars of Sirius-like systems including six giants and 12 dwarfs. Atmospheric parameters, stellar masses, and abundances of 24 elements (C, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Sr, Y, Zr, Ba, La, Ce, and Nd) are determined homogeneously. The abundance patterns in these sample stars show that most of the elements in our sample follow the behaviour of field stars with similar metallicity. As expected, s-process elements in four known Ba giants show overabundance. A weak correlation was found between anomalies of s-process elemental abundance and orbital separation, suggesting that the orbital separation of the binaries could not be the main constraint to differentiate strong Ba stars from mild Ba stars. Our study shows that the large mass (>0.51 M⊙) of a WD companion in a binary system is not a sufficient condition to form a Ba star, even if the separation between the two components is small. Although not sufficient, it seems to be a necessary condition since Ba stars with lower mass WDs in the observed sample were not found. Our results support that [s/Fe] and [hs/ls] ratios of Ba stars are anti-correlated with the metallicity. However, the different levels of s-process overabundance among Ba stars may not be dominated mainly by the metallicity.

PM2.5 water-soluble elements in the southeastern United States: automated analytical method development, spatiotemporal distributions, source apportionment, and implications for heath studies

NASA Astrophysics Data System (ADS)

Fang, T.; Guo, H.; Verma, V.; Peltier, R. E.; Weber, R. J.

2015-06-01

Water-soluble redox-active metals are potentially toxic due to the ability to catalytically generate reactive oxygen species (ROS) in vivo, leading to oxidative stress. As part of the Southeastern Center for Air Pollution and Epidemiology (SCAPE), we developed a method to quantify water-soluble elements, including redox-active metals, from a large number of filter samples (N = 530) in support of the Center's health studies. PM2.5 samples were collected during 2012-2013 at various sites (three urban, two rural, a near-road, and a road-side site) in the southeastern US, using high-volume samplers. Water-soluble elements (S, K, Ca, Ti, Mn, Fe, Cu, Zn, As, Se, Br, Sr, Ba, and Pb) were determined by extracting filters in deionized water and re-aerosolized for analyses by X-ray fluorescence (XRF) using an online aerosol element analyzer (Xact, Cooper Environmental). Concentrations ranged from detection limits (nominally 0.1 to 30 ng m-3) to 1.2 μg m-3, with S as the most abundant element, followed by Ca, K, Fe, Cu, Zn, and Ba. Positive Matrix Factorization (PMF) identified four factors that were associated with specific sources based on relative loadings of various tracers. These include: brake/tire wear (with tracers Ba and Cu); biomass burning (K); secondary formation (S, Se, and WSOC); and mineral dust (Ca). Of the four potentially toxic and relatively abundant metals (redox active Cu, Mn, Fe, and redox-inactive Zn), 51 % of Cu, 32 % of Fe, 17 % of Mn, and 45 % of Zn, were associated with the brake/tire factor. Mn was mostly associated with the mineral dust factor (45 %). These two factors were higher in warm (dryer) periods that favored particle re-suspension. Zn was found in a mixture of factors, with 26 % associated with mineral dust, 14 % biomass burning, and 13 % secondary formation. Roughly 50 % of Fe and 40 % of Cu was apportioned to the secondary formation factor, likely through increased solubility by sulfur-driven aerosol acidity. Linkages between sulfate and water-soluble Fe and Cu may account for some of the past observed associations between sulfate/sulfur oxide and health outcomes. For Cu, Mn, Fe, and Zn, only Fe was correlated with PM2.5 mass (r = 0.73-0.80). Overall, mobile source emissions generated through mechanical processes (re-entrained road dust, tire and break wear) and processing by secondary sulfate were major contributors to water-soluble metals known to be capable of generating ROS.

Toxic elements and bio-metals in Cantharellus mushrooms from Poland and China.

PubMed

Falandysz, Jerzy; Chudzińska, Maria; Barałkiewicz, Danuta; Drewnowska, Małgorzata; Hanć, Anetta

2017-04-01

Data on multi-trace element composition and content relationships have been obtained for Cantharellus cibarius, C. tubaeformis, and C. minor mushrooms from Poland and China by inductive coupled plasma-dynamic reaction cell-mass spectroscopy. There is no previous data published on As, Li, V, Tl, and U in chanterelles from Poland and on Ba, Co, Cr, Ni, Rb, and Sr in chanterelles from China. The results implied a role of the soil background geochemistry at the collection site with the occurrence of Ag, As, Ba, Cr, Cs, Li, Mn, Pb, Rb, Sr, U, and V in the fruiting bodies. Both geogenic Cd and anthropogenic Cd can contribute in load of this element in chanterelles from the Świetokrzyskie Mts. region in Poland, while geogenic source can be highly dominant in the background areas of Yunnan. An essentiality of Cu and Zn and effort by mushroom to maintain their physiological regulation could be reflected by data for Cantharellus mushrooms from both regions of the world, but its geogenic source (and possibly anthropogenic) can matter also in the region of the Świetokrzyskie Mountains in Poland. The elements Co, Ni, and Tl were at the same order of magnitude in contents in C. cibarius in Poland and Yunnan, China. C. tubaeformis differed from C. cibarius by a lower content of correlated Co, Ni, and Zn. Soil which is polymetallic and highly weathered in Yunnan can be suggested as a natural geogenic source of greater concentrations of As, Ba, Cr, Li, Pb, Sr, U, and V in the chanterelles there while lower of Mn and Rb, when related to chanterelles in Poland. A difference in Cs content between the sites can be attributed as an effect of the 137 Cs release from the Chernobyl accident, in which Poland was much more affected than Yunnan, where deposition was negligible.

Disentangling controls on element impurities of bivalve shells

NASA Astrophysics Data System (ADS)

Zhao, Liqiang; Schöne, Bernd R.; Mertz-Kraus, Regina

2017-04-01

Trace and minor elements of bivalve shells can potentially serve as proxies of past environmental change. However, retrieving environmental information from element impurities of bivalve shells remains an extremely challenging task. A central difficulty concerns the fact that extrinsic and intrinsic factors governing the element incorporation are poorly constrained. Within the framework of the ARAMACC project, we aim to decipher the complexity of the incorporation of trace and minor elements into bivalve shells and explore their full potential as proxies of environmental change. More specifically, the following questions were tackled. (1) How are trace and minor elements transported from the ambient environment to the calcifying front? (2) How is their incorporation into the shells affected by environmental and physiological variables? Our findings lend support to the general assumption that divalent ions (e.g., Cu2+, Mn2+, Zn2+ and Pb2+) share the same transport pathways as Ca2+ because of similar ionic radii and electrochemical properties. However, results obtained for Mg2+, Sr2+ and Ba2+ are particularly interesting as they are at odds with existing hypotheses on the incorporation of these three elements, i.e., intracellular Ca2+ pathways (via Ca2+ channels and Ca2+-ATPase) are likely not responsible for their incorporation. Despite the existence of strong physiological interference, some encouraging results were found, in particular (1) strong, positive relationships between the Sr, Ba and Mn contents of the shells and concentrations in the ambient water, (2) only minor effects of growth rate (which is closely linked to the rate of crystal growth and hence, kinetics) on the amounts of Na, Sr, Ba and Mn incorporation into the shells. Overall, our findings demonstrate that environmental and physiological controls on the element incorporation do not have to be mutually exclusive, i.e., if environmental changes outweigh physiological influences, one could still expect that trace and minor elements of bivalve shells serve as promising environmental proxies.

Site-selective doping and superconductivity in (La1-yPry)(Ba2-xLax)Cu3O7+δ

NASA Astrophysics Data System (ADS)

Mitzi, D. B.; Feffer, P. T.; Newsam, J. M.; Webb, D. J.; Klavins, P.; Jacobson, A. J.; Kapitulnik, A.

1988-10-01

Samples in the quaternary system (La1-yPry)(Ba2-xLax)Cu3O7+δ have been prepared and characterized using x-ray and neutron diffraction, thermogravimetric analysis, and transport and magnetic measurements. Pr substitutes on the oxygen-depleted La layers for y>0.0, while La substitutes on the Ba sites for x>0.0. The effect of doping on each site is inferred to be primarily local, affecting immediately adjacent Cu-O layers. The similar suppression of superconductivity that accompanies doping on each of the two distinct sites apparently correlates with the degree of oxidation of the Cu-O sheets (and not the chains), indicating that the sheets support the high temperature superconductivity. Comparison of orthorhombic and tetragonal samples with similar Ba:La ratios (and y=0) demonstrates that the orthorhombic phase yields the largest Meissner signals and highest transition temperatures in the La(Ba2-xLax)Cu3O7+δ system. The effect on superconductivity of oxygen-vacancy configuration in the Cu-O chain layers is proposed to derive, indirectly, from their influence on the Cu-O sheets. In addition, optimally superconducting La(Ba2-xLax)Cu3O7+δ samples exhibit interesting normal-state magnetic properties, with a paramagnetic susceptibility that decreases steadily with temperature between 350 K and Tc.

Non-linear second harmonic generation (SHG) studies of BaTiO3/SrTiO3 superlattices

NASA Astrophysics Data System (ADS)

Vlahos, Eftihia; Lee, Che-Hui; Wu, Pingping; Wung Bark, Chung; Jang, Ho Won; Folkman, Chad; Hyub Baek, Seung; Park, J. W.; Biegalski, Mike; Tenne, Dmitri; Schlom, Darrell; Chen, Long-Qing; Eom, Chang-Beom; Gopalan, Venkatraman

2010-03-01

Theoretical phase-field simulations predict that certain types of superlattices consisting of alternating (BaTiO3)n/(SrTiO3)n layers have novel vortex domain wall configurations which give rise to exceptionally high polarization tunability combined with negligible polarization hysteresis. Optical second harmonic generation (SHG) was used to probe the phase and transition temperatures of multilayer (BaTiO3)m/(SrTiO3)n superlattices, as a function of epitaxial strain. In addition, in-plane electro-optic measurements were carried out. The experimental results are in excellent agreement both with theoretical predictions, as well as the temperature-strain phase diagram obtained experimentally from UV Raman studies. The ferroelectric, in-plane SHG signal, from the tensile strained SrTiO3 layers reveals an mm2 point group symmetry, whereas the point group symmetry of the compressively strained BaTiO3 layers, was determined to be 4mm.

Major and EDXRF Trace Element Chemical Analyses of Volcanic Rocks from Lassen Volcanic National Park and Vicinity, California

USGS Publications Warehouse

Clynne, Michael A.; Muffler, L.J.P.; Siems, D.F.; Taggart, J.E.; Bruggman, Peggy

2008-01-01

This open-file report presents WDXRF major-element chemical data for late Pliocene to Holocene volcanic rocks collected from Lassen Volcanic National Park and vicinity, California. Data for Rb, Sr, Ba, Y, Zr, Nb, Ni, Cr, Zn and Cu obtained by EDXRF are included for many samples. Data are presented in an EXCEL spreadsheet and are keyed to rock units as displayed on the Geologic Map of Lassen Volcanic National Park and vicinity (Clynne and Muffler, in press). Location of the samples is given in latitude and longitude in degrees and decimal minutes and in decimal degrees.

Solid state proton and electron mediating membrane and use in catalytic membrane reactors

DOEpatents

White, James H.; Schwartz, Michael; Sammells, Anthony F.

2001-01-01

Mixed electron- and proton-conducting metal oxide materials are provided. These materials are useful in fabrication of membranes for use in catalytic membrane reactions, particularly for promoting dehydrogenation of hydrocarbons, oligomerization of hydrocarbons and for the decomposition of hydrogen-containing gases. Membrane materials are perovskite compounds of the formula: AB.sub.1-x B'.sub.x O.sub.3-y where A=Ca, Sr, or Ba; B=Ce, Tb, Pr or Th; B'=Ti, V, Cr, Mn, Fe, Co, Ni or Cu; 0.2.ltoreq.x.ltoreq.0.5, and y is a number sufficient to neutralize the charge in the mixed metal oxide material.

Solid state proton and electron mediating membrane and use in catalytic membrane reactors

DOEpatents

White, James H.; Schwartz, Michael; Sammells, Anthony F.

2000-01-01

Mixed electron- and proton-conducting metal oxide materials are provided. These materials are useful in fabrication of membranes for use in catalytic membrane reactions, particularly for promoting dehydrogenation of hydrocarbons, oligomerization of hydrocarbons and for the decomposition of hydrogen-containing gases. Membrane materials are perovskite compounds of the formula: AB.sub.1-x B'.sub.x O.sub.3-y where A=Ca, Sr, or Ba; B=Ce, Tb, Pr or Th; B'=Ti, V, Cr, Mn, Fe, Co, Ni or Cu; 0.2

Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Barry M.; McCaffrey, John G., E-mail: john.mccaffrey@nuim.ie

2016-01-28

Isolation of the heavier alkaline earth metals Ba and Sr in the solid rare gases (RGs) Ar, Kr, and Xe is analysed with absorption spectroscopy and interpreted partly with the assistance of ab initio calculations of the diatomic M ⋅ RG ground state interaction potentials. The y{sup 1}P←a{sup 1}S resonance transitions in the visible spectral region are used to compare the isolation conditions of these two metal atom systems and calcium. Complex absorption bands were recorded in all three metal atom systems even after extensive sample annealing. Coupled cluster calculations conducted on the ground states of the nine M ⋅more » RG diatomics (M = Ca, Sr, and Ba; RG = Ar, Kr, and Xe) at the coupled cluster single, double, and non-iterative triple level of theory revealed long bond lengths (>5 Å) and shallow bound regions (<130 cm{sup −1}). All of the M ⋅ RG diatomics have bond lengths considerably longer than those of the rare gas dimers, with the consequence that isolation of these metal atoms in a single substitutional site of the solid rare gas is unlikely, with the possible exception of Ca/Xe. The luminescence of metal dimer bands has been recorded for Ba and Sr revealing very different behaviours. Resonance fluorescence with a lifetime of 15 ns is observed for the lowest energy transition of Sr{sub 2} while this transition is quenched in Ba{sub 2}. This behaviour is consistent with the absence of vibrational structure on the dimer absorption band in Ba{sub 2} indicating lifetime broadening arising from efficient relaxation to low-lying molecular states. More extensive 2D excitation-emission data recorded for the complex site structures present on the absorption bands of the atomic Ba and Sr systems will be presented in future publications.« less

PIXE and ICP-MS Analysis of Andrographis Paniculata Medicinal Plant

NASA Astrophysics Data System (ADS)

Chandrasekhar Rao, J.; Naidu, B. G.; Sarita, P.; Srikanth, S.; Naga Raju, G. J.

2017-08-01

The concentrations of elements Li, Be, Al, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Ag, Cd, Ba, Pb and U in Andrographis Paniculata medicinal plant used in the treatment of Diabetes Mellitus were determined by using Particle Induced X-ray Emission (PIXE) and Inductively Coupled Plasma Mass Spectroscopy (ICP-MS) techniques. This plant was collected from four different geographical locations in Andhra Pradesh, India in order to assess the regional variation of elemental concentrations. Appreciable levels of K, Ca, Cr, Mn, Cu and Zn determined in this plant can be correlated to the antidiabetic property of Andrographis Paniculata since these elements are known to regulate and potentiate insulin action. Presence of toxic elements As, Cd and Pb necessitates the adoption of precautionary measures while prescribing dosage of the herbal medicine prepared from this plant for the treatment diabetes mellitus.

Critical Current Properties in Longitudinal Magnetic Field of YBCO Superconductor with APC

NASA Astrophysics Data System (ADS)

Kido, R.; Kiuchi, M.; Otabe, E. S.; Matsushita, T.; Jha, A. K.; Matsumoto, K.

The critical current density (Jc) properties of the Artificial Pinning Center (APC) introduced YBa2Cu3O7 (YBCO) films in the longitudinal magnetic field were measured. Y2O3 or Y2BaCuO5 (Y211) was introduced as APCs to YBCO, and YBCO films with APC were fabricated on SrTiO3 single crystal substrate. The sizes of Y2O3 and Y211 were 5-10 nm and 10-20 nm, respectively. As a result, Jc enhancement in the longitudinal magnetic field was observed in Y2O3 introduced YBCO films. However, it was not observed in Y211 introduced YBCO films. Therefore, it was considered that Jc properties in the longitudinal magnetic field were affected by introducing of small size APC, and it was necessary that APC does not disturb the current pathway in the superconductor.

Electronic Structure of HgBa2CaCu2O(6+delta) Epitaxial films measured by x-ray Photoemission

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Rupp, M.; Gupta, A.; Tsuei, C. C.

1995-01-01

The electronic structure and chemical states of HgBa2CaCu20(sub 6 + delta), epitaxial films have been studied with x-ray photelectron spectroscopy. Signals from the superconducting phase dominate all the core-level spectra, and a clear Fermi edge is observed in the valence-band region. The Ba, Ca, Cu, and O core levels are similar to those of Tl2Ba2CaCu208(+)O(sub 6 + delta), but distinct differences are observed in the valence bands which are consistent with differences in the calculated densities of states.

A comprehensive study of magnetic exchanges in the layered oxychalcogenides Sr 3 Fe 2 O 5 Cu 2 Q 2 ( Q = S, Se)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lü, Minfeng; Mentré, Olivier; Gordon, Elijah E.

2017-12-01

The layered oxysulfide Sr3Fe2O5Cu2S2 was prepared, and its crystal structure and magnetic properties were characterized by synchrotron X-ray diffraction (XRD), powder neutron diffraction (PND), Mössbauer spectroscopy measurements and by density functional theory (DFT) calculations. In addition, the spin exchange interactions leading to the ordered magnetic structure of Sr3Fe2O5Cu2S2 were compared with those of its selenium analogue Sr3Fe2O5Cu2Se2. The oxysulfide Sr3Fe2O5Cu2S2 adopts a G-type antiferromagnetic (AFM) structure at a temperature in the range 485–512 K, which is comparable with the three-dimensional (3D) AFM ordering temperature, TN ≈ 490 K, found for Sr3Fe2O5Cu2Se2. Consistent with this observation, the spin exchange interactions ofmore » the magnetic (Sr3Fe2O5)2+ layers are slightly greater (but comparable) for oxysulfide than for the oxyselenide. Attempts to reduce or oxidize Sr3Fe2O5Cu2S2 using topochemical routes yield metallic Fe.« less

Effect of spin-orbit coupling on excitonic levels in layered chalcogenide-fluorides

NASA Astrophysics Data System (ADS)

Zakutayev, Andriy; Kykyneshi, Robert; Kinney, Joseph; McIntyre, David H.; Schneider, Guenter; Tate, Janet

2008-03-01

BaCuChF (Ch=S,Se,Te) comprise a family of wide-bandgap p-type semiconductors. Due to their high transparency and conductivity, they have potential applications as components of transparent thin-film transistors, solar cells and light-emitting devices. Thin films of BaCuChF have been deposited on MgO by pulsed laser deposition (PLD). Solid solutions BaCuS1-xSexTeF and BaCuSe1-xTex have been prepared by PLD of alternating thin BaCuChF layers. All films were deposited at elevated substrate temperatures. They are preferentially c-axis oriented, conductive and transparent in the visible part of the spectrum. Double excitonic peaks have been observed in the absorption spectrum of these films in the temperature range from 80 to 300K. The separation between the peaks in the doublet increases with the increase of atomic mass of the chalcogen. It also increases with the increase of the heavy chalcogen component x in the solid solutions. This separation most likely is caused by the effect of spin-orbit coupling in the chalcogen atoms on excitonic levels in BaCuChF.

New Phases of YBaCuGeO Superconductors Identified from X-ray Diffraction and Infra-red Absorption Measurements

NASA Astrophysics Data System (ADS)

Abo-Arais, Ahmed; Dawoud, Mohamad Ahmad Taher

2005-01-01

X-ray powder diffraction patterns and infra-red absorption spectra have been evaluated and analysed for the Y1 Ba2 Cu3 O7-d - Gex compound samples prepared by the solid state reaction with x values ranging from 0.0 to 1.13. All samples show bulk superconductivity above liquid nitrogen temperature using the levitation test (Meissner effect). Samples with Ge content up to x = 0.2 have offset Tc between 83K and 92K while the sample with x = 1.13 shows semiconducting behavior above 100K. As a result of the solid state interaction between YBCO and Ge, new phases are observed and determined, mainly three phases are concluded from X-ray powder diffraction analysis: (i) Ba2GeO4 (ii) Y2BaCuO5 (iii) BaCO3. The unit cell parameters a, b and c of the orthorhombic superconducting phase are calculated for all the prepared samples. The anisotropy factor is evaluated and related to the new structural phases in YBCO-Ge composite system. The I-R absorption spectra for the samples with orthorhombic symmetry have been determined. The phonon modes between ~ 400 cm-1 and 630 cm-1 are attributed to the Cu - O octahedron and pyramid vibrations for the CuO2 -planes and CuO-chains, while the peaks in the range from ~ 700 cm-1 to ~ 860 cm-1 may be due to defects such as the new phase Ba2GeO4 and the green phase Y2BaCuO5. The obtained results are discussed according to the superconductor - semi-conductor composite model and with the phonon-mediated charge transfer between CuO2 -planes and CuO- chains through apex oxygen (BaO).

A new series of oxycarbonate superconductors (Cu(0.5)C(0.5))(m)Ba(m+1)Ca(n-1)Cu(n)O2(m+n)+1

NASA Technical Reports Server (NTRS)

Takayama-Muromachi, E.; Kawashima, T.; Matsui, Y.

1995-01-01

We found a new series of oxycarbonate superconductors in the Ba-CaCu-C-O system under high pressure of 5 GPa. Their ideal formula is (Cu(0.5)C(0.5)(m)Ba(m+1)Ca(n-1)Cu(n)O2)((m+n)+1) ((Cu,C)-m(m+1)(n-1)n). Thus far, n = 3, 4 members of the m = 1 series, (Cu,C)-1223 and (Cu,C)-1234, have been prepared in bulk while n = 4, 5 members, (Cu,C)-2334 and (Cu,C)-2345, have been prepared for the m = 2 series. (Cu,C)-1223 shows superconductivity below 67 K while T(sub c)'s of other compounds are above 110 K. In particular, (Cu,C)-1234 has the highest T(sub c) of 117 K.

Method of forming a dielectric thin film having low loss composition of Ba.sub.x Sr.sub.y Ca.sub.1-x-y TiO.sub.3 : Ba.sub.0.12-0.25 Sr.sub.0.35-0.47 Ca.sub.0.32-0.53 TiO.sub.3

DOEpatents

Xiang, Xiao-Dong; Chang, Hauyee; Takeuchi, Ichiro

2000-01-01

A dielectric thin-film material for microwave applications, including use as a capacitor, the thin-film comprising a composition of barium strontium calcium and titanium of perovskite type (Ba.sub.x Sr.sub.y Ca.sub.1-x-y)TiO.sub.3. Also provided is a method for making a dielectric thin film of that formula over a wide compositional range through a single deposition process.

Ionomic profiling of Nicotiana langsdorffii wild-type and mutant genotypes exposed to abiotic stresses.

PubMed

Ardini, Francisco; Soggia, Francesco; Abelmoschi, Maria Luisa; Magi, Emanuele; Grotti, Marco

2013-01-01

To provide a new insight into the response of plants to abiotic stresses, the ionomic profiles of Nicotiana langsdorffii specimens have been determined before and after exposure to toxic metals (chromium) or drought conditions. The plants were genetically transformed with the rat glucocorticoid receptor (GR) or the gene for Agrobacterium rhizogenes rolC, because these modifications are known to produce an imbalance in phytohormone equilibria and a significant change in the defence response of the plant. Elemental profiles were obtained by developing and applying analytical procedures based on inductively coupled plasma atomic emission and mass spectrometry (ICP-AES/MS). In particular, the removal of isobaric interferences affecting the determination of Cr and V by ICP-MS was accomplished by use of a dynamic reaction cell, after optimization of the relevant conditions. The combined use of ICP atomic emission and mass spectrometry enabled the determination of 29 major and trace elements (Ba, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, P, Pb, Pt, Rb, S, Sb, Sn, Sr, Te, V, W, Y, and Zn) in different parts of the plants (roots, stems, and leaves), with high accuracy and precision. Multivariate data processing and study of element distribution patterns provided new information about the ionomic response of the target organism to chemical treatment or water stress. Genetic modification mainly affected the distribution of Bi, Cr, Mo, Na, and S, indicating that these elements were involved in biochemical processes controlled by the GR or rolC genes. Chemical stress strongly affected accumulation of several elements (Ba, Ca, Fe, Ga, K, Li, Mn, Mo, Na, P, Pb, Rb, S, Sn, Te, V, and Zn) in different ways; for Ca, Fe, K, Mn, Na, and P the effect was quite similar to that observed in other studies after treatment with other transition elements, for example Cu and Cd. The effect of water deficit was less evident, mainly consisting in a decrease of Ba, Cr, Na, and Sr in roots.

The Late Paleozoic magmatic evolution of the Aqishan-Yamansu belt, Eastern Tianshan: Constraints from geochronology, geochemistry and Sr-Nd-Pb-Hf isotopes of igneous rocks

NASA Astrophysics Data System (ADS)

Zhao, Liandang; Chen, Huayong; Zhang, Li; Zhang, Weifeng; Yang, Juntao; Yan, Xuelu

2018-03-01

The Aqishan-Yamansu belt in the Eastern Tianshan (Xinjiang, NW China) is an important mineralization belt. The belt mainly comprises Carboniferous volcanic, volcaniclastic and clastic rocks, and hosts many intermediate-felsic intrusions and Fe (-Cu) deposits. The biotite diorite, felsic brecciated tuff, granodiorite and syenite from the western Aqishan-Yamansu belt are newly zircon U-Pb dated to be 316.7 ± 1.4 Ma, 315.6 ± 2.6 Ma, 305.8 ± 1.9 Ma and 252.5 ± 1.4 Ma, respectively. The mafic rocks (mafic brecciated tuff and diabase porphyry) are tholeiitic to calc-alkaline series, LILE-rich (e.g., Rb, Ba and Pb), HFSE-depleted (e.g., Nb and Ta), and have high Mg#(44-60), Nb/Ta (15.0-20.0), Ba/La (>30) and Ba/Nb (>57) values/ratios, and low Th/Yb ratios (<1), probably originating from mantle wedge metasomatized by slab-derived fluids. The intermediate-felsic igneous rocks are LILE-rich, HFSE-depleted, with high Sr and Y contents showing typical of normal arc magma affinity. Moreover, the depleted εHf(t) (>2.10) and positive εNd(t) (>5.7), combined with variable Nb/Ta ratios (9.52-21.4), Y/Nb ratios (1.47-39.7) and Pb isotopes (206Pb/204Pb = 16.225-17.640, 207Pb/204Pb = 15.454-15.520, 208Pb/204Pb = 37.097-38.025) suggest that these rocks were magma mixing products between juvenile crustal-derived magmas and minor mantle-derived magmas. Combined published works with our new ages, geochemical and isotopic data, we propose that the Aqishan-Yamansu belt was an Early Carboniferous fore-arc basin during the southward subduction of the Kangguer oceanic slab beneath the Yili-Central Tianshan block. With the continuing southward subduction, the Aqishan-Yamansu fore-arc basin initiated to close, which generated the mafic and intensive intermediate-felsic magmatism associated with regional Fe (-Cu) mineralization.

Exposure of children to metals via tap water ingestion at home: Contamination and exposure data from a nationwide survey in France.

PubMed

Le Bot, Barbara; Lucas, Jean-Paul; Lacroix, Françoise; Glorennec, Philippe

2016-09-01

29 inorganic compounds (Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cu, Fe, Gd, K, Mg, Mn, Mo, Na, Nd, Ni, Pb, Sb, Se, Sr, Tl, U, V and Zn) were measured in the tap water of 484 representative homes of children aged 6months to 6years in metropolitan France in 2008-2009. Parents were asked whether their children consumed tap water. Sampling design and sampling weights were taken into account to estimate element concentrations in tap water supplied to the 3,581,991 homes of 4,923,058 children aged 6months to 6years. Median and 95th percentiles of concentrations in tap water were in μg/L: Al: <10, 48.3, As: 0.2, 2.1; B: <100, 100; Ba: 30.7, 149.4; Ca: 85,000, 121,700; Cd: <0.5, <0.5; Ce: <0.5, <0.5; Co: <0.5, 0.8; Cr: <5, <5; Cu: 70, 720; K: 2210, 6740; Fe: <20, 46; Mn: <5, <5; Mo: <0.5, 1.5; Na: 14,500, 66,800; Ni: <2, 10.2; Mg: 6500, 21,200; Pb: <1, 5.4; Sb: <0.5, <0.5; Se: <1, 6.7; Sr: 256.9, 1004; Tl: <0.5, <0.5; U: <0.5, 2.4; V: <1, 1; Zn: 53, 208. Of the 2,977,123 young children drinking tap water in France, some were drinking water having concentrations above the 2011 World Health Organization drinking-water quality guidelines: respectively 498 (CI 95%: 0-1484) over 700μg/L of Ba; 121,581 (CI 95%: 7091-236,070) over 50mg/L of Na; 2044 (CI 95%: 0-6132) over 70μg/L of Ni, and 78,466 (17,171-139,761) over 10μg/L of Pb. Since it is representative, this tap water contamination data can be used for integrated exposure assessment, in conjunction with diet and environmental (dust and soil) exposure data. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ligand reprogramming in dinuclear helicate complexes: a consequence of allosteric or electrostatic effects?

PubMed

Jeffery, John C; Rice, Craig R; Harding, Lindsay P; Baylies, Christian J; Riis-Johannessen, Thomas

2007-01-01

The ditopic ligand 6,6'-bis(4-methylthiazol-2-yl)-3,3'-([18]crown-6)-2,2'-bipyridine (L(1)) contains both a potentially tetradentate pyridyl-thiazole (py-tz) N-donor chain and an additional "external" crown ether binding site which spans the central 2,2'-bipyridine unit. In polar solvents (MeCN, MeNO(2)) this ligand forms complexes with Zn(II), Cd(II), Hg(II) and Cu(I) ions via coordination of the N donors to the metal ion. Reaction with both Hg(II) and Cu(I) ions results in the self-assembly of dinuclear double-stranded helicate complexes. The ligands are partitioned by rotation about the central py--py bond, such that each can coordinate to both metals as a bis-bidentate donor ligand. With Zn(II) ions a single-stranded mononuclear species is formed in which one ligand coordinates the metal ion in a planar tetradentate fashion. Reaction with Cd(II) ions gives rise to an equilibrium between both the dinuclear double-stranded helicate and the mononuclear species. These complexes can further coordinate s-block metal cations via the remote crown ether O-donor domains; a consequence of which are some remarkable changes in the binding modes of the N-donor domains. Reaction of the Hg(II)- or Cd(II)-containing helicate with either Ba(2+) or Sr(2+) ions effectively reprogrammes the ligand to form only the single-stranded heterobinuclear complexes [MM'(L(1))](4+) (M=Hg(II), Cd(II); M'=Ba(2+), Sr(2+)), where the transition and s-block cations reside in the N- and O-donor sites, respectively. In contrast, the same ions have only a minor structural impact on the Zn(II) species, which already exists as a single-stranded mononuclear complex. Similar reactions with the Cd(II) system result in a shift in equilibrium towards the single-stranded species, the extent of which depends on the size and charge of the s-block cation in question. Reaction of the dicopper(I) double-stranded helicate with Ba(2+) shows that the dinuclear structure still remains intact but the pitch length is significantly increased.

A new RE + 011 TSIG method for the fabrication of high quality and large size single domain YBCO bulk superconductors

NASA Astrophysics Data System (ADS)

Yang, W. M.; Chen, L. P.; Wang, X. J.

2016-02-01

High quality single domain YBCO bulk superconductors, 20 mm in diameter, have been fabricated using a new top seeded infiltration and growth method (called the RE + 011 TSIG method), with a new solid phase (Y2O3 + xBaCuO2) instead of the conventional Y2BaCuO5 solid phase, x = 0, 0.5, 1.0, 1.2, 1.5, 1.8, 2.0, 2.5, 3.0. The effects of different BaCuO2 contents x on the growth morphology, microstructure, and levitation force have been investigated. The results show that the levitation force of the YBCO bulks first increases and then decreases with increasing x, and reaches maximum levitation forces of about 49.2 N (77 K, 0.5 T, with the traditional liquid phase of YBa2Cu3O y + 3 BaCuO2 + 2 CuO) and 47 N (77.3 K, 0.5 T, with the new liquid phase of Y2O3 + 10 BaCuO2 + 6 CuO) when x = 1.2, which is much higher than that of the samples fabricated with the conventional solid phases (23 N). The average Y2BaCuO5 particle size is about 1 μm, which is much smaller than the 3.4 μm in the samples prepared with the conventional Y2BaCuO5 solid phase; this means that the flux pinning force of the sample can be improved by using the new solid phase. Based on this method, single domain YBCO bulks 40 mm, 59 mm, and 93 mm in diameter have also been fabricated using the TSIG process with the new solid phases (Y2O3 + 1.2BaCuO2). These results indicate that the new TSIG process developed by our lab is a very important and practical method for the fabrication of low cost, large size, and high quality single domain REBCO bulk superconductors.

Geochemistry of oceanic igneous rocks - Ridges, islands, and arcs - With emphasis on manganese, scandium, and vanadium

USGS Publications Warehouse

Doe, B.R.

1997-01-01

A database on a number of elements in oceanic volcanic rocks is presented, including the principal major-element oxides - SiO2, TiO2, Al2O3, Fe2O3(T), MnO, MgO, CaO, Na2O, K2O, and P2O5 (where T refers to total iron) - and the trace elements - Ba, Ce, Cr, Cu, Ni, Sc, Sr, V, Pb (mainly by isotope dilution), Yb, Zn, and Zr. Interpretations are given for transition metals, with emphasis on Mn, Sc, and V, in order to determine the concentration of the elements in primitive melts and assess their trends in magmatic differentiation. Transition metals are not enriched in plagioclase, so all are incompatible with pure plagioclase removal - that is, they become enriched in the melt. Both Cr and Ni are known to be highly compatible with olivine separation - i.e., they are depleted in the melt early in differentiation. Also, Sc is compatible with clinopyroxene (Cpx) removal from the melt and is depleted by separation of Cpx. Copper does not fit well in any of the principal silicates, but Cu, like Ni, is greatly enriched in sulfides that may remain in the source or separate from the magma. Decreasing Ni abundances and increasing Cu contents during differentiation are a sign of olivine separation. In the analysis presented herein, V - in the absence of Cpx separation - is found to behave remarkably like the moderately incompatible element Zn, and these two elements add to the list of element pairs of similar incompatibility whose ratios are insensitive to differentiation and to submarine weathering as well. Both are enhanced in titanomagnetite, so both would he compatible during titanomagnetite separation. When Cpx separates, however, V becomes compatible like Sc, but Zn remains incompatible. Thus, decreasing V (and Sc) contents and increasing Zn contents during differentiation are a sign of Cpx separation. Manganese often behaves much like Zn and therefore is moderately incompatible, but Mn is less compatible than Zn and V in titanomagnetite. Thus, decreasing Zn and V with increasing Mn is an indication of titanomagnetite removal. Dual compatible and incompatible trends with differentiation are found chiefly for Cu, Sc, and Sr. Distinguishing mid-ocean ridge basalts (MORB), oceanic-island volcanic rocks (OIV), and island-arc volcanic rocks (IAV) may be accomplished by plots of Ce/Yb versus Ba/Ce, where OIV plot to higher values of Ce/Yb than do MORB, and IAV data plot to higher values of Ba/Ce than do those of MORB. These ratios do not seem to be significantly affected by submarine weathering.

Application of ICP-OES for evaluating energy extraction and production wastewater discharge impacts on surface waters in Western Pennsylvania.

PubMed

Pancras, Joseph Patrick; Norris, Gary A; Landis, Matthew S; Kovalcik, Kasey D; McGee, John K; Kamal, Ali S

2015-10-01

Oil and gas extraction and coal-fired electrical power generating stations produce wastewaters that are treated and discharged to rivers in Western Pennsylvania with public drinking water system (PDWS) intakes. Inductively coupled plasma optical emission spectroscopy (ICP-OES) was used to quantify inorganic species in wastewater and river samples using a method based on EPA Method 200.7 rev4.4. A total of 53 emission lines from 30 elements (Al, As, B, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, Tl, V, and Zn) were investigated. Samples were prepared by microwave-assisted acid digestion using a mixture of 2% HNO3 and 0.5% HCl. Lower interferences and better detection characteristics resulted in selection of alternative wavelengths for Al, As, Sb, Mg, Mo, and Na. Radial view measurements offered accurate determinations of Al, Ba, K, Li, Na, and Sr in high-brine samples. Spike recovery studies and analyses of reference materials showed 80-105% recoveries for most analytes. This method was used to quantify species in samples with high to low brine concentrations with method detection limits a factor of 2 below the maximum contaminant limit concentrations of national drinking water standards. Elements B, Ca, K, Li, Mg, Na, and Sr were identified as potential tracers for the sources impacting PDWS intakes. Usability of the ICP-OES derived data for factor analytic model applications was also demonstrated. Published by Elsevier B.V.

The circumvention of the natural biopurification of calcium along nutrient pathways by atmospheric inputs of industrial lead

NASA Astrophysics Data System (ADS)

Elias, Robert W.; Hirao, Yoshimitsu; Patterson, Clair C.

1982-12-01

Biopurification factors for Ca with respect to Sr, Ba, and natural, uncontaminated Pb were measured for different nutrient-consumer pairs in a remote subalpine ecosystem. The factor for Sr is expressed as: (nutrient Sr/Ca) ÷ (consumer Sr/Ca). Similar expressions were used for Ba/Ca and Pb/Ca. It was found that Ca was biopurified of Sr 3-fold, of Ba 16-fold, and of Pb 100-fold in going from rock to sedge leaves. In going from sedge leaf to vole, Ca was biopurified of Sr 4-fold, of Ba 8-fold, and of Pb 16-fold. In going from meadow vole to pine marten, Ca was biopurified of Sr 6-fold, of Ba 7-fold, and of Pb 1.1-fold. Similar ranges of values for these factors were obtained for detrital and amphibian food chains. Fluxes of industrial lead entering the ecosystem as precipitation and dry deposition were measured and it was found that 40% of the lead in soil humus and soil moisture, 82% of the lead in sedge leaves, 92% of the lead in vole, and 97% of the lead in marten was industrial. The natural skeletal Pb/Ca ratio in carnivores (4 × 10 -8) was determined by means of corrections for inputs of industrial lead, food chain relationships, and measured biopurification factors for the ecosystem studied. This represents a 1700-fold reduction of the average Pb/Ca ratio in igneous rocks at the earth's surface (6.4 × 10 -5) by the compounding of successive Pb biopurification factors in transferring Ca from rock to carnivore. The natural ratio is similar to the value of 6 × 10 -8 observed for Pb/Ca in the bones of Peruvians who lived 2000 years ago but is 1/900th of the value of about 3.5 × 10 -5 for the skeletal Pb/Ca ratio found in present day Americans. This study shows experimentally how the Ba/Ca ratio in average surface igneous rock (3 × 10 -3) has been reduced 800-fold through compounding of successive biopurification steps to provide the skeletal Ba/Ca ratio of about 4 × 10 -6 observed in humans. It also provides biopurification factors for Sr and Ba among a number of nutrient-consumer pairs which anthropologists can use to delineate degrees of herbivory in diets of hominids within the last 10,000 years.

Explaining the Ba, Y, Sr, and Eu abundance scatter in metal-poor halo stars: constraints to the r-process

NASA Astrophysics Data System (ADS)

Cescutti, G.; Chiappini, C.

2014-05-01

Context. Thanks to the heroic observational campaigns carried out in recent years we now have large samples of metal-poor stars for which measurements of detailed abundances exist. In particular, large samples of stars with metallicities -5 < [Fe/H] <-1 and measured abundances of Sr, Ba, Y, and Eu are now available. These data hold important clues on the nature of the contribution of the first stellar generations to the enrichment of our Galaxy. Aims: We aim to explain the scatter in Sr, Ba, Y, and Eu abundance ratio diagrams unveiled by the metal-poor halo stars. Methods: We computed inhomogeneous chemical evolution models for the Galactic halo assuming different scenarios for the r-process site: the electron-capture (EC) supernovae and the magnetorotationally driven (MRD) supernovae scenarios. We also considered models with and without the contribution of fast-rotating massive stars (spinstars) to an early enrichment by the s-process. A detailed comparison with the now large sample of stars with measured abundances of Sr, Ba, Y, Eu, and Fe is provided (both in terms of scatter plots and number distributions for several abundance ratios). Results: The scatter observed in these abundance ratios of the very metal-poor stars (with [Fe/H] <-2.5) can be explained by combining the s-process production in spinstars, and the r-process contribution coming from massive stars. For the r-process we have developed models for both the EC and the MRD scenarios that match the observations. Conclusions: With the present observational and theoretical constraints we cannot distinguish between the EC and the MRD scenarios in the Galactic halo. Independently of the r-process scenarios adopted, the production of elements by an s-process in spinstars is needed to reproduce the spread in abundances of the light neutron capture elements (Sr and Y) over heavy neutron capture elements (Ba and Eu). We provide a way to test our suggestions by means of the distribution of the Ba isotopic ratios in a [Ba/Fe] or [Sr/Ba] vs. [Fe/H] diagram. Appendix A is available in electronic form at http://www.aanda.org

On the photo-luminescence properties of sol–gel derived undoped and Dy{sup 3+} ion doped nanocrystalline Scheelite type AMoO{sub 4} (A = Ca, Sr and Ba)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jena, Paramananda; Gupta, Santosh K., E-mail: santufrnd@gmail.com; Natarajan, V.

2015-04-15

Nanocrystalline Scheelite type Dy doped AMoO{sub 4} [where A = Ba, Sr and Ca] samples were prepared by acrylamide assisted sol–gel process and characterized by XRD, FT-Raman, FTIR, SEM and photoluminescence (PL). PL of undoped sample shows blue/green emission in CaMoO{sub 4} and SrMoO{sub 4} but multicolour visible emission leading to near white light in BaMoO{sub 4} nanoparticles; the origin of which is explained. It was observed that on doping 0.5 mol% of Dy{sup 3+} in molybdate samples complete energy transfer takes place in case of SrMoO{sub 4} and BaMoO{sub 4}, but host contributed substantially in Dy doped BaMoO{sub 4}more » sample, resulting in biexponential decay. It was also observed that symmetry around Dy{sup 3+} decreases as the size of alkaline earth ion increases. Due to combined blue, yellow and red colour emission in dysprosium doped sample; all samples showed near white light emission under UV and near UV excitation.« less

Ae2Sb2X4F2 (Ae = Sr, Ba): new members of the homologous series Ae2M(1+n)X(3+n)F2 designed from rock salt and fluorite 2D building blocks.

PubMed

Kabbour, Houria; Cario, Laurent

2006-03-20

We have designed new compounds within the homologous series Ae2F2M(1+n)X(3+n) (Ae = Sr, Ba; M = main group metal; n = integer) built up from the stacking of 2D building blocks of rock salt and fluorite types. By incrementally increasing the size of the rock salt 2D building blocks, we have obtained two new n = 1 members of this homologous series, namely, Sr2F2Sb2Se4 and Ba2F2Sb2Se4. We then succeeded in synthesizing these compounds using a high-temperature ceramic method. The structure refinements from the powder or single-crystal X-ray diffraction data confirmed presence of the expected alternating stacking of fluorite [Ae2F2] (Ae = Sr, Ba) and rock salt [Sb2Se4] 2D building blocks. However the Ba derivative shows a strong distortion of the [Sb2Se4] block and a concomitant change of the Sb atom coordination likely related to the lone-pair activity.

Natural and anthropic effects on hydrochemistry and major and trace elements in the water mass of a Spanish Pyrenean glacial lake set.

PubMed

Santolaria, Zoe; Arruebo, Tomás; Pardo, Alfonso; Rodríguez-Casals, Carlos; Matesanz, José María; Lanaja, Francisco Javier; Urieta, José Santiago

2017-07-01

This study presents the key hydrochemical characteristics and concentration levels of major (Ca, Mg, Na, Si, K, Sr, Fe) and trace (Ba, Sc, Cr, Mn, Al, As, Li, Co, Cu, U, Pb, Hg, Au, Sn, Zn, Cd, Ag, Ni) elements in the water mass of four selected Pyrenean cirque glacial lakes (Sabocos, Baños, Truchas and Escalar tarns) with different catchment features, between 2010 and 2013. Resulting data set is statistically analyzed to discriminate between the natural or anthropic origin of the elements. Analyses indicate that in all cases, the main source of most major and trace elements is geological weathering, being thus individual bedrock composition the main driver of differences between lakes. Several anthropogenic sources of airborne Cu, Sc, Co, and Cr must be also considered. The shallowness of the lake is also a factor that may influence element cycling and concentration levels in its water mass. Concentrations of anthropogenic elements were low, comparable to those reported in other glacial lakes, way below the WHO, US EPA, EC, and Spanish legal limits for drinking water quality, indicating the absence of serious pollution. Toxic heavy metals Cd, Pb, Hg, and Zn were not detected in any of the tarns.

Synthesis of high-oxidation Y-Ba-Cu-O phases in superoxygenated thin films

NASA Astrophysics Data System (ADS)

Zhang, H.; Gauquelin, N.; McMahon, C.; Hawthorn, D. G.; Botton, G. A.; Wei, J. Y. T.

2018-03-01

It is known that solid-state reaction in high-pressure oxygen can stabilize high-oxidation phases of Y-Ba-Cu-O superconductors in powder form. We extend this superoxygenation concept of synthesis to thin films which, due to their large surface-to-volume ratio, are more reactive thermodynamically. Epitaxial thin films of YBa2Cu3O7 -δ grown by pulsed laser deposition are annealed at up to 700 atm O2 and 900 ∘C , in conjunction with Cu enrichment by solid-state diffusion. The films show the clear formation of Y2Ba4Cu7O15 -δ and Y2Ba4Cu8O16 as well as regions of YBa2Cu5O9 -δ and YBa2Cu6O10 -δ phases, according to scanning transmission electron microscopy, x-ray diffraction, and x-ray absorption spectroscopy. Similarly annealed YBa2Cu3O7 -δ powders show no phase conversion. Our results demonstrate a route of synthesis towards discovering more complex phases of cuprates and other superconducting oxides.

Study of the superconducting properties of the Bi-Ca-Sr-Cu-O system

NASA Technical Reports Server (NTRS)

Khan, Musheer H.; Naqvi, S. M. M. R.; Zia-Ul-haq, S. M.

1991-01-01

High Temperature Superconductivity in the Bi-Ca-Sr-Cu-O System has been observed and has attracted considerable attention in 1988. The 80 K superconductivity phase has been identified to have a composition of Bi2CaSr2Cu2Ox, while the 110 K phase as reported in the literature has a possible composition of Bi2Ca2Sr2Cu3O(x). Researchers present here a study of the electrical properties of bulk samples of the slowly cooled and rapidly quenched 2:1:2:2 system. The samples used in this study were prepared from appropriate amounts of Bi2O3, CuO, SrCO3, CaCO3.

Trace and Ultra-trace Elements in the Deepest Part of the Vostok Ice Core, Antarctica: Geochemical Characterization of the Sub-glacial Lake Environment

NASA Astrophysics Data System (ADS)

Turetta, C.; Planchon, F.; Gabrielli, P.; Cozzi, G.; Cairns, W.; Barbaro, E.; Petit, J. R.; Bulat, S.; Boutron, C.; Barbante, C.

2016-12-01

We present in this study comprehensive data on the occurrence of 25 trace and ultra-trace elements in the deepest part of the Vostok ice core. The determination of Li, Na, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Cu, Zn, As, Se, Rb, Sr, Mo, Ag, Cd, Sb, Ba, Pb, Bi and U has been performed in the different types of ice encountered from 3271 m to 3609 m of depth, corresponding to atmospheric ice, glacial flour and to accreted ice originating from the freezing of Lake Vostok waters. From atmospheric ice and glacial flour, the relative contributions of primary aerosols were evaluated for each element using a chemical mass balance approach in order to provide a first order evaluation of their partition between soluble (sea-salt) and insoluble (wind-blown dust) fractions in the ice. Sea-salt spray aerosols are the main source of impurities to the ice for certain elements (Na, Mg and K levels, and in a lesser extent to Ca, Sr, Rb, Li and U) while for other elements (Al, V, Cr, Mn, Fe, Co, Cu, Zn, Mo, Sb, Ba and Pb as well as the non sea salt fractions of Mg, K, Ca, Sr, Rb, Li and U) dust inputs appear to primarily control their depositional variability. For the glacial flour, the comparable levels of elements with the overlying atmospheric ice suggest that incorporation of abrasion debris at the glacier is quite limited in the sections considered. For the accreted ice originating from the subglacial waters of Lake Vostok, we observed a major chemical shift in the composition of the ice showing two distinct trends that we assumed to be derived from the chemical speciation of elements. The study of the glacier ice and the glacial flour has allowed us to perform a detailed characterisation of elemental abundances related to the aerosol sources variability and also to illustrate the interaction between the ice-sheet and the bedrock.

Preferential Eu Site Occupation and Its Consequences in the Ternary Luminescent Halides AB 2 I 5 : Eu 2 + ( A = Li – Cs ; B = Sr , Ba)

DOE PAGES

Fang, C.  M.; Biswas, Koushik

2015-07-22

Several rare-earth-doped, heavy-metal halides have recently been identified as potential next-generation luminescent materials with high efficiency at low cost. AB 2I 5:Eu 2+ (A=Li–Cs; B=Sr, Ba) is one such family of halides. Its members, such as CsBa 2I 5:Eu 2+ and KSr 2I 5:Eu 2+, are currently being investigated as high-performance scintillators with improved sensitivity, light yield, and energy resolution less than 3% at 662 keV. Within the AB 2I 5 family, our first-principles-based calculations reveal two remarkably different trends in Eu site occupation. The substitutional Eu ions occupy both eightfold-coordinated B1(VIII) and the sevenfold-coordinated B2(VII) sites in the Sr-containingmore » compounds. However, in the Ba-containing crystals, Eu ions strongly prefer the B2(VII)sites. This random versus preferential distribution of Eu affects their electronic properties. The calculations also suggest that in the Ba-containing compounds one can expect the formation of Eu-rich domains. These results provide atomistic insight into recent experimental observations about the concentration and temperature effects in Eu-doped CsBa 2I 5. We discuss the implications of our results with respect to luminescent properties and applications. We also hypothesize Sr, Ba-mixed quaternary iodides ABa VIIISr VIII 5:Eu as scintillators having enhanced homogeneity and electronic properties.« less

(Ba1- x Bi0.33 x Sr0.67 x )(Ti1- x Bi0.67 x V0.33 x )O3 and (Ba1- x Bi0.5 x Sr0.5 x )(Ti1- x Bi0.5 x Ti0.5 x )O3 solid solutions: phase evolution, microstructure, dielectric properties and impedance analysis

NASA Astrophysics Data System (ADS)

Chen, Xiuli; Li, Xiaoxia; Yan, Xiao; Liu, Gaofeng; Zhou, Huanfu

2018-06-01

Perovskite solid solution ceramics of (Ba1- x Bi0.33 x Sr0.67 x )(Ti1- x Bi0.67 x V0.33 x )O3 and (Ba1- x Bi0.5 x Sr0.5 x )(Ti1- x Bi0.5 x Ti0.5 x )O3 (BBSTBV, BBSTBT, 0.02 ≤ x ≤ 0.2) were prepared by the traditional solid state reaction technique. The phase evolution, microstructure and dielectric properties of BBSTBV and BBSTBT ceramics were researched. X-Ray diffraction results illustrated that both BBSTBV and BBSTBT could form a homogenous solid solution which has a similar structure with BaTiO3. The optimized properties of (Ba0.8Bi0.1Sr0.1)(Ti0.8Bi0.1Ti0.1)O3 ceramics with stable ɛ r ( 1769-2293), small Δ ɛ/ ɛ 25 °C values (± 15%) over a broad temperature range from - 58 to 151 °C and low tan δ ≤ 0.03 from - 11 to 131 °C were obtained. In the high-temperature region, the relaxation and conduction process are attributed to the thermal activation and the oxygen vacancies may be the ionic charge carriers in perovskite ferroelectrics.

Assessment of 28 trace elements and 17 amino acid levels in muscular tissues of broiler chicken (Gallus gallus) suffering from arsenic trioxide.

PubMed

Li, Si-Wen; He, Ying; Zhao, Hong-Jing; Wang, Yu; Liu, Juan-Juan; Shao, Yi-Zhi; Li, Jing-Lun; Sun, Xiao; Zhang, Li-Na; Xing, Ming-Wei

2017-10-01

The contents of 28 trace elements, 17 amino acid were evaluated in muscular tissues (wings, crureus and pectoralis) of chickens in response to arsenic trioxide (As 2 O 3 ). A total of 200 one-day-old male Hy-line chickens were fed either a commercial diet (C-group) or an As 2 O 3 supplement diet containing 7.5mg/kg (L-group), 15mg/kg (M-group) or 30mg/kg (H-group) As 2 O 3 for 90 days. The elements content was analyzed by inductively coupled plasma mass spectrometry (ICP-MS). Under As 2 O 3 exposure, the concentration of As were elevated 8.87-15.76 fold, 7.93-15.63 fold and 5.94-12.45 fold in wings, crureus and pectoralis compared to the corresponding C-group, respectively. 19 element levels (lithium (Li), magnesium (Mg), aluminum (Al), silicon (Si), kalium (K), vanadium (V), chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), selenium (Se), strontium (Sr), molybdenum (Mo), cadmium (Cd), tin (Sn), antimony (Sb), barium (Ba), mercury (Hg) and lead (Pb), 9 element levels (K, Co, Ni, Cu, As, Se, Sr, Sn, Ba and Hg) and 4 element levels (Mn, cobalt (Co), As, Sr and Ba) were significantly increased (P < 0.05) in wing, crureus and pectoralis, respectively. 2 element levels (sodium (Na) and zinc (Zn)), 5 element levels (Li, Na, Si, titanium (Ti and Cr), 13 element levels (Li, Na, Mg, K, V, Cr, iron (Fe), Cu, Zn, Mo, Sn, Hg and Pb) were significantly decreased (P < 0.05) in wing muscle, crureus and pectoralis, respectively. Additionally, in crureus and pectoralis, the content of total amino acids (TAA) was no significant alterations in L and M-group and then increased approximately 10.2% and 7.6% in H-group, respectively (P < 0.05). In wings, the level of total amino acids increased approximately 10% in L-group, whereas it showed unchanged in M and H-group compared to the corresponding C-group. We also observed that significantly increased levels of proline, cysteine, aspartic acid, methionine along with decrease in the tyrosine levels in muscular tissues compared to the corresponding C-group. In conclusion, the residual of As in the muscular tissues of chickens were dose-dependent and disrupts trace element homeostasis, amino acids level in muscular tissues of chickens under As 2 O 3 exposure. Additionally, the response (trace elements and amino acids) were different in wing, thigh and pectoral of chick under As 2 O 3 exposure. This study provided references for further study of heavy metal poisoning and may be helpful to understanding the toxicological mechanism of As 2 O 3 exposure in muscular tissues of chickens. Copyright © 2017 Elsevier Inc. All rights reserved.

Isotopic and Chemical Evidence for Primitive Aqueous Alteration in the Tagish Lake Meteorite

NASA Astrophysics Data System (ADS)

Sakuma, Keisuke; Hidaka, Hiroshi; Yoneda, Shigekazu

2018-01-01

Aqueous alteration is one of the primitive activities that occurred on meteorite parent bodies in the early solar system. The Tagish Lake meteorite is known to show an intense parent body aqueous alteration signature. In this study, quantitative analyses of the alkaline elements and isotopic analyses of Sr and Ba from acid leachates of TL (C2-ungrouped) were performed to investigate effects of aqueous alteration. The main purpose of this study is to search for isotopic evidence of extinct 135Cs from the Ba isotopic analyses in the chemical separates from the Tagish Lake meteorite. Barium isotopic data from the leachates show variable 135Ba isotopic anomalies (ε = ‑2.6 ∼ +3.6) which correlatewith 137Ba and 138Ba suggesting a heterogeneous distribution of s- and r-rich nucleosynthetic components in the early solar system. The 87Rb–87Sr and 135Cs–135Ba decay systems on TL in this study do not provide any chronological information. The disturbance of the TL chronometers is likely a reflection of the selective dissolution of Cs and Rb given the relatively higher mobility of Cs and Rb compared to Ba and Sr, respectively, during fluid mineral interactions.

Development of Long REBCO with BMO Coated Conductors by PLD Method with High Production Rate

NASA Astrophysics Data System (ADS)

Ibi, A.; Yoshida, T.; Taneda, T.; Yoshizumi, M.; Izumi, T.; Shiohara, Y.

We have been developing long REBa2Cu3O7-δ (RE: Y, Gd and Eu etc.) with BaMO3 (M: Zr, Sn and Hf etc.) coated conductors by the combination of the ion-beam assisted deposition (IBAD) and the pulsed laser deposition (PLD) methods. REBa2Cu3O7-δ with BaMO3 coated conductors showed high in-field performance, therefore, these coated conductors could be expected for the industrial and commercial applications at high temperatures in magnetic fields. However, to realize the low production cost for long REBa2Cu3O7-δ with BaMO3 coated conductors, improvement of the production rate of the REBa2Cu3O7-δ layers containing BaMO3 rods with maintaining high superconducting properties is required. To solve these problems, we have tried deposition of the REBa2Cu3O7-δ layers with high superconducting properties by the PLD method with high production rate. As a result, we have successfully fabricated EuBa2Cu3O7-δ layers containing BaHfO3 rods with high in-field Jc and Ic by the PLD method with high production rate. This EuBa2Cu3O7-δ with BaHfO3 coated conductor exhibit a high Ic value of 412 and 48.7 A/cm-width at 77 K in self-field and 3 T, respectively at the deposition rate of about 40 μm/h and the production rate of 10 m/h for a 1.35 μm EuBCO layer thick.

Temperature dependence of positron annihilation parameters in Tl-Ba-Ca-Cu-O superconductors

NASA Astrophysics Data System (ADS)

Sundar, C. S.; Bharathi, A.; Ching, W. Y.; Jean, Y. C.; Hor, P. H.; Meng, R. L.; Huang, Z. J.; Chu, C. W.

1990-08-01

The results of positron lifetime and Doppler broadened line-shape parameter measurements as a function of temperature, across Tc, in the Tl-Ba-Ca-Cu-O superconductors are presented. The bulk lifetime in the normal state is found to decrease with the increase in the number of CuO2 layers. Different temperature dependencies of the annihilation parameters are observed in the various Tl systems containing different numbers of CuO2 layers. In the Tl2Ba2Ca2Cu3O10 system, an increase in lifetime is observed below Tc, whereas in Tl2Ba2CaCu2O8, a decrease in lifetime is seen below Tc. In the Tl2Ba2CuO6 system, the lifetime is observed to be temperature independent. The different temperature variations of positron annihilation parameters are discussed in the light of the positron density distribution, obtained with use of the results of the self-consistent orthogonalized linear combination of atomic orbitals band-structure calculations. It is argued that the different temperature dependencies of the annihilation parameters is related to the positron density distribution within the unit cell and arise due to local charge transfer in the vicinity of the CuO2 layer in the superconducting state.

Co-precipitation of radium with barium and strontium sulfate and its impact on the fate of radium during treatment of produced water from unconventional gas extraction.

PubMed

Zhang, Tieyuan; Gregory, Kelvin; Hammack, Richard W; Vidic, Radisav D

2014-04-15

Radium occurs in flowback and produced waters from hydraulic fracturing for unconventional gas extraction along with high concentrations of barium and strontium and elevated salinity. Radium is often removed from this wastewater by co-precipitation with barium or other alkaline earth metals. The distribution equation for Ra in the precipitate is derived from the equilibrium of the lattice replacement reaction (inclusion) between the Ra(2+) ion and the carrier ions (e.g., Ba(2+) and Sr(2+)) in aqueous and solid phases and is often applied to describe the fate of radium in these systems. Although the theoretical distribution coefficient for Ra-SrSO4 (Kd = 237) is much larger than that for Ra-BaSO4 (Kd = 1.54), previous studies have focused on Ra-BaSO4 equilibrium. This study evaluates the equilibria and kinetics of co-precipitation reactions in Ra-Ba-SO4 and Ra-Sr-SO4 binary systems and the Ra-Ba-Sr-SO4 ternary system under varying ionic strength (IS) conditions that are representative of brines generated during unconventional gas extraction. Results show that radium removal generally follows the theoretical distribution law in binary systems and is enhanced in the Ra-Ba-SO4 system and restrained in the Ra-Sr-SO4 system by high IS. However, the experimental distribution coefficient (Kd') varies widely and cannot be accurately described by the distribution equation, which depends on IS, kinetics of carrier precipitation and does not account for radium removal by adsorption. Radium removal in the ternary system is controlled by the co-precipitation of Ra-Ba-SO4, which is attributed to the rapid BaSO4 nucleation rate and closer ionic radii of Ra(2+) with Ba(2+) than with Sr(2+). Carrier (i.e., barite) recycling during water treatment was shown to be effective in enhancing radium removal even after co-precipitation was completed. Calculations based on experimental results show that Ra levels in the precipitate generated in centralized waste treatment facilities far exceed regulatory limits for disposal in municipal sanitary landfills and require careful monitoring of allowed source term loading (ASTL) for technically enhanced naturally occurring materials (TENORM) in these landfills. Several alternatives for sustainable management of TENORM are discussed.

A study on the thermal conversion of scheelite-type ABO4 into perovskite-type AB(O,N)3.

PubMed

Li, Wenjie; Li, Duan; Gao, Xin; Gurlo, Aleksander; Zander, Stefan; Jones, Philip; Navrotsky, Alexandra; Shen, Zhijian; Riedel, Ralf; Ionescu, Emanuel

2015-05-07

Phase-pure scheelite AMoO4 and AWO4 (A = Ba, Sr, Ca) were thermally treated under an ammonia atmosphere at 400 to 900 °C. SrMoO4 and SrWO4 were shown to convert into cubic perovskite SrMoO2N and SrWO1.5N1.5, at 700 °C and 900 °C respectively, and to form metastable intermediate phases (scheelite SrMoO4-xNx and SrWO4-xNx), as revealed by X-ray diffraction (XRD), elemental analysis and FTIR spectroscopy. High-temperature oxide melt solution calorimetry reveals that the enthalpy of formation for SrM(O,N)3 (M = Mo, W) perovskites is less negative than that of the corresponding scheelite oxides, though the conversion of the scheelite oxides into perovskite oxynitrides is thermodynamically favorable at moderate temperatures. The reaction of BaMO4 with ammonia leads to the formation of rhombohedral Ba3M2(O,N)8 and the corresponding binary metal nitrides Mo3N2 and W4.6N4; similar behavior was observed for CaMO4, which converted upon ammonolysis into individual oxides and nitrides. Thus, BaMO4 and CaMO4 were shown to not provide access to perovskite oxynitrides. The influence of the starting scheelite oxide precursor, the structure distortion and the degree of covalency of the B-site-N bond are discussed within the context of the formability of perovskite oxynitrides.

Effect of alkaline earth modifier on the optical and structural properties of Cu2+ doped phosphate glasses as a bandpass filter

NASA Astrophysics Data System (ADS)

Farouk, M.; Samir, A.; El Okr, M.

2018-02-01

Glasses of composition [16RO-3Al2O3sbnd 6CuOsbnd 20Na2Osbnd 55P2O5], where R is the alkaline earth (R = Mg, Ca, Sr and Ba mol. %), were prepared by conventional melt quenching technique. The glass samples were characterized by X-ray diffraction, infrared spectroscopy, and spectrophotometer. XRD patterns show no sharp peaks indicating the non-crystalline nature of the prepared glasses. The density and molar volume of the glass systems were determined in order to study their structures. These results revealed that addition of alkaline earth elements leads to the formation of non-bridging oxygens (NBOs) and expands (opens up) the structure. The infrared spectra were analyzed to quantify the present phosphate groups. The optical absorption spectra of Cu2+ ions show the characteristic broadband single of Cu2+ ions in octahedral symmetry. The band gap was estimated following two methodologies. The first method considers the band edge of the transmission, while the second approach relays on the estimated values of the optical constants. A decent agreement for the band gap values using the two methods was obtained.

An Industry-Scale Mass Marking Technique for Tracing Farmed Fish Escapees

PubMed Central

Warren-Myers, Fletcher; Dempster, Tim; Fjelldal, Per Gunnar; Hansen, Tom; Swearer, Stephen E.

2015-01-01

Farmed fish escape and enter the environment with subsequent effects on wild populations. Reducing escapes requires the ability to trace individuals back to the point of escape, so that escape causes can be identified and technical standards improved. Here, we tested if stable isotope otolith fingerprint marks delivered during routine vaccination could be an accurate, feasible and cost effective marking method, suitable for industrial-scale application. We tested seven stable isotopes, 134Ba, 135Ba, 136Ba, 137Ba, 86Sr, 87Sr and 26Mg, on farmed Atlantic salmon reared in freshwater, in experimental conditions designed to reflect commercial practice. Marking was 100% successful with individual Ba isotopes at concentrations as low as 0.001 µg. g-1 fish and for Sr isotopes at 1 µg. g-1 fish. Our results suggest that 63 unique fingerprint marks can be made at low cost using Ba (0.0002 – 0.02 $US per mark) and Sr (0.46 – 0.82 $US per mark) isotopes. Stable isotope fingerprinting during vaccination is feasible for commercial application if applied at a company level within the world’s largest salmon producing nations. Introducing a mass marking scheme would enable tracing of escapees back to point of origin, which could drive greater compliance, better farm design and improved management practices to reduce escapes. PMID:25738955

Dielectric properties of (CuO, CaO2, and BaO)y/CuTl-1223 composites

NASA Astrophysics Data System (ADS)

Mumtaz, M.; Kamran, M.; Nadeem, K.; Jabbar, Abdul; Khan, Nawazish A.; Saleem, Abida; Tajammul Hussain, S.; Kamran, M.

2013-07-01

We synthesized (CuO, CaO2, and BaO)y/Cu0.5Tl0.5Ba2Ca2Cu3O10-δ (y = 0, 5%, 10%, 15%) composites by solid-state reaction and characterized them by x-ray diffraction, scanning electron microscopy, dc-resistivity, and Fourier transform infrared spectroscopy. Frequency and temperature dependent dielectric properties, such as real and imaginary parts of the dielectric constant, dielectric loss, and ac-conductivity of these composites were studied by capacitance and conductance measurements as a function of frequency (10 kHz to 10 MHz) and temperature (78 to 300 K). X-ray diffraction analysis reveals that the characteristic behavior of the superconductor phase and the structure of Cu0.5Tl0.5Ba2Ca2Cu3O10-δ are nearly undisturbed by doping with nanoparticles. Scanning electron microscopy images show the improvement in the intergranular linking between the superconducting grains occurring with increasing nanoparticle concentration. Microcracks are healed up with these nanoparticles, and superconducting volume fraction is also increased. Dielectric properties of these composites strongly depend on the frequency and temperature. Zero resistivity critical temperature and dielectric properties show opposite trends with the addition of nanoparticles to the Cu0.5Tl0.5Ba2Ca2Cu3O10-δ superconductor matrix.

Studying the local structures of novel materials using the Extended X-ray Absorption Fine Structure technique

NASA Astrophysics Data System (ADS)

Jiang, Yu

2009-12-01

In this dissertation, investigations on the local lattice structures for a variety of novel materials using Extended X-ray Absorption Fine Structure (EXAFS) technique are presented. Different experiment schemes were applied to obtain EXAFS data with high quality, and some interesting results were obtained by careful analysis. The power of the EXAFS technique was once again proved. In Chapter 1, I first briefly introduce the EXAFS theory and experiments, then give readers who are not familiar with this technique a short introduction on data reduction and analysis, and finally discuss some problems that are easily ignored in the interpretation of the experiment results. In Chapter 2, a temperature-dependent EXAFS investigation of La 1-xCaxMnO 3 is presented for the concentration range that spans the ferromagnetic-insulator (FMI) to ferromagnetic-metal (FMM) transition region, x = 0.16, 0.18, 0.20, and 0.22; the titrated hole concentrations are slightly higher y = 0.2, 0.22, 0.24, and 0.25 respectively. In Chapter 3, I report EXAFS studies of n- and p-type Ba8Ga 16Ge30 samples (type I clathrate) at the Ga, Ge, and Ba K-edges, to probe the local structure, particularly around the Ba atoms located inside 20- and 24-atom cages (Ba1 and Ba2 sites respectively) formed of Ga/Ge atoms. In agreement with diffraction analysis we find Ba2 is off-center, with a component in the bc plane (0.15 A) comparable to that found in diffraction; however, under the assumption of a stiff cage we also require a significant a component. This suggests a coupling or attraction between the Ba2 atoms and the hexagonal rings at the top or bottom of the cage that encloses the Ba2 site. In Chapter 4, I report detailed degradation and rejuvenation studies for AC electro-luminescence (EL) devices made using the phosphor ZnS:Cu,CI. We find that the AC EL emission spectra vary considerably with AC driving frequency but all spectra can be fit to a sum of four Gaussians. The combined experiments place strong constraints on the mechanisms for degradation and rejuvenation and suggest that EL degradation is most likely caused by either Cu or Cl diffusion under high E-fields, while thermal diffusion at slightly elevated temperatures without E-fields present, re-randomizes the (isolated) dopant distributions. In Chapter 5, I present a temperature-dependent EXAFS/XANES investigation of La1-xSrxCoO 3 (LSCO) over a wide doping concentration range (0 ≤ x ≤ 0.35). These experiments do not support the existence of a significant fraction of Co sites with an intermediate spin (IS) state, for which there is a JT active eg electron on the Co atoms. We cannot, however, exclude the possibility of a tiny fraction of sites having a JT distortion or some other (non-JT active) means of producing an IS state. The bulk samples are well ordered out to at least the third neighbors (Co-Co) while the nano-particles show increased disorder and a reduction in coordination for Co-Co. XANES data are also presented and, for both bulk and nano-particle samples, there is essentially no edge shift with increasing Sr concentration and no significant change in the first pre-edge peak with Sr concentration or changing temperature (4-300K). This indicates that when holes are introduced via Sr doping, Co remains close to Co3+; we argue that the holes go primarily into the O 2p bands. Bond-valence sums also indicate no change in Co valence.

Optical anisotropy of Bi2Sr2CaCu2O8

NASA Astrophysics Data System (ADS)

Kim, J. H.; Bozovic, I.; Mitzi, D. B.; Kapitulnik, A.; Harris, J. S., Jr.

1990-04-01

The optical anisotropy of Bi2Sr2CaCu2O8 in the 0.08-0.5-eV region is investigated by polarized reflectance measurements on single crystals. A very large anisotropy is found in this spectral region. The in-plane reflectance exhibits metallic behavior, while the c-axis reflectance exhibits insulatorlike behavior. This result is consistent with the large anisotropy found in the resistivity of Bi2Sr2CaCu2O8. Our spectroscopic data suggest that Bi2Sr2CaCu2O8 is a quasi-two-dimensional metal similar to La2-xSrxCuO4.

Superconducting glass-ceramics in the Bi-Sr-Ca-Cu-O system

NASA Technical Reports Server (NTRS)

De Guire, Mark R.; Kim, Cheol J.; Bausal, Narottam P.

1990-01-01

Differential thermal analysis, XRD, SEM, and resistivity measurements, have been used to study the recrystallization during various heat treatments of a Bi1.5SrCaCu2O(z) glass obtained by rapid quenching from the melt. Heating at 450 C formed the Bi(2+x)Sr(2-x)-CuO(z) solid solution designated 'R'. Between 765 and 845 C, R reacts slowly with the glass to form the 80 K superconductor Bi2(Sr,Ca)3Cu2O(z), together with CuO. Heating for 7 days at the higher temperature, followed by slow cooling, raised the temperature of zero resistance to 77 K.

Synthesis, structural and optical properties of (ALa)(FeMn)O6 (A = Ba and Sr) double perovskites

NASA Astrophysics Data System (ADS)

Kumar, Dinesh; Sudarshan, V.; Singh, Akhilesh Kumar

2018-05-01

Here, we report structural and optical properties of ALaFeMnO6 (A = Ba and Sr) double perovskite synthesized via auto-combustion followed by calcinations process. Rietveld refinement of structure using x-ray diffraction data reveals that BaLaFeMnO6 crystallizes into cubic crystal structure with space group Pm-3m while SrLaFeMnO6 crystallizes into rhombohedral crystal structure having space group R-3c. The absorption spectrum measurement using UV-Vis spectroscopy reveals that these samples are prefect insulator having energy band gap between conduction and valence band of the order of 6 eV.

Major and trace elements in organically or conventionally produced milk.

PubMed

Hermansen, John E; Badsberg, Jens H; Kristensen, Troels; Gundersen, Vagn

2005-08-01

A total of 480 samples of milk from 10 organically and 10 conventionally producing dairy farms in Denmark and covering 8 sampling periods over 1 year (triplicate samplings) were analysed for 45 trace elements and 6 major elements by high-resolution inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. Sampling, sample preparation, and analysis of the samples were performed under carefully controlled contamination-free conditions. The dairy cattle breeds were Danish-Holstein or Jersey. Sources of variance were quantified, and differences between production systems and breeds were tested. The major source of variation for most elements was week of sampling. Concentrations of Al, Cu, Fe, Mo, Rb, Se, and Zn were within published ranges. Concentrations of As, Cd, Cr, Mn and Pb were lower, and concentrations of Co and Sr were higher than published ranges. Compared with Holsteins, Jerseys produced milk with higher concentrations of Ba, Ca, Cu, Fe, Mg, Mn, Mo, P, Rh, and Zn and with a lower concentration of Bi. The organically produced milk, compared with conventionally produced milk, contained a significantly higher concentration of Mo (48 v. 37 ng/g) and a lower concentration of Ba (43 v. 62 ng/g), Eu (4 v. 7 ng/g), Mn (16 v. 20 ng/g) and Zn (4400 v. 5150 ng/g respectively). The investigation yielded typical concentrations for the following trace elements in milk, for which no or very few data are available: Ba, Bi, Ce, Cs, Eu, Ga, Gd, In, La, Nb, Nd, Pd, Pr, Rh, Sb, Sm, Tb, Te, Th, Ti, Tl, U, V, Y, and Zr.

[Effect of Eu(Pr) substitution at Ba sites on microstructure and superconductivity in EuBa2Cu3O7-delta ceramics].

PubMed

Peng, Zhen-sheng; Wang, Zhi-he

2004-04-01

Ceramics of Eu1+xBa2-xCu3O7-delta with x = 0.0, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5 and EuBa2-xPrxCu3O7-delta with x=0.0, 0.05, 0.1, 0.2, 0.3, 0.4 have been synthesized and investigated by X-ray diffraction, resistivity, and Raman spectroscopy. The results show that the transition of crystal structure from orthorhombic to tetragonal occurs and the criticaltemperature decreases withthe increase in doping concentration x. The Raman spectra show that the frequency of the Cu(1)-O(4) stretching mode andthe Cu(2)-(2, 3) out-of-phase mode shifts to higher wave number with increasing doping concentration x.

Profile and bioconcentration of minerals by King Bolete (Boletus edulis) from the Płocka Dale in Poland.

PubMed

Frankowska, Aneta; Ziółkowska, Joanna; Bielawski, Leszek; Falandysz, Jerzy

2010-01-01

This study aimed to provide basic data on the composition of metallic elements, including toxicologically important Cd and Hg, in popular and prized wild King Bolete mushrooms. We investigated the importance of soil substratum as a source of these metals. ICP-OES and CV-AAS were applied to determine the profile of Al, Ba, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, Sr and Zn in caps and stipes of King Bolete mushroom and in the surface layer of soil (0-10 cm) from the Płocka Dale area of Poland. Hg, Cu, Cd, Zn, Mg and K exhibited bioconcentration factors (BCF) > 1. Specifically, Hg, Cu and Cd (mean BCFs for caps were 110, 19 and 16, respectively) were efficiently bioconcentrated by King Bolete, while other elements were bioexcluded (BCF < 1). Cadmium was present in the caps at mean levels of 5.5 ± 2.4 mg kg(-1) dry weight (dw) and mercury at levels of 4.9 ± 1.4 mg kg(-1) dw, both occurring at elevated concentrations in those King Bolete mushrooms surveyed.

Singularity in the positive Hall coeffcient near pre-onset temperatures in high-Tc superconductors

NASA Astrophysics Data System (ADS)

Vezzoli, G. C.; Chen, M. F.; Craver, F.; Moon, B. M.; Safari, A.; Burke, T.; Stanley, W.

1990-10-01

Hall measurements using continuous extremely slow cooling and reheating rates as well as employing eqiulibrium point-by-point conventional techniques reveals a clear anomally in RH at pre-onset temperatures near Tc in polycrystalline samples Y1Ba2Cu3O7 and Bi2Sr2Ca2Cu3O10. The anomaly has the appearance of a singularity of Dirac-delta function which parallels earlier work on La1-xSrxCuO4. Recent single crystal work on the Bi-containing high-Tc superconductor is in accord with a clearcut anomaly. The singularity is tentatively interpreted to be associated (upon cooling) with initially the removal of positive holes from the hopping conduction system of the normal state such as from the increased concentration of bound virtual excitons due to increased exciton and hole lifetimes at low temperature. Subsequently the formation of Cooper pairs by mediation from these centers (bound-holes) and/or bound excitons) may cause an ionization of these bound virtual excitons thereby re-introducing holes and electrons into the conduction system at Tc.

A new series of oxycarbonate superconductors (Cu{sub 0.5}C{sub 0.5}){sub m}Ba{sub m+1}Ca{sub n-1}Cu{sub n}O{sub 2}({sub m+n})+1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Takayama-Muromachi, E.; Kawashima, T.; Matsui, Y.

1994-12-31

We found a new series of oxycarbonate superconductors in the Ba-Ca-Cu-C-O system under high pressure of 5 GPa. Their ideal formula is (Cu{sub 0.5}C{sub 0.5}){sub m}Ba{sub m+1}Ca{sub n-1}Cu{sub n}O{sub 2}({sub m+n})+1 ((Cu,C)-m(m+1)(n-1)n). Thus far, n=3, 4 members of the m=1 series, (Cu,C)-1223 and (Cu,C)-1234, have been prepared in bulk while n=4, 5 members, (Cu,C)-2334 and (Cu,C)-2345, have been prepared for the m=2 series. (Cu,C)-1223 shows superconductivity below 67 K while T{sub c}`s of other compounds are above 110 K. In particular, (Cu,C)=1234 has the highest T{sub c} of 117 K.

Microstructural and thermal properties of pure BaFe{sub 12}O{sub 19} and Sr doped barium ferrite (Ba{sub 0.9}Sr{sub 0.1}Fe{sub 12}O{sub 19}) synthesized by auto combustion method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Taufeeq, Saba, E-mail: sabataufeeq23@gmail.com; Parveen, Azra; Agrawal, Shraddha

2016-05-23

Nanoparticles (NPs) of Pure BaFe{sub 12}O{sub 19} and Strontium doped Barium Ferrite (Ba{sub 0.9}Sr{sub 0.1}Fe{sub 12}O{sub 19}) have been successfully synthesized by Auto combustion method using citric acid as a chelating agent and calcined at 450°C for 3 hrs and 850°C for 4 hrs. Microstructural studies were carried by XRD and SEM techniques. Structural studies suggest that the crystal system remains hexagonal even with the doping of Strontium. The XRD analysis confirms the formation of the structures in the nanometer regime and the peaks are the evidence of the crystalline phase. The SEM images shows the morphology of surface ofmore » the samples. The thermal property studied by TGA shows the weight loss which is with varying the temperature and weight loss also varies with Sr doping. The TGA analysis exhibits the loss of weight at different temperatures.« less

Modification of energy band alignment and electric properties of Pt/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}/Pt thin-film ferroelectric varactors by Ag impurities at interfaces

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirsch, S.; Komissinskiy, P., E-mail: komissinskiy@oxide.tu-darmstadt.de; Flege, S.

2014-06-28

We report on the effects of Ag impurities at interfaces of parallel-plate Pt/Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}/Pt thin film ferroelectric varactors. Ag impurities occur at the interfaces due to diffusion of Ag from colloidal silver paint used to attach the varactor samples with their back side to the plate heated at 600–750 °C during deposition of Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3}. X-ray photoelectron spectroscopy and secondary ion mass spectrometry suggest that amount and distribution of Ag adsorbed at the interfaces depend strongly on the adsorbent surface layer. In particular, Ag preferentially accumulates on top of the Pt bottom electrode. The presence of Agmore » significantly reduces the barrier height between Pt and Ba{sub 0.6}Sr{sub 0.4}TiO{sub 3} leading to an increased leakage current density and, thus, to a severe degradation of the varactor performance.« less

Band-gap tuning and magnetic properties of heterovalent ions (Ba, Sr and Ca) substituted BiFeO{sub 3} nanoparticles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chauhan, Sunil, E-mail: sunilchauhanjiit@gmail.com; Kumar, Manoj; Katyal, S. C.

2016-05-23

A Comparative study of heterovalent Ba, Sr and Ca ions substitution on the structural, vibrational, optical and magnetic properties of BiFeO{sub 3} nanoparticles was carried out. The distorted rhombohedral structure was confirmed from both X-ray diffraction and Raman spectroscopy techniques in pure BiFeO{sub 3} and Bi{sub 0.85}A{sub 0.15}FeO{sub 3} (A= Ba, Sr and Ca) samples. UV-Visible spectroscopy results show that the band-gap of BiFeO{sub 3} nanoparticles can be tuned by heterovalent ions substitution from 2.12 eV for BiFeO{sub 3} to 2.10, 2.06 and 2.03 eV for Ca, Sr and Ba substituted BiFeO{sub 3} nanoparticles respectively. The magnetic measurements indicate enhancementmore » in magnetization for heterovalent A{sup 2+} substituted BiFeO{sub 3} samples and the magnetization increases with increase of ionic radius of the substituted ions.« less

Influence of MO/MF2 modifiers (M = Ca, Sr, Ba) on spectroscopic properties of Eu3+ ions in germanate and borate glasses

NASA Astrophysics Data System (ADS)

Zur, Lidia; Janek, Joanna; Pietrasik, Ewa; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.

2016-11-01

Series of Eu3+-doped lead-free germanate and borate glasses were synthesized. The MO glass modifiers (M = Ca, Sr or Ba) were partially or totally substituted by MF2 in chemical composition. In contrast to samples modified by CaO/CaF2 or SrO/SrF2, the germanate glass samples containing BaO and/or BaF2 are fully amorphous, while the lead-free borate glasses are fully amorphous, independently from glass modifiers. Effect of glass modifiers on spectroscopic properties of Eu3+ were systematically investigated. For that reason, excitation and emission spectra of Eu3+ ions in examined systems were registered. Based on the emission spectra, ratio of integrated luminescence intensity of the 5D0 → 7F2 transition to that of the 5D0 → 7F1 transition (R factor) was calculated. Moreover, the luminescence decay curves were collected and the luminescence lifetimes of the 5D0 excited state of Eu3+ ions were determined in function of MF2 concentration.

Superconductivity above 100 K in Bi(Pb)-Ca-Sr-Cu-O films made by thermal decomposition of metal carboxylates

NASA Astrophysics Data System (ADS)

Klee, M.; de Vries, J. W. C.; Brand, W.

1988-11-01

Superconducting layers in the Bi(Pb)-Ca-Sr-Cu-O system are prepared by thermal decomposition of metal carboxylates. The films are deposited on MgO single crystal and ceramic substrates using a spin-coating and dip-coating process. The Bi-Ca-Sr-Cu-O films consist mainly of the low- Tc phase ( c-axis=3.073 nm), whereas partial substitution of Bi by Pb favours the formation of the high- Tc phase ( c-axis=3.707 nm). Films deposited on MgO (100) are strong c-axis preferentially oriented grown. While the Bi-Ca-Sr-Cu-O films show a step in the resistance versus temperature curve ( Tcf⋍80 K) due to the presence of the low- Tc and the high- Tc phase, the Bi(Pb)-Ca-Sr-Cu-O films have an onset at 110 K and are superconducting at 104 K. The temperature dependence of the critical current indicates that in the Bi-Ca-Sr-Cu-O system weak links of superconductor-isolator-superconductor type are present, while in the Bi(Pb)-Ca-Sr-Cu-O samples the contact is formed by normal-metal barriers. Using magnetic fields up to 5 T, the anisotropy of the resistive transition of the high- Tc phase was studied. In Bi(Pb)-Ca-Sr-Cu-O films the anisotropy ratio is about 18, and the corresponding coherence lengths are ξ ab(0)⋍3.6 nm and ξ c(0)⋍0.2 nm. These values are nearly the same as in the low- Tc phase.

Positron annihilation study of Y 1- xPr xBa 2Cu 3O 7

NASA Astrophysics Data System (ADS)

Zhao, Y. G.; Cao, B. S.; Yu, W. Z.; Du, Z. H.; Wang, Y. J.; Luo, C. Y.; Hu, H.; Wang, S.; Yang, J. H.; He, A. S.; Gu, B. L.

1995-02-01

A positron annihilation study of Y 1- xPr xBa 2Cu 3O 7 was performed. The results showed that charge transfer between the CuO 2 planes and 1D CuO chains upon Pr doping, as proposed in the literature, did not occur. Pr doping suppressed the anomaly of positron annihilation lifetime near and below Tc which has been observed in YBa 2Cu 3O 7. The perfection of the 1D CuO chains was reduced by Pr doping and this may be partly responsible for the increase of resistivity with Pr doping, and finally the semiconducting behaviour of DC resistivity in Y 1- xPr xBa 2Cu 3O 7 with x > 0.6.

Growth, improved thermal stability and spectral properties of Yb3+-ions doped high temperature phase α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions

NASA Astrophysics Data System (ADS)

Pan, Shangke; Zhang, Jianyu; Pan, Jianguo

2018-02-01

To investigate the cause of the thermal instability of Yb3+-ions doped Ba3Gd(BO3)3 crystal grown from Czochralski technique, the low temperature phase β-Ba3Gd(BO3)3 powder was synthesized at the temperature of 800 °C. To inhibit the phase transition of high temperature phase Yb:α-Ba3Gd(BO3)3 during the crystal growth process, co-doping ions Sr2+, Ca2+ and La3+ ions were introduced in Yb:α-Ba3Gd(BO3)3 crystal. The melting point increased and the thermal stability of Yb:α-Ba3Gd(BO3)3 crystal was improved by co-doping ions. The absorption peaks of co-doped crystals centered at 976 nm with FWHM of 11, 11 and 12 nm and the absorption cross sections were 3.40 × 10-21 cm2, 4.00 × 10-21 cm2 and 2.66 × 10-21 cm2, respectively. The emission cross sections at 1040 nm were 2.19 × 10-21 cm2, 2.53 × 10-21 cm2 and 1.93 × 10-21 cm2, respectively. The fluorescence times of co-doped by Sr2+, Ca2+ and La3+ ions were shorter than that of Yb:α-Ba3Gd(BO3)3 crystal. So Yb:α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions will be more suitable for LD-pumping laser.

Comparative study of flux pinning, creep and critical currents between YBaCuO crystals with and without Y2BaCuO5 inclusions

NASA Technical Reports Server (NTRS)

Murakami, Masato; Gotoh, Satoshi; Fujimoto, Hiroyuki; Koshizuka, Naoki; Tanaka, Shoji

1991-01-01

In the Y-Ba-Cu-O system, YBa2Cu3O(x) phase is produced by the following peritectic reaction: Y2BaCuO5 + liquid yields 2YBa2Cu3O(x). Through the control of processing conditions and starting compositions, it becomes possible to fabricate large crystals containing fine Y2BaCuO5(211) inclusions. Such crystals exhibit Jc values exceeding 10000 A/sq cm at 77 K and 1T. Recently, researchers developed a novel process which can control the volume fraction of 211 inclusions. Elimination of 211 inclusions is also possible. In this study, researchers prepared YBaCuO crystals with and without 211 inclusions using the novel process, and compared flux pinning, flux creep and critical currents. Magnetic field dependence of Jc for YBaCuO crystals with and with 211 inclusions is shown. It is clear that fine 211 inclusions can contribute to flux pinning. It was also found that flux creep rate could be reduced by increasing flux pinning force. Critical current density estimates based on the conventional flux pinning theory were in good agreement with experimental results.

Determining baseline element composition of lichens. II. Hypogymnia enteromorpha and Usnea spp. at Redwood National Park, California

USGS Publications Warehouse

Gough, L.P.; Jackson, L.L.; Sacklin, J.A.

1988-01-01

Hypogymnia enteromorpha and Usnea spp. were collected in the Little Bald Hills ultramafic region of Redwood National Park, California, to establish element-concentration norms. Baselines are presented for Ba, Ca, Cu, Mn, Ni, P, Sr, V, and Zn for both lichen species; for Li, Mg, and K for H. enteromorpha; and for Al, Ce, Cr, Co, Fe, Na, and Ti for Usnea. Element concentrations of future collections of this same material can be used to monitor possible air quality changes anticipated from mining activities planned nearby. The variability in the element concentrations was partitioned between geographical distance increments and sample preparation and analysis procedures. In general, most of this variability was found in samples less than a few hundreds of meters apart rather than those at about 1 km apart. Therefore, except for Ba and Co, no large geographical element-concentration trends were observed. Samples of both species contained elevated levels of Ni and Mg, which probably reflect the ultramafic terrain over which they occur.

Practical and quality-control aspects of multi-element analysis with quadrupole ICP-MS with special attention to urine and whole blood.

PubMed

De Boer, Jan L M; Ritsema, Rob; Piso, Sjoerd; Van Staden, Hans; Van Den Beld, Wilbert

2004-07-01

Two screening methods were developed for rapid analysis of a great number of urine and blood samples within the framework of an exposure check of the population after a firework explosion. A total of 56 elements was measured including major elements. Sample preparation consisted of simple dilution. Extensive quality controls were applied including element addition and the use of certified reference materials. Relevant results at levels similar to those found in the literature were obtained for Co, Ni, Cu, Zn, Sr, Cd, Sn, Sb, Ba, Tl, and Pb in urine and for the same elements except Ni, Sn, Sb, and Ba in blood. However, quadrupole ICP-MS has limitations, mainly related to spectral interferences, for the analysis of urine and blood, and these cause higher detection limits. The general aspects discussed in the paper give it wider applicability than just for analysis of blood and urine-it can for example be used in environmental analysis.

Luminescence Properties of Self-Activated Mm(VO4)2 (M = Mg, Ca, Sr, and Ba) Phosphors Synthesized by Solid-State Reaction Method.

PubMed

Min, Xin; Huang, Zhaohui; Fang, Minghao; Liu, Yan'gai; Tang, Chao; Wu, Xiaowen

2016-04-01

In this paper, M3(VO4)2 (M = Mg, Ca, Sr, and Ba) self-activated phosphors were prepared by a solid-state reaction method at 1,000 °C for 5 h. The phase formation and micrographs were analyzed by X-ray diffraction and scanning electron microscopy. The Ca3(VO4)2 phosphor does not show any emission peaks under excitation with ultraviolet (UV) light. However, the M3(VO4)2 (M = Mg, Sr, and Ba) samples are effectively excited by UV light chips ranging from 200 nm to 400 nm and exhibit broad emission bands due to the charge transfer from the oxygen 2p orbital to the vacant 3d orbital of the vanadium in the VO4. The color of these phosphors changes from yellow to light blue via blue-green with increasing ionic radius from Mg to Sr to Ba. The luminescence lifetimes and quantum yield decrease with the increasing unit cell volume and V-V distance, in the order of Mg3(VO4)2 to Sr3(VO4)2 to Ba3(VO4)2. The emission intensity decreases with the increase of temperatures, but presents no color shift. This confirms that these self-activated M3(VO4)2 phosphors can be suggested as candidates of the single-phase phosphors for light using UV light emitting diodes (LEDs).

Optical plasma monitoring of Y-Ba-Cu-O rf sputter target transients

NASA Astrophysics Data System (ADS)

Klein, J. D.; Yen, A.

1989-12-01

The plasma emission spectra resulting from rf sputtering Y-Ba-Cu-O targets were observed as a function of sputter time. Although most lines of the observed spectra are not attributable to target species, peaks associated with each of the cation elements were resolved. The Ba and Cu peaks can be used as tracking indicators of process conditions. For example, switching from an O2/Ar sputter atmosphere to pure Ar enhanced the Ba peak much more than that associated with Cu. The emission spectra from a newly fabricated target exhibited a slow first-order transient response in seeking equilibrium with the rf plasma. The transient response of a previously sputtered target is also first order but has a much shorter time constant.

Characteristics of energy harvesting using BaTiO3/Cu laminates with changes in temperature

NASA Astrophysics Data System (ADS)

Mori, K.; Takeuchi, H.; Narita, F.

2018-03-01

The energy harvesting characteristics of piezoelectric/copper (BaTiO3/Cu) laminates rising from sharp temperature changes were investigated both numerically and experimentally. First, a phase field simulation was performed to determine the temperature-dependent piezoelectric coefficient and permittivity values. Then, the output voltages of the BaTiO3/Cu laminates were calculated for variations from room temperature to either a cryogenic temperature (77 K) or a higher temperature (333 K) using a 3D finite element simulation with the properties calculated from the phase field simulation. Finally, the output voltages of the piezoelectric BaTiO3/Cu laminates were measured for the same temperature changes and were compared to the simulation results.

Magneto-optical properties of BaTiO3/La0.76Sr0.24MnO3/BaTiO3 heterostructures

NASA Astrophysics Data System (ADS)

Moog, M.; Singamaneni, S. R.; Prater, J. T.; Biegalski, M. D.; Tsui, F.

2018-05-01

The magnetic properties of epitaxial BaTiO3/La0.76Sr0.24MnO3/BaTiO3 (BTO/LSMO/BTO) heterostructures have been studied using magneto-optic Kerr effect (MOKE) technique. Both longitudinal and polar MOKE were probed as a function of magnetic field and temperature (in the range between 80 and 320 K) for epitaxial films of BTO/LSMO/BTO and LSMO grown on TiO2-terminated SrTiO3 (001) substrates by pulsed laser deposition technique. The LSMO film without the BTO layers exhibits nearly square field-dependent MOKE hysteresis loops with low saturation fields below a bulk-like Curie temperature (TC) of ˜ 350K. In contrast, the film with the BTO layers exhibits a significantly suppressed TC of 155 K, accompanied by significantly enhanced coercive fields and perpendicular magnetic anisotropy.

A new Cu–cysteamine complex: structure and optical properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Lun; Chen, Wei; Schatte, Gabriele

2014-06-07

Here we report the structure and optical properties of a new Cu–cysteamine complex (Cu–Cy) with a formula of Cu3Cl(SR)2 (R ¼ CH2CH2NH2). This Cu–Cy has a different structure from a previous Cu–Cy complex, in which both thio and amine groups from cysteamine bond with copper ions. Single-crystal X-ray diffraction and solid-state nuclear magnetic resonance results show that the oxidation state of copper in Cu3Cl(SR)2 is +1 rather than +2. Further, Cu3Cl(SR)2 has been observed to show intense photoluminescence and X-ray excited luminescence. More interesting is that Cu3Cl(SR)2 particles can produce singlet oxygen under irradiation by light or X-ray. This indicatesmore » that Cu3Cl(SR)2 is a new photosensitizer that can be used for deep cancer treatment as X-ray can penetrate soft tissues. All these findings mean that Cu3Cl(SR)2 is a new material with potential applications for lighting, radiation detection and cancer treatment.« less

Electronic structure and bonding interactions in Ba1- x Sr x Zr0.1Ti0.9O3 ceramics

NASA Astrophysics Data System (ADS)

Mangaiyarkkarasi, Jegannathan; Sasikumar, Subramanian; Saravanan, Olai Vasu; Saravanan, Ramachandran

2017-06-01

An investigation on the precise electronic structure and bonding interactions has been carried out on Ba1- x Sr x Zr0.1Ti0.9O3 (short for BSZT, x = 0, 0.05, 0.07 and 0.14) ceramic systems prepared via high-temperature solid state reaction technique. The influence of Sr doping on the BSZT structure has been examined by characterizing the prepared samples using PXRD, UV-visible spectrophotometry, SEM and EDS. Powder profile refinement of X-ray data confirms that all the synthesized samples have been crystallized in cubic perovskite structure with single phase. Charge density distribution of the BSZT systems has been completely analyzed by the maximum entropy method (MEM). Co-substitution of Sr at the Ba site and Zr at the Ti site into the BaTiO3 structure presents the ionic nature between Ba and O ions and the covalent nature between Ti and O ions, revealed from MEM calculations. Optical band gap values have been evaluated from UV-visible absorption spectra. Particles with irregular shapes and well defined grain boundaries are clearly visualized from SEM images. The phase purity of the prepared samples is further confirmed by EDS qualitative spectral analysis.

Electrical characterization of Mn doped-(Ba{sub 0.3}Sr{sub 0.7})Mn{sub x}(Ti{sub 0.9}Zr{sub 0.1}){sub 1-x}O{sub 3} ceramics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahmood, A.; Materials Research Laboratory, Institute of Physics & Electronics, University of Peshawar, 25120; Department of Engineering Materials, University of Sheffield, Sheffield S1 3JD

2015-12-15

Highlights: • Solid state processing of the (Ba{sub 0.3}Sr{sub 0.7})Mn{sub x}(Ti{sub 0.9}Zr{sub 0.1}){sub 1−x}O{sub 3} ceramics. • Mn incorporated on the Ti-site into the host lattice of (Ba{sub 0.3}Sr{sub 0.7})Mn{sub x}(Ti{sub 0.9}Zr{sub 0.1}){sub 1−x}O{sub 3}. • NTCR behavior was observed in the sintered samples. - Abstract: (Ba{sub 0.3}Sr{sub 0.7})Mn{sub x}(Ti{sub 0.9}Zr{sub 0.1}){sub 1-x}O{sub 3} (x = 0.00, 0.013, 0.015 and 0.05) ceramics were prepared by solid state sintering route at the 1500 °C for 6 h in air. Effect of Mn substitution on the structure of Ba{sub 0.3}Sr{sub 0.7}(Ti0{sub .9}Zr{sub 0.1}){sub 1−x}O{sub 3} perovskite was investigated systematically. Dielectric and impedancemore » spectroscopic studies were conducted to understand the electronic microstructure of the Ba{sub 0.3}Sr{sub 0.7}(Ti0{sub .9}Zr{sub 0.1}){sub 1−x}O{sub 3} ceramics. Sample with x = 0.05 showed the highest dielectric constant (ϵ{sub r} = 1826) and low dielectric loss (tanδ = 0.001) at 10 kHz, around the room temperature, while the sample with x = 0.00 showed good microwave (MW) dielectric properties (Qf{sub o} = 838 and ϵ{sub r} = 550). The impedance spectroscopic analysis confirmed the electrical homogeneity of the samples with x = 0.013, 0.015 and 0.05, where grain boundaries dominated the conduction mechanism. Similarly, the sample with x = 0.00 was found to possess both grain boundary and bulk resistive contributions.« less

Pre-Steady-State Kinetics of Ba-Ca Exchange Reveals a Second Electrogenic Step Involved in Ca2+ Translocation by the Na-Ca Exchanger

PubMed Central

Haase, Andreas; Hartung, Klaus

2009-01-01

Kinetic properties of the Na-Ca exchanger (guinea pig NCX1) expressed in Xenopus oocytes were investigated with excised membrane patches in the inside-out configuration and photolytic Ca2+ concentration jumps with either 5 mM extracellular Sr2+ or Ba2+. After a Ca2+ concentration jump on the cytoplasmic side, the exchanger performed Sr-Ca or Ba-Ca exchange. In the Sr-Ca mode, currents are transient and decay in a monoexponential manner similar to that of currents in the Ca-Ca exchange mode described before. Currents recorded in the Ba-Ca mode are also transient, but the decay is biphasic. In the Sr-Ca mode the amount of charge translocated increases at negative potentials in agreement with experiments performed in the Ca-Ca mode. In the Ba-Ca mode the total amount of charge translocated after a Ca2+ concentration jump is ∼4 to 5 times that in Ca-Ca or Sr-Ca mode. In the Ba-Ca mode the voltage dependence of charge translocation depends on the Ca2+ concentration on the cytosolic side before the Ca2+ concentration jump. At low initial Ca2+ levels (∼0.5 μM), charge translocation is voltage independent. At a higher initial concentration (1 μM Ca2+), the amount of charge translocated increases at positive potentials. Biphasic relaxation of the current was also observed in the Ca-Ca mode if the external Ca2+ concentration was reduced to ≤0.5 mM. The results reported here and in previous publications can be described by using a 6-state model with two voltage-dependent conformational transitions. PMID:19486679

Bioturbating animals control the mobility of redox-sensitive trace elements in organic-rich mudstone

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harazim, Dario; McIlroy, Duncan; Edwards, Nicholas P.

Bioturbating animals modify the original mineralogy, porosity, organic content, and fabric of mud, thus affecting the burial diagenetic pathways of potential hydrocarbon source, seal, and reservoir rocks. High-sensitivity, synchrotron rapid scanning X-ray fluorescence elemental mapping reveals that producers of phycosiphoniform burrows systematically partition redox-sensitive trace elements (i.e., Fe, V, Cr, Mn, Co, Ni, Cu, and As) in fine-grained siliciclastic rocks. Systematic differences in organic carbon content (total organic carbon >1.5 wt%) and quality (Δ 13C org~0.6‰) are measured between the burrow core and host sediment. The relative enrichment of redox-sensitive elements in the burrow core does not correlate with significantmore » neo-formation of early diagenetic pyrite (via trace metal pyritization), but is best explained by physical concentration of clay- and silt-sized components. A measured loss (~–15%) of the large-ionic-radius elements Sr and Ba from both burrow halo and core is most likely associated with the release of Sr and Ba to pore waters during biological ( in vivo) weathering of silt- to clay-sized lithic components and feldspar. In conclusion, this newly documented effect has significant potential to inform the interpretation of geochemical proxy and rock property data, particularly from shales, where elemental analyses are commonly employed to predict reservoir quality and support paleoenvironmental analysis.« less

Bioturbating animals control the mobility of redox-sensitive trace elements in organic-rich mudstone

DOE PAGES

Harazim, Dario; McIlroy, Duncan; Edwards, Nicholas P.; ...

2015-10-07

Bioturbating animals modify the original mineralogy, porosity, organic content, and fabric of mud, thus affecting the burial diagenetic pathways of potential hydrocarbon source, seal, and reservoir rocks. High-sensitivity, synchrotron rapid scanning X-ray fluorescence elemental mapping reveals that producers of phycosiphoniform burrows systematically partition redox-sensitive trace elements (i.e., Fe, V, Cr, Mn, Co, Ni, Cu, and As) in fine-grained siliciclastic rocks. Systematic differences in organic carbon content (total organic carbon >1.5 wt%) and quality (Δ 13C org~0.6‰) are measured between the burrow core and host sediment. The relative enrichment of redox-sensitive elements in the burrow core does not correlate with significantmore » neo-formation of early diagenetic pyrite (via trace metal pyritization), but is best explained by physical concentration of clay- and silt-sized components. A measured loss (~–15%) of the large-ionic-radius elements Sr and Ba from both burrow halo and core is most likely associated with the release of Sr and Ba to pore waters during biological ( in vivo) weathering of silt- to clay-sized lithic components and feldspar. In conclusion, this newly documented effect has significant potential to inform the interpretation of geochemical proxy and rock property data, particularly from shales, where elemental analyses are commonly employed to predict reservoir quality and support paleoenvironmental analysis.« less

Structure evolution upon chemical and physical pressure in (Sr{sub 1−x}Ba{sub x}){sub 2}FeSbO{sub 6}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tiittanen, T.; Karppinen, M., E-mail: maarit.karppinen@aalto.fi

Here we demonstrate the gradual structural transformation from the monoclinic I2/m to tetragonal I4/m, cubic Fm-3m and hexagonal P6{sub 3}/mmc structure upon the isovalent larger-for-smaller A-site cation substitution in the B-site ordered double-perovskite system (Sr{sub 1−x}Ba{sub x}){sub 2}FeSbO{sub 6}. This is the same transformation sequence previously observed up to Fm-3m upon heating the parent Sr{sub 2}FeSbO{sub 6} phase to high temperatures. High-pressure treatment, on the other hand, transforms the hexagonal P6{sub 3}/mmc structure of the other end member Ba{sub 2}FeSbO{sub 6} back to the cubic Fm-3m structure. Hence we may conclude that chemical pressure, physical pressure and decreasing temperature allmore » work towards the same direction in the (Sr{sub 1−x}Ba{sub x}){sub 2}FeSbO{sub 6} system. Also shown is that with increasing Ba-for-Sr substitution level, i.e. with decreasing chemical pressure effect, the degree-of-order among the B-site cations, Fe and Sb, decreases. - Graphical abstract: In the (Sr{sub 1−x}Ba{sub x}){sub 2}FeSbO{sub 6} double-perovskite system the gradual structural transformation from the monoclinic I2/m to tetragonal I4/m, cubic Fm-3m and hexagonal P6{sub 3}/mmc structure is seen upon the isovalent larger-for-smaller A-site cation substitution. High-pressure treatment under 4 GPa extends stability of the cubic Fm-3m structure within a wider substitution range of x. - Highlights: • Gradual structural transitions upon A-cation substitution in (Sr{sub 1−x}Ba{sub x}){sub 2}FeSbO{sub 6.} • With increasing x structure changes from I2/m to I4/m, Fm-3m and P6{sub 3}/mmc. • Degree of B-site order decreases with increasing x and A-site cation radius. • High-pressure treatment extends cubic Fm-3m phase stability for wider x range. • High-pressure treatment affects bond lengths mostly around the A-cation.« less

Studies of superconducting materials with muon spin rotation

NASA Technical Reports Server (NTRS)

Davis, Michael R.; Stronach, Carey E.; Kossler, W. J.; Schone, H. E.; Yu, X. H.; Uemura, Y. J.; Sternlieb, B. J.; Kempton, J. R.; Oostens, J.; Lankford, W. F.

1989-01-01

The muon spin rotation/relaxation technique was found to be an exceptionally effective means of measuring the magnetic properties of superconductors, including the new high temperature superconductor materials, at the microscopic level. The technique directly measures the magnetic penetration depth (type II superconductors (SC's)) and detects the presence of magnetic ordering (antiferromagnetism or spin-glass ordering were observed in some high temperature superconductor (HTSC's) and in many closely related compounds). Extensive studies of HTSC materials were conducted by the Virginia State University - College of William and Mary - Columbia University collaboration at Brookhaven National Laboratory and TRIUMF (Vancouver). A survey of LaSrCuO and YBaCaCuO systems shows an essentially linear relationship between the transition temperature T(sub c) and the relaxation rate. This appears to be a manifestation of the proportionality between T(sub c) and the Fermi energy, which suggests a high energy scale for the SC coupling, and which is not consistent with the weak coupling of phonon-mediated SC. Studies of LaCuO and YBaCuO parent compounds show clear evidence of antiferromagnetism. YBa2Cu(3-x)CO(x)O7 shows the simultaneous presence of spin-glass magnetic ordering and superconductivity. Three-dimensional SC, (Ba, K) BiO3, unlike the layered CuO-based compounds, shows no suggestion of magnetic ordering. Experimental techniques and theoretical implications are discussed.

Exposure of women to trace elements through the skin by direct contact with underwear clothing.

PubMed

Nguyen, Thao; Saleh, Mahmoud A

2017-01-02

Heavy metals pose a potential danger to human health when present in textile materials. In the present study, inductive coupled plasma mass spectrometry (ICPMS) was used to determine the concentrations and the identity of extractable inorganic elements from different brands of women undergarments. A total of 120 samples consisting of 63 cottons, 44 nylons and 13 polyesters manufactured in 14 different countries having different colors were analyzed for their extractable metals contents. Elements analyzed were Ag, Al, As, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Li, Mg, Mn, Na, Ni, Pb, Sb, Se, Sr, Ti, V and Zn. Cotton undergarments were rich in Al, Fe and Zn, nylon undergarments had high levels of Cr, Cu and Al, while polyester fabrics contained higher levels of Ni and Fe compared to cotton or nylon. With respect to manufacturing countries, China, Egypt and India showed the highest concentrations of metals in all fabrics. With respect to the color, black garments were characteristic by high concentration of Fe, blue colors with Cu, brown garments with Fe and Cu, green garments with Cu and Fe, pink garments with Al, purple garments with Al and Cu and red garments with Cr, Zn and Al. The consumer should be made aware of the potential dangers of these metals in their clothing.

Thermochemical process for recovering Cu from CuO or CuO.sub.2

DOEpatents

Richardson, deceased, Donald M.; Bamberger, Carlos E.

1981-01-01

A process for producing hydrogen comprises the step of reacting metallic Cu with Ba(OH).sub.2 in the presence of steam to produce hydrogen and BaCu.sub.2 O.sub.2. The BaCu.sub.2 O.sub.2 is reacted with H.sub.2 O to form Cu.sub.2 O and a Ba(OH).sub.2 product for recycle to the initial reaction step. Cu can be obtained from the Cu.sub.2 O product by several methods. In one embodiment the Cu.sub.2 O is reacted with HF solution to provide CuF.sub.2 and Cu. The CuF.sub.2 is reacted with H.sub.2 O to provide CuO and HF. CuO is decomposed to Cu.sub.2 O and O.sub.2. The HF, Cu and Cu.sub.2 O are recycled. In another embodiment the Cu.sub.2 O is reacted with aqueous H.sub.2 SO.sub.4 solution to provide CuSO.sub.4 solution and Cu. The CuSO.sub.4 is decomposed to CuO and SO.sub.3. The CuO is decomposed to form Cu.sub.2 O and O.sub.2. The SO.sub.3 is dissolved to form H.sub.2 SO.sub.4. H.sub.2 SO.sub.4, Cu and Cu.sub.2 O are recycled. In another embodiment Cu.sub.2 O is decomposed electrolytically to Cu and O.sub.2. In another aspect of the invention, Cu is recovered from CuO by the steps of decomposing CuO to Cu.sub.2 O and O.sub.2, reacting the Cu.sub.2 O with aqueous HF solution to produce Cu and CuF.sub.2, reacting the CuF.sub.2 with H.sub.2 O to form CuO and HF, and recycling the CuO and HF to previous reaction steps.

Second harmonic generation response of the cubic chalcogenides Ba( 6-x)Sr x[Ag( 4-y)Sn( y/4)](SnS 4) 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haynes, Alyssa S.; Liu, Te-Kun; Frazer, Laszlo

We synthesized the barium/strontium solid solution sequence Ba 6-xSr x[Ag( 4-y)Sn( y/4)](SnS 4) 4 for nonlinear optical (NLO) applications in the infrared (IR) via a flux synthesis route. All title compounds are isotypic, crystallizing in the cubic space group Imore » $$\\bar{_4}$$ 3d and are composed of a three-dimensional (3D) anionic framework of alternating corner-sharing SnS 4 and AgS 4 tetrahedra charge balanced by Ba and Sr. The shrinkage of Ba/Sr-S bond lengths causes the tetrahedra in the anionic framework to become more distorted, which results in a tunable band gap from 1.58 to 1.38 eV with increasing x values. The performance of the barium limit (x=0) is also superior to that of Sr (x=6), but surprisingly second harmonic generation (SHG) of the solid solution remains strong and is insensitive to the value of x over the range 0-3.8. Results show that the non-type-I phase-matched SHG produced by these cubic chalcogenides display intensities higher than the benchmark AgGaSe 2 from 600 to 1000 nm.« less

Effect of Sr doping on structural and magnetic behavior of SmBa1-xSrxCo2O5+δ (x = 0 and 1)

NASA Astrophysics Data System (ADS)

Kumari, Archana; Dhanasekhar, C.; Das, A. K.

2018-05-01

Layered double perovskite, SmBa1-xSrxCo2O5+δ (x = 0, δ = 0.5 and x = 1, δ = 1) samples were prepared by solid state reaction method. X-ray diffraction studies show that the SmBaCo2O5.5 sample crystallizes in the orthorhombic crystal structure with Pmmm space group, whereas SmSrCo2O6 sample crystallizes in the orthorhombic crystal structure with Pnma space group. The temperature dependent magnetization of the SmBaCo2O5.5 sample shows a paramagnetic (PM)-ferromagnetic (FM) and a FM-antiferromagnetic (AFM) transitions at TC = 267 K and TN = 221 K, respectively. In contrast, the SmSrCo2O6 sample shows a PM-FM transition at TC = 175 K. According to Goodenough-Kanamori-Anderson rules, the ferromagnetic behavior in SmSrCo2O6 can be understood from the super exchange interaction between the intermediate spin Co3+ and low spin Co4+ via O2- (IS Co3+ -O2- - LS Co4+). The change in magnetic entropy (ΔSMmax) is found to be maximum for the SmSrCo2O6 sample.

Increased Curie Temperature Induced by Orbital Ordering in La0.67Sr0.33MnO3/BaTiO3 Superlattices.

PubMed

Zhang, Fei; Wu, Biao; Zhou, Guowei; Quan, Zhi-Yong; Xu, Xiao-Hong

2018-01-17

Recent theoretical studies indicated that the Curie temperature of perovskite manganite thin films can be increased by more than an order of magnitude by applying appropriate interfacial strain to control orbital ordering. In this work, we demonstrate that the regular intercalation of BaTiO 3 layers between La 0.67 Sr 0.33 MnO 3 layers effectively enhances ferromagnetic order and increases the Curie temperature of La 0.67 Sr 0.33 MnO 3 /BaTiO 3 superlattices. The preferential orbital occupancy of e g (x 2 -y 2 ) in La 0.67 Sr 0.33 MnO 3 layers induced by the tensile strain of BaTiO 3 layers is identified by X-ray linear dichroism measurements. Our results reveal that controlling orbital ordering can effectively improve the Curie temperature of La 0.67 Sr 0.33 MnO 3 films and that in-plane orbital occupancy is beneficial to the double exchange ferromagnetic coupling of thin-film samples. These findings create new opportunities for the design and control of magnetism in artificial structures and pave the way to a variety of novel magnetoelectronic applications that operate far above room temperature.

Electronic structure of Pr{sub 1{minus}x}Y{sub x}Ba{sub 2}Cu{sub 3}O{sub y} (x=0, 0.5, and 1.0)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kakinuma, K.; Fueki, K.

1997-08-01

In order to elucidate the reason why PrBa{sub 2}Cu{sub 3}O{sub y}is not a superconductor, we examined the Pr valence and measured the oxygen nonstoichiometry and the conductivity at temperatures up to 1200 K for three kinds of oxides, PrBa{sub 2}Cu{sub 3}O{sub y}, (Pr{sub 0.5}Y{sub 0.5})Ba{sub 2}Cu{sub 3}O{sub y}, and YBa{sub 2}Cu{sub 3}O{sub y}. The valence of Pr was found to be +3. Any difference was not found in oxygen nonstoichiometry and conductivity among three kinds of oxides. We analyzed the data of oxygen nonstoichiometry on the basis of defect thermodynamics and calculated the numbers of Cu{sup +}, Cu{sup 2+}, andmore » Cu{sup 3+} ions in the unit cell as a function of y. The number of Cu{sup 3+} ions (the amount of holes) was found to be proportional to ({Delta}y){sup 1.6}({Delta}y=y{minus}6.0), whereas the conductivity was found to be proportional to ({Delta}y){sup 3.2} in these oxides. We interpreted the remarkable increase of {sigma} with {Delta}y as an evidence of the increase of both mobility and hole concentration with {Delta}y. At high temperatures, we detected the conductivity minimum {sigma}{sub min} which was found in the log{sub 10}{sigma}{minus}log{sub 10}P{sub O{sub 2}} plot at constant temperatures. From the slope of the Arrhenius plot for {sigma}{sub min}, the band gap was determined to be 1.21, 1.32, and 1.37 eV for PrBa{sub 2}Cu{sub 3}O{sub y}, (Pr{sub 0.5}Y{sub 0.5})Ba{sub 2}Cu{sub 3}O{sub y} and YBa{sub 2}Cu{sub 3}O{sub y}, respectively. We determined the conductivity of the same oxygen content as a function of temperature from 4.2 to 1200 K. The energy gap {Delta}E between the acceptor level and the top of the valence band was calculated from the slope of the Arrhenius plot for conductivity. {Delta}E for superconducting YBa{sub 2}Cu{sub 3}O{sub y} and (Pr{sub 0.5}Y{sub 0.5})Ba{sub 2}Cu{sub 3}O{sub y} were zero at 300 K but that for nonsuperconducting PrBa{sub 2}Cu{sub 3}O{sub y} was 20 meV at 100 K even for y=6.93. (Abstract Truncated)« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sangeetha, N. S.; Smetana, V.; Mudring, A. -V.

Here, crystals of SrMn 2Sb 2 and BaMn 2Sb 2 were grown using Sn flux and characterized by powder and single-crystal x-ray diffraction, respectively, and by single-crystal electrical resistivity ρ, heat capacity C p, and magnetic susceptibility χ measurements versus temperature T, and magnetization versus field M(H) isotherm measurements. SrMn 2Sb 2 adopts the trigonal CaAl 2Si 2-type structure, whereas BaMn 2Sb 2 crystallizes in the tetragonal ThCr 2Si 2-type structure. The ρ(T) data indicate semiconducting behaviors for both compounds with activation energies of ≳0.35 eV for SrMn 2Sb 2 and 0.16 eV for BaMn 2Sb 2. The χ(T) andmore » C p(T) data reveal antiferromagnetic (AFM) ordering at T N = 110 K for SrMn 2Sb 2 and 450 K for BaMn 2Sb 2. The anisotropic χ(T≤T N) data also show that the ordered moments in SrMn 2Sb 2 are aligned in the hexagonal ab plane, whereas the ordered moments in BaMn 2Sb 2 are aligned collinearly along the tetragonal c axis. The ab-plane M(H) data for SrMn 2Sb 2 exhibit a continuous metamagnetic transition at low fields 02Sb 2 exhibits no metamagnetic transitions up to 5.5 T. The χ(T) and C p(T) data for both SrMn 2Sb 2 and BaMn 2Sb 2 indicate strong dynamic short-range AFM correlations above their respective T N up to at least 900 K within a local-moment picture, corresponding to quasi-two-dimensional magnetic behavior. The present results and a survey of the literature for Mn pnictides with the CaAl 2Si 2 and ThCr 2Si 2 crystal structures show that the T N values for the CaAl 2Si 2-type compounds are much smaller than those for the ThCr 2Si 2-type materials.« less

Versatile fluoride substrates for Fe-based superconducting thin films

NASA Astrophysics Data System (ADS)

Kurth, F.; Reich, E.; Hänisch, J.; Ichinose, A.; Tsukada, I.; Hühne, R.; Trommler, S.; Engelmann, J.; Schultz, L.; Holzapfel, B.; Iida, K.

2013-04-01

We demonstrate the growth of Co-doped BaFe2As2 (Ba-122) thin films on CaF2 (001), SrF2 (001), and BaF2 (001) single crystal substrates using pulsed laser deposition. All films are grown epitaxially despite of a large misfit of -10.6% for BaF2 substrate. For all films, a reaction layer is formed at the interface confirmed by X-ray diffraction and for the films grown on CaF2 and BaF2 additionally by transmission electron microscopy. The superconducting transition temperature of the film on CaF2 is around 27 K, whereas the corresponding values of the films on SrF2 and BaF2 are around 22 K and 21 K, respectively. The Ba-122 on CaF2 shows almost identical crystalline quality and superconducting properties as films on Fe-buffered MgO.

Catalytic removal of phenol from gas streams by perovskite-type catalysts.

PubMed

Chen, Dai Ling; Pan, Kuan Lun; Chang, Moo Been

2017-06-01

Three perovskite-type catalysts prepared by citric acid method are applied to remove phenol from gas streams with the total flow rate of 300mL/min, corresponding to a GHSV of 10,000/hr. LaMnO 3 catalyst is first prepared and further partially substituted with Sr and Cu to prepare La 0.8 Sr 0.2 MnO 3 and La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 , and catalytic activities and fundamental characteristics of these three catalysts are compared. The results show that phenol removal efficiency achieved with La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 reaches 100% with the operating temperature of 200°C and the rate of mineralization at 300°C is up to 100%, while the phenol removal efficiencies achieved with La 0.8 Sr 0.2 MnO 3 and LaMnO 3 are up to 100% with the operating temperature of 300°C and 400°C, respectively. X-ray photoelectron spectroscopy (XPS) analysis shows that the addition of Sr and Cu increases the lattice oxygen of La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 , and further increases mobility or availability of lattice oxygen. The results indicate that La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 has the best activity for phenol removal among three catalysts prepared and the catalytic activity of phenol oxidation is enhanced by the introduction of Sr and Cu into LaMnO 3 . Apparent activation energy of 48kJ/mol is calculated by Mars-Van Krevelen Model for phenol oxidation with La 0.8 Sr 0.2 Mn 0.8 Cu 0.2 O 3 as catalyst. Copyright © 2016. Published by Elsevier B.V.

Synchrotron X-ray studies of epitaxial ferroelectric thin films and nanostructures

NASA Astrophysics Data System (ADS)

Klug, Jeffrey A.

The study of ferroelectric thin films is a field of considerable scientific and technological interest. In this dissertation synchrotron x-ray techniques were applied to examine the effects of lateral confinement and epitaxial strain in ferroelectric thin films and nanostructures. Three materials systems were investigated: laterally confined epitaxial BiFeO3 nanostructures on SrTiO3 (001), ultra-thin commensurate SrTiO 3 films on Si (001), and coherently strained films of BaTiO3 on DyScO3 (110). Epitaxial films of BiFeO3 were deposited by radio frequency magnetron sputtering on SrRuO3 coated SrTiO 3 (001) substrates. Laterally confined nanostructures were fabricated using focused ion-beam processing and subsequently characterized with focused beam x-ray nanodiffraction measurements with unprecedented spatial resolution. Results from a series of rectangular nanostructures with lateral dimensions between 500 nm and 1 mum and a comparably-sized region of the unpatterned BiFeO3 film revealed qualitatively similar distributions of local strain and lattice rotation with a 2-3 times larger magnitude of variation observed in those of the nanostructures compared to the unpatterned film. This indicates that lateral confinement leads to enhanced variation in the local strain and lattice rotation fields in epitaxial BiFeO3 nanostructures. A commensurate 2 nm thick film of SrTiO3 on Si was characterized by the x-ray standing wave (XSW) technique to determine the Sr and Ti cation positions in the strained unit cell in order to verify strain-induced ferroelectricity in SrTiO3/Si. A Si (004) XSW measurement at 10°C indicated that the average Ti displacement from the midpoint between Sr planes was consistent in magnitude to that predicted by a density functional theory (DFT) calculated ferroelectric structure. The Ti displacement determined from a 35°C measurement better matched a DFT-predicted nonpolar structure. The thin film extension of the XSW technique was employed to measure the polar displacement of the Ba cations in a 50 nm thick coherently strained BaTiO3 film on DyScO3 (110). An analysis assuming a bulk-like ratio between the Ti and Ba displacements found that the polar shift of Ba cations was larger than in bulk BaTiO3, which was consistent with strain-induced enhancement of ferroelectric polarization in BaTiO3/DyScO3 (110).

Hydrogen production from water using copper and barium hydroxide

DOEpatents

Bamberger, Carlos E.; Richardson, deceased, Donald M.

1979-01-01

A process for producing hydrogen comprises the step of reacting metallic Cu with Ba(OH).sub.2 in the presence of steam to produce hydrogen and BaCu.sub.2 O.sub.2. The BaCu.sub.2 O.sub.2 is reacted with H.sub.2 O to form Cu.sub.2 O and a Ba(OH).sub.2 product for recycle to the initial reaction step. Cu can be obtained from the Cu.sub.2 O product by several methods. In one embodiment the Cu.sub.2 O is reacted with HF solution to provide CuF.sub.2 and Cu. The CuF.sub.2 is reacted with H.sub.2 O to provide CuO and HF. CuO is decomposed to Cu.sub.2 O and O.sub.2. The HF, Cu and Cu.sub.2 O are recycled. In another embodiment the Cu.sub.2 O is reacted with aqueous H.sub.2 SO.sub.4 solution to provide CuSO.sub.4 solution and Cu. The CuSO.sub.4 is decomposed to CuO and SO.sub.3. The CuO is decomposed to form Cu.sub.2 O and O.sub.2. The SO.sub.3 is dissolved to form H.sub.2 SO.sub.4. H.sub.2 SO.sub.4, Cu and Cu.sub.2 O are recycled. In another embodiment Cu.sub.2 O is decomposed electrolytically to Cu and O.sub.2. In another aspect of the invention, Cu is recovered from CuO by the steps of decomposing CuO to Cu.sub.2 O and O.sub.2, reacting the Cu.sub.2 O with aqueous HF solution to produce Cu and CuF.sub.2, reacting the CuF.sub.2 with H.sub.2 O to form CuO and HF, and recycling the CuO and HF to previous reaction steps.

Geochemical landscapes of the conterminous United States; new map presentations for 22 elements

USGS Publications Warehouse

Gustavsson, N.; Bolviken, B.; Smith, D.B.; Severson, R.C.

2001-01-01

Geochemical maps of the conterminous United States have been prepared for seven major elements (Al, Ca, Fe, K, Mg, Na, and Ti) and 15 trace elements (As, Ba, Cr, Cu, Hg, Li, Mn, Ni, Pb, Se, Sr, V, Y, Zn, and Zr). The maps are based on an ultra low-density geochemical survey consisting of 1,323 samples of soils and other surficial materials collected from approximately 1960-1975. The data were published by Boerngen and Shacklette (1981) and black-and-white point-symbol geochemical maps were published by Shacklette and Boerngen (1984). The data have been reprocessed using weighted-median and Bootstrap procedures for interpolation and smoothing.

Analysis of eight argonne premium coal samples by X-ray fluorescence spectrometry

USGS Publications Warehouse

Evans, J.R.; Sellers, G.A.; Johnson, R.G.; Vivit, D.V.; Kent, J.

1990-01-01

X-ray fluorescence spectrometric methods were used in the analysis of eight Argonne Premium Coal Samples. Trace elements (Cr, Ni, Cu, Zn, Rb, Sr, Y, Zr, Nb, Ba, La, and Ce) in coal ash were determined by energy-dispersive X-ray fluorescence spectrometry; major elements (Na, Mg, Al, Si, P, S, K, Ca, Ti, Mn, and Fe) in coal ash and trace elements (Cl and P) in whole coal were determined by wavelength-dispersive X-ray fluorescence spectrometry. The results of this study will be used in a geochemical database compiled for these materials from various analytical techniques. The experimental XRF methods and procedures used to determine these major and trace elements are described.

Transmittance of optical materials from 0.17 micro to 3.0 micro.

PubMed

McCarthy, D E

1967-11-01

The transmittance of thirty-one optical materials is given from 0.17, micro to 3.0 micro. Included are NaCl, KBr, CsBr, CsI, CaF(2), BaF(2), NaF, TlBr, TICL, KRS-5, KRS-6, T-12, KC, CuC, T O(2), ADP, KDP, SrTiO(3), GaP, CaCO(3), CdSe, As(2)S(3), ruby, Al(2)O(3), Irtran 1-6, and quartz. All are synthetic with the exception of CaCO(3). In many cases, the short wavelength cutoff of the synthetic materials is less than that which has been reported for naturally occurring materials.

[Determination of twenty one elements in lithium hexafluorophosphate by ICP-AES].

PubMed

Fang, Yi-wen; Hao, Zhi-feng; Song, Yi-bing; Sun, Chang-yong; Yu, Jian; Yu, Lin

2005-02-01

One gram (+/- 0.0001 g) of lithium hexafluorophosphate was weighed exactly under dry atmosphere and was dissolved with an adequate amount of dimethyl carbonate (DMC). After the sample solution was pretreated with a series of methods, Be, Cu, Pb, Ca, Zr, Co, Mg, V, Ti, Mo, Ni, Mn, Sr, Zn, K, Al, Ba, Cd, Fe, Cr and Na were determined by ICP-AES. The results show that the recoveries of standard addition were 93.3%-102.1%, and the relative standard deviations (n = 11) were 0%-3.56%. The method is efficient, accurate and easy to operate. It has been applied to the determination of lithium hexafluorophosphate products with satisfactory results.

Biogeochemical study of termite mounds: a case study from Tummalapalle area of Andhra Pradesh, India.

PubMed

Arveti, Nagaraju; Reginald, S; Kumar, K Sunil; Harinath, V; Sreedhar, Y

2012-04-01

Termite mounds are abundant components of Tummalapalle area of uranium mineralization of Cuddapah District of Andhra Pradesh, India. The systematic research has been carried out on the application of termite mound sampling to mineral exploration in this region. The distribution of chemical elements Cu, Pb, Zn, Ni, Co, Cr, Li, Rb, Sr, Ba, and U were studied both in termite soils and adjacent surface soils. Uranium accumulations were noticed in seven termite mounds ranging from 10 to 36 ppm. A biogeochemical parameter called "Biological Absorption Coefficient" of the termite mounds indicated the termite affected soils contained huge amounts of chemical elements than the adjacent soils.

Metal (Ca, Ba, Sr, Pb) heptafluorotantalates(V): Synthesis, Raman spectra and crystal structures

NASA Astrophysics Data System (ADS)

Bunič, Tina; Tramšek, Melita; Goreshnik, Evgeny; Žemva, Boris

2007-01-01

MTaF 7 (M = Ca, Sr, Ba, Pb) were prepared by the reaction of MF 2 + Ta + F 2 (Ca, Sr, Ba) or MF 2 + TaF 5 in anhydrous HF. CaTaF 7 crystallizes in a monoclinic P2 1/ a space group, a = 9.793(3) Å, b = 11.608(3) Å, c = 13.359(4) Å, β = 90.539(13)°, V = 1518.5(7) Å 3. All Ta atoms possess distorted pentagonal-bipyramidal environment with Ta-F distances of 1.878(14)-2.044(13) Å. Three crystallographically independent Ca atoms have coordination number 8. Ca-F distances lie in the range of 2.239(16)-2.836(17) Å. Each Ca 2+ and TaF 72- moiety is bonded to 6 counter-ions. BaTaF 7 crystallizes in a cubic system, space group Pa3¯,a = 9.9009(3)Å, V = 970.56(5) Å 3. Coordination sphere around Ta atom is mono-capped trigonal prism with a Ta-F distance of 1.916(5)-2.004(5) Å. Two crystallographically independent barium atoms have different coordination numbers: for Ba1 C.N. is 12 with Ba1-F distances of 6 × 2.761(5) Å and 6 × 2.858(5) Å, for Ba2 C.N. is 14 with Ba2-F bond lengths 6 × 2.718(5), 2 × 2.814(8) and 6 × 3.236(5) Å. Ba 2+ and TaF 72- moieties are bonded to 8 neighbors. Isostructural PbTaF 7 and SrTaF 7 appear to be monoclinic, space group P2 1/ m, a = 4.8657(11) Å, b = 7.2298(16) Å, c = 6.7370(16) Å, β = 93.932(13)°, V = 236.44(9) Å 3 for PbTaF 7, and a = 4.875(3) Å, b = 7.196(4) Å, c = 6.7218(13) Å, β = 94.265(10), V = 235.2(2) Å for SrTaF 7. Tantalum coordination polyhedron may be described as a distorted mono-capped trigonal prism with the capping atom located on one of the rectangular faces with Ta-F distances of 1.868(3)-1.982(3) Å (PbTaF 7) and 1.908(16)-2.019(12) Å (SrTaF 7). Lead (or strontium) atoms are 9-coordinated and may be viewed as strongly distorted tri-capped trigonal prism, Pb-F 2.438(4)-2.669(3) Å, Sr-F 2.501(19)-2.860(19) Å. Each cation is connected to 8 anions.

A-site deficient La0.2Sr0.7TiO3-δ anode material for proton conducting ethane fuel cell to cogenerate ethylene and electricity

NASA Astrophysics Data System (ADS)

Liu, Subiao; Behnamian, Yashar; Chuang, Karl T.; Liu, Qingxia; Luo, Jing-Li

2015-12-01

A site deficient La0.2Sr0.7TiO3-δ (LSTA) and a highly proton conductive electrolyte BaCe0.7Zr0.1Y0.2O3-δ (BCZY) are synthesized by using solid state reaction method. The performance of the electrolyte-supported single cell, comprised of LSTA + Cr2O3 + Cu//BCZY//(La0.60Sr0.40)0.95Co0.20Fe0.80O3-δ (LSCF)+BCZY, is fabricated and investigated. LSTA shows remarkably high electrical performance, with a conductivity as high as 27.78 Scm-1 at 1150 °C in a 10% H2/N2 reducing atmosphere. As a main anode component, it shows good catalytic activity towards the oxidation of ethane, causing the power density to considerably increase from 158.4 mW cm-2 to 320.9 mW cm-2 and the ethane conversion to significantly rise from 12.6% to 30.9%, when the temperature increases from 650 °C to 750 °C. These changes agree well with the polarization resistance which dramatically decreases from 0.346 Ωcm2 to 0.112 Ωcm2. EDX measurement shows that no element diffusion exists (chemical compatibility) between anode (LSTA + Cr2O3+Cu) and electrolyte (BCZY). With these properties, the pure phase LSTA is evaluated as a high electro-catalytic activity anode material for ethane proton conducting solid oxide fuel cell (PC-SOFC).

Point-contact tunneling in monophasic and polyphasic Y-Ba-Cu-O samples: Experiment and model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gonnelli, R.S.; Andreone, D.; Lacquaniti, V.

1989-02-01

Tunneling experiments using large-area point-contact structures have been performed on several monophasic polycrystalline Ba/sub 2/Cu/sub 3/O/sub 7-//sub delta/ samples and on polyphasic samples containing, mixed with the previous superconducting phase, also about 11% of the so-called green phase (BaY/sub 2/CuO/sub 5/). Both niobium and Y-Ba-Cu-O tips were used as counterelectrodes and measurements were made at 4.2 and 77 K. Results obtained at different experimental conditions show great reproducibility indicating the presence of the gap voltage at about 20 mV in the dynamic resistance curves. A phenomenological model was then developed to interpret in a quantitative way our data by meansmore » of a decomposition of the experimental conductance into a background component and a superconducting-tunneling component. The former results essentially in a parabolic contribution versus the bias voltage typical of a tunneling between normallike junction electrodes while the latter component is smeared out in voltage by a large amount of broadening. Using the model in a least-squares fit of the experimental data of Nb/Y-Ba-Cu-O junctions, values V/sub G/ = 21.3 +- 0.8 mV and V/sub G/ = 22.0 +- 0.6 mV for the voltage gaps at 4.2 K of monophasic and polyphasic materials, respectively, have been determined. These results have been well confirmed by measurements on Y-Ba-Cu-O/Y-Ba-Cu-O junctions while, at 77 K, there are no indications of a superconducting tunneling. We obtained also the parameters of the background conductance, which indicates the presence of a nonsuperconducting layer at the surface of the material.« less

Growth and Characterization of Reduced Dimensionality Superconductor-Related Phases by Molecular Beam Epitaxy

DTIC Science & Technology

1998-02-01

BaTiO3 Ferromagnets M., = 1.4 g SrRuO3 Colossal Magnetoresistance AR/RH > 104~ (6 T) (La,Sr)MnO 3 3 submitted to JOM B4Ti 3O12 PbUiO 3 (Ba,K)BiO3 YBa2C...films, perhaps as a result of those films being closer to the correct Ba/Ti stoichiometric ratio. This is seen in Fig. 5, where data for the permittivity ...as a function of temperature is shown for a 60 nm thick BaTiO 3 film (Note Permittivity BSS-12 -- Ls BSS12 that as explained earlier, this film

Metal-halide mixtures for latent heat energy storage

NASA Technical Reports Server (NTRS)

Chen, K.; Manvi, R.

1981-01-01

Alkali metal and alkali halide mixtures are identified which may be suitable for thermal energy storage at temperatures above 600 C. The use of metal-halides is appropriate because of their tendency to form two immiscible melts with a density difference, which reduces scale formation and solidification on heat transfer surfaces. Also, the accumulation of phase change material along the melt interface is avoided by the self-dispersing characteristic of some metal-halides, in particular Sr-SrCl2, Ba-BaCl2, and Ba-BaBr2 mixtures. Further advantages lie in their high thermal conductivities, ability to cope with thermal shock, corrosion inhibition, and possibly higher energy densities.

Point contact Andreev reflection spectroscopic (PCARS) studies on 122-type iron-based superconductors

NASA Astrophysics Data System (ADS)

Lu, Xin; Park, W. K.; Greene, L. H.; Yuan, H. Q.; Chen, G. F.; Luo, G. L.; Wang, N. L.; Sefat, A. S.; McGuire, M. A.; Jin, R.; Sales, B. C.; Mandrus, D.; Gillett, J.; Sebastian, S. E.

2010-03-01

PCARS is applied to investigate the superconducting gap in iron pnictide single crystal superconductors of the AFe2As2 (A=Ba, Sr) family with two categories of G(V) curves observed [1]: one where Andreev reflection (AR) is present for (Ba0.6K0.4)Fe2As2 and Ba(Fe0.9Co0.1)2As2, and the other without AR but a V^2/3 shape for Sr0.6Na0.4Fe2As2 and Sr(Fe0.9Co0.1)2As2. The latter is also observed in the nonsuperconducting parent compound BaFe2As2. Mesoscopic phase-separated coexistence of magnetic and superconducting orders is considered to explain distinct behaviors. A gap size ˜3.0-4.0 meV with 2δ0/kBTc˜2.0-2.6 is observed for PCARS on Ba0.6K0.4Fe2As2. For the Ba(Fe0.9Co0.1)2As2, G(V) curves typically display a zero-bias conductance peak, sometimes with a V-shape background. [1] Xin Lu et al., arXiv:0910.4230

Microwave assisted extraction for trace element analysis of plant materials by ICP-AES.

PubMed

Borkowska-Burnecka, J

2000-11-01

Application of microwave assisted extraction for the decomposition and dissolution of plant samples for trace metal determination by ICP-AES was examined. Dried onion, leaves of spinach beet and three reference materials CTA-OTL-1, CTA-VTL-2 and CL-1 were analyzed. Water, EDTA and hydrochloric acid (0.01, 0.10 and 1.0 M, respectively) were used as leaching solutions. The extraction efficiency was investigated by comparison of the results with those obtained after microwave wet digestion. HCl was found to be very suitable for quantitative extraction of B, Ba, Cd, Cu, Mn, Ni, Pb, Sr and Zn from the samples. For reference materials, the measured concentrations are well consistent with the certified values. The use of EDTA led to a complete extraction of B, Cd, Ni, Pb, Sr and Zn. Water was found to be a good leaching solution for boron. For extraction with HCl and EDTA, the RSD values for the concentrations measured were below 8% for most of the elements.

Simplified multi-element analysis of ground and instant coffees by ICP-OES and FAAS.

PubMed

Szymczycha-Madeja, Anna; Welna, Maja; Pohl, Pawel

2015-01-01

A simplified alternative to the wet digestion sample preparation procedure for roasted ground and instant coffees has been developed and validated for the determination of different elements by inductively coupled plasma optical emission spectrometry (ICP-OES) (Al, Ba, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sr, Zn) and flame atomic absorption spectrometry (FAAS) (Ca, Fe, K, Mg, Na). The proposed procedure, i.e. the ultrasound-assisted solubilisation in aqua regia, is quite fast and simple, requires minimal use of reagents, and demonstrated good analytical performance, i.e. accuracy from -4.7% to 1.9%, precision within 0.5-8.6% and recovery in the range 93.5-103%. Detection limits of elements were from 0.086 ng ml(-1) (Sr) to 40 ng ml(-1) (Fe). A preliminary classification of 18 samples of ground and instant coffees was successfully made based on concentrations of selected elements and using principal component analysis and hierarchic cluster analysis.

Multielement analysis of Canadian wines by inductively coupled plasma mass spectrometry (ICP-MS) and multivariate statistics.

PubMed

Taylor, Vivien F; Longerich, Henry P; Greenough, John D

2003-02-12

Trace element fingerprints were deciphered for wines from Canada's two major wine-producing regions, the Okanagan Valley and the Niagara Peninsula, for the purpose of examining differences in wine element composition with region of origin and identifying elements important to determining provenance. Analysis by ICP-MS allowed simultaneous determination of 34 trace elements in wine (Li, Be, Mg, Al, P, Cl, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Mo, Ag, Cd, Sb, I, Cs, Ba, La, Ce, Tl, Pb, Bi, Th, and U) at low levels of detection, and patterns in trace element concentrations were deciphered by multivariate statistical analysis. The two regions were discriminated with 100% accuracy using 10 of these elements. Differences in soil chemistry between the Niagara and Okanagan vineyards were evident, without a good correlation between soil and wine composition. The element Sr was found to be a good indicator of provenance and has been reported in fingerprinting studies of other regions.

Analytical dependence of effective atomic number on the elemental composition of matter and radiation energy in the range 10-1000 keV

NASA Astrophysics Data System (ADS)

Eritenko, A. N.; Tsvetiansky, A. L.; Polev, A. A.

2018-01-01

In the present paper, a universal analytical dependence of effective atomic number on the composition of matter and radiation energy is proposed. This enables one to consider the case of a strong difference in the elemental composition with respect to their atomic numbers over a wide energy range. The contribution of photoelectric absorption and incoherent and coherent scattering during the interaction between radiation and matter is considered. For energy values over 40 keV, the contribution of coherent scattering does not exceed approximately 10% that can be neglected at a further consideration. The effective atomic numbers calculated on the basis of the proposed relationships are compared to the results of calculations based on other methods considered by different authors on the basis of experimental and tabulated data on mass and atomic attenuation coefficients. The examination is carried out for both single-element (e.g., 6C, 14Si, 28Cu, 56Ba, and 82Pb) and multi-element materials. Calculations are performed for W1-xCux alloys (x = 0.35; x = 0.4), PbO, ther moluminescent dosimetry compounds (56Ba, 48Cd, 41Sr, 20Ca, 12Mg, and 11Na), and SO4 in a wide energy range. A case with radiation energy between the K- and L1-absorption edges is considered for 82Pb, 74W, 56Ba, 48Cd, and 38Sr. This enables to substantially simplify the calculation of the atomic number and will be useful in technical and scientific fields related to the interaction between X-ray/gamma radiation and matter.

p-tert-Butylcalix[6]arene hexacarboxylic acid as host for Pb(ii), Sr(ii) and Ba(ii)†

PubMed Central

Adhikari, Birendra Babu; Zhao, Xiang; Derakhshan, Shahab

2015-01-01

p-tert-Butylcalixarene hexacarboxylic acid initially binds with low symmetry, to later adopt a highly symmetric up-down alternating conformation in the presence of Pb, Sr or Ba. The conformational dynamics for the three ions are distinct, from 15 hours, to 20 days, to 38 days, respectively. PMID:25198172

Theoretical investigation on thermoelectric properties of (Ca,Sr,Ba)Fe2(As/Bi)2 compounds under temperature

NASA Astrophysics Data System (ADS)

Jayalakshmi, D. S.; Sundareswari, M.; Viswanathan, E.; Das, Abhijeet

2018-04-01

The electrical conductivity, resistivity and Seebeck coefficient, Pauli magnetic susceptibility and power factor are computed under temperature (100 K - 800 K) in steps of 100 K for the theoretically designed compounds namely (Ca,Sr,Ba)Fe2Bi2 and their parent compounds namely (Ca,Sr,Ba)Fe2As2 by using Boltzmann transport theory interfaced to the Wien2k program. The Bulk modulus, electron phonon coupling constant, thermoelectric figure of merit (ZT) and transition temperature are calculated for the optimized anti ferromagnetic phase of the proposed compounds. The results are discussed for the novel compounds in view of their superconductivity existence and compared with their parent unconventional superconducting compounds.

Enhance D. C. resistivity of Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} ceramic by acceptor (Mn) doping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharma, Hakikat, E-mail: sharmahakikat@yahoo.in; Arya, G. S.; Pramar, Kusum

2015-05-15

In the present work, we prepared Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} and Mn (2 and 3 at % on Ti site) doped Ba{sub 0.7}Sr{sub 0.3}TiO{sub 3} ceramic by sol- gel method. The samples were characterized by X-ray diffraction (XRD). The XRD patterns reveled that Mn ions did not change the perovskite structure of BST (70/30). The dielectric measurements proved that dielectric constant decreased with Mn doping. The dc resistivity was studied by using I-V measurements. The dc resistivity of the BST increased with Mn doping, which suppressed the leakage current.

All high Tc edge-geometry weak links utilizing Y-Ba-Cu-O barrier layers

NASA Technical Reports Server (NTRS)

Hunt, B. D.; Foote, M. C.; Bajuk, L. J.

1991-01-01

High quality YBa2Cu3O(7-x) normal-metal/YBa2Cu3O(7-x) edge-geometry weak links have been fabricated using nonsuperconducting Y-Ba-Cu-O barrier layers deposited by laser ablation at reduced growth temperatures. Devices incorporating 25-100 A thick barrier layers exhibit current-voltage characteristics consistent with the resistively shunted junction model, with strong microwave and magnetic field response at temperatures up to 85 K. The critical currents vary exponentially with barrier thickness, and the resistances scale linearly with Y-Ba-Cu-O interlayer thickness and device area, indicating good barrier uniformity, with an effective mormal metal coherence length of 20 A.

A deep hydrothermal fault zone in the lower oceanic crust, Samail ophiolite Oman

NASA Astrophysics Data System (ADS)

Zihlmann, B.; Mueller, S.; Koepke, J.; Teagle, D. A. H.

2017-12-01

Hydrothermal circulation is a key process for the exchange of chemical elements between the oceans and the solid Earth and for the extraction of heat from newly accreted crust at mid-ocean ridges. However, due to a dearth of samples from intact oceanic crust, or continuous samples from ophiolites, there remain major short comings in our understanding of hydrothermal circulation in the oceanic crust, especially in the deeper parts. In particular, it is unknown whether fluid recharge and discharge occurs pervasively or if it is mainly channeled within discrete zones such as faults. Here, we present a description of a hydrothermal fault zone that crops out in Wadi Gideah in the layered gabbro section of the Samail ophiolite of Oman. Field observations reveal a one meter thick chlorite-epidote normal fault with disseminated pyrite and chalcopyrite and heavily altered gabbro clasts at its core. In both, the hanging and the footwall the gabbro is altered and abundantly veined with amphibole, epidote, prehnite and zeolite. Whole rock mass balance calculations show enrichments in Fe, Mn, Sc, V, Co, Cu, Rb, Zr, Nb, Th and U and depletions of Si, Ca, Na, Cr, Zn, Sr, Ba and Pb concentrations in the fault rock compared to fresh layered gabbros. Gabbro clasts within the fault zone as well as altered rock from the hanging wall show enrichments in Na, Sc, V, Co, Rb, Zr, Nb and depletion of Cr, Ni, Cu, Zn, Sr and Pb. Strontium isotope whole rock data of the fault rock yield 87Sr/86Sr ratios of 0.7046, which is considerably more radiogenic than fresh layered gabbro from this locality (87Sr/86Sr = 0.7030 - 0.7034), and similar to black smoker hydrothermal signatures based on epidote, measured elsewhere in the ophiolite. Altered gabbro clasts within the fault zone show similar values with 87Sr/86Sr ratios of 0.7045 - 0.7050, whereas hanging wall and foot wall display values only slightly more radiogenic than fresh layered gabbro.The secondary mineral assemblages and strontium isotope compositions of the fault rock, clasts and hanging wall indicate interaction with a seawater-derived hydrothermal fluid during oceanic spreading at an ancient mid-ocean ridge. The considerable elemental mass changes in the fault rocks and surrounds compared to the primary layered gabbros suggests extensive hydrothermal fluid flow and exchange deep within the ocean crust.

Spin dynamics near a putative antiferromagnetic quantum critical point in Cu-substituted BaFe 2 As 2 and its relation to high-temperature superconductivity

DOE PAGES

Kim, M. G.; Wang, M.; Tucker, G. S.; ...

2015-12-02

We present the results of elastic and inelastic neutron scattering measurements on nonsuperconducting Ba(Fe 0.957Cu 0.043) 2As 2, a composition close to a quantum critical point between antiferromagnetic (AFM) ordered and paramagnetic phases. By comparing these results with the spin fluctuations in the low-Cu composition as well as the parent compound BaFe 2As 2 and superconducting Ba(Fe 1–xNi x) 2As 2 compounds, we demonstrate that paramagnon-like spin fluctuations are evident in the antiferromagnetically ordered state of Ba(Fe 0.957Cu 0.043) 2As 2, which is distinct from the AFM-like spin fluctuations in the superconducting compounds. Our observations suggest that Cu substitution decouplesmore » the interaction between quasiparticles and the spin fluctuations. In addition, we show that the spin-spin correlation length ξ(T) increases rapidly as the temperature is lowered and find ω/T scaling behavior, the hallmark of quantum criticality, at an antiferromagnetic quantum critical point.« less

Multi-proxy Reconstructions of the Eastern Equatorial Pacific: Measuring Sr/Ca, Ba/Ca, and Li/Mg in Modern Corals Using ICP-OES

NASA Astrophysics Data System (ADS)

Cheung, A. H.; Cole, J. E.; Vetter, L.; Jimenez, G.; Thompson, D. M.; Tudhope, A. W.

2017-12-01

Sea surface temperature (SST) in the Eastern Equatorial Pacific (EEP) exhibits large variability on multiple timescales. These variations are often related to modes of climate variability that exert significant influence on global climate, such as the El Niño Southern Oscillation. However, the short length and sparsity of instrumental data in the EEP limits our ability to discern changes in this region. Geochemical signals in corals can help extend instrumental data further back in time. While δ18O and Sr/Ca are the most commonly analyzed geochemical tracers of SST in corals, they often have site-specific complications. Several alternatives (e.g., Li/Mg) have been proposed to overcome these challenges, but have yet to be applied to long climate records, in part due to the cost and time required to measure these elements. Here, we develop a new method that uses Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) to analyze Li/Mg, Sr/Ca, and Ba/Ca ratios in coral aragonite. We apply this method to two Porites spp. corals collected from the northern Galapagos archipelago (Wolf and Darwin Islands). We specifically assess the fidelity of Li/Mg and Sr/Ca to reconstruct SST, and Ba/Ca to reconstruct upwelling conditions. Our results confirm that both Li/Mg and Sr/Ca track SST. We show that despite analytical noise, downcore reconstructions of Li/Mg have the potential to provide additional information about SST that is not present in reconstructions generated from Sr/Ca alone. Skeletal Ba/Ca shows little relationship with upwelling, perhaps because of the distance of our sites from the center of upwelling in the southern Galapagos. These results demonstrate the potential for analyzing Sr, Li, Ba, Mg simultaneously in corals with a cost- and time- efficient method, which may be applied to coral paleoclimate sites worldwide.

Wet chemical techniques for passivation of YBa2Cu3O7(7-x)

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Foote, M. C.; Hunt, B. D.

1989-01-01

Wet chemical techniques are described for treatment of YBa2Cu3O(7-x) surfaces, resulting in the formation of native compounds with little or no reactivity to water. Promising native compounds include CuI, BaSO4, CuS, Cu2S, and the oxalates, all of which are either insoluble or have very low solubility in water. Treatment with dilute HI results in the formation of a native iodide film which is 80-90 percent CuI with small amounts of YI3 and BaI2. Treatment with dilute H2SO4 results in the formation of a film which is 95 percent BaSO4 and 5 percent Y2(SO4)3. Cu2S is formed on the surface with a dilute Na2S solution. An oxalate film with equal amounts of Y2(C2O4)3 and BaC2O4 results from treatment with dilute oxalic acid. X-ray photoelectron spectra show no significant changes when the sulfide, sulfate, or oxalate films are dipped in water, while the iodide film shows evidence of Cu(OH)2 formation.

Interaction of overlayers of Al and Rb with single-crystalline surfaces of Bi2Sr2CaCu2O8

NASA Astrophysics Data System (ADS)

Lindberg, P. A. P.; Wells, B. O.; Shen, Z.-X.; Dessau, D. S.; Lindau, I.; Spicer, W. E.; Mitzi, D. B.; Kapitulnik, A.

1990-03-01

Photoemission results from Al and Rb interfaces with single crystals of Bi2Sr2CaCu2O8 high-temperature superconductors are reported. The Al and Rb adsorbates are found to react quite differently with the Bi2Sr2CaCu2O8 substrate. While adatoms of Rb significantly affect only the Bi and O atoms in the top atomic layer, the Al adsorbate profoundly disrupts the bonding character of the whole Bi2Sr2CaCu2O8 material. For Al, the Bi and Cu states are strongly reduced, and the Sr and O states show evidence of oxidized components. In addition, Al causes a strong out-diffusion of oxygen from the bulk. The differences in the reactivity of Al and Rb are discussed in terms of the different mobility of the two atoms.

Surface and electronic structure of Bi-Ca-Sr-Cu-O superconductors studied by LEED, UPS and XPS

NASA Astrophysics Data System (ADS)

Shen, Z.-X.; Lindberg, P. A. P.; Wells, B. O.; Lindau, I.; Spicer, W. E.; Mitzi, D. B.; Eom, C. B.; Kapitulnik, A.; Geballe, T. H.; Soukiassian, P.

1989-02-01

Single crystal and polycrystalline samples of Bi2CaSr2Cu2O8 have been studied by various surface sensitive techniques, including low energy electron diffraction (LEED), ultraviolet photoemission spectroscopy (UPS) and x-ray photoemission spectroscopy (XPS). The surface structure of the single crystals was characterized by LEED to be consistent with that of the bulk structure. Our data suggest that Bi2CaSr2Cu2O8 single crystals are very stable in the ultrahigh vacuu. No change of XPS spectra with temperature was observed. We have also studied the electronic structure of Bi2Sr2CuO6, which has a lower superconducting transition temperature Tc. Comparing the electronic structure of the two Bi-Ca-Sr-Cu-O superconductors, an important difference in the density of states near EF was observed which seems to be related to the difference in Tc.

Interface Control of Ferroelectricity in an SrRuO3 /BaTiO3 /SrRuO3 Capacitor and its Critical Thickness.

PubMed

Shin, Yeong Jae; Kim, Yoonkoo; Kang, Sung-Jin; Nahm, Ho-Hyun; Murugavel, Pattukkannu; Kim, Jeong Rae; Cho, Myung Rae; Wang, Lingfei; Yang, Sang Mo; Yoon, Jong-Gul; Chung, Jin-Seok; Kim, Miyoung; Zhou, Hua; Chang, Seo Hyoung; Noh, Tae Won

2017-05-01

The atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (PO2) during growth plays an important role in controlling the interfacial terminations of SrRuO 3 /BaTiO 3 /SrRuO 3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high PO2 (around 150 mTorr), usually exhibits a mixture of RuO 2 -BaO and SrO-TiO 2 terminations. By reducing PO2, the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO 2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interface Control of Ferroelectricity in an SrRuO 3/BaTiO 3/SrRuO 3 Capacitor and its Critical Thickness

DOE PAGES

Shin, Yeong Jae; Kim, Yoonkoo; Kang, Sung -Jin; ...

2017-03-03

Here, the atomic-scale synthesis of artificial oxide heterostructures offers new opportunities to create novel states that do not occur in nature. The main challenge related to synthesizing these structures is obtaining atomically sharp interfaces with designed termination sequences. In this study, it is demonstrated that the oxygen pressure (P O2) during growth plays an important role in controlling the interfacial terminations of SrRuO 3/BaTiO 3/SrRuO 3 (SRO/BTO/SRO) ferroelectric (FE) capacitors. The SRO/BTO/SRO heterostructures are grown by a pulsed laser deposition method. The top SRO/BTO interface, grown at high P O2 (around 150 mTorr), usually exhibits a mixture of RuO 2-BaOmore » and SrO-TiO 2 terminations. By reducing P O2, the authors obtain atomically sharp SRO/BTO top interfaces with uniform SrO-TiO 2 termination. Using capacitor devices with symmetric and uniform interfacial termination, it is demonstrated for the first time that the FE critical thickness can reach the theoretical limit of 3.5 unit cells.« less

High- T c superconductivity at the interface between the CaCuO 2 and SrTiO 3 insulating oxides

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di Castro, D.; Cantoni, C.; Ridolfi, F.

2015-09-28

At interfaces between complex oxides it is possible to generate electronic systems with unusual electronic properties, which are not present in the isolated oxides. One important example is the appearance of superconductivity at the interface between insulating oxides, although, until now, with very low T c. We report the occurrence of high T c superconductivity in the bilayer CaCuO 2/SrTiO 3, where both the constituent oxides are insulating. In order to obtain a superconducting state, the CaCuO 2/SrTiO 3 interface must be realized between the Ca plane of CaCuO 2 and the TiO 2 plane of SrTiO 3. Only inmore » this case can oxygen ions be incorporated in the interface Ca plane, acting as apical oxygen for Cu and providing holes to the CuO 2 planes. In addition, a detailed hole doping spatial profile can be obtained by scanning transmission electron microscopy and electron-energy-loss spectroscopy at the O K edge, clearly showing that the (super)conductivity is confined to about 1–2 CaCuO 2 unit cells close to the interface with SrTiO 3. The results obtained for the CaCuO 2/SrTiO 3 interface can be extended to multilayered high T c cuprates, contributing to explaining the dependence of T c on the number of CuO 2 planes in these systems.« less

Effects of antimony substitution on bismuth based superconductors

NASA Technical Reports Server (NTRS)

Barrientos, Alfonso

1990-01-01

The effect of Sb substitution and simultaneous substitution of Pb and Sb on the superconducting transition temperatures in the BiSrCaCuO system is investigated. The 2:2:2:3 phase is of particular interest since any small increase in the transition temperature could be of great interest. More that 90 different samples were prepared based on 2:2:2:3 stoichiometry in the BiSrCaCuO system. After this preliminary attempt, four different families of samples were investigated. In the first family of samples, Bi was substituted by Sb to form Bi(1.9)Sb(0.1)Sr2Ca2Cu3O(y). The second group of samples were prepared by simultaneous addition of Pb and Sb with nominal composition Bi(1.8)Pb(0.1)Sb(0.1)Sr2Ca2Cu3O(y). The third and fourth groups were prepared to determine the effect created when the Pb concentration is increased with the nominal compositions being Bi(1.7)Pb(0.1)Sr2Ca2Cu3O(y) and Bi(1.6)Sb(0.1)Sr2Ca2Cu3O(y). The results of these investigations are presented with a discussion.

Selenium and other elements in juvenile striped bass from the San Joaquin Valley and San Francisco Estuary, California

USGS Publications Warehouse

Saiki, Michael K.; Palawski, Donald U.

1990-01-01

Concentrations of selenium and other trace elements were determined in 55 whole body samples of juvenile anadromous striped bass (Morone saxatilis) from the San Joaquin Valley and San Francisco Estuary, California. The fish (≤1 yr old—the predominant life stage in the San Joaquin Valley) were collected in September–December 1986 from 19 sites in the Valley and 3 sites in the Estuary, and analyzed for the following elements: aluminum (Al), arsenic (As), boron (B), barium (Ba), beryllium (Be), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), magnesium (Mg), molybdenum (Mo), nickel (Ni), lead (Pb), selenium (Se), strontium (Sr), vanadium (V), and zinc (Zn). When compared to concentrations in whole freshwater fish measured by surveys from other waters, a few samples contained higher levels, of As, Cd, Cu, Pb, and Se. The median concentrations of Al, As, Cu, Fe, Mg, Se, and Sr also differed significantly (P⩽0.05) among sites. However, only Se concentrations were highest (up to 7.9 μg/g dry weight) in samples from Valley sites exposed to agricultural subsurface (tile) drainwater; concentrations were lower in samples collected elsewhere. Water quality variables—especially those strongly influenced by tile drainwater (conductivity, total dissolved solids, total alkalinity, and total hardness)—were also significantly correlated (P⩽0.05) with Se concentrations in fish. Selenium concentrations in striped bass from the Estuary were only one-fourth to one-half the concentrations measured in the most contaminated fish from the San Joaquin River.

The Dart estuary, Devon, UK: a case study of chemical dynamics and pollutant mobility

NASA Astrophysics Data System (ADS)

Schuwerack, P.-M. M.; Neal, M.; Neal, C.

2007-01-01

Water, sediments and gill and digestive gland tissues of adult common shore crab (Carcinus maenas), collected at Noss Marina, Sandquay (Britannia Royal Naval College), the Dartmouth Pier, Warfleet Cove and Sugary Cove in the Dart estuary, Devon, UK, were analysed for major, minor and trace elements in spring 2004. Total acid-available measurements analysed included the truly dissolved component and acid-available sediments. Trace metal concentrations are associated largely with particulate and micro-particulate/colloidal phases, the latter being able to pass through standard filter papers. Wide ranges of chemical concentrations were found in the water, sediments and tissues at all the locations. In the water column, 48% of the variance is linked to the sea-salt component (Cl, Na, K, Ca, Mg, B, Li and Sr) and the sediment-associated acid-available fractions are linked to Fe-rich lithogenous materials (Ba, Co, Cu, Fe, Mn, V and Zn). In the sediments, trace elements of Cd, Co, Cr, Fe, Pb, Mn, Ni and V are correlated with the sea salts and associated with the fraction of fine sediments within the total sediment. In the gills and the digestive gland tissues of crabs, high concentrations of Al, Cu and Fe are found and there are correlations between acid-available trace metals of Cu, Cr, Fe, Mn, Ni, Sr and Zn. The relationships between trace metal contaminants, their site-specific concentrations, their temporal and spatial variability and the effects of human activities, such as moorland/agriculture with historic mining and recreational activities in the lower Dart estuary, are discussed.

Interfacial dislocations in (111) oriented (Ba 0.7Sr 0.3)TiO 3 films on SrTiO 3 single crystal

DOE PAGES

Shen, Xuan; Yamada, Tomoaki; Lin, Ruoqian; ...

2015-10-08

In this study, we have investigated the interfacial structure of epitaxial (Ba,Sr)TiO 3 films grown on (111)-oriented SrTiO 3 single-crystal substrates using transmission electron microscopy (TEM) techniques. Compared with the (100) epitaxial perovskite films, we observe dominant dislocation half-loop with Burgers vectors of a<110> comprised of a misfit dislocation along <112>, and threading dislocations along <110> or <100>. The misfit dislocation with Burgers vector of a <110> can dissociate into two ½ a <110> partial dislocations and one stacking fault. We found the dislocation reactions occur not only between misfit dislocations, but also between threading dislocations. Via three-dimensional electron tomography,more » we retrieved the configurations of the threading dislocation reactions. The reactions between threading dislocations lead to a more efficient strain relaxation than do the misfit dislocations alone in the near-interface region of the (111)-oriented (Ba 0.7Sr 0.3)TiO 3 films.« less

Synchrotron X-ray diffraction study of the Ba{sub 1−x}SrSnO{sub 3} solid solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Prodjosantoso, Anti K., E-mail: Prodjosantoso@yahoo.com; Zhou, Qingdi; Kennedy, Brendan J.

At room temperature the sequence of phases with increasing amounts of strontium in the stannate perovskite system Ba{sub 1−x}SrSnO{sub 3} has been established from high resolution synchrotron X-ray powder diffraction. The observed sequence orthorhombic (Pbnm), orthorhombic (Ibmm), tetragonal (I4/mcm), and cubic (Pm3-bar m) is a consequence of the sequential introduction of cooperative tilting of the corner sharing SnO{sub 6} octahedra. The cell volume changes smoothly across the series with no obvious discontinuities associated with the phase transitions. - Graphical abstract: Portions of the synchrotron X-ray diffraction profiles (λ=0.82453 Å) from selected Ba{sub 1−x}Sr{sub x}SnO{sub 3} samples together with the resultsmore » of fitting by the Rietveld method. Highlights: ► Structures of the stannate perovskites Ba{sub 1−x}SrSnO{sub 3} refined from synchrotron XRD. ► The sequence Pm3-bar m→I4/mcm→Ibmm→Pbnm results from tilting of the octahedra. ► The tilting maintains optimal bonding of the cations seen from the BVS analysis.« less

Computational study of Ca, Sr and Ba under pressure

NASA Astrophysics Data System (ADS)

Jona, F.; Marcus, P. M.

2006-05-01

A first-principles procedure for the calculation of equilibrium properties of crystals under hydrostatic pressure is applied to Ca, Sr and Ba. The procedure is based on minimizing the Gibbs free energy G (at zero temperature) with respect to the structure at a given pressure p, and hence does not require the equation of state to fix the pressure. The calculated lattice constants of Ca, Sr and Ba are shown to be generally closer to measured values than previous calculations using other procedures. In particular for Ba, where careful and extensive pressure data are available, the calculated lattice parameters fit measurements to about 1% in three different phases, both cubic and hexagonal. Rigid-lattice transition pressures between phases which come directly from the crossing of G(p) curves are not close to measured transition pressures. One reason is the need to include zero-point energy (ZPE) of vibration in G. The ZPE of cubic phases is calculated with a generalized Debye approximation and applied to Ca and Sr, where it produces significant shifts in transition pressures. An extensive tabulation is given of structural parameters and elastic constants from the literature, including both theoretical and experimental results.

Synthesis of MSnO{sub 3} (M = Ba, Sr) nanoparticles by reverse micelle method and particle size distribution analysis by whole powder pattern modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmed, Jahangeer; Blakely, Colin K.; Bruno, Shaun R.

2012-09-15

Highlights: ► BaSnO{sub 3} and SrSnO{sub 3} nanoparticles synthesized using the reverse micelle method. ► Particle size and size distribution studied by whole powder pattern modeling. ► Nanoparticles are of optimal size for investigation in dye-sensitized solar cells. -- Abstract: Light-to-electricity conversion efficiency in dye-sensitized solar cells critically depends not only on the dye molecule, semiconducting material and redox shuttle selection but also on the particle size and particle size distribution of the semiconducting photoanode. In this study, nanocrystalline BaSnO{sub 3} and SrSnO{sub 3} particles have been synthesized using the microemulsion method. Particle size distribution was studied by whole powdermore » pattern modeling which confirmed narrow particle size distribution with an average size of 18.4 ± 8.3 nm for SrSnO{sub 3} and 15.8 ± 4.2 nm for BaSnO{sub 3}. These values are in close agreement with results of transmission electron microscopy. The prepared materials have optimal microstructure for successive investigation in dye-sensitized solar cells.« less

Mechanochemical synthesis of MgF2 - MF2 composite systems (M = Ca, Sr, Ba)

NASA Astrophysics Data System (ADS)

Scholz, G.; Breitfeld, S.; Krahl, T.; Düvel, A.; Heitjans, P.; Kemnitz, E.

2015-12-01

The capability of mechanochemical synthesis for the formation of MgF2-MF2 (M: Ca, Sr, Ba) composites, solid solutions or well-defined compounds was tested applying a fluorination of different fluorine-free metal sources with NH4F directly at milling. No evidence was found for a substitution of Mg2+ with Ca2+ (Sr2+, Ba2+) ions, or vice versa, in rutile or fluorite structure. However, an equimolar ratio of Mg2+ to the second cation allows the mechanochemical synthesis of tetrafluoromagnesates, MMgF4, which is more and more hampered the smaller the radius of the cation M2+ is. BaMgF4 is formed even phase pure from the acetates, SrMgF4 can only be observed in a mixture accompanied by the binary fluorides. In addition, 19F MAS NMR spectra along with calculations of 19F isotropic chemical shift values according to the superposition model point to the formation of a metastable phase of CaMgF4, which disappears at thermal treatment and decomposes into the binary fluorides CaF2 and MgF2.

Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

NASA Astrophysics Data System (ADS)

Kirillov, D.; Bozovic, I.; Geballe, T. H.; Kapitulnik, A.; Mitzi, D. B.

1988-12-01

Raman spectra of Bi2Sr2CaCu2O8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi2Sr2CaCu2O8 and YBa2Cu3O7 was found.

Integrated elemental and Sr-Nd-Pb-Hf isotopic studies of Mesozoic mafic dykes from the eastern North China Craton: implications for the dramatic transformation of lithospheric mantle

NASA Astrophysics Data System (ADS)

Liu, Shen; Feng, Caixia; Santosh, M.; Feng, Guangying; Coulson, Ian M.; Xu, Mengjing; Guo, Zhuang; Guo, Xiaolei; Peng, Hao; Feng, Qiang

2018-02-01

Evolution of the lithospheric mantle beneath the North China Craton (NCC) from its Precambrian cratonic architecture until Paleozoic, and the transformation to an oceanic realm during Mesozoic, with implications on the destruction of cratonic root have attracted global attention. Here we present geochemical and isotopic data on a suite of newly identified Mesozoic mafic dyke swarms from the Longwangmiao, Weijiazhuang, Mengjiazhuang, Jiayou, Huangmi, and Xiahonghe areas (Qianhuai Block) along the eastern NCC with an attempt to gain further insights on the lithospheric evolution of the region. The Longwangmiao dykes are alkaline with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N > 4.3) and EM1-like Sr-Nd-Pb-Hf isotopic signature ((87Sr/86Sr) i > 0.706; ε Nd (t) < -6.3, (206Pb/204Pb) i > 16.6, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.8, ε Hf (t) < -22.4). The Weijiazhuang dykes are sub-alkaline with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N > 3.7), and display similar EM1-like isotopic features ((87Sr/86Sr) i > 0.706; ε Nd (t) < -7.0, (206Pb/204Pb) i > 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) < -23.3). The Mengjiazhuang dykes are also sub-alkaline with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N > 2.4) and EM1-like isotopic features((87Sr/86Sr) i > 0.706; ε Nd (t) < -18.4, (206Pb/204Pb) i > 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) < -8.6). The Jiayou dykes also display sub-alkaline affinity with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N > 3.7) and EM1-like Sr-Nd-Pb-Hf isotopic features ((87Sr/86Sr) i > 0.706; ε Nd(t) < -15.3, (206Pb/204Pb) i > 16.7, (207Pb/204Pb) i > 15.4, (208Pb/204Pb) i > 36.9, ε Hf (t) < -18.4). The Huangmi dykes are alkaline (with Na2O + K2O ranging to more than 5.9 wt.%)) with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N > 9.3) and EM1-like isotopic composition ((87Sr/86Sr) i > 0.705; ε Nd (t) < -15.1, (206Pb/204Pb) i > 16.9, (207Pb/204Pb) i > 15.5, (208Pb/204Pb) i > 36.9, ε Hf (t) < -12.2). The Xiahonghe dykes are alkaline with LILE (Ba and K)- and LREE-enrichment ((La/Yb) N = 2.12-2.84) and similar EM1-like Sr-Nd-Pb-Hf isotopic signature ((87Sr/86Sr) i > 0.705; ε Nd (t)<-18.0, (206Pb/204Pb) i > 16.9, (207Pb/204Pb) i > 15.5, (208Pb/204Pb) i > 36.9, ε Hf (t) < -8.6). Our data from the various mafic dyke suites suggest that the magmas were derived from EM1-like lithospheric mantle, corresponding to lithospheric mantle modified by the previously foundered lower crust beneath the eastern NCC. Our results suggest contrasting lithospheric evolution from Triassic (212 Ma) to Cretaceous (123 Ma) beneath the NCC. These mafic dykes mark an important phase of lithospheric thinning in the eastern North China Craton.

High ferroelectric polarization in c-oriented BaTiO 3 epitaxial thin films on SrTiO 3/Si(001)

DOE PAGES

Scigaj, M.; Chao, C. H.; Gázquez, J.; ...

2016-09-21

The integration of epitaxial BaTiO 3 films on silicon, combining c-orientation, surface flatness, and high ferroelectric polarization is of main interest towards its use in memory devices. This combination of properties has been only achieved so far by using yttria-stabilized zirconia buffer layers. Here, the all-perovskite BaTiO 3/LaNiO 3/SrTiO 3 heterostructure is grown monolithically on Si(001). The BaTiO 3 films are epitaxial and c-oriented and present low surface roughness and high remnant ferroelectric polarization around 6 μC/cm 2. Lastly, this result paves the way towards the fabrication of lead-free BaTiO 3 ferroelectric memories on silicon platforms.

Biomonitoring of 30 trace elements in urine of children and adults by ICP-MS.

PubMed

Heitland, Peter; Köster, Helmut D

2006-03-01

The paper provides physicians and clinical chemists with statistical data (concentration ranges, geometric mean values, selected percentiles, etc.) about 30 urinary trace elements in order to determine whether people have trace element deficiencies or have been exposed to higher elemental concentrations. Morning urine samples of 72 children and 87 adults from two geographical areas of Germany were collected and the elements Li, Be, V, Cr, Mn, Ni, Co, Cu, Zn, Ga, As, Se, Rb, Sr, Mo, Rh, Pd, Ag, Cd, In, Sn, Sb, Cs, Ba, Pt, Au, Pb, Tl, Bi and U were determined by inductively coupled plasma mass spectrometry (ICP-MS) with a new octopole based collision/reaction cell. The urine samples were analysed directly after a simple 1/5 (V/V) dilution with deionised water and nitric acid. Information on exposure conditions of all human subjects were collected by questionnaire-based interviews. The described concentration data down to the ng/l range are very useful for the formulation of reference values. For some elements either new data are described (e.g., for V, Ga, In, Bi, Rh, Mn) or differences to earlier studies were found (e.g., for Be, As). For other elements (e.g., Sb, Se, Mo, Ba, Cu, Zn, Li) our results are in good correlation with previous studies and also complemented with urinary trace element concentrations for children.

Large critical current densities and pinning forces in CSD-grown superconducting GdBa2Cu3O7-x -BaHfO3 nanocomposite films

NASA Astrophysics Data System (ADS)

Cayado, Pablo; Erbe, Manuela; Kauffmann-Weiss, Sandra; Bühler, Carl; Jung, Alexandra; Hänisch, Jens; Holzapfel, Bernhard

2017-09-01

GdBa2Cu3O7-x -BaHfO3 (GdBCO-BHO) nanocomposite (NC) films containing 12 mol% BHO nanoparticles were prepared by chemical solution deposition (CSD) following the TFA route on SrTiO3 (STO) single crystals and buffered metallic tapes supplied by two different companies: Deutsche Nanoschicht GmbH and SuperOx. We optimized the preparation of our GdBCO-BHO solutions with acetylacetone making the film synthesis very robust and reproducible, and obtained 220 nm films with excellent superconducting properties. We show the structural, morphological and superconducting properties of the films after a careful optimization of the processing parameters (growth temperature, oxygen partial pressure and heating ramp). The films reach critical temperatures (T c) of ˜94 K, self-field critical current densities (J c) of >7 MA cm- 2 and maximum pinning force densities (F p) of ˜16 GN m- 3 at 77 K on STO and T c of ˜94.5 K and J c > 1.5 MA cm- 2 on buffered metallic tapes. The transport properties under applied magnetic fields are significantly improved with respect to the pristine GdBCO films. The GdBCO-BHO NC films on STO present epitaxial c-axis orientation with excellent out-of-plane and in-plane texture. The films are, in general, very dense with a low amount of pores and only superficial indentations. On the other hand, we present, for the first time, a systematic study of CSD-grown GdBCO-BHO NC films on buffered metallic tapes. We have used the optimized growth conditions for STO as a reference and identified some limitations on the film synthesis that should be overcome for further improvement of the films’ superconducting properties.

First-Principles Prediction of Two-Dimensional Electron Gas Driven by Polarization Discontinuity in Nonpolar/Nonpolar AHfO3/SrTiO3 (A=Ca, Sr, and Ba) Heterostructures

NASA Astrophysics Data System (ADS)

Cheng, Jianli; Nazir, Safdar; Yang, Kesong

By using first-principles electronic structure calculations, we explored the possibility of producing two-dimensional electron gas (2DEG) in nonpolar/nonpolar AHfO3/SrTiO3 (A = Ca, Sr, and Ba) heterostructures (HS). Two types of interfaces, AO/TiO2 and HfO2/SrO, each with AO and HfO2 surface terminations, are modeled, respectively. The polarization domain and resulting interfacial electronic property are found to be more sensitive to the surface termination of the film rather than the interface model. As film thickness increases, an insulator-to-metal transition (IMT) is found in all the HS with HfO2 surface termination: for AO/TiO2 interfaces, predicted critical film thickness for an IMT is about 7, 6, and 3 unit cells for CaHfO3/SrTiO3, SrHfO3/SrTiO3, and BaHfO3/SrTiO3, respectively; for HfO2/SrO interfaces, the critical film thickness is about 7.5, 5.5, and 4.5 unit cells, respectively. In contrast, for the HS with AO surface termination, only CaHfO3/SrTiO3 exhibits an IMT with a much larger critical film thickness about 11 - 12 unit cells. This work is expected to stimulate further experimental investigation to the interfacial conductivity in the nonpolar/nonpolar AHfO3/SrTiO3 HS. National Science Foundation and Department of Defense National Security Science and Engineering Faculty Fellowship.

Synthesis and coordination chemistry of TpC*MI complexes where M=Mg, Ca, Sr, Ba and Zn and TpC*=tris[3-(2-methoxy-1,1-dimethyl)pyrazolyl]hydroborate.

PubMed

Chisholm, Malcolm H; Gallucci, Judith C; Yaman, Gulsah

2009-01-14

Reactions involving MI2 where M=Mg, Ca, Sr, Ba or Zn and M'TpC* where M'=Na or Tl and TpC*=tris[3-methoxy-1,1-dimethyl)pyrazolyl]hydroborate in tetrahydrofuran are described leading to the isolation and characterization of the complexes TpC*MgI, , TpC*CaI, , TpC*SrI, , TpC*SrI(THF), , TpC*BaI, , TpC*BaI(pz*H), , where pz*H=3-(2-methoxyl-1,1-dimethyl)pyrazole, TpC*BaI.1/2toluene, and TpC*ZnI, . The compounds , , , , and have been characterized by single-crystal X-ray crystallography. Compounds and are isostructural and are salt-like containing kappa6-TpM+ cations and I- anions. In all other structures, the iodide is bound to the metal and TpC* is kappa6 bonded to the group 2 M(2+) ions. Reactions involving TpC*CaI, , and sodium or lithium alkoxides or amides failed to yield the amide or alkoxide calcium TpC* derivative, though related reactions involving TpC*ZnI, , and KOSiMe3 proceeded quantitatively to yield kappa3TpC*ZnOSiMe3, , which was also structurally characterized and shown to have the kappa3-TpC* bound ligand.

Epitaxial growth of SrTiO3/YBa2Cu3O7 - x heterostructures by plasma-enhanced metalorganic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Liang, S.; Chern, C. S.; Shi, Z. Q.; Lu, P.; Safari, A.; Lu, Y.; Kear, B. H.; Hou, S. Y.

1994-06-01

We report heteroepitaxial growth of SrTiO3 on YBa2Cu3O7-x/LaAlO3 substrates by plasma-enhanced metalorganic chemical vapor deposition. X-ray diffraction results indicated that SrTiO3 films were epitaxially grown on a (001) YBa2Cu3O7-x surface with [100] orientation perpendicular to the surface. The film composition, with Sr/Ti molar ratio in the range of 0.9 to 1.1, was determined by Rutherford backscattering spectrometry and energy dispersive spectroscopy. The thickness of the SrTiO3 films is 0.1-0.2 μm. The epitaxial growth was further evidenced by high-resolution transmission electron microscopy and selected area diffraction. Atomically abrupt SrTiO3/YBa2Cu3O7-x interface and epitaxial growth with [100]SrTiO3∥[001]YBa2Cu3O7-x were observed in this study. The superconducting transition temperature of the bottom YBa2Cu3O7-x layer, as measured by ac susceptometer, did not significantly degrade after the growth of overlayer SrTiO3. The capacitance-voltage measurements showed that the dielectric constant of the SrTiO3 films was as high as 315 at a signal frequency of 100 KHz. The leakage current density through the SrTiO3 films is about 1×10-6 A/cm2 at 2-V operation. Data analysis on the current-voltage characteristic indicated that the conduction process is related to bulk-limited Poole-Frenkel emission.

Novel configuration of processing bulk textured YB 2Cu 3O 7-x superconductor by seeded infiltration growth method

NASA Astrophysics Data System (ADS)

Cao, Haitao; Moutalbi, Nahed; Harnois, Christelle; Hu, Rui; Li, Jinshan; Zhou, Lian; Noudem, Jacques G.

2010-01-01

Mono-domain YBa 2Cu 3O 7-x (Y123) bulk superconductors have been processed using seeded infiltration growth technique (SIG). The combination of melt infiltrated liquid source (Ba 3Cu 5O 8) into the Y 2BaCuO 5 (Y211) pre-form and the nucleation of Y123 domain from SmBa 2Cu 3O 7 crystal seed has been investigated. The different configurations of SIG process were compared in this study. In addition, the effect of the starting Y211 particles size has been studied. The results reveal that, the Y211 particle size and different configurations strongly influence the properties of the final bulk superconductor sample.

Preparation and study of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) composite multiferroics

NASA Astrophysics Data System (ADS)

Murtaza, Tahir; Ali, Javid; Khan, M. S.

2018-07-01

The parent and mixed spinel-perovskite composite of (1 - x)CuFe2O4-xBaTiO3 (x = 0, 0.1 and 1) has been prepared by solid-state reaction method and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer spectroscopy, magnetometry and P-E lope tracer. The XRD results showed the formation of single phase tetragonal spinel CuFe2O4 and tetragonal perovskite BaTiO3 at room temperature, further XRD of composite 0.1CuFe2O4-0.9BaTiO3 reflects the two crystallographic phases with 1:9 ratio. The SEM micrographs show the homogeneous and uniform formation of the samples. Through EDAX analysis, the chemical composition of the sample is found to be same as the nominal composition. The high field Mossbauer data of CuFe2O4 sample shows the ferrimagnetic ordering in the sample. The observed M-H and P-E loops of the composite 0.1CuFe2O4-0.9BaTiO3 sample show the presence of spontaneous magnetization and spontaneous electric polarization indicating the multiferroic nature of the sample.

Electronic Structure of Tl2Ba2CuO(6+Delta) Epitaxial Films Measured by X-Ray Photoemission

NASA Technical Reports Server (NTRS)

Vasquez, R. P.; Ren, Z. F.; Wang, J. H.

1996-01-01

The valence electronic structure and core levels of Tl2Ba2CuO(6 + delta) (Tl-2201) epitaxial films have been measured with X-ray photoelectron spectroscopy and are compared to those of Tl2Ba2CaCu2O(8 + delta) (Tl-2212). Changes in the Tl-2201 core-level binding energies with oxygen doping are consistent with a change in the chemical potential. Differences between the Tl-2201 and Tl-2212 measured densities of states are consistent with the calculated Cu 3d and Tl 6s partial densities of states.

Baseline element concentrations in soils and plants, Wattenmeer National Park, North and East Frisian Islands, Federal Republic of Germany

USGS Publications Warehouse

Severson, R.C.; Gough, L.P.; van den Boom, G.

1992-01-01

Baseline element concentrations are given for dune grass (Ammophilia arenaria), willow (Salix repens), moss (Hylocomium splendens) and associated surface soils. Baseline and variability data for pH, ash, Al, As, Ba, C, Ca, Cd, Ce, Co, Cr, Cu, Fe, Hg, K, La, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, S, Sc, Se, Sr, Th, Ti, V, Y, Yb, and Zn are reported; however, not all variables are reported for all media because, in some media, certain elements were below the analytical detection limit. Spatial variation in element concentration between five Frisian Islands are given for each of the sample media. In general, only a few elements in each media showed statistically significant differences between the islands sampled. The measured concentrations in all sample media exhibited ranges that cannot be attributed to anthropogenic additions of trace elements, with the possible exception of Hg and Pb in surface soils.Baseline element concentrations are given for dune grass (Ammophilia arenaria), willow (Salix repens), moss (Hylocomium splendens) and associated surface soils. Baseline and variability data for pH, ash, Al, As, Ba, C, Ca, Cd, Ce, Co, Cr, Cu, Fe, Hg, K, La, Li, Mg, Mn, Na, Nb, Nd, Ni, P, Pb, S, Sc, Se, Sr, Th, Ti, V, Y, Yb, and Zn are reported; however, not all variables are reported for all media because, in some media, certain elements were below the analytical detection limit. Spatial variation in element concentration between five Frisian Islands are given for each of the sample media. In general, only a few elements in each media showed statistically significant differences between the islands sampled. The measured concentrations in all sample media exhibited ranges that cannot be attributed to anthropogenic additions of trace elements, with the possible exception of Hg and Pb in surface soils.

Reference levels of trace elements in hair samples from children and adolescents in Madrid, Spain.

PubMed

Llorente Ballesteros, María Teresa; Navarro Serrano, Irene; Izquierdo Álvarez, Silvia

2017-09-01

Hair samples are used as a tool to evaluate environmental exposure to contaminants and metabolic status in the individual. However, the use of human hair is controversial, mainly because of the lack of well-defined reference levels. In the case of Spain, very few biomonitoring studies have investigated these issues in infants, children or adolescents. To establish reference levels for trace elements in children and teenagers in Madrid, Spain. Inductively coupled plasma mass spectrometry (ICP-MS) was used to measure Al, As, Ag, Ba, Bi, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Se, Sr, Tl and Zn levels in hair samples from 648 healthy children and adolescents (253 boys and 395 girls) between April 2008 and December 2009. Median levels were as follows: Al 18.5μg/g, As 0.07μg/g, Ag 196ng/g, Ba 0.5μg/g, Bi 0.01μg/g, Cd 18.3ng/g, Cr 0.4μg/g, Co 14.5ng/g, Cu 25.7μg/g, Fe 15.5μg/g, Mn 328ng/g, Mo 0.04μg/g, Ni 0.5μg/g, Pb 0.70μg/g, Se 0.5μg/g, Sr 1.29μg/g, Tl 0.28ng/g and Zn 121μg/g. The values of trace elements here described could be considered as possible reference ranges for hair samples from children and adolescents aged 0-18 years living in the Madrid region (central Spain). These values could also be selected as a preliminary screening tool to assess exposure sources and to generate information needed to develop prevention strategies and likewise could be a complement to other diagnostic procedures. Copyright © 2016 Elsevier GmbH. All rights reserved.

Determination of mineral contents of wild Boletus edulis mushroom and its edible safety assessment.

PubMed

Su, Jiuyan; Zhang, Ji; Li, Jieqing; Li, Tao; Liu, Honggao; Wang, Yuanzhong

2018-04-06

This study aimed to determine the contents of main mineral elements of wild Boletus edulis and to assess its edible safety, which may provide scientific evidence for the utilization of this species. Fourteen mineral contents (Ba, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Na, Ni, Sr, V and Zn) in the caps and stipes of B. edulis as well as the corresponding surface soils collected from nine different geographic regions in Yunnan Province, southwest China were determined. The analyses were performed using inductively coupled plasma atomic emission spectrometer (ICP-AES) after microwave digestion. Measurement data were analyzed using variance and Pearson correlation analysis. Edible safety was evaluated according to the provisionally tolerable weekly intake (PTWI) of heavy metals recommended by United Nations Food and Agriculture Organization and World Health Organization (FAO/WHO). Mineral contents were significantly different with the variance of collection areas. B. edulis showed relative abundant contents of Ca, Fe, Mg and Na, followed by Ba, Cr, Cu, Mn and Zn, and the elements with the lower content less were Cd, Co, Ni, Sr and V. The elements accumulation differed significantly in caps and stipes. Among them, Cd and Zn were bioconcentrated (BCF > 1) while others were bioexcluded (BCF < 1). The mineral contents in B. edulis and its surface soil were positively related, indicating that the elements accumulation level was related to soil background. In addition, from the perspective of food safety, if an adult (60 kg) eats 300 g fresh B. edulis per week, the intake of Cd in most of tested mushrooms were lower than PTWI value whereas the Cd intakes in some other samples were higher than this standard. The results indicated that the main mineral contents in B. edulis were significantly different with respect to geographical distribution, and the Cd intake in a few of regions was higher than the acceptable intakes with a potential risk.

Slurry micro-sampling technique for use in argon-helium microwave induced plasma optical emission spectrometry.

PubMed

Ślachciński, Mariusz

2016-12-01

The Flow Focusing Pneumatic Nebulizer (FFPN) working at low liquid flow rates was evaluated for the elemental analysis in slurried samples by argon-helium microwave induced plasma optical emission spectrometry (MIP-OES). The obtained results achieved were compared with commercially available V-groove Babington type nebulizer (VBPN). A univariate approach and the simplex optimization procedure were used to achieve optimized conditions and derive analytical figures of merit. Analytical performance of the micro nebulization system was characterized by a determination of the limits of detection (LODs), the precision (RSDs) and the wash-out times for Ba, Ca, Cd, Cu, Fe, Mg, Mn, Pb and Sr. The experimental concentration detection limits for simultaneous determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σ blank criterion, peak height) were 0.9, 0.2, 0.3, 0.2, 0.3, 0.1, 0.2, 0.4, 0.4 and 0.3ngmL -1 for Ba, Ca, Cd, Cu, Fe, Mg, Mn, Pb and Sr, respectively. The method offers relatively good precision (RSD ranged from 5% to 8%) for micro-slurry sampling analysis. Analyses of the certified reference materials (NRCC DOLT-2, GBW 07302 and SRM 2710) were performed in order to determine the accuracy available with the presented nebulization systems. The measured contents of elements in the reference materials were in satisfactory agreement with the certified values. In addition, these elements were determined in two real samples. Slurry concentration up to 3% m/v (particles <20μm), prepared in 10% m/v HCl through the application of ultrasonic agitation, was used with calibration by the standard addition technique. An ultrasonic probe was used to homogenize the slurry in the polypropylene bottle just before its introduction into the nebulizer. The nebulizers exhibited no clogging problems. Copyright © 2016 Elsevier B.V. All rights reserved.

Chemical partitioning of fine particle-bound metals on haze-fog and non-haze-fog days in Nanjing, China and its contribution to human health risks

NASA Astrophysics Data System (ADS)

Li, Huiming; Wu, Hongfei; Wang, Qin'geng; Yang, Meng; Li, Fengying; Sun, Yixuan; Qian, Xin; Wang, Jinhua; Wang, Cheng

2017-01-01

Information on chemical partitioning and associated risk of airborne metals, particularly during a haze-fog episode, is limited. Fine particulate matter (PM2.5) was collected during a severe haze-fog event in winter and non-haze-fog periods in summer and fall from an urban region of a typical Chinese mega-city, Nanjing. The particulate-bound metals (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, Pb, Sr, Ti, V, and Zn) were chemically fractionated in a four-step sequential extraction procedure and human health risk was assessed. During the haze-fog episode, PM2.5 was extremely elevated with a mean concentration of 281 μg/m3 (range: 77-431 μg/m3), whereas the mean PM2.5 concentrations in summer and fall periods were 86 μg/m3 (range: 66-111 μg/m3) and 77 μg/m3 (range: 42-131 μg/m3), respectively. All elements had significantly higher concentrations and many metals exceeded relevant limits on haze-fog days. K, Na, Sr, Zn, Mo, Ca, Cd, Mg, Mn, Cu, Ba, Cr and As all showed relatively high proportions of the soluble and exchangeable fraction and strong bio-accessible potential. High temperature and humidity may increase the bio-accessible fraction of many airborne metals. The hazard index for potential toxic metals was 0.115, which was lower than the safe limit (1). However, the combined carcinogenic risk was 1.32 × 10- 6 for children and 5.29 × 10- 6 for adults, with both values being higher than the precautionary criterion (10- 6). Results of this study provide information for the behavior and risk mitigation of airborne metals.

Liquidus Diagram of the Ba-Y-Cu-O System in the Vicinity of the Ba2YCu3O6+x Phase Field

PubMed Central

Wong-Ng, Winnie; Cook, Lawrence P.

1998-01-01

This paper describes the melting equilibria in the vicinity of the high Tc phase Ba2YCu3O6+x, including evidence for two Ba-Y-Cu-O immiscible liquids. Melting equilibria have been investigated in purified air using a combination of differential thermal analysis (DTA), thermogravimetric analysis (TGA), powder x-ray diffraction (XRD), MgO wick entrapment of liquid for analysis, scanning electron microscopy (SEM) coupled with energy dispersive x-ray analysis (EDS), and hydrogen reduction for determination of copper oxidation state. For relatively barium-rich compositions, it was necessary to prepare the starting materials under controlled atmosphere conditions using BaO. A liquidus diagram was derived from quantitative data for the melts involved in various melting reactions. In general the 1/2(Y2O3) contents of the melts participating in these equilibria were low (mole fraction <4 %). The primary phase field of Ba2YCu3O6+x occurs at a mole fraction of <2.0 % 1/2Y2O3 and lies very close along the BaO-CuOx edge, extending from a mole fraction of ≈43 % CuO to a mole fraction of ≈76 % CuO. It is divided by a liquid miscibility gap and extends on either side about this gap. The topological sequence of melting reactions associated with the liquidus is presented as a function of temperature. Implications for the growth of Ba2YCu3O6+x crystals are discussed. PMID:28009382

Investigation on gamma and neutron radiation shielding parameters for BaO/SrO‒Bi2O3‒B2O3 glasses

NASA Astrophysics Data System (ADS)

Sayyed, M. I.; Lakshminarayana, G.; Dong, M. G.; Ersundu, M. Çelikbilek; Ersundu, A. E.; Kityk, I. V.

2018-04-01

In this work, mass attenuation coefficients (μ/ρ), effective atomic number (Zeff), electron density (Ne), mean free path (MFP), and half-value layer (HVL) of 20 BaO/SrO‒(x) Bi2O3‒(80‒x) B2O3 glasses (where x=10, 20, 30, 40, 50 and 60 mol%) were calculated using WinXCom program and MCNP5 code. The obtained (μ/ρ) results using both MCNP5 code and WinXCom program were in good agreement. It is found that the addition of Bi2O3 leads to increase the Zeff values in both BaO/SrO‒Bi2O3‒B2O3 glass systems. However, the Zeff values of the BaO‒Bi2O3‒B2O3 glass system are higher than those of the SrO‒Bi2O3‒B2O3 glasses. The fast neutrons effective removal cross sections (ΣR) for 20 SrO‒40 Bi2O3‒40 B2O3 glass is the highest among all studied glasses. The calculated half-value layer values were compared with different glass systems and it was found that the shielding properties of the selected glasses are comparable or even better than other glass systems such as phosphate glasses.

Interdiffusion effect on strained La0.8Ba0.2MnO3 thin films by off-axis sputtering on SrTiO3 (100) substrates

NASA Astrophysics Data System (ADS)

Chou, Hsiung; Hsu, S. G.; Lin, C. B.; Wu, C. B.

2007-02-01

Strained La0.8Ba0.2MnO3 thin films on SrTiO3 (100) substrate are grown by an off-axis sputtering technique. It is found that the ferromagnetic temperature TC increases for thinner films. Secondary ion mass spectroscopy indicates that Sr diffuses partially into the film, making it structurally nonuniform. The region close to the film/substrate interface acts as La1-x(SryBa1-y)xMnO3 with a near negligible y for the as grown film and a non-negligible amount of y for the high-temperature postannealed film. The enhancement of TC is attributed to the combination of the strain and interdiffusion effects.

Electrical-transport properties and microwave device performance of sputtered TlCaBaCuO superconducting thin films

NASA Technical Reports Server (NTRS)

Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

1992-01-01

The paper describes the processing and electrical transport measurements for achieving reproducible high-Tc and high-Jc sputtered TlCaBaCuO thin films on LaAlO3 substrates, for microelectronic applications. The microwave properties of TlCaBaCuO thin films were investigated by designing, fabricating, and characterizing microstrip ring resonators with a fundamental resonance frequency of 12 GHz on 10-mil-thick LaAlO3 substrates. Typical unloaded quality factors for a ring resonator with a superconducting ground plane of 0.3 micron-thickness and a gold ground plane of 1-micron-thickness were above 1500 at 65 K. Typical values of penetration depth at 0 K in the TlCaBaCuO thin films were between 7000 and 8000 A.

Characterization of the insulator barrier and the superconducting transition temperature in GdBa{sub 2}Cu{sub 3}O{sub 7−δ}/BaTiO{sub 3} bilayers for application in tunnel junctions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Navarro, H., E-mail: henrynavarro@cab.cnea.gov.ar; Sirena, M.; Haberkorn, N.

2015-07-28

The optimization of the superconducting properties in a bottom electrode and the quality of an insulator barrier are the first steps in the development of superconductor/insulator/superconductor tunnel junctions. Here, we study the quality of a BaTiO{sub 3} tunnel barrier deposited on a 16 nm thick GdBa{sub 2}Cu{sub 3}O{sub 7−δ} thin film by using conductive atomic force microscopy. We find that the tunnel current is systematically reduced (for equal applied voltage) by increasing the BaTiO{sub 3} barrier thickness between 1.6 and 4 nm. The BaTiO{sub 3} layers present an energy barrier of ≈1.2 eV and an attenuation length of 0.35–0.5 nm (depending on the appliedmore » voltage). The GdBa{sub 2}Cu{sub 3}O{sub 7−δ} electrode is totally covered by a BaTiO{sub 3} thickness above 3 nm. The presence of ferroelectricity was verified by piezoresponse force microscopy for a 4 nm thick BaTiO{sub 3} top layer. The superconducting transition temperature of the bilayers is systematically suppressed by increasing the BaTiO{sub 3} thickness. This fact can be associated with stress at the interface and a reduction of the orthorhombicity of the GdBa{sub 2}Cu{sub 3}O{sub 7−δ}. The reduction in the orthorhombicity is expected by considering the interface mismatch and it can also be affected by reduced oxygen stoichiometry (poor oxygen diffusion across the BaTiO{sub 3} barrier)« less

Pollution Assessment of Toxic and Potentially Toxic Elements in Agricultural Soils of the City Addis Ababa, Ethiopia.

PubMed

Aschale, Minbale; Sileshi, Yilma; Kelly-Quinn, Mary; Hailu, Dereje

2017-02-01

Due to the significantly fast urban expansion and increased industrial activities, the soils in the farms in Addis Ababa are contaminated by some toxic and potentially toxic elements (As, V, Cr, Fe, Co, Ni, Cu, B, Ba, Sr, Zn, Mn, Pb and Cd) in varying degrees. The mean concentrations of Cr, Ni, As and B in most of the soil farms were found to be higher than the maximum recommended limits. The mean concentrations of Cd, Cu, Pb, Co, Ni and Mn were found to be higher than the background soil concentrations given for uncontaminated soils. Multivariate analyses coupled with correlation analysis were used to identify possible sources. The geo-accumulation index values for Cr, Mn and Pb indicated that the farm soils were unpolluted to moderately polluted as a result of anthropogenic activities. A comprehensive environmental management strategy should be formulated by the government to measure further pollution of the farmland soil.

Transport properties of stripe-ordered high T c cuprates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jie, Qing; Han, Su Jung; Dimitrov, Ivo

Transport measurements provide important characterizations of the nature of stripe order in the cuprates. Initial studies of systems such as La 1.6-xNd 0.4Sr xCuO₄ demonstrated the strong anisotropy between in-plane and c-axis resistivities, but also suggested that stripe order results in a tendency towards insulating behavior within the planes at low temperature. More recent work on La 2-xBa xCuO₄ with x = 1/8 has revealed the occurrence of quasi-two-dimensional superconductivity that onsets with spin-stripe order. The suppression of three-dimensional superconductivity indicates a frustration of the interlayer Josephson coupling, motivating a proposal that superconductivity and stripe order are intertwined in amore » pair-density-wave state. Complementary characterizations of the low-energy states near the Fermi level are provided by measurements of the Hall and Nernst effects, each revealing intriguing signatures of stripe correlations and ordering. We review and discuss this work.« less

Dissolved trace elements in a nitrogen-polluted river near to the Liaodong Bay in Northeast China.

PubMed

Bu, Hongmei; Song, Xianfang; Guo, Fen

2017-01-15

Dissolved trace element concentrations (Ba, Fe, Mn, Si, Sr, and Zn) were investigated in the Haicheng River near to the Liaodong Bay in Northeast China during 2010. Dissolved Ba, Fe, Mn, and Sr showed significant spatial variation, whereas dissolved Fe, Mn, and Zn displayed seasonal variations. Conditions such as water temperature, pH, and dissolved oxygen were found to have an important impact on redox reactions involving dissolved Ba, Fe, and Zn. Dissolved Fe and Mn concentrations were regulated by adsorption or desorption of Fe/Mn oxyhydroxides and the effects of organic carbon complexation on dissolved Ba and Sr were found to be significant. The sources of dissolved trace elements were found to be mainly from domestic sewage, industrial waste, agricultural surface runoff, and natural origin, with estimated seasonal and annual river fluxes established as important inputs of dissolved trace elements from the Haicheng River into the Liaodong Bay or Bohai Sea. Copyright © 2016 Elsevier Ltd. All rights reserved.

Carbon Dioxide Gas Sensors and Method of Manufacturing and Using Same

NASA Technical Reports Server (NTRS)

Hunter, Gary W. (Inventor); Xu, Jennifer C. (Inventor)

2014-01-01

A gas sensor comprises a substrate layer; a pair of interdigitated metal electrodes, said electrodes include upper surfaces, the electrodes selected from the group consisting of Pt, Pd, Au, Ir, Ag, Ru, Rh, In, Os, and their alloys. A first layer of solid electrolyte staying in between electrode fingers and partially on said upper surfaces of said electrodes, said first layer selected from NASICON, LISICON, KSICON and.beta.''-Alumina. A second layer of metal carbonate(s) as an auxiliary electrolyte engaging said upper surfaces of the electrodes and the first solid electrolyte. The metal carbonates selected from the group consisting of the following ions Na.sup.+, K.sup.+, Li.sup.+, Ag.sup.+, H.sup.+, Pb.sup.2+, Sr.sup.2+, Ba.sup.2+, and any combination thereof. An extra layer of metal oxide selected from the group consisting of SnO.sub.2, In.sub.2O.sub.3, TiO.sub.2, WO.sub.3, ZnO, Fe.sub.2O.sub.3, ITO, CdO, U.sub.3O.sub.8, Ta.sub.2O.sub.5, BaO, MoO.sub.2, MoO.sub.3, V.sub.2O.sub.5, Nb.sub.2O.sub.5, CuO, Cr.sub.2O.sub.3, La.sub.2O.sub.3, RuO.sub.3, RuO.sub.2, ReO.sub.2, ReO.sub.3, Ag.sub.2O, CoO, Cu.sub.2O, SnO, NiO, Pr.sub.2O.sub.3, BaO, PdO.sub.2, HfO.sub.3, HfO.sub.3 or other metal oxide and their mixtures residing above and in engagement with the second electrolyte to improve sensor performance and/or to reduce sensor heating power consumption.

Interaction of ultra-depleted MORBs with plagioclase: implications for CO2/Ba ratios

NASA Astrophysics Data System (ADS)

Shimizu, K.; Hauri, E.; Saal, A. E.; Perfit, M. R.; Hekinian, R.

2017-12-01

Carbon in Earth's upper mantle can significantly reduce its solidus temperature, which in turn can affect other physical properties through generation of partial melt. Carbon content in the depleted upper mantle can be estimated using ultra-depleted mid-ocean ridge basalt (UD-MORB) glasses and melt inclusions that are undersaturated in CO2. CO2 has been shown to behave as a highly incompatible element during mantle melting both through natural samples and experiments. Given its highly incompatible behavior, CO2/Ba and CO2/Nb ratios in CO2 undersaturated UD-MORBs have been used to estimate the CO2/Ba and CO2/Nb ratios and carbon content in Earth's upper mantle. A potential issue with part of this approach is the effect of melt-plagioclase chemical interaction on the CO2/Ba ratios in UD-MORBs. Plagioclase is ubiquitous in the oceanic crust and is enriched in Ba relative to other phases. Chemical interactions (assimilation and/or diffusion) between MORB melts and plagioclase bearing rocks have been shown to affect the Ba (and Sr and Eu) concentrations in MORBs, implying that such processes may also affect their CO2/Ba ratio. Hence, understanding the effect of chemical interaction between plagioclase and UD-MORBs is important for having better constraints on CO2/Ba ratio and carbon content in Earth's upper mantle. In this study, we report on the compositions of olivine-hosted melt inclusions and glasses from the Siqueiros and Garrett transform faults. A subset of melt inclusions in lavas from both transform faults show potential signatures of chemical interaction with plagioclase such as low CO2/Ba, Nb/Ba, and Nd/Sr. CO2 degassing cannot explain the low CO2/Ba ratio in the samples as they are undersaturated in CO2. To better understand the effect of chemical interaction with plagioclase on the composition of UD-MORBs, we model end-member scenarios, which are (1) assimilation of plagioclase and (2) diffusion of elements from plagioclase into the UD-MORBs. In general, the trends produced by these end-member scenarios bracket those observed in the samples (trends between CO2/Ba, Nb/Ba, and Nd/Sr as well as between Al2O3, FeO, and MgO). Hence, chemical interaction with plagioclase may affect the CO2/Ba ratio in UD-MORBs, and care should be taken to evaluate this effect using Nd/Sr and Nb/Ba ratios.

Processing effects on the microstructure and dielectric properties of hydrothermal barium titanate and (barium,strontium)titanate thin films

NASA Astrophysics Data System (ADS)

McCormick, Mark Alan

The goal of this work was to produce BaTiO3 and BaxSr (1-x)TiO3 (BST) thin films with high dielectric constants, using a low-temperature (<100°C) hydrothermal synthesis route. To accomplish this, titanium metal-organic precursor films were spin-cast onto metal-coated glass substrates and converted to polycrystalline BaTiO3 or BST upon reacting in aqueous solutions of Ba(OH)2 or Ba(OH)2 and Sr(OH)2. The influences of solution molarity, processing temperature, and reaction time on thin film reaction kinetics, microstructure, and dielectric properties were examined for BaTiO3 films. Post-deposition annealing at temperatures as low as 200°C substantially affected the lattice parameter, dielectric constant, and dielectric loss. This behavior is explained in terms of hydroxyl defect incorporation during film formation. Current-voltage (I-V) measurements were performed to determine the dominant conduction mechanism(s) during application of a do field, and to extract the metal/ceramic barrier height. In particular, Schottky barrier-limited conduction and Poole-Frenkel conduction were investigated as potential leakage mechanisms. For BST thin films, film stoichiometry deviated from the initial solution composition, with a preferred incorporation of Sr2+ into the perovskite lattice. The dielectric constant of the BST films was measured as a function of composition (Ba:Sr ratio) and temperature over the range 25--150°C. Finally, capacitance-voltage (C-V) measurements were made for BST films to determine the influence of film composition on dielectric tunability.

Crystal structures of the double perovskites Ba{sub 2}Sr{sub 1-} {sub x} Ca {sub x} WO{sub 6}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, W.T.; Akerboom, S.; IJdo, D.J.W.

2007-05-15

Structures of the double perovskites Ba{sub 2}Sr{sub 1-} {sub x} Ca {sub x} WO{sub 6} have been studied by the profile analysis of X-ray diffraction data. The end members, Ba{sub 2}SrWO{sub 6} and Ba{sub 2}CaWO{sub 6}, have the space group I2/m (tilt system a {sup 0} b {sup -} b {sup -}) and Fm3-barm (tilt system a {sup 0} a {sup 0} a {sup 0}), respectively. By increasing the Ca concentration, the monoclinic structure transforms to the cubic one via the rhombohedral R3-bar phase (tilt system a {sup -} a {sup -} a {sup -}) instead of the tetragonal I4/mmore » phase (tilt system a {sup 0} a {sup 0} c {sup -}). This observation supports the idea that the rhombohedral structure is favoured by increasing the covalency of the octahedral cations in Ba{sub 2} MM'O{sub 6}-type double perovskites, and disagrees with a recent proposal that the formation of the {pi}-bonding, e.g., d {sup 0}-ion, determines the tetragonal symmetry in preference to the rhombohedral one. - Graphical abstract: Enlarged sections showing the evolution of the basic (222) and (400) reflections in Ba{sub 2}Sr{sub 1-} {sub x} Ca {sub x} WO{sub 6}. Tick marks below are the positions of Bragg's reflections calculated using the space groups I2/m (x=0), R3-bar (x=0.25, 0.5 and 0.75) and Fm3-barm (x=1), respectively.« less

A Compilation of Metals and Trace Elements Extracted from Materials Relevant to Pharmaceutical Applications such as Packaging Systems and Devices.

PubMed

Jenke, Dennis; Rivera, Christine; Mortensen, Tammy; Amin, Parul; Chacko, Molly; Tran, Thang; Chum, James

2013-01-01

Nearly 100 individual test articles, representative of materials used in pharmaceutical applications such as packaging and devices, were extracted under exaggerated conditions and the levels of 32 metals and trace elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ge, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, Zn, and Zr) were measured in the extracts. The extracting solvents included aqueous mixtures at low and high pH and an organic solvent mixture (40/60 ethanol water). The sealed vessel extractions were performed by placing an appropriate portion of the test articles and an appropriate volume of extracting solution in inert extraction vessels and exposing the extraction units (and associated extraction blanks) to defined conditions of temperature and duration. The levels of extracted target elements were measured by inductively coupled plasma atomic emission spectroscopy. The overall reporting threshold for most of the targeted elements was 0.05 μg/mL, which corresponds to 0.5 μg/g for the most commonly utilized extraction stoichiometry (1 g of material per 10 mL of extracting solvent). The targeted elements could be classified into four major groups depending on the frequency with which they were present in the over 250 extractions reported in this study. Thirteen elements (Ag, As, Be, Cd, Co, Ge, Li, Mo, Ni, Sn, Ti, V, and Zr) were not extracted in reportable quantities from any of the test articles under any of the extraction conditions. Eight additional elements (Bi, Cr, Cu, Mn, Pb, Sb, Se, and Sr) were rarely extracted from the test articles at reportable levels, and three other elements (Ba, Fe, and P) were infrequently extracted from the test articles at reportable levels. The remaining eight elements (Al, B, Ca, Mg, Na, S, Si, and Zn) were more frequently present in the extracts in reportable quantities. These general trends in accumulation behavior were compared to compiled lists of elements of concern as impurities in pharmaceutical products. Nearly 100 individual test articles, representative of materials used in pharmaceutical applications such as packaging and devices, were extracted under exaggerated conditions, and the levels of thirty-two metals and trace elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ge, Li, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Se, Si, Sn, Sr, Ti, V, Zn, and Zr) were measured in the extracts. The targeted elements could be classified into four major groups depending on the frequency with which they were present in the extractions reported in this study: those elements that were not extracted in reportable quantities from any of the test articles under any of the extraction conditions, those elements that were rarely extracted from the test articles at reportable levels, those elements that were infrequently extracted from the test articles at reportable levels, and those elements that were more frequently present in the extracts in reportable quantities.

Determination of the Extent of Trace Metals Pollution in Soils, Sediments and Human Hair at e-Waste Recycling Site in Ghana.

PubMed

Tokumaru, Takashi; Ozaki, Hirokazu; Onwona-Agyeman, Siaw; Ofosu-Anim, John; Watanabe, Izumi

2017-10-01

The concentrations of trace elements (Mg, Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, As, Se, Rb, Sr, Y, Mo, Cd, In, Sn, Sb, Cs, Ba, Tl, Pb, and Bi) in soils, sediment, human hair, and foodstuff collected around the electronic waste (e-waste) recycling sites in Accra, Ghana were detected using inductively coupled plasma-mass spectrometry (ICP-MS). High levels of Cu, Zn, Mo, Cd, In, Sn, Sb, and Pb were observed in soils collected from the e-waste recycling sites. Four sequential extraction procedures were used to evaluate the mobility and bioavailability of metals (Cu, Zn, Cd, Sb, and Pb). Especially, the results showed that Cd and Zn in soils were mostly recovered in exchangeable fraction (respectively 58.9 and 62.8%). Sediment collected from around the site had enrichment of Zn, Sn, Sb, Mo, In, Pb, and Bi. The concentrations of Cu, Mo, Cd, Sb, and Pb in human hair were significantly higher than those collected from the control site (p < 0.01). Additionally, hierarchical cluster analysis reviewed that these elements were derived from e-waste activities. The results of Pb isotopic ratios in the samples indicate that Pb in human hair possibly originated from contaminated soils, fish, and foodstuff.

Strategic Positioning and Biased Activity of the Mitochondrial Calcium Uniporter in Cardiac Muscle*

PubMed Central

De La Fuente, Sergio; Fernandez-Sanz, Celia; Vail, Caitlin; Agra, Elorm J.; Holmstrom, Kira; Sun, Junhui; Mishra, Jyotsna; Williams, Dewight; Finkel, Toren; Murphy, Elizabeth; Joseph, Suresh K.; Sheu, Shey-Shing; Csordás, György

2016-01-01

Control of myocardial energetics by Ca2+ signal propagation to the mitochondrial matrix includes local Ca2+ delivery from sarcoplasmic reticulum (SR) ryanodine receptors (RyR2) to the inner mitochondrial membrane (IMM) Ca2+ uniporter (mtCU). mtCU activity in cardiac mitochondria is relatively low, whereas the IMM surface is large, due to extensive cristae folding. Hence, stochastically distributed mtCU may not suffice to support local Ca2+ transfer. We hypothesized that mtCU concentrated at mitochondria-SR associations would promote the effective Ca2+ transfer. mtCU distribution was determined by tracking MCU and EMRE, the proteins essential for channel formation. Both proteins were enriched in the IMM-outer mitochondrial membrane (OMM) contact point submitochondrial fraction and, as super-resolution microscopy revealed, located more to the mitochondrial periphery (inner boundary membrane) than inside the cristae, indicating high accessibility to cytosol-derived Ca2+ inputs. Furthermore, MCU immunofluorescence distribution was biased toward the mitochondria-SR interface (RyR2), and this bias was promoted by Ca2+ signaling activity in intact cardiomyocytes. The SR fraction of heart homogenate contains mitochondria with extensive SR associations, and these mitochondria are highly enriched in EMRE. Size exclusion chromatography suggested for EMRE- and MCU-containing complexes a wide size range and also revealed MCU-containing complexes devoid of EMRE (thus disabled) in the mitochondrial but not the SR fraction. Functional measurements suggested more effective mtCU-mediated Ca2+ uptake activity by the mitochondria of the SR than of the mitochondrial fraction. Thus, mtCU “hot spots” can be formed at the cardiac muscle mitochondria-SR associations via localization and assembly bias, serving local Ca2+ signaling and the excitation-energetics coupling. PMID:27637331

Synthesis, structure, and magnetic properties of new layered phosphate halides Sr2Cu5(PO4)4X2·8H2O (X = Cl, Br) with a crown-like building unit.

PubMed

Qiu, Chaoqun; He, Zhangzhen; Cui, Meiyan; Tang, Yingying; Chen, Sihuai

2017-03-27

Two new compounds Sr 2 Cu 5 (PO 4 ) 4 X 2 ·8H 2 O (X = Cl and Br) are synthesized by a conventional hydrothermal method. Sr 2 Cu 5 (PO 4 ) 4 Cl 2 ·8H 2 O crystallizes in the tetragonal system with a space group of P42 1 2, while Sr 2 Cu 5 (PO 4 ) 4 Br 2 ·8H 2 O crystallizes in the space group P4/nmm, which are found to have a similar framework of layered structure, in which the crown-like {Cu 5 (PO 4 ) 4 X 2 } building units connect to each other forming a 2D corrugated sheet with vacancies, while the Sr 2+ cations are located along the vacancies. The spin lattice of two compounds built by Cu 2+ ions shows a new type of corrugated square. Magnetic measurements confirmed that both Sr 2 Cu 5 (PO 4 ) 4 X 2 ·8H 2 O (X = Cl and Br) exhibit antiferromagnetic ordering at low temperatures. A fit of theoretical model shows exchange interaction J = -25.62 K for the Cl-analogue and J/k B = -26.47 K for the Br-analogue.

Distribution of chemical elements in attic dust as reflection of their geogenic and anthropogenic sources in the vicinity of the copper mine and flotation plant.

PubMed

Balabanova, Biljana; Stafilov, Trajče; Sajn, Robert; Bačeva, Katerina

2011-08-01

The main aim of this article was to assess the atmospheric pollution with heavy metals due to copper mining Bučim near Radoviš, the Republic of Macedonia. The open pit and mine waste and flotation tailings are continually exposed to open air, which leads to winds carrying the fine particles into the atmosphere. Samples of attic dust were examined as historical archives of mine emissions, with the aim of elucidating the pathways of pollution. Dust was collected from the attics of 29 houses, built between 1920 and 1970. Nineteen elements (Ag, Al, As, Ba, Ca, Cd, Co, Cr, Cu, Li, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, and Zn) were analyzed by atomic emission spectrometry with inductively coupled plasma. The obtained values of the investigated elements in attic dust samples were statistically processed using nonparametric and parametric analysis. Factor analysis revealed three factors governing the source of individual chemical elements. Two of them grouping Ca, Li, Mg, Mn, and Sr (Factor 1) and Co, Cr, and Ni (Factor 2) can be characterized as geogenic. The third factor grouping As, Cu, and Pb is anthropogenic and mirrors dust fallout from mining operation and from flotation tailings. Maps of areal deposition were prepared for this group of elements, from which correlation of these anthropogenic born elements was confirmed.

Serum concentrations of trace elements and their relationships with paraoxonase-1 in morbidly obese women.

PubMed

Luciano-Mateo, Fedra; Cabré, Noemí; Nadal, Martí; García-Heredia, Anabel; Baiges-Gaya, Gerard; Hernández-Aguilera, Anna; Camps, Jordi; Joven, Jorge; Domingo, José Luis

2018-07-01

The metabolic alterations associated with obesity include mineral dysregulation. Essential trace elements are nutrients with a relevant function in a large number of cellular processes and multiple roles in the correct functioning of metabolic enzymes. Paraoxonase-1 (PON1) is an antioxidant and anti-inflammatory enzyme that is compromised in obesity. In the present study, the potential alterations in trace elements in morbidly obese women were assessed in relation to serum PON1 activity and concentration, as well as to other obesity-related comorbidities such as diabetes mellitus and fatty liver. We recruited 41 morbidly obese women and 51 control individuals. The serum concentrations of 30 elements, PON1 paraoxonase and lactonase activities, and PON1 concentration were measured. We observed significant alterations in the levels of As, Ba, Cu, Ca, Fe, Mg, Na, Se, Sr, and Zn in obese women; some of them (As, Ca, Cr, Cu, Mg, and Se) being significantly correlated with serum PON1 values. The most relevant changes were observed in the concentrations of As, Sr and Mg, the last of which was also significantly associated with diabetes mellitus. The current results raise the possibility that increased ingestion and/or storage of a number of trace elements may be factors predisposing to obesity-related comorbidities and metabolic alterations. Copyright © 2018 Elsevier GmbH. All rights reserved.

Reduced anti-ferromagnetism promoted by Zn 3d 10 substitution at CuO 2 planar sites of Cu 0.5Tl 0.5Ba 2Ca 3Cu 4O 12-δ superconductors

NASA Astrophysics Data System (ADS)

Mumtaz, M.; Khan, Nawazish A.

2009-11-01

The role of charge carriers in ZnO 2/CuO 2 planes of Cu 0.5Tl 0.5Ba 2Ca 3Cu 4-yZn yO 12-δ material in bringing about superconductivity has been explained. Due to suppression of anti-ferromagnetic order with Zn 3d 10 ( S=0) substitution at Cu 3d 9(S={1}/{2}) sites in the inner CuO 2 planes of Cu 0.5Tl 0.5Ba 2Ca 3Cu 4O 12-δ superconductor, the distribution of charge carriers becomes homogeneous and optimum, which is evident from the enhanced superconductivity parameters. The decreased c-axis length with the increase of Zn doping improves interlayer coupling and hence the three dimensional (3D) conductivity in the unit cell is enhanced. Also the softening of phonon modes with the increased Zn doping indicates that the electron-phonon interaction has an essential role in the mechanism of high- Tc superconductivity in these compounds.

Assessment of the Coral Temperature Proxies for Orbicella faveolata in the Southwestern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Vara, M. A.; DeLong, K. L.; Herrmann, A. D.; Ouellette, G., Jr.; Richey, J. N.

2017-12-01

Coral Sr/Ca is a robust proxy of sea surface temperature (SST); however, discrepancies in the Sr/Ca-SST relationship among colonies of the same species may reduce confidence in absolute temperature reconstructions. Furthermore, terrestrial carbonate weathering can provide local sources of Sr and/or Ca to coastal waters that may disrupt the temperature-based coral Sr/Ca signal. Thus other trace metal SST proxies have been suggested to circumvent these issues (Li/Ca, Li/Mg, and Sr-U). Coral Ba/Ca has been used as a proxy for runoff and coastal upwelling, and therefore may be used to identify intervals when these processes overprint the Sr/Ca-SST signal. This study tests multiple coral SST proxies using reproducibility assessments to determine the best performing SST proxy. We conduct these assessments with cores recovered in 1991 by the U.S. Geological Survey from five Orbicella faveolata colonies from three reefs offshore of Veracruz, Mexico (19.06°N, 96.93°W) in water depths varying from 3 to 12 m. Previous studies found micromilling the complex skeletal structure of O. faveolata challenging and that monthly resolution may not recover full seasonal cycles. We use a laser ablation inductively coupled plasma mass spectrometer to simultaneously sample this coral's structure at weekly intervals spanning 8 years for Li/Ca, Li/Mg, Sr-U, Sr/Ca, and Ba/Ca. Here we found coral Li/Ca means and seasonal variations are similar among colonies thus this proxy may capture absolute temperature and SST variability. Similar to previous research with Porites corals, Li/Ca in these O. faveolata corals decreases with increases in SST with similar slopes and intercepts. During the last 10 years of these corals' lives, coral Sr/Ca analysis reveals a mean shift among colonies suggesting an external source could have disrupted the Sr/Ca signal, possibly seasonal runoff and/or winter upwelling common to Veracruz waters. Coral Ba/Ca analyses reveals elevated values in winters that coincide with increases in coral Sr/Ca in the deeper colony suggesting upwelling is occurring at that location. However, the coral Ba/Ca does not coincide with increase coral Sr/Ca in the shallower coral indicating no direct influence from runoff. Coral Li/Mg and Sr-U do not show substantial seasonal variations as expected with a coral-SST proxy.

Doping experiments on low-dimensional oxides and a search for unusual magnetic properties of magnesium aluminum boride

NASA Astrophysics Data System (ADS)

Hill, Julienne Marie

Doping experiments on La2CuO4, Sr2CuO 3 and SrCu2(BO3)2 were performed with the intent of synthesizing new metallic low-dimensional cuprate oxide compounds. Magnetic susceptibility chi(T) measurements on a polycrystalline La 2CuO4 sample chemically oxidized at room temperature in aqueous NaClO showed superconductivity with a superconducting transition temperature Tc of 42.6 K and a Meissner fraction of 26%. We were unable to electrochemically oxidize La2CuO4 in a nonaqueous solution of tetramethylammonium hydroxide (TMAOH) and methanol. Sr2CuO 3 was found to decompose upon exposure to air and water. Electron paramagnetic resonance, isothermal magnetization M(H) and chi(T) measurements on the primary decomposition product, Sr2Cu(OH)6, were consistent with a nearly isolated, spin S = 1/2, local moment model for the Cu +2 spins. From a fit of chi(T) by the Curie-Weiss law and of the M(H) isotherms by a modified Brillouin function, the weakly antiferromagnetic exchange interaction between adjacent Cu+2 spins in Sr 2Cu(OH)6 was found to be J/kB = 1.06(4) K. Doping studies on SrCu2(BO3)2 were inconclusive. chi(T) measurements on an undoped polycrystalline sample of SrCu2(BO 3)2, a sample treated with distilled water, and a sample treated with aqueous NaClO showed no qualitative differences between the samples. In addition, chi(T) and M(H, T) studies of the ultra-hard material MgAlB14 were carried out in search of superconductivity or ferromagnetism in this compound. chi(T) measurements on a powder sample revealed temperature-independent diamagnetism from 1.8 K up to room temperature with a Curie-Weiss impurity concentration equivalent to ˜1 mol% of spin-1/2 ions. In contrast, M(H, T) data on hot pressed samples showed evidence of ferromagnetic transitions above ˜330 K. Scanning electron microscopy and Auger microprobe analysis of the hot pressed samples indicated that the observed ferromagnetism was likely due to Fe impurities.

Film growth and structure design in the barium oxide-strontium oxide-titanium dioxide system

NASA Astrophysics Data System (ADS)

Fisher, Patrick J.

This thesis describes the growth and characterization of thin films in the SrO-BaO-TiO2 system. The films are grown by molecular beam cpitaxy (MBE) and pulsed laser deposition (PLD) on ceramic substrates, and characterized using X-ray diffraction (XRD), atomic force microscopy (AFM), reflection-high energy electron diffraction (RHEED), and transmission electron microscopy (TEM). Films are grown with varied global and initial local stoichiometries, with the goal of determining the stability of specific cation organizations. Simple oxides, TiO2 (anatase) and SrO (rock salt) were grown on oxide substrates using MBE. Growth conditions, including substrate material, substrate temperature, O3 flux, and metal flux, are varied in each case. It is observed that the growth morphology of anatase is highly dependent on the ozone flux, with fluxes of 1.00 sccm and greater resulting in flat anatase surfaces. Increased roughness at higher substrate was determined to be a result of rutile inclusions. Growth oscillations are observed in the RHEED intensity for both TiO2 and SrO in overlapping regions of growth space, indicating 2D growth modes. Varied shuttering sequences were used during MBE growth of perovskites: globally non-stoichiometric films, as well as locally non-stoichiometric but globally stoichiometric perovskite. Films were grown within a (SrO) m(TiO2)n framework, where growth cycles involved m monolayers of SrO followed by n monolayers of TiO2. XRD results indicate that Ruddlesden-Popper defects, that is, rock salt double layers, enable incorporation of all levels of Sr excess, whereas excess Ti is observed to incorporate into the perovskite structure only at extreme excesses. A series of films with m equal to n were grown; that is, multiple monolayers of SrO deposited followed by multiple monolayers of TiO2. These initially locally non-stoichiometric arrangements interreact to form highly crystalline perovskite, even with layer thicknesses of up to 33 monolayers. The Ba0.6Sr0.4TiO3 films were characterized for their microwave dielectric properties, and were found to have high dielectric constants (epsilonr ˜1300 in each case, implying high tunabilities) but high tan delta values as well. The mechanisms by which the perovskite structure incorporates cation excesses is discussed, and it is argued that two probable mechanisms, one involving plane-sharing of Ti and Sr cations and the other involving rock salt multilayers, also enable the observed transport necessary for multilayer reaction. Working under the argument that these mechanisms involve low-energy architectures, a novel homologous series of phases based on rock salt multilayers is grown using monotayer control: the SrmTiO2+ m series, with each TiO2 monolayer followed by m SrO monolayers (m = 1-5). The phases in this series were characterized structurally, and an in-plane contraction was observed between the m = 2 and m = 3 phases, which is argued to be a relaxation of the SrO monolayers. Considering Ti-excess organizations, the BaTi2O5 structure is grown and observed to nucleate over a narrow window of growth conditions and substrates. LaAlO 3(100) promotes the nucleation of anatasc and ejection of perovskite; SrTiO3(100) promotes the nucleation of perovskite and ejection of TiO2; importantly, MgO(100) promotes the nucleation (010)-oriented BaTi2O5 growing with multiple domains. A BaTi2 O5 buffer layer was then used to promote the inclusion of Sr into (Ba,SOTi205 epilayers. Sr incorporation into a perovskite-related structure was observed to occur over the full range of (Ba,Sr)Ti2O 5 compositions.

Finite size effect on the magnetic excitations spectra, phonons and heat conduction of the quasi- one-dimensional spin chains system SrCuO2

NASA Astrophysics Data System (ADS)

Bounoua, Dalila; Saint-Martin, Romuald; Petit, Sylvain; Bourdarot, Frédéric; Pinsard-Gaudart, Loreynne

2018-05-01

We report inelastic neutron scattering measurements of the phonons modes, in the one-dimensional half integer spin chains cuprate SrCuO2. We study the longitudinal and the transverse modes propagating in the direction of the chains, along Q (0 0 L) and Q (2 0 L), respectively. On the other hand, we investigate the effect of substitution by impurities in the corresponding doped compounds, namely, SrCu0.99M0.01O2 with M=Mg or Zn, and La0.01Sr0.99CuO2. Our results evidence a systematic strong spinon-phonon interaction leading to an important decrease of the phonon scattered intensity as well as a decrease of the group velocity of the transverse acoustic modes upon substitution, and a shift of the transverse optical B3 u mode in the La-doped SrCuO2, in terms of energy.

Growth of Nucleation Sites on Pd-doped Bi_2Sr_2Ca1 Cu_2O_8+δ

NASA Astrophysics Data System (ADS)

Kouzoudis, D.; Finnemore, D. K.; Xu, Ming; Balachandran

1996-03-01

Enviromental Scanning Electron Microscope has shown evidence that during the growth of Bi_2Sr_2Ca_2Cu_3O_10+δ from mixed powders of Pb-doped Bi_2Sr_2Ca_1Cu_2O_8+δ and other oxides, a dense array of hillocks or mesas grow at the interface between an Ag overlay and Pb doped Bi_2Sr_2Ca_1Cu_2O_8+δ grains. These hillocks develop a texture that looks like ''chicken pox'' during the ramp up to the reaction temperature starting at about 700^circ C and they are about 500 to 1000 nm across and are spaced at about 500 to 1000 nm. If there is no Ag, this texture does not develop. Preliminary measurments indicate that the hillocks are re-crystallization of (Bi,Pb)_2Sr_2Ca_1Cu_2O_8+δ and are definetely not a Pb rich phase

Growth of nucleation sites on Pb-doped Bi2Sr2Ca1Cu2O8 + delta

NASA Astrophysics Data System (ADS)

Finnemore, D. K.; Xu, Ming; Kouzoudis, D.; Bloomer, T.; Kramer, M. J.; McKernan, Stuart; Balachandran, U.; Haldar, Pradeep

1996-01-01

In the growth of Bi2Sr2Ca2Cu3O10+δ from mixed powders of Pb-doped Bi2Sr2Ca1Cu2O8+δ and other oxides, it has been discovered that a dense array of hillocks or mesas grow at the interface between a Ag overlay and Pb-doped Bi2Sr2Ca1Cu2O8+δ grains during the ramp up to the reaction temperature. As viewed in an environmental scanning electron microscope, the Ag coated grains develop a texture that looks like ``chicken pox'' growing on the grains at about 700 °C. These hillocks are about 100 nm across and are spaced at about 500 to 1000 nm. If there is no Ag, this texture does not develop. Preliminary measurements indicate that the hillocks are a recrystallization of (Bi,Pb)2Sr2Ca1Cu2O8+δ, and are definitely not a Pb rich phase.

Processing, electrical and microwave properties of sputtered Tl-Ca-Ba-Cu-O superconducting thin films

NASA Technical Reports Server (NTRS)

Subramanyam, G.; Kapoor, V. J.; Chorey, C. M.; Bhasin, K. B.

1993-01-01

A reproducible fabrication process has been established for TlCaBaCuO thin films on LaAlO3 substrates by RF magnetron sputtering and post-deposition processing methods. Electrical transport properties of the thin films were measured on patterned four-probe test devices. Microwave properties of the films were obtained from unloaded Q measurements of all-superconducting ring resonators. This paper describes the processing, electrical and microwave properties of Tl2Ca1Ba2Cu2O(x) 2122-plane phase thin films.

Y1Ba2Cu3O(6+delta) growth on thin Y-enhanced SiO2 buffer layers on silicon

NASA Technical Reports Server (NTRS)

Robin, T.; Mesarwi, A.; Wu, N. J.; Fan, W. C.; Espoir, L.; Ignatiev, A.; Sega, R.

1991-01-01

SiO2 buffer layers as thin as 2 nm have been developed for use in the growth of Y1Ba2Cu3O(6+delta) thin films on silicon substrates. The SiO2 layers are formed through Y enhancement of silicon oxidation, and are highly stoichiometric. Y1Ba2Cu3O(6+delta) film growth on silicon with thin buffer layers has shown c orientation and Tc0 = 78 K.

Single crystals of the 96 K superconductor (Hg,Cu)Ba2CuO4+δ: Growth, structure and magnetism

NASA Astrophysics Data System (ADS)

Pelloquin, D.; Hardy, V.; Maignan, A.; Raveau, B.

1997-02-01

Single crystals of the 1201 (n = 1) (Hg,Cu)Ba2CuO4+δ mercury based cuprate have been grown by using a simple process without dry box. The as-synthesized crystals exhibit constant Tc(onset) of 96 K with sharp superconducting transitions. The electron microscopy coupled with EDX analyses evidence a ``1201''-type structure while a mercury deficiency is observed balanced by an excess of copper. The structural refinements based on single-crystal X-ray diffraction data confirm the electron deficiency on the Hg site (0,0,0) and show a splitting of the latter along the c axis correlated to the partial substitution of Cu for Hg. This structural study leads to the following formula Hg0.84Cu0.16Ba2CuO4.19. The magnetic study of a large crystal (1.1 × 0.38 × 0.065 mm3) shows that the (Hg,Cu)-1201 crystals exhibit an irreversibility line higher than that of the 1201 Hg0.8Bi0.2Ba2CuO4+δ crystal (Tc = 75 K). From the reversible magnetization, a λab(0) = 2470 Å value can be extrapolated. Using a 3D-2D decoupling formula, we obtain γ = 29 for the electronic anisotropy of this phase.