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1

Mechanical Properties of Alkaline-Earth Doped Lanthanum Gallate  

SciTech Connect

Report on mechanical properties of Lanthanum Gallate. Lanthanum gallate doped with alkaline earths was prepared from combustion-synthesized powders. Mechanical properties of the doped gallates were evaluated as a function of composition and temperature.

Baskaran, Suresh; Lewinsohn, Charles A.; Chou, Y S.; Qian, Maoxu; Stevenson, Jeffry W.; Armstrong, Timothy R.

1999-08-01

2

EXTENT OF PARTICULATE MARKER (SAMARIUM, LANTHANUM AND CERIUM) MOVEMENT FROM ONE DIGESTA PARTICLE TO ANOTHER 1'2  

Microsoft Academic Search

SUMMARY An in vitro and in vivo experiment was performed to determine the extent of move- ment of samarium (Sm), cerium (Ce), and lanthanum (La) from the original feedstuff upon which they were adsorbed to other feed particles. The rare-earth elements were demon- strated to be tenaciously bound to the parti- culate phase, with essentially none of the element occuring

Gary F. Hartnell; Larry D. Satter

3

Electrical properties of lanthanum doped barium titanate ceramics  

SciTech Connect

Pure and lanthanum doped barium titanate (BT) ceramics were prepared by sintering pellets at 1300 deg. C for 8 h, obtained from nanopowders synthesized by the polymeric precursor method. XRD results showed formation of a tetragonal structure. The presence of dopants changed the tetragonal structure to pseudo-cubic. The polygonal grain size was reduced up to 300 nm with addition of lanthanum as a donor dopant. Determined dielectric properties revealed that lanthanum modified BT ceramics possessed a diffused ferroelectric character in comparison with pure BT that is a classical ferroelectric material. In doped BT phase transition temperatures were shifted to lower temperatures and dielectric constant values were much higher than in pure BT. A modified Currie Weiss law was used to explore the connection between the doping level and degree of diffuseness of phase transitions. Impedance spectroscopy measurements were carried out at different temperatures in order to investigate electrical resistivity of materials and appearance of a PTCR effect. - Highlights: {yields} Pure and lanthanum doped BaTiO{sub 3} were prepared by polymeric precursors method. {yields} Change of structure from tetragonal to pseudo-cubic. {yields} Lanthanum as a donor dopant influenced on change of ferro-para phase transition. {yields} The diffuseness factor indicated the formation of diffuse ferroelectric material. {yields} Lanthanum affected on PTCR effect appearance in BT ceramics.

Vijatovic Petrovic, M.M., E-mail: miravijat@yahoo.com [Institute for Multidisciplinary Research, Belgrade University, Kneza Viseslava 1, Belgrade (Serbia); Bobic, J.D. [Institute for Multidisciplinary Research, Belgrade University, Kneza Viseslava 1, Belgrade (Serbia); Ramoska, T.; Banys, J. [Faculty of Physics, Vilnius University, Sauletekio al. 9, Vilnius (Lithuania); Stojanovic, B.D. [Institute for Multidisciplinary Research, Belgrade University, Kneza Viseslava 1, Belgrade (Serbia)

2011-10-15

4

Reaction mechanism between lanthanum manganite and yttria doped cubic zirconia  

Microsoft Academic Search

The reactivity between lanthanum deficient lanthanum manganite, La0.9MnO3, and yttria doped cubic zirconia (YSZ) has been examined at the temperature range between 1250°C and 1400°C. The reaction product of La2Zr2O7 was observed after some induced period, which depended on the reaction temperature and the yttrium content in YSZ. The induced period increased with increasing Y2O3 content in ZrO2. The reaction

M Mori; T Abe; H Itoh; O Yamamoto; G. Q Shen; Y Takeda; N Imanishi

1999-01-01

5

Spectroscopy of vanadium (III) doped gallium lanthanum sulphide chalcogenide glass  

Microsoft Academic Search

Vanadium doped gallium lanthanum sulphide glass (V:GLS) displays three absorption bands at 580, 730, and 1155 nm identified by photoluminescence excitation measurements. Broad photoluminescence, with a full width at half maximum of ~500 nm, is observed peaking at 1500 nm when exciting at 514, 808, and 1064 nm. The fluorescence lifetime and quantum efficiency at 300 K were measured to

M. Hughes; H. Rutt; D. Hewak; R. J. Curry

2007-01-01

6

Passive gain-equalized wide-band erbium-doped fiber amplifier using samarium-doped fiber  

Microsoft Academic Search

A passive gain-equalization technique of erbium-doped fiber amplifier (EDFA) using a samarium-doped fiber to obtain wide-band flattened gain operation is reported. In the wavelength range from 1529-1559-nm, small inter-channel gain variations can be achieved. This simple technique is suitable for multiwavelength wide-band in-line-amplifier cascaded transmission applications.

Shien-Kuei Liaw; Yung-Kuang Chen

1996-01-01

7

Raman spectral analysis of TiO2 thin films doped with rare-earth samarium.  

PubMed

TiO(2) thin films doped with rare-earth samarium were prepared on a quartz plate by the sol-gel/spin-coating technique. The samples were annealed at 700 °C to 1100 °C, and the Raman spectra of the samples were obtained. Analyses of Raman spectra show that samarium doping can inhibit the anatase-rutile phase transition. Samarium doping can refine grains of TiO(2) thin films and increase the internal stress, thereby preventing lattice vibration. Nanocrystalline TiO(2) thin films obviously show the phonon confinement effect, i.e., the blueshift of characteristic Raman peak and full width at half-height increase, and the peak shapes asymmetrically broaden with a decrease in the grain sizes of the samples. PMID:22859033

Yang, Chang-Hu; Ma, Zhong-Quan

2012-08-01

8

Some properties of strontium-doped lanthanum chromite  

Microsoft Academic Search

The properties of strontium-doped lanthanum chromite (La0·84Sr0·16CrO3) are discussed, with particular attention to its application as an electrode material for MHD power generation. The influence of firing temperature on the ceramic properties and the behaviour of strontium carbonate as a sintering agent are described. The thermal conductivity is 5·1 w m?1 degk?1 between 1100 and 2000°k, and the thermal expansion

D B Meadowcroft

1969-01-01

9

Magnetoelectric behavior of sodium doped lanthanum manganites  

NASA Astrophysics Data System (ADS)

Nanocrystalline samples of sodium doped manganites with compositional formula La1-xNaxMnO3 (0.025<=x<=0.25) were prepared by polyvinyl alcohol assisted precursor method. After characterizing the samples by x-ray diffraction and transmission electron microscopy a systematic investigation of electrical, magnetic, and thermopower properties has been undertaken. The resistivity data were analyzed using effective medium approximation. From the analysis it has been found that the metallic fraction is increasing up to x=0.10 and remains constant with further doping. A close examination of the resistivity data clearly indicates that the sodium doped samples are slowly transformed from colossal magnetoresistance behavior to charge ordering behavior. Thermoelectric power data at low temperatures were analyzed by considering the magnon drag concept, while the high temperature data were explained by small polaron conduction mechanism.

Kalyana Lakshmi, Y.; Venkataiah, G.; Reddy, P. Venugopal

2009-07-01

10

Expansion on reduction of calcium doped lanthanum chromite  

SciTech Connect

Doped lanthanum chromites have been considered as interconnect materials for the solid oxide fuel cell (SOFC) because of their favorable chemical and electrical properties under both oxidizing and reducing environments. Several investigators have studied the materials properties of the doped lanthanum chromites to optimize their overall performance as an interconnect material. These properties include electrical conductivity, thermal expansion, sinterability, and chemical compatibility with other cell components. These properties are optimized by the amount of dopants substituted into chromite which are usually Ca or Sr. Figure 1 shows the range of values for these properties. Another important characteristic becoming more of a concern as investigators are building SOFC stacks is that doped lanthanum chromite expands when reduced in a low oxygen partial pressure (pO{sub 2}) (<10{sup -12} atm). Plates used to separate oxidizing and fuel gases can deform because of the pO{sub 2} gradient across the interconnect material. This presentation is a summary of work which will be presented at the Fourth International Symposium on Solid Oxide Fuel Cells. In this article, the possible causes of expansion on reduction of the interconnect will be discussed by using a two-dimensional crystal model. The biaxial strain of the stack is calculated under the assumption that the cell components are forced to remain planar. From this, the maximum stress buildup in the interconnect and electrolyte is estimated. In addition, the effects of thermal expansion mismatch and expansion on reduction of the interconnect are compared, and the optimum interconnect composition from a mechanical standpoint is reported.

Carter, J.D.; Hendriksen, P.V.; Mogensen, M. [Riso National Lab., Roskilde (Denmark). Materials Dept.

1995-07-01

11

Mechanical properties of magnesia-doped lanthanum chromite versus temperature  

Microsoft Academic Search

Magnesia-doped lanthanum chromite is a potential material for use in solid oxide fuel cells as an interconnector due to its resistance to oxidation and reduction. The strength and toughness of La(Cr{sub 0.9}Mg{sub 0.1})Oâ were measured from 25 to 1,000 C in the as-fired reduced state and after oxidation. The as-fired samples showed a peak in toughness of approximately 3.9 MPa·m¹²

Charles S. Montross; Harumi Yokokawa; Masayuki Dokiya; Lambert Bekessy

1995-01-01

12

Low temperature processing of dense samarium-doped CeO 2 ceramics: sintering and grain growth behaviors  

Microsoft Academic Search

Samarium-doped CeO2 is a leading electrolyte for applications in solid oxide fuel cells (SOFCs), which requires a typical sintering temperature of 1400–1600 °C. By synthesizing reactive powders via carbonate precipitation, fully dense CeO2 ceramics doped with 0–20 at.% of samarium have been fabricated in this work via pressureless sintering at a significantly lowered temperature of 1000 °C. The resultant ceramics

Ji-Guang Li; Takayasu Ikegami; Toshiyuki Mori

2004-01-01

13

Cathodoluminescence microanalysis of irradiated microcrystalline and nanocrystalline samarium doped BaFCl.  

PubMed

BaFCl:Sm3+ is an efficient photoluminescent storage phosphor for ionizing radiation. Cathodoluminescence (CL) microanalysis enables the Sm2+ and Sm3+ oxidation states of samarium doped BaFCl to be easily identified, provides information about electron-beam and X-ray induced modification of BaFCl:Sm, and enables the synthesis dependent spatial distribution of samarium dopants of <100 ppm concentration to be determined with sub-100 nm resolution at 295 K. CL spectroscopy of BaFCl:Sm particles reveals broad CL emissions at ? 360 and ?500 nm associated with V k (Cl-) and oxygen-vacancy defects in the BaFCl host lattice and fine structure CL emissions associated with major 4GJ ? 6HJ (Sm3+) and 5DJ ? 7FJ (Sm2+) transitions. CL microanalysis shows samarium dopants are uniformly distributed in conventional sintered microcrystalline BaFCl:Sm. In contrast, CL investigations reveal that for BaFCl:Sm nanoparticles, which have been prepared using a co-precipitation method, with greatly improved Sm3+ ? Sm2+ conversion efficiency, the samarium dopants are concentrated near the particle surface resulting in a BaFCl:Sm3+ shell surrounding the BaFCl core, which is stable to energetic irradiation. PMID:23164246

Stevens-Kalceff, Marion A; Liu, Zhiqiang; Riesen, Hans

2012-11-20

14

Oxygen tracer diffusion in polycrystalline calcium-doped lanthanum chromites  

SciTech Connect

Acceptor-doped lanthanum chromites have been considered as one of the most promising materials for interconnectors in solid-oxide fuel cells (SOFCs). Oxygen tracer diffusion in polycrystalline (La,Ca)CrO{sub 3{minus}{delta}} was studied by the gas-solid isotope exchange reaction in combination with a depth-profiling technique using secondary-ion mass spectroscopy, which allowed determination of coefficients of lattice and grain-boundary diffusion separately. A significant contribution of fast grain-boundary diffusion was confirmed. The lattice diffusion coefficient increased with increased acceptor content and decreased oxygen partial pressure, which was consistent with the currently established point defect model and, thereby, suggested that the lattice oxide ions diffused by a vacancy mechanism.

Yasuda, Isamu; Ogasawara, Kei; Hishinuma, Masakazu [Tokyo Gas Co., Ltd. (Japan). Fundamental Technology Research Lab.

1997-12-01

15

Sol-gel synthesis of strontium-doped lanthanum manganite  

SciTech Connect

This paper reports on strontium-doped lanthanum manganite powders that were prepared using a peroxide acetate salt based solution. The stable sol was peptized by reacting ammonium hydroxide with the precursor solution. The amorphous dried gel powders exhibit a high energy level, due to their high cations coordination and small particles, to develop the perovskite phase. This crystalline phase development from powders containing monocarboxylate ligands was characterized by thermal analysis (TG, DTG, DTA), X-ray diffraction, and IR spectroscopy. The transformation from amorphous powders into a crystallized homogeneous oxycarbonate phase in a first stage corresponds to an exothermal DTA peak at 270{degrees} C. X-ray diffraction patterns and IR spectra showed similar behavior of the powders after complete organic removal, during the conversion into perovskite phase starting at approximately 630{degrees} C and achieved about 700{degrees} C, as well as during the sintering process.

Bilger, S.; Syskakis, E.; Naoumidis, A.; Nickel, H. (Research Center Juelich, Inst. for Reactor Materials, 5170 Juelich (DE))

1992-04-01

16

Creep and Fatigue Behavior of SnAg Solders With Lanthanum Doping  

Microsoft Academic Search

In this paper, extensive testing was conducted to study the effects of Lanthanum (La) doping on the creep and fatigue behavior of SnAg lead free solder alloys. Variables considered in this paper include doping amount, aging temperature, and aging time. The experimental data show that rare earth element (RE) doping increases SnAg solders creep resistance by about 15%. Meanwhile, RE

Min Pei; Jianmin Qu

2008-01-01

17

Altering the equilibrium condition in Sr-doped lanthanum manganite.  

SciTech Connect

The material of choice for a solid oxide fuel cell cathode based on a yttria-stabilized zirconia (YSZ) electrolyte is doped lanthanum manganite, (La, Sr)MnO{sub 3}. It excels at many of the attributes necessary for a system to work at the required operating temperature and is flexible enough to allow for materials optimization. Although strontium-doping increases the electronic conductivity of the material, the ionic conductivity of the material remains negligible under operating conditions. Studies have shown that the internal equilibrium of the material heavily favors oxidation of the manganese and rather than the loss of lattice oxygen as a charge compensation mechanism. This lack of oxygen vacancies in the structure retards the ability of the material to conduct oxygen ions; thus the optimized system requires a large number of engineered triple point boundary locations to work efficiently. We have successfully doped the host LSM lattice to alter the interred equilibrium of the material to increase its ionic conductivity and thus lower the cathodic overpotential of the system. Our presentation will discuss these new materials, the results of cell tests, and a number of characterization experiments performed.

Carter, J. D.; Krumpelt, M.; Vaughey, J.; Wang, X.

1999-05-28

18

Photoluminescence of samarium-doped TiO{sub 2} nanotubes  

SciTech Connect

Samarium (Sm)-modified TiO{sub 2} nanotubes (TNTs) were synthesized by low-temperature soft chemical processing. X-ray powder diffraction analyses of the synthesized Sm-doped and non-doped TNTs show a broad peak near 2{theta}=10{sup o}, which is typical of TNTs. The binding energy of Sm {sup 3}d{sub 5/2} for 10 mol% Sm-doped TNT (1088.3 eV) was chemically shifted from that of Sm{sub 2}O{sub 3} (1087.5 eV), showing that Sm existed in the TiO{sub 2} lattice. Sm-doped TNTs clearly exhibited red fluorescence, corresponding to the doped Sm{sup 3+} ion in the TNT lattice. The Sm-doped TNT excitation spectrum exhibited a broad curve, which was similar to the UV-vis optical absorption spectrum. Thus, it was considered that the photoluminescence emission of Sm{sup 3+}-doped TNT with UV-light irradiation was caused by the energy transfer from the TNT matrix via the band-to-band excitation of TiO{sub 2} to the Sm{sup 3+} ion. - Graphical Abstract: Samarium-doped TiO{sub 2} nanotubes (TNTs) having a nanotubular structure were synthesized by soft chemical route. It was revealed that the energy associated by the band-to-band excitation of TNT matrix transferred to the doped Sm{sup 3+} ions in the lattice, resulting in emission of strong and visible red fluorescence. Highlights: > Sm-doped TiO{sub 2} nanotubes synthesized by low-temperature soft chemical processing. > Sm{sup 3+} substitutes Ti{sup 4+} ions in the nanotube lattice. > Clear fluorescent emission due to the f-f transition at the Sm{sup 3+} in a crystal field environment. > Band-to-band excitation of TiO{sub 2} and followed energy transfer to Sm{sup 3+} causes the luminescence.

Park, Dong Jin [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Sekino, Tohru, E-mail: sekino@tagen.tohoku.ac.jp [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Tsukuda, Satoshi [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Hayashi, Asuka [Institute of Scientific and Industrial Research (ISIR), Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Kusunose, Takafumi [Faculty of Engineering, Kagawa University, Hayashi 2217-20, Takamatsu, Kagawa 761-0396 (Japan); Tanaka, Shun-Ichiro [Institute of Multidisciplinary Research for Advanced Materials (IMRAM), Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan)

2011-10-15

19

Thermal-expansion behaviors and mechanisms for Ca or Sr-doped lanthanum manganite perovskites under oxidizing atmospheres  

Microsoft Academic Search

The thermal expansion behavior and mechanism of A-site-deficient lanthanum manganite perovskites, La{sub 1-x}MnOâ (0 < x ⤠0.1), and alkaline earth metal (AE)-doped lanthanum manganite perovskites, La{sub 1-x}AEâMnOâ (AE = Ca and Sr, 0 ⤠x ⤠0.4), under oxidizing atmospheres have been investigated. The average linear thermal expansion coefficients of the AE-doped lanthanum manganites decreased with increasing Ca content

Masashi Mori; Yoshiko Hiei; Nigel M. Sammes; Geoff A. Tompsett

2000-01-01

20

YBCO bulk superconductors doped with gadolinium and samarium  

NASA Astrophysics Data System (ADS)

The YBa2Cu3O7-? (YBCO, Y123) bulk single-grain superconductors doped with GdBa2Cu3Oy (Gd123) or SmBa2Cu3Oz (Sm123) were prepared by the Top-seeded melt-growth process. The growth conditions of the samples were optimized for different dopant concentrations. Wavelength-dispersive spectrometry (WDS) confirmed that prepared samples contain besides dopants also Sm from the seed and Yb from the substrate. The critical temperature, Tc increases with increasing dopant concentration in the studied range. Peak effect in the field dependences of critical current density, Jc(B) at 77 K was observed.

Volochová, Daniela; Piovar?i, Samuel; Radušovská, Monika; Antal, Vitaliy; Ková?, Jozef; Jurek, Karel; Jirsa, Miloš; Diko, Pavel

2013-11-01

21

Synchrotron X-ray Study of Thin Film Samarium Doped BiFeO3 at the Morphotropic Phase Boundary  

Microsoft Academic Search

Samarium doped bismuth ferrite (BSFO) is a good lead free candidate for piezoelectric applications. For Sm concentrations of ˜14%, BSFO is at a morphotropic phase boundary (MPB) between two structural phases much like lead zirconium titanate (PZT). We have conducted a high resolution synchrotron x-ray diffraction study of Sm doped BiFeO3 films at a composition near the MPB. Films of

Samuel Emery; Barrett Wells; Ching-Jung Cheng; Nagarajan Valanoor; Daisuke Kan; Ichiro Takeuchi

2010-01-01

22

Processing and electrical properties of alkaline earth-doped lanthanum gallate  

Microsoft Academic Search

Oxides exhibiting substantial oxygen ion conductivity are utilized in a number of high-temperature applications, including solid oxide fuel cells, oxygen separation membranes, membrane reactors, and oxygen sensors. Alkaline earth-doped lanthanum gallate powders were prepared by glycine\\/nitrate combustion synthesis. Compacts of powders synthesized under fuel-rich conditions were sintered to densities greater than 97% of theoretical. Appropriate doping with Sr or Ba

J. W. Stevenson; T. R. Armstrong; D. E. McCready; L. R. Pederson; W. J. Weber

1997-01-01

23

Order parameters in lanthanum gallate lightly doped with manganese and paramagnetic resonance  

NASA Astrophysics Data System (ADS)

The Cr3+ centers have been revealed, transitions at room temperature have been identified, and spin Hamiltonian parameters have been determined for the Cr3+ and Fe3+ triclinic centers in lanthanum gallate lightly doped with manganese. The principal axes of the fourth-rank fine-structure tensor for the Fe3+ triclinic centers have been established and used to determine the order parameters, i.e., the angles of rotation of oxygen octahedra of lanthanum gallate with respect to the perovskite structure. The order parameter in the rhombohedral phase has been estimated.

Vazhenin, V. A.; Potapov, A. P.; Artyomov, M. Yu.; Guseva, V. B.

2010-09-01

24

Synthesis of monodisperse samarium-doped ceria nanocrystals via a microemulsion-mediated hydrothermal method with secondary light irradiation treatment  

Microsoft Academic Search

Monodisperse samarium-doped ceria nanocrystals have been rapidly synthesized by a microemulsion-mediated hydrothermal method with secondary light irradiation treatment. The microemulsion system consists of cetyltrimethyl ammonium bromide and n-butanol and n-octane, acting as the surfactant, cosurfactant and oil phase, respectively. The as-synthesized nano powder is characterized by well-dispersed rhombohedral particles with their size in the range of 75 to 85nm. The

Junliang Liu; Jiamei Ye; Ping Liu; Lei Chen; Ming Zhang

2011-01-01

25

Tape casting and sintering of strontium-doped lanthanum chromite for a planar solid oxide fuel cell bipolar plate  

Microsoft Academic Search

Nonagglomerated strontium-doped lanthanum chromite powders were prepared by a modified Pechini resinintermediate process and tape cast to form bipolar plates for a planar solid oxide fuel cell. An air-sintering technique for the strontium-doped lanthanum chromite was developed, which involved placing the green tape between CrâOâ-fired plates. The sintering process was found to be diffusion controlled, with densification beginning at the

Lone-Wen Tai; Paul A. Lessing

1991-01-01

26

Thermoluminescent dosimetric characteristics of irradiated ternary alkali halides doped with lanthanum  

NASA Astrophysics Data System (ADS)

In the present study thermoluminesce properties of Lanthanum doped KCl0.2NaClxNaBr0.8-x ternary crystals with ? - irradiation has been carried out. The crystals were grown by slow evaporation and doped with rare earth Lanthanum ion. The grown crystals were irradiated with ? - radiation for dosages of 25 kGy, 50 kGy and 100 kGy. The results show that TL intensity as well as the peak position of the glow curves change with time of exposure. In few compositions, there is no change in intensity with time whereas; in few other compositions there is a small fading of intensity with time. Study reveals that these crystals have high capacity to store optical energy.

Maruthi, G.; Chandramani, R.

2013-02-01

27

Electrode material for high-temperature oxygen partial pressure electrochemical sensors: Strontium-doped lanthanum chromite  

Microsoft Academic Search

The electrochemical behavior of 20% strontium-doped lanthanum chromite (SDLC), deposited onto a 8% yttria-stabilized zirconia (YSZ) solid electrolyte, has been investigated. The electromotive force developed across the interface SDLC\\/YSZ and a Pt\\/YSZ reference at 0.21 atm (air) corresponds to the Nernst theoretical relationship. This behavior has been tested between 700° and 1000 °C in the ranges 100–10?5 and 10?13–10?20 atm

Giovanni B. Barbi; Andrea Casiraghi; Claudio M. Mari

1983-01-01

28

Sintering characteristics and thermal expansion behavior of Li-doped lanthanum chromite perovskites depending upon preparation method and Sr doping  

Microsoft Academic Search

The sintering characteristics and thermal expansion behaviors of Li-doped lanthanum chromite perovskites (La1?xSrxCr1?yLiyO3; x=0, 0.1, 0.2; y=0.01, 0.02, 0.05) synthesized by the Pechini method have been investigated. The solubility limit of Li into the perovskites decreases with increasing Sr content. Li doping to the perovskites improved sintering characteristics; however, the Pechini method did not bring the effect expected on the

Eisaku Suda; Bernard Pacaud; Thierry Seguelong; Yasuo Takeda

2002-01-01

29

Copper doped lanthanum strontium ferrite for reduced temperature solid oxide fuel cells  

Microsoft Academic Search

Copper doped lanthanum strontium ferrite showed superior kinetics for the electro-reduction of oxygen. The generic formulation was La1?xSrxCu1?yFeyO3 (LSCuF) where x ranged from 0.2 to 0.3 and y varied from 0 to 0.4. Doping with copper improved the electrocatalytic activity compared with undoped material. In oxygen, the La0.7Sr0.3Cu0.2Fe0.8O3 sample showed current densities approximately 2–3 times that of La0.7Sr0.3FeO3 and 10

Greg W. Coffey; John S. Hardy; Olga A. Marina; Larry R. Pederson; Peter C. Rieke; Ed C. Thomsen

2004-01-01

30

Copper Doped Lanthanum Strontium Ferrite for Reduced Temperature Solid Oxide Fuel Cells  

Microsoft Academic Search

Copper doped lanthanum strontium ferrite showed superior kinetics for the electro-reduction of oxygen. The generic formulation was La1-xSrxCu1-yFeyO3 (LSCuF) where x ranged from 0 to 0.4 and y varied from 0 to 0.5. La1-xSrxFeO3 (LSF) without copper doping and with x equal to 0.2 is the composition currently used in our laboratory for oxygen reduction cathodes in solid oxide fuel

Greg W. Coffey; John S. Hardy; Olga A. Marina; Larry R. Pederson; Peter C. Rieke; Ed C. Thomsen

2005-01-01

31

Processing and electrical properties of alkaline earth-doped lanthanum gallate  

SciTech Connect

Oxides exhibiting substantial oxygen ion conductivity are utilized in a number of high-temperature applications, including solid oxide fuel cells, oxygen separation membranes, membrane reactors, and oxygen sensors. Alkaline earth-doped lanthanum gallate powders were prepared by glycine/nitrate combustion synthesis. Compacts of powders synthesized under fuel-rich conditions were sintered to densities greater than 97% of theoretical. Appropriate doping with Sr or Ba on the A-site of the perovskite structure, and Mg on the B-site, resulted in oxygen ion conductivity higher than that of yttria-stabilized zirconia (YSZ), and high ionic transference numbers. Doping with Ca and Mg resulted in lower conductivity than YSZ. Thermal expansion coefficients of the doped gallates were higher than that of YSZ.

Stevenson, J.W.; Armstrong, T.R.; McCready, D.E.; Pederson, L.R.; Weber, W.J. [Pacific Northwest National Lab., Richland, WA (United States). Materials and Chemical Sciences Dept.

1997-10-01

32

Copper Doped Lanthanum Strontium Ferrite for Reduced Temperature Solid Oxide Fuel Cells  

SciTech Connect

Copper doped lanthanum strontium ferrite showed superior kinetics for the electro-reduction of oxygen. The generic formulation was La1-xSrxCu1-yFeyO3 (LSCuF) where x ranged from 0 to 0.4 and y varied from 0 to 0.5. La1-xSrxFeO3 (LSF) without copper doping and with x equal to 0.2 is the composition currently used in our laboratory for oxygen reduction cathodes in solid oxide fuel cells. Doping with copper improved the electrocatalytic activity compared with undoped material. This improvement was confirmed with cyclic voltammetric studies on half cells and on full fuel cell tests. Copper doped materials have unusual electrochemical characteristics and copper apparently undergoes a one electron reduction at overpotentials less than -0.1 volt. This occurred only in air but not in oxygen.

Coffey, Greg W.; Hardy, John S.; Marina, Olga A.; Pederson, Larry R.; Rieke, Peter C.; Thomsen, Ed C.

2005-09-15

33

Cobalt doped lanthanum chromite material suitable for high temperature use  

DOEpatents

A high temperature, solid electrolyte electrochemical cell, subject to thermal cycling temperatures of between about 25.degree. C. and about 1200.degree. C., capable of electronic interconnection to at least one other electrochemical cell and capable of operating in an environment containing oxygen and a fuel, is made; where the cell has a first and second electrode with solid electrolyte between them, where an improved interconnect material is applied along a portion of a supporting electrode; where the interconnect is made of a chemically modified lanthanum chromite, containing cobalt as the important additive, which interconnect allows for adjustment of the thermal expansion of the interconnect material to more nearly match that of other cell components, such as zirconia electrolyte, and is stable in oxygen containing atmospheres such as air and in fuel environments.

Ruka, Roswell J. (Churchill, PA)

1986-01-01

34

Cobalt doped lanthanum chromite material suitable for high temperature use  

DOEpatents

A high temperature, solid electrolyte electrochemical cell, subject to thermal cycling temperatures of between about 25 C and about 1,200 C, capable of electronic interconnection to at least one other electrochemical cell and capable of operating in an environment containing oxygen and a fuel, is made; where the cell has a first and second electrode with solid electrolyte between them, where an improved interconnect material is applied along a portion of a supporting electrode; where the interconnect is made of a chemically modified lanthanum chromite, containing cobalt as the important additive, which interconnect allows for adjustment of the thermal expansion of the interconnect material to more nearly match that of other cell components, such as zirconia electrolyte, and is stable in oxygen containing atmospheres such as air and in fuel environments. 2 figs.

Ruka, R.J.

1986-12-23

35

Effect of a-site cation deficiency and YSZ additions on sintering and properties of doped lanthanum manganite  

SciTech Connect

The sintering behavior of Ca- and Sr-doped lanthanum manganite (the preferred SOFC cathode material) is highly dependent on the relative proportion of A and B site cations in the material. In general, A-site cation deficiency increases sintered density. The effect of additions of YSZ to lanthanum manganite (to expand the reactive region at the cathode/electrolyte interface and improve thermal expansion and sintering shrinkage matches) on sintering and other properties will also be reported.

Stevenson, J.W.; Armstrong, T.R.; Weber, W.J.

1995-06-01

36

A high-performance ceramic fuel cell with samarium doped ceria–carbonate composite electrolyte at low temperatures  

Microsoft Academic Search

An anode-supported ceramic fuel cell with samarium doped ceria (SDC)–carbonate (Li2CO3–Na2CO3) composite electrolyte was fabricated by a hot-press technique and tested at 450–600°C. NiO and lithiated NiO were used as the anode and cathode, respectively, with an effective electrode area of 3.14cm2. An open-circuit voltage (OCV) of 1.04V and a current density of 0.70A\\/cm2 at 0.6V was achieved with dry

Jianbing Huang; Lizhai Yang; Ruifeng Gao; Zongqiang Mao; Cheng Wang

2006-01-01

37

Energetics of magnesium, strontium, and barium doped lanthanum gallate perovskites  

Microsoft Academic Search

LaGaO3 perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol–gel method and characterized. Enthalpies of formation from constituent oxides at 298K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three

Jihong Cheng; Alexandra Navrotsky

2004-01-01

38

Tape casting and sintering of strontium-doped lanthanum chromite for a planar solid oxide fuel cell bipolar plate  

SciTech Connect

Nonagglomerated strontium-doped lanthanum chromite powders were prepared by a modified Pechini resinintermediate process and tape cast to form bipolar plates for a planar solid oxide fuel cell. An air-sintering technique for the strontium-doped lanthanum chromite was developed, which involved placing the green tape between Cr{sub 2}O{sub 3}-fired plates. The sintering process was found to be diffusion controlled, with densification beginning at the surface and proceeding to the interior. A bipolar plate of 2-mm thickness was fired to more than 9.3.5% theoretical density when fired at 1670{degrees}C for 7 h.

Tai, L.W.; Lessing, P.A. (New Mexico Inst. of Mining and Technology, Socorro, NM (US))

1991-01-01

39

Spectral properties of Ce3+ doped yttrium lanthanum oxide transparent ceramics  

NASA Astrophysics Data System (ADS)

Ce3+-doped yttrium lanthanum oxide (Y0.9La0.1)2O3 transparent ceramics is fabricated with nanopowders and sintered in H2 atmosphere. The spectral properties of Ce:(Y0.9La0.1)2O3 transparent ceramics are investigated. There appear two characteristic absorption peaks of Ce3+ ions at 230 nm and 400 nm, separately. It is found that Ce3+ ions can efficiently produce emission at 384 nm from (Y0.9La0.1)2O3 transparent ceramic host, while the emission is completely quenched in Re2O3 (Re = Y, Lu, La) host materials.

Yang, Qiu-Hong; Zhou, Hong-Xu; Lu, Shen-Zhou

2010-02-01

40

Electro-optic effects in thin-film lanthanum-doped lead zirconate titanate.  

PubMed

We report the deposition and characterization of highly oriented thin-film lanthanum-doped lead zirconate titanate (28/0/100) on fused-silica substrates by rf planar magnetron sputtering. The quadratic electro-optic effect gives a birefringence of Deltan ~ 0.018 at an applied field of 39 kV/mm. Optical modulation at a switching speed of 3 nsec (instrumentation limited) is achieved. Results of optically induced decay of the birefringence in these films are also reported. PMID:19759740

Mukherjee, A; Brueck, S R; Wu, A Y

1990-02-01

41

Czochralski growth and characterization of neodymium-doped strontium lanthanum aluminate (ASL:Nd) single crystals  

Microsoft Academic Search

Nd-doped strontium lanthanum aluminate crystals, Nd:ASL (Sr1?xNdyLax?yMgxAl12?xO19), with an extended composition parameter x (0.05 and 0.5) have been grown by the Czochralski pulling technique. Structural and compositional properties of the as-grown crystals have been studied using X-ray diffraction, chemical microanalysis and optical spectroscopy. The results show that high crystalline perfection and large size crystals of both compositions can be grown.

L. Gheorghe; V. Lupei; A. Lupei; C. Gheorghe; C. Varona; P. Loiseau; G. Aka; D. Vivien; B. Ferrand

2005-01-01

42

Characterisation of samarium and nitrogen co-doped TiO2 films prepared by chemical spray pyrolysis  

NASA Astrophysics Data System (ADS)

The sol-gel chemical spray pyrolysis method was used to deposit samarium and nitrogen co-doped TiO2 films onto a quartz substrate at a growth temperature of 450 °C using pulsed spray solution feed, followed by annealing at 500 °C for 2 h in air. The obtained films exhibited anatase structure independent of the doping level. According to XRD analysis, the mean crystallite size of the undoped TiO2, TiO2:N(25) and TiO2:N(5):Sm(5) films was 32, 38 and 20 nm, respectively. According to AFM, the undoped TiO2 film consisted of agglomerates with a size of 30-200 nm. N-doping (25 at%) transformed the agglomerates into individually distinctive grains with a size of ca. 30 nm, while Sm doping (5 at%) caused a significant decrease in the average diameter of the agglomerates to ca. 100 nm. The RMS roughness of the undoped TiO2 film was 1.7 nm; doping resulted in the formation of smoother films with RMS roughness of 0.9-1.4 nm. XPS data indicated that the Sm and N dopants were incorporated into the TiO2 crystal lattice and/or adsorbed on the surface of the film. An increasing nitrogen concentration in the spray solution correlates to a systematic suppressing of the photoluminescence intensity of Sm3+.

Oja Acik, I.; Kiisk, V.; Krunks, M.; Sildos, I.; Junolainen, A.; Danilson, M.; Mere, A.; Mikli, V.

2012-11-01

43

Heterogeneous photocatalytic decomposition of benzene on lanthanum-doped TiO2 film at ambient temperature.  

PubMed

Lanthanum-doped anatase TiO2 thin films on glass prepared via a sol-gel process have been shown to have much higher photocatalytic activity for the degradation of gaseous benzene than pure anatase TiO2 thin film. The photodecomposition of benzene on both types of TiO2 films follows the first-order kinetics while the CO(2) and CO formation followed the zero-order kinetics. GC/MS identification of the intermediates produced during the photodegradation of benzene revealed that doping lanthanum into TiO2 thin film favors a cleavage of benzene ring. An optimal lanthanum amount with respect to photocatalytic activity was about 2.5 wt% (La2O3/TiO2). PMID:16814365

Zhang, Shicheng; Zheng, Zhijian; Wang, Jinhe; Chen, Jianmin

2006-06-30

44

X-Ray Diffraction, FTIR, and NMR Characterization of Sol–Gel Alumina Doped with Lanthanum and Cerium  

Microsoft Academic Search

Alumina doped with La and Ce was prepared by using the sol–gel technique. The doping concentrations were alternatively 2 and 5 wt% for each element. Samples were characterized as a function of temperature by using X-ray powder diffraction and FTIR spectroscopy. MAS-NMR studies showed that lanthanum and cerium interacted with alumina and produced a compound with aluminum ions in tetrahedral

A. Vazquez; T. López; R. Gómez; Bokhimi; A. Morales; O. Novaro

1997-01-01

45

Influence of lanthanum doping on the dielectric, ferroelectric and relaxor behaviour of barium bismuth titanate ceramics  

NASA Astrophysics Data System (ADS)

Barium lanthanum bismuth titanate (Ba1-(3/2)xLaxBi4Ti4O15, x = 0-0.4) ceramics were fabricated using the powders synthesized via the solid-state reaction route. X-ray powder diffraction analysis confirmed the above compositions to be monophasic and belonged to the m = 4 member of the Aurivillius family of oxides. The effect of the partial presence of La3+ on Ba2+ sites on the microstructure, dielectric and relaxor behaviour of BaBi4Ti4O15 (BBT) ceramics was investigated. For the compositions pertaining to x <= 0.1, the dielectric constant at both room temperature and in the vicinity of the temperature of the dielectric maximum (Tm) of the parent phase (BBT) increased significantly with an increase in x while Tm remained almost constant. Tm shifted towards lower temperatures accompanied by a decrease in the magnitude of the dielectric maximum (?m) with an increase in the lanthanum content (0.1 < x <= 0.4). The dielectric relaxation was modelled using the Vogel-Fulcher relation and a decrease in the activation energy for frequency dispersion with increasing x was observed. The frequency dispersion of Tm was found to decrease with an increase in lanthanum doping, and for compositions corresponding to x >= 0.3, Tm was frequency independent. Well-developed P(polarization)-E(electric field) hysteresis loops were observed at 150 °C for all the samples and the remanent polarization (2Pr) was improved from 6.3 µC cm-2 for pure BBT to 13.4 µC cm-2 for Ba0.7La0.2Bi4Ti4O15 ceramics. Dc conductivities and associated activation energies were evaluated using impedance spectroscopy.

Kumar, Sunil; Varma, K. B. R.

2009-04-01

46

Relaxor properties of lanthanum-doped bismuth layer-structured ferroelectrics  

NASA Astrophysics Data System (ADS)

Several polycrystalline samples of bismuth layer-structured ferroelectrics (BLSF) family doped by lanthanum, Bi4-xLaxTi3O12, SrBi4-xLaxTi4O15, Sr2Bi4-xLaxTi5O18, and (Bi,La)4Ti3O12-Sr(Bi,La)4Ti4O15, were prepared by the traditional solid-state reaction method. Their ferroelectric and dielectric properties were investigated. The dielectric measurement data showed that the content of lanthanum determined the ferroelectric characteristics of the compounds. In each series samples, they behaved as normal ferroelectrics for small x, but all of them tended to become relaxors when x was increased. The critical value of the La content causing relaxor characteristics is different for the different BLSFs due to the difference of the number of strontium atoms in their crystal structures. The appearance of the relaxor behavior was attributed to a ferroelectric microdomain state induced by random fields.

Chen, Xiao-Bing; Hui, Rong; Zhu, Jun; Lu, Wang-Ping; Mao, Xiang-Yu

2004-11-01

47

Cathodic polarization of strontium-doped lanthanum ferrite in proton-conducting solid oxide fuel cell  

Microsoft Academic Search

The cathodic polarization of strontium-doped lanthanum ferrite, La1?xSrxFeO3??, was studied in the hydrogen–oxygen fuel cell using proton-conducting SrCe0.95Yb0.05O3?? as an electrolyte. The overpotential of La0.7Sr0.3FeO3?? cathode was smaller than those of other perovskite-type oxides such as La0.7Sr0.3MnO3?? and La0.7Sr0.3CoO3??, and platinum at 773–973 K. The best cathodic performance was obtained for La0.7Sr0.3FeO3?? heat-treated at 1173 K. The cathode resistance of

Hiroyuki Yamaura; Tetsuya Ikuta; Hidenori Yahiro; Genji Okada

2005-01-01

48

Copper Doped Lanthanum Strontium Ferrite for Reduced Temperature Solid Oxide Fuel Cells  

SciTech Connect

Copper doped lanthanum strontium ferrite showed superior kinetics for the electro-reduction of oxygen. The generic formulation was La1xSrxCu1yFeyO3 (LSCuF) where x ranged from 0.2 to 0.3 and y varied from 0 to 0.4. Doping with copper improved the electrocatalytic activity compared with undoped material. In oxygen, the La0.7Sr0.3Cu0.2Fe0.8O3 sample showed current densities approximately 2–3 times that of La0.7Sr0.3FeO3 and 10 times that of La0.8Sr0.2FeO3. This improvement was confirmed with cyclic voltammetric studies on half cells and on full fuel cell tests. Copper doped materials have unusual electrochemical characteristics and copper apparently undergoes a one electron reduction at overpotentials less than *0.1 V. This occurred only in air but not in oxygen.

Coffey, Greg W.; Hardy, John S.; Marina, Olga A.; Pederson, Larry R.; Rieke, Peter C.; Thomsen, Ed C.

2004-11-30

49

Intrinsic creep resistance of two solid oxygen fuel cell electrolytes: Cubic zirconia versus doped lanthanum gallate. Interim report, December 1998--January 1999  

SciTech Connect

Knowledge of the creep parameters for cubic zirconia and doped lanthanum gallate allowed for a determination of the intrinsic creep resistance of each material in the temperature range from 800 to 1000 deg C, where they are to be utilized as electrolytes in solid oxygen fuel cells. The results revealed that the intrinsic creep resistance of cubic zirconia is much higher than that of doped lanthanum gallate. This is most likely a result of their different crystal structures.

Wolfenstine, J.

1999-03-01

50

Samarium doped ceria–(Li\\/Na) 2CO 3 composite electrolyte and its electrochemical properties in low temperature solid oxide fuel cell  

Microsoft Academic Search

A composite of samarium doped ceria (SDC) and a binary carbonate eutectic (52mol% Li2CO3\\/48mol% Na2CO3) is investigated with respect to its morphology, conductivity and fuel cell performances. The morphology study shows the composition could prevent SDC particles from agglomeration. The conductivity is measured under air, argon and hydrogen, respectively. A sharp increase in conductivity occurs under all the atmospheres, which

Jing Di; Mingming Chen; Chengyang Wang; Jiaming Zheng; Liangdong Fan; Bin Zhu

2010-01-01

51

Top electrode-dependent resistance switching behaviors of lanthanum-doped ZnO film memory devices  

NASA Astrophysics Data System (ADS)

Lanthanum-doped ZnO (Zn0.99La0.01O) polycrystalline thin films were deposited on Pt/Ti/SiO2/Si substrates by a chemical solution deposition method. Metal/La-doped ZnO/Pt sandwich structures were constructed by depositing different top electrodes (Ag and Pt). Unipolar switching and bipolar switching characteristics were investigated in Pt/La-doped ZnO/Pt and Ag/La-doped ZnO/Pt structures, respectively. Compared with the undoped devices (Pt/ZnO/Pt and Ag/ZnO/Pt), the La-doped devices exhibits superior resistive switching performances, such as narrow distribution of the resistive switching properties (R ON, R OFF, V Set, and V Reset), higher R OFF/R ON ratio and sharp switching transition.

Xu, Dinglin; Xiong, Ying; Tang, Minghua; Zeng, Baiwen

2013-10-01

52

Effects of calcination on microscopic and mesoscopic structures in Ca and Sr-doped nano-crystalline lanthanum chromites  

Microsoft Academic Search

Calcination behavior of nano-crystalline lanthanum chromites doped with calcium and strontium has been probed by Fourier transform infrared spectroscopy, X-ray diffraction and small-angle neutron scattering as a function of temperature. Infrared spectroscopic results imply that over a range of temperatures, some intermediate phase of dopant chromates evolve and then dissolve back, which has also been confirmed by the XRD. Neutron

Himal Bhatt; J. Bahadur; M. N. Deo; S. Ramanathan; K. K. Pandey; D. Sen; S. Mazumder; Surinder M. Sharma

2011-01-01

53

Low-temperature proton spin lattice relaxation maxima of lanthanum hydrides doped with paramagnetic rare earth ions  

NASA Astrophysics Data System (ADS)

The low-temperature proton spin-lattice relaxation is analysed for lanthanum hydrides LaHx intentionally doped with Gd or Ce. These paramagnetic impurities were also characterized by static magnetic susceptibility and electron spin resonance measurements. A quantitative description of the proton relaxation rate maxima, as well as of the electron spin relaxation data, is presented. These analyses indicate that the density of states at the rare earth site disappears only for x \\gtrsim 2.9 .

Leyer, S.; Barnes, R. G.; Buschhaus, C.; Fischer, G.; Pilawa, B.; Pongs, B.; Tinner, A.; Dormann, E.

2004-09-01

54

Effect of rare earth doping on thermo-physical properties of lanthanum zirconate ceramic for thermal barrier coatings  

Microsoft Academic Search

The effect of rare earth doping on thermo-physical properties of lanthanum zirconate was investigated. Oxide powders of various compositions La2Zr2O7 were synthesized by coprecipitation-calcination method. High-temperature dilatometer, DSC, and laser thermal diffusivity methods were used to analyze thermal expansion coefficient (TEC), specific heat, and thermal diffusivity. The results showed that CeO2 doped pyrochlores La2(Zr1.8Ce0.2)2O7 and La1.7(DyNd)0.15(Zr0.8Ce0.2)2O7 had higher TEC than

Hongming ZHOU; Danqing YI

2008-01-01

55

Magnetocaloric effect in potassium doped lanthanum manganite perovskites prepared by a pyrophoric method.  

PubMed

The magnetocaloric effect (MCE) in fine grained perovskite manganites of the type La(1-x)K(x)MnO(3) (0lanthanum manganite enhances the Curie temperature (T(C)) of the system from 260.4 K (x = 0.05) to 309.7 K (x = 0.15). A large magnetic entropy change associated with the ferromagnetic-paramagnetic transition has been observed. The maximum entropy change |?S(M)(Max)| in an applied field of 1 T shows an enhancement by ?10% with increase in K content up to x = 0.15. La(0.85)K(0.15)MnO(3) exhibits the largest |?S(M)(Max)| value of 3.00 J kg(-1) K(-1) at 310 K amongst the compounds investigated. Moreover, the maximum magnetic entropy change exhibits a linear dependence with applied magnetic field. The estimated adiabatic temperature change at T(C) and at 1 T field also increases with K doping, being a maximum of 2.1 K for the La(0.85)K(0.15)MnO(3) compound. The relative cooling power (RCP) of La(1-x)K(x)MnO(3) compounds is estimated to be about one-third of that of the prototype magnetic refrigerant material (pure Gd). However, La(1-x)K(x)MnO(3) compounds possess an MCE around room temperature, which is comparable to that of Gd. Further, tailoring of their T(C), higher chemical stability, lower eddy current heating and lower cost of synthesis are some of the attractive features of K doped lanthanum manganites that are advantageous for a magnetic refrigerant. The temperature dependence of the magnetic entropy change (?S(M)) measured under various magnetic fields is explained fairly well using the Landau theory of phase transitions. Contributions of magnetoelastic and electron interaction are found to have a strong influence in the magnetocaloric effect of manganites. PMID:21690875

Das, Soma; Dey, T K

2006-07-31

56

Intense Red Catho- and Photoluminescence from 200 nm Thick Samarium Doped Amorphous AlN Thin Films  

NASA Astrophysics Data System (ADS)

Samarium (Sm) doped aluminum nitride (AlN) thin films are deposited on silicon (100) substrates at 77 K by rf magnetron sputtering method. Thick films of 200 nm are grown at 100-200 watts RF power and 5-8 m Torr nitrogen, using a metal target of Al with Sm. X-ray diffraction results show that films are amorphous. Cathodoluminescence (CL) studies are performed and four peaks are observed in Sm at 564, 600, 648, and 707 nm as a result of 4G5/2 ? 6H5/2, 4G5/2 ? 6H7/2, 4G5/2 ? 6H9/2, and 4G5/2 ? 6H11/2 transitions. Photoluminescence (PL) provides dominant peaks at 600 and 707 nm while CL gives the intense peaks at 600 nm and 648 nm, respectively. Films are thermally activated at 1,200 K for half an hour in a nitrogen atmosphere. Thermal activation enhances the intensity of luminescence.

Maqbool, Muhammad; Ali, Tariq

2009-07-01

57

Rietveld analysys and electrical properties of lanthanum doped BiFeO 3 ceramics  

Microsoft Academic Search

Lanthanum-modified bismuth ferrite ceramics, Bi1?xLaxFeO3 (BLFO), with x ranging from 0 to 0.30 were obtained using a polymeric precursor solution. Orthorhombicity of the system raised with the increase of lanthanum content in the BFO crystal lattice. No secondary phases were evident after lanthanum addition. This study underlines the role of the preparation route on the structural and morphological characteristic of

A. Z. Simões; Filiberto Gonzalez Garcia; Carla dos Santos Riccardi

2009-01-01

58

Fission gas transport and its interactions with irradiation-induced defects in lanthanum doped ceria  

NASA Astrophysics Data System (ADS)

To help understand the mechanisms of irradiation-induced defect formation and evolution in nuclear fuel, systematic experimental efforts have been carried out. Ceria (CeO2) was selected as a surrogate material for Uranium Dioxide (UO2) due to many similar properties. Lanthanum (La) was chosen as a dopant in CeO2 to investigate the effect of impurities. The presence of La in the CeO2 lattice introduces a predictable initial concentration of oxygen vacancies, making it possible to characterize hypostoichiometric effects in CeO2. The influence of two La concentrations, 5% and 25%, were examined.In situ Transmission Electron Microscopy (TEM) experiments were used to study the evolution of defect clusters and the influence of irradiation with two common fission products: Xe and Kr. The irradiations were performed on thin film, single crystal materials. The irradiation damage caused formation of dislocation loopsat 600 °C and defect clusters at room temperature. Dislocation networks form as the result of interactions of defect clusters. The dislocation loops were determined to be mainly of 1/9[1 1 1] interstitial type loops. Quantitative results were obtained to characterize the fluence and temperature effects of irradiation. Slow defect kinetics were found with irradiation on 25% La doped CeO2 at 600 °C and it is attributed to the higher concentration of oxygen vacancies due to high La dopant level.

Yun, D.; Ye, B.; Oaks, A. J.; Chen, W.; Kirk, M. A.; Rest, J.; Yacout, A. M.; Stubbins, J. F.

2012-02-01

59

Temperature behavior of dielectric and piezoelectric properties of samarium-doped lead titanate ceramics  

Microsoft Academic Search

The dielectric and electromechanical coupling properties of Sm-doped and Mn-doped PbTiO3 ceramics were investigated from 4.2 to 300 K. The upper and lower limits of the ceramic dielectric and piezoelectric properties were calculated by averaging the single-domain constants that were determined from a phenomenological theory. Comparisons of the measured and calculated properties were then made. The measured dielectric permittivity ?T33

J. N. Kim; MICHAEL J. HAUN; SEI JOO JANG; L. E. Cross; X. R. Xue

1989-01-01

60

Nuclear Magnetic Resonance Studies of Pure and Samarium-Doped CAF2 Crystals.  

National Technical Information Service (NTIS)

The spin-lattice relaxation time T1 of Fluorine-19 was measured over a temperature range of 77 to 1300K in natural and synthetic CaF2 crystals and in CaF2 crystals doped with 0.05% Sm, 0.16% Sm, and 1.20% Sm. Most of the data was taken with the magnetic f...

R. J. Lysiak P. P. Mahendroo

1965-01-01

61

Doped lanthanum nickelates with a layered perovskite structure as bifunctional cathode catalysts for rechargeable metal-air batteries.  

PubMed

Rechargeable metal-air batteries have attracted a great interest in recent years because of their high energy density. The critical challenges facing these technologies include the sluggish kinetics of the oxygen reduction-evolution reactions on a cathode (air electrode). Here, we report doped lanthanum nickelates (La2NiO4) with a layered perovskite structure that serve as efficient bifunctional electrocatalysts for oxygen reduction and evolution in an aqueous alkaline electrolyte. Rechargeable lithium-air and zinc-air batteries assembled with these catalysts exhibit remarkably reduced discharge-charge voltage gaps (improved round-trip efficiency) as well as high stability during cycling. PMID:24053465

Jung, Kyu-Nam; Jung, Jong-Hyuk; Im, Won Bin; Yoon, Sukeun; Shin, Kyung-Hee; Lee, Jong-Won

2013-09-23

62

Optical Characteristic Improvement of Neodymium-Doped Lanthanum Fluoride Thin Films Grown by Pulsed Laser Deposition for Vacuum Ultraviolet Application  

NASA Astrophysics Data System (ADS)

Neodymium-doped lanthanum fluoride (Nd3+:LaF3) thin films were successfully grown on MgF2(001) substrates by pulsed laser deposition. Photoluminescence spectra revealed a dominant peak at 173 nm with a decay time of 7.8 ns, which is similar to the results obtained from a bulk Nd3+:LaF3 crystal. Improvements in crystalline quality and vacuum ultraviolet (VUV) luminescence quantum efficiency were achieved by substrate heating, with optimum results being obtained at 400 °C. These results would open up possibilities in the development of a light-emitting device operating in the VUV region.

Ieda, Mirai; Ishimaru, Tatsuya; Ono, Shingo; Yamanoi, Kohei; Cadatal-Raduban, Marilou; Shimizu, Toshihiko; Sarukura, Nobuhiko; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

2012-02-01

63

The thermodynamic characteristics of point defects and the mechanism of charge transfer in lanthanum cobaltite doped with strontium and nickel  

Microsoft Academic Search

The specific conductivity and thermal electromotive force (EMF) coefficient of lanthanum cobaltite doped with strontium and\\u000a nickel La0.9Sr0.1Co0.9Ni0.1O3?? were measured over the temperature and pressure ranges 1023–1223 K and 10?6?1 atm. The oxide was found to exhibit metallic-type conductivity (800 ??1 cm?1 ? ? ? 1150 ??1 cm?1) and small positive thermal EMF coefficient values. A joint analysis of the

A. N. Petrov; V. A. Cherepanov; T. V. Aksenova; L. Ya. Gavrilova

2006-01-01

64

Site-selective 900 nm quasi-three-level laser emission in Nd-doped strontium lanthanum aluminate  

Microsoft Academic Search

Neodymium-doped strontium lanthanum aluminate crystals Sr1-xLax-yNdyMgxAl12-xO19 contain two structural Nd centers with slightly different spectroscopic properties, whose proportion is determined by the composition parameter x. By choosing a composition with x=0.4, which grants the dominance of one of these centers (the center C1), whose properties are suitable for quasi-three-level Nd laser scheme, efficient 901 nm continuous-wave laser emission (slope efficiency

G. Aka; D. Vivien; V. Lupei

2004-01-01

65

Exchange bias and its tuning in magnetic compensated Nd doped ferromagnetic samarium metal  

NASA Astrophysics Data System (ADS)

Sm metal is a ferromagnet with a very small net magnetization as it comprises nearly compensated local moment (4f-orbital moment slightly greater than the 4f-spin moment) which is coupled to conduction electrons via RKKY exchange mechanism and results in antiferromagnetically coupled alignment between total local moment and the contribution from conduction electron polarization. Ferromagnetic Sm metal is considered to be in spin surplus state, as it yields magnetic compensation on doping with RE-ions (e.g., Nd) belonging to the first half of 4f-series. The results pertaining to identification and tuning of the exchange bias (EB) field in Nd doped Sm metal are presented.

Pandya, Swati; Ramakrishnan, S.; Grover, A. K.

2013-02-01

66

Effect of samarium doping on the properties of solid-state synthesized multiferroic bismuth ferrite  

Microsoft Academic Search

Problems in the synthesis of phase-pure BiFeO3, a multiferroic material, are well known and presence of other phases often leads to inferior properties. Work reported here was carried out to obtain pure phase BiFeO3 via a solid-state-reaction method in both pure and Sm-doped form. X-ray diffraction (XRD) of the calcined undoped samples showed that maximum amount of pure BiFeO3 phase

K. S. Nalwa; A. Garg; A. Upadhyaya

2008-01-01

67

Determination of the variation of the fluorescence line positions of ruby, strontium tetraborate, alexandrite, and samarium-doped yttrium aluminum garnet with pressure and temperature  

NASA Astrophysics Data System (ADS)

The pressure and temperature dependent fluorescence line-shift of strontium tetraborate has been measured concurrently with x-ray diffraction from the pressure standards sodium chloride or gold. Temperature was found to have a small effect on the fluorescence line-shift under pressure. We found a maximum pressure uncertainty of +/-1.8 GPa at 25 GPa (7.2%) and 857 K when making no temperature correction. The fluorescence line-shifts for ruby, Alexandrite, and samarium-doped yttrium aluminum garnet were also determined, using our strontium tetraborate calibration to determine pressure and a thermocouple to measure temperature. Fluorescence measurements were extended up to 800 K for ruby and Alexandrite. Temperature was found to have a small effect on the fluorescence line-shift of samarium-doped yittrium aluminum garnet. We found a maximum uncertainty of +/-2.7 GPa at 25 GPa (11.1%) and 857 K when no temperature correction was applied. We determined equations relating to the fluorescence line position from these data, which include a cross derivative term to account for the combined effect of pressure and temperature. We present a method to independently determine pressure and/or temperature from combined fluorescence line-shift measurements of a pair of optical sensors.

Raju, Selva Vennila; Zaug, Joseph M.; Chen, Bin; Yan, Jinyuan; Knight, Jason W.; Jeanloz, Raymond; Clark, Simon M.

2011-07-01

68

The effect of Pr co-dopant in samarium doped ceria  

NASA Astrophysics Data System (ADS)

The compositions of Ce0.8-xSm0.2PrxO2-? (x=0, 0.02, 0.04, 0.06) were prepared through the sol-gel route. The effect of Pr addition on the crystal structure, densification and thermal expansion of Ce0.8Sm0.2O2-? was studied. The powder X-ray diffraction (XRD) analysis showed that all the samples exhibit a fluorite structure. The lattice parameters and volume of the unit cell increase with Pr doping. Density of all the samples is more than 90% of theoretical density. The thermal expansion was measured using dilatometric technique in the temperature range 30-1000°C and it was observed that the thermal expansion increased linearly with increasing temperature for all the samples.

Venkatesh, V.; Kumar, V. Prashanth; Reddy, Y. S.; Reddy, C. Vishnuvardhan

2013-02-01

69

Optical and transport properties of lanthanum-doped stannate BaSnO3  

NASA Astrophysics Data System (ADS)

BaSnO3 crystallizes in a cubic perovskite structure and exhibits insulating behaviour. It can be made conducting by reducing a small fraction of Sn4+ into Sn2+ under an O2-free atmosphere. This can be achieved through the solid solution Ba1-xLaxSnO3-? which is a mixed phase for x > 0.02, behaviour readily understood in terms of the lone pair cation Sn2+. The magnetic susceptibility was measured down to 4.2 K and is less than 1.7 × 10-5 emu cgs mol-1 consistent with collective electron behaviour. The Mössbauer spectrum exhibits a wide unsplit peak with a quadrupole doublet of 3.18 mm s-1 and an isomer shift of 0.12 mm s-1 characteristic of Sn4+and corroborating the delocalization of the stereo chemical pair 5s2. The band gap Eg was found to be 3.12 eV; further indirectly allowed inter-band transition occurs at 2.85 eV. The transport properties of Ba0.98La0.02SnO3-? indicate n-type conductivity (?300 K = 4.03 ?-1 cm-1), little temperature dependence, with an activation energy ?E of ~1 meV and an electron mobility ?300 K ~ 0.1 cm2 V-1 s-1, thermally activated. The conduction occurs by small polaron hopping between mixed valence Sn4+/2+ ions. The observed conductivity is greater than that coming from La-substitution with one-electron doping implying the existence of oxygen vacancies. The electrons are believed to travel in the Sn-5s conduction band with an effective mass of 3.7 mo. The non-linear dependence of Ln ? versus T-1 at low temperatures could result from a predominant variable range hopping as suggested by the linear variation of log ? versus T-0.25. The electron localization may be attributed to the random distribution of lanthanum as well as oxygen vacancies.

Hadjarab, B.; Bouguelia, A.; Trari, M.

2007-10-01

70

Phase Stability Analysis of Lanthanum-Doped Alumina During Synthesis and Sintering  

NASA Astrophysics Data System (ADS)

The aim of this research was to study the phase stability during synthesis and consolidation of nanocrystalline lanthanum-doped gamma-Al2O 3 powders. We used solution combustion synthesis by dissolving precursor nitrate compounds and an organic fuel in a pre-heated muffle furnace at 500°C. Several preliminary syntheses were carried out in order to obtain the correct fuel-to-oxidizer ratio necessary for the production of the desired lanthanum-doped gamma-Al 2O3. The as-synthesized powders were then heat-treated at 1000°C for 2 hours in order to remove impurities and improve the crystallinity of the powders. Sintered circular specimens were made by pressing the heat-treated powders and subsequently annealing them at 1800°C for 4 hours. The use of this material in optical windows requires that the material have high strength and optical transparency. Elimination of all the pores during sintering is therefore crucial. In addition, preparing specimens of the gamma-Al2O3 phase is optimal, since the crystal structure is cubic and transparency is more readily achievable. Several different samples with varying weight percents of La were attempted to determine how much of the La could effectively prevent the gamma-Al2O 3 phase from transforming into the more stable alpha-Al2O 3 phase. The different phases of compounds produced with increasing amounts of La were also identified. The as-synthesized and heat-treated powders as well as the annealed circular discs were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The average particle sizes of the powders were determined by dynamic light scattering (DLS). XRD experiments showed that the gamma-alumina phase was stabilized when the powders were calcined at 1000°C with 5 wt% La, 10 wt% La and 13 wt% La. Increasing the amount of La resulted in the formation of the La compounds LaAlO3 in the heat-treated powders containing 15 wt% La and above and LaAl11O18 in the sintered specimens. Crystallite sizes of the heat-treated powders were determined from the XRD line profile analysis of the peaks and were less than 50 nm for the heat-treated powders. Dynamic light scattering experiments were carried out to analyze the average particle sizes of the as-synthesized powders as well as the powders heat treated at 1000°C for two hours. In all the DLS plots for the as-synthesized powders, particle sizes were less than 500 nm, while some of the heat-treated powders had sizes greater than 500 nm, and some even greater than 1 mum. The average particle sizes are considerably larger than the crystallite sizes because particles are generally formed from the agglomeration of crystallites and will therefore have larger sizes. SEM was done to analyze the morphology of the heat-treated powders as well as the sintered specimens. Only the specimens that contained 5 wt% La and 44.4 wt% La (the lowest and highest amounts, respectively) were analyzed, since the microstructures of the specimens with intermediate La amounts do not change much from each other. It was seen from the micrographs that the heat-treated powders were agglomerated. The SEM pictures of the 5 wt% La and 44.4 wt% La specimens showed that both specimens had grains which adopted a more or less hexagonal shape, and this was more defined in the Al2 O3:44.4 wt% La specimen since it contained a larger amount of the secondary phase LaAl11O18 which has a hexagonal structure. Both specimens contained pores at the triple points of the grains as well as internal porosity. The Al2O3:5 wt% La specimens had larger grain sizes ranging from ~2.0 mum to 17 mum compared to the ~2.0 mum to 3.0 mum grain sizes for the Al2O3:44.4 wt% La specimens. This observation could probably be due to the effect of particle pinning which occurs when a specimen has secondary particles in its microstructure that pins or hinders the growth of grains. Density measurements were done using the Archimedes' method. The percent densities of all sintered specimens were above 80% of the theoretical densities. Theoretical densities were calculated for ea

Ngwa Nforbi, Lum-Ngwegia

71

Investigations of lanthanum doping on magnetic properties of nano cobalt ferrites  

Microsoft Academic Search

The magnetic properties of nano-crystallite cobalt lanthanum ferrite (CoLaxFe2-x O4) with varied quantities of lanthanum (x?=?0, 0.1, 0.15, 0.2, 0.25, 0.3) prepared by co-precipitation method have been studied by vibrating sample magnetometer (VSM)\\u000a and LCR meter. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the size, structure, and morphology\\u000a of the ferrite samples. The average crystallite size varied from

Pawan Kumar; S. K. Sharma; M. Knobel; Jagdish Chand; M. Singh

72

Dielectric properties and substitution mechanism of samarium-doped Ba{sub 0.68}Sr{sub 0.32}TiO{sub 3} ceramics  

SciTech Connect

Ba{sub 0.68}Sr{sub 0.32}TiO{sub 3} ceramics of perovskite structure are prepared by solid state reaction method with addition of x mol% Sm{sub 2}O{sub 3}, and their dielectric properties are investigated. It is found that, integrating with the lattice parameters and tolerance factor t, there is an alternation of substitution preference of Sm{sup 3+} for the host cations in perovskite lattice. Owing to the replacement of Sm{sup 3+} ions for Ba{sup 2+} ions in the A site, T{sub c} rises with the increase of Sm{sub 2}O{sub 3} doping when the doping content is below 0.1 mol%; meanwhile, when the content is more than 0.1 mol%, Sm{sup 3+} ions tend to occupy the B-site, causing a drop of T{sub c}. Owing to the modifications of Sm{sup 3+} doping, dielectric constant, dissipation factor and temperature stability of dissipation factor are influenced remarkably, making it a superior candidate for environment-friendly applications. Moreover, the creation of oxygen vacancies controls the dielectric constant when the addition is above 0.1 mol%, so the dielectric constant decreases with increasing of samarium.

Li Yuanliang [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)], E-mail: lylll2007@yahoo.cn; Qu Yuanfang [Key Laboratory for Advanced Ceramics and Machining Technology of Ministry of Education, Tianjin University, Tianjin 300072 (China)

2009-01-08

73

Electronic structure and photocatalytic water splitting of lanthanum-doped Bi{sub 2}AlNbO{sub 7}  

SciTech Connect

Bi{sub 2-x}La{sub x}AlNbO{sub 7} (0 {<=} x {<=} 0.5) photocatalysts were synthesized by the solid-state reaction method and characterized by powder X-ray diffraction (XRD), infrared (IR) spectra and ultraviolet-visible (UV-vis) spectrophotometer. The band gaps of the photocatalysts were estimated from absorption edge of diffuse reflectance spectra, which were increased by the doping of lanthanum. It was found from the electronic band structure study that orbitals of La 5d, Bi 6p and Nb 4d formed a conduction band at a more positive level than Bi 6p and Nb 4d orbitals, which results in increasing the band gap. Photocatalytic activity for water splitting of Bi{sub 1.8}La{sub 0.2}AlNbO{sub 7} was about 2 times higher than that of nondoped Bi{sub 2}AlNbO{sub 7}. The increased photocatalytic activity of La-doped Bi{sub 2}AlNbO{sub 7} was discussed in relation to the band structure and the strong absorption of OH groups at the surface of the catalyst.

Li Yingxuan [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China); Chen Gang [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)], E-mail: gchen@hit.edu.cn; Zhang Hongjie; Li Zhonghua [Department of Applied Chemistry, Harbin Institute of Technology, Harbin 150001 (China)

2009-04-02

74

Preparation and characterization of TiO 2 photocatalysts co-doped with iron (III) and lanthanum for the degradation of organic pollutants  

Microsoft Academic Search

Titanium dioxide photocatalysts co-doped with iron (III) and lanthanum were prepared by a facile sol–gel method. The structure of catalysts was characterized by X-ray diffraction (XRD), Raman spectroscopy, UV–vis diffuse reflectance spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activities of the samples were evaluated by the degradation of methylene blue in aqueous solutions under visible light (?>420nm) and UV

Qiangqiang Wang; Shihua Xu; Fenglei Shen

2011-01-01

75

Oxide ion conductivity of double doped lanthanum gallate perovskite type oxide  

Microsoft Academic Search

Doping transition metal cation is known to enhance the electronic conduction of solid electrolytes, however, the ionic conduction\\u000a can also be improved by those dopants. In this investigation, the oxide ion conductivity of LaGaO3 based oxide doped with transition metal cations such as Fe, Co, Ni, Mn, and Cu for the Ga site was studied. It was found\\u000a that doping

T. Ishihara; H. Furutani; T. Yamada; Y. Takita

1997-01-01

76

Effects of magnetization on hole localization and MnO{sub 6} octahedra disorder in hole-doped lanthanum manganese perovskites  

SciTech Connect

The authors review the distortions of the MnO{sub 6} octahedra reduced by magnetization in hole-doped lanthanum manganese perovskites. The systems they consider include the colossal magnetoresistance (CMR) samples La{sub 1{minus}x}Ca{sub x}MnO{sub 3} (x = 0.21, 0.25, 0.30), La{sub 0.76}Ba{sub 0.33}MnO{sub 3}, and a poorer quality La{sub 0.76}Pb{sub 0.33}MnO{sub 3} sample. They also report preliminary work on three samples of oxygen-doped LaMnO{sub 3+{delta}} and a lanthanum-deficient La{sub 0.9}MnO{sub 3} sample. They find the same exponential relationship between the removal of the distortion and the sample magnetization in the Ba- and Pb-doped CMR samples as was found previously for the Ca doped samples. The MnO{sub 6} distortion in the oxygen-doped materials is found to slightly reduce below the magnetic transition, although much less so than in the CMR samples. Above T{sub C}, the antiferromagnetic LaMnO{sub 3.006} sample shows a softer temperature dependence of the Mn-O bond length distribution broadening. Surprisingly, even this sample shows deviations from thermal (Debye) behavior near T{sub N}, possibly due to FM coupling within MnO planes.

Booth, C.H.; Brosha, E.L.; Kwei, G.H. [Los Alamos National Lab., NM (United States); Bridges, F. [Univ. of California, Santa Cruz, CA (United States). Physics Dept.; Neumeier, J.J. [Florida Atlanta Univ., Boca Raton, FL (United States). Physics Dept.

1998-12-31

77

Solid oxide fuel cells with doped lanthanum gallate electrolyte and LaSrCoO{sub 3} cathode, and Ni-samaria-doped ceria cermet anode  

SciTech Connect

The electrode performance of a single solid-oxide fuel cell (SOFC) was evaluated using a 500 {micro}m thick La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}O{sub 0.3} (LSGM) as the electrolyte membrane. A doped lanthanum cobaltite, La{sub 0.6}Sr{sub 0.4}CoO{sub 3{minus}{delta}} was selected as the cathode material, and a samaria-doped ceria-NiO composite powder was used as the anode material. The spray-pyrolysis method was applied for synthesis of the starting powders of the cathode and anode. In this study, different microstructures of the cathode were obtained by varying the sintering temperature from 950 to 1200 C. High power density (the maximum power density of the cell was about 425 mW/cm{sup 2}, which is 95% of the theoretical value) of the solid oxide fuel cell at 800 C was achieved. The cell performance showed that, with a proper choice of electrode materials with optimized microstructure and LSGM as the electrolyte, a SOFC operating at temperatures T{sub op} {le} 800 is a realistic goal.

Maric, R.; Ohara, Satoshi; Fukui, Takehisa [Japan Fine Ceramics Center, Nagoya (Japan); Yoshida, Hiroyuki; Nishimura, Masayoshi; Inagaki, Toru [Kansai Electric Power Co., Inc., Hyogo (Japan); Miura, Kazuhiro [Kanden Kakou Co., Ltd., Hyogo (Japan)

1999-06-01

78

Combined Magnetic Phase Diagram of Cation and Anion doped Lanthanum Cuprates  

Microsoft Academic Search

We have studied doping dependences of antiferromagnetic (AF) transition temperature TN in La2CuO4+deltafor 0 < delta< 0.01. For delta< 0.005, we have observed and stabilized a weak ferromagnetic-like anomaly that appears right before TN. The suppression of TN due to doped holes is identical to that in La2-xSrxCuO4 for 0< x 0.005, we observed a phase separation into a TN

Zheng Wu

2005-01-01

79

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer  

DOEpatents

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO.sub.3 particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO.sub.3 particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr.sub.2 O.sub.3 on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO.sub.3 layer coated with CaO and Cr.sub.2 O.sub.3 surface deposit at from about 1000.degree. C. to 1200.degree. C. to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO.sub.3 layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power.

Singh, Prabhakar (Export, PA); Ruka, Roswell J. (Pittsburgh, PA)

1995-01-01

80

Method and closing pores in a thermally sprayed doped lanthanum chromite interconnection layer  

DOEpatents

A dense, substantially gas-tight electrically conductive interconnection layer is formed on an air electrode structure of an electrochemical cell by (A) providing an air electrode surface; (B) forming on a selected portion of the electrode surface, a layer of doped LaCrO{sub 3} particles doped with an element or elements selected from Ca, Sr, Ba, Mg, Co, Ni, Al and mixtures thereof by thermal spraying doped LaCrO{sub 3} particles, either by plasma arc spraying or flame spraying; (C) depositing a mixture of CaO and Cr{sub 2}O{sub 3} on the surface of the thermally sprayed layer; and (D) heating the doped LaCrO{sub 3} layer coated with CaO and Cr{sub 2}O{sub 3} surface deposit at from about 1,000 C to 1,200 C to substantially close the pores, at least at a surface, of the thermally sprayed doped LaCrO{sub 3} layer. The result is a dense, substantially gas-tight, highly doped, electrically conductive interconnection material bonded to the electrode surface. A solid electrolyte layer can be applied to the nonselected portion of the air electrode. A fuel electrode can be applied to the solid electrolyte, to form an electrochemical cell, for example for generation of electrical power. 5 figs.

Singh, P.; Ruka, R.J.

1995-02-14

81

Study of specific absorption rate of strontium doped lanthanum manganite nanoparticles for self-controlled hyperthermia applications  

NASA Astrophysics Data System (ADS)

Magnetic and magnetothermal properties of strontium doped lanthanum manganite La1-xSrxMnO3 nanoparticles have been studied with the strontium concentration x varying between 0.15 and 0.45. La1-xSrxMnO3 nanoparticles were prepared by the citrate gel route. XRD results show that all samples exhibit the characteristic perovskite structure with average particle sizes between 33 and 44 nm. Adiabatic magnetothermia measurements were carried out in an RF magnetic field of 800 A/m and 214 kHz. Both magnetic and thermomagnetic behaviors are governed by the strontium content of the samples. The saturation magnetization, Curie temperature and specific absorption rate (SAR) vary non-monotonically with x. The SAR of the nanoparticles has been calculated using the linear response theory and good agreement with the experimental data has been observed. The intrinsic loss power (ILP) has been obtained from the SAR values. ILP values of our samples are comparable to those of magnetite.

Rashid, Amin ur; Ahmed, Ashfaq; Ahmad, S. N.; Shaheen, S. A.; Manzoor, Sadia

2013-12-01

82

Preparation and photocatalytic activity of magnetic samarium-doped mesoporous titanium dioxide at the decomposition of methylene blue under visible light  

NASA Astrophysics Data System (ADS)

Preparation of samarium-doped mesoporous titanium dioxide (Sm/MTiO2) coated magnetite (Fe3O4) photocatalysts (Sm/MTiO2/Fe3O4) and their activities under visible light were reported. The catalysts with Sm/MTiO2 shell and a Fe3O4 core were prepared by coating photoactive Sm/MTiO2 onto a magnetic Fe3O4 core through the hydrolysis of tetrabutyltitanate (Ti(OBu)4, TBT) with precursors of Sm(NO3)3 and TBT in the presence of Fe3O4 nanoparticles. The morphological, structural and optical properties of the prepared samples were characterized by BET surface area, transmission electron microscopy (TEM), X-ray diffraction (XRD) and UV-vis absorption spectroscopy. The effect of Sm ion content on the photocatalytic activity was studied. The photocatalytic activities of obtained photocatalysts under visible light were estimated by measuring the decomposition rate of methylene blue (MB, 50 mg/L) in an aqueous solution. The results showed that the prepared photocatalyst was activated by visible light and used as effective catalyst in photooxidation reactions. In addition, the possibility of cyclic usage of the prepared photocatalyst was also confirmed. Moreover, Sm/MTiO2 was tightly bound to Fe3O4 and could be easily recovered from the medium by a simple magnetic process. It can therefore be potentially applied for the treatment of water contaminated by organic pollutants.

Shi, Zhongliang; Lai, Hong; Yao, Shuhua

2012-08-01

83

Dielectric relaxation and alternating current conductivity of polyvinylidene fluoride doped with lanthanum chloride  

NASA Astrophysics Data System (ADS)

X-ray diffraction (XRD), dielectric constant (?'), dielectric loss factor (\\eh''), and ac conductivity (?ac) of pure and LaCl3-doped polyvinylidene fluoride (PVDF) have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 140-450 K and 0.1-1000 kHz, respectively. XRD results reveal that pure and LaCl3-PVDF samples are in the ?-phase. The incorporation of La3+ ions within the PVDF polymer matrix forms complexes which reduce the order structure of PVDF. Three relaxation processes, namely; ?, ?a, and ?c were observed for pure PVDF. The first relaxation can be explained based on space charge formation or Maxwell-Wagner polarization. The second one occurs around the glass transition temperature, Tg, and is related to the micro-Brownian motion of the main polymer chain. It becomes broad and shifted to higher temperatures with the doping of LaCl3. The third process appears below the melting temperature of PVDF and can be attributed to molecular motions of the main polymer chain. The behavior of the ac conductivity shows that the conduction mechanism of pure, 5 wt. % and 10 wt. % of LaCl3-doped PVDF samples is follows the correlated barrier hopping (CBH) model, while 3 wt. % of LaCl3-doped PVDF exhibits a small polaron tunneling (SPT) conduction.

Hassen, A.; Hanafy, T.; El-Sayed, S.; Himanshu, A.

2011-12-01

84

Spin Freezing and Recovery of Sublattice Magnetization in Lightly Doped Lanthanum Cuprate  

SciTech Connect

{sup 139}La NQR studies in lightly doped La{sub 2}Cu{sub 1-x}Li{sub x}O{sub 4} and La{sub 1.8-x}Eu{sub 0.2}Sr{sub x}CuO{sub 4} are reviewed. A strong enhancement of the {sup 139}La relaxation rate with a peak accompanied by a sudden increase of the local field at low T has been observed similarly to La{sub 2-x}Sr{sub x}CuO{sub 4}. The anomalous magnetic properties are discussed in the light of the microscopic segregation of doped holes into hole-rich domain walls separating undoped AF domains.

Suh, B.J.; Hammel, P.C.; Sarrao, J.L.; Thompson, J.D.; Fisk, Z.; Hucker, M.; Buchner, B.

1998-10-24

85

Study of incommensurate phases in Lanthanum-doped zirconium-rich Lead Zirconate Titanate ceramics  

NASA Astrophysics Data System (ADS)

The microstructure and nanostructure of zirconium-rich Pb(Zr,Ti)O3 ceramics doped with small amounts of La which are right at transition between the ferroelectric (FE) and antiferroelectric (AFE) orderings has been examined using Transmission Electron Microscopy (TEM) imaging and diffraction. In this region, the La doping frustrates the formation of simple FE or AFE phases and promotes long period ordered phases (2-3 nm) with ordering along <110> with unit cells incommensurate with the primitive cubic unit cell. We show that the domain structure in these materials is closely related to that previously observed in AFE PbZrO3. Moreover, precision measurements of crystallographic tilts at domain boundaries using Kikuchi diffraction methods also confirms the close relationship to PbZrO3. The domains also contain a nanostructure perpendicular to the long-period ordering direction, but the reasons for the appearance of this nanostructure remain unclear.

Villaurrutia, R.; MacLaren, I.; Peláiz-Barranco, A.

2010-07-01

86

Phase stability and processing of strontium and magnesium doped lanthanum gallate  

Microsoft Academic Search

Fuel Cells are one of the most promising energy transformers with respect to ecological and environmental issues. Solid Oxide Fuel Cells (SOFC) are all solid-state devices. One of the challenges to improve a SOFC is to lower the operating temperature while maintaining or increasing its output voltage. Undoped LaGaO3 is an insulator, doping transforms it into an oxygen-ionic conductor. Sr

Feng Zheng

2000-01-01

87

Electronic Structure of Doped Lanthanum Cuprates Studied with Resonant Inelastic X-Ray Scattering  

SciTech Connect

We report a comprehensive Cu K-edge resonant inelastic x-ray scattering (RIXS) investigation of La{sub 2-x}Sr{sub x}CuO{sub 4} (LSCO) for 0 {le} x {le} 0.35, stripe-ordered La{sub 1.875}Ba{sub 0.125}CuO{sub 4} (LBCO), and La{sub 2}Cu{sub 0.96}Ni{sub 0.04}O{sub 4} (LCNO) crystals. The RIXS spectra measured at three high-symmetry momentum-transfer (q) positions are compared as a function of doping and for the different dopants. The spectra in the energy range 1-6 eV can be described with three broad peaks, which evolve systematically with increased doping. The most systematic trend was observed for q = ({pi},0) corresponding to the zone boundary. As hole doping increased, the spectral weight transfer from high energies to low energies is nearly linear with x at this q. We interpret the peaks as interband transitions in the context of existing band models for this system, assigning them to Zhang-Rice band {yields} upper Hubbard band, lower-lying band {yields} upper Hubbard band, and lower-lying band {yields} Zhang-Rice band transitions. The spectrum of stripe-ordered LBCO was also measured, and found to be identical to the correspondingly doped LSCO, except for a relative enhancement of the near-infrared peak intensity at {approx}1.5-1.7 eV. The temperature dependence of this near-infrared peak in LBCO was more pronounced than for other parts of the spectrum, continuously decreasing in intensity as the temperature was raised from 25 to 300 K. Finally, we find that 4% Ni substitution in the Cu site has a similar effect on the spectra as does Sr substitution in the La site.

Hill, J.P.; Ellis, D.S.; Kim, J.; Zhang, H.; Gu, G.; Komiya, S.; Ando, Y.; Casa, D.; Gog, T.; Kim, Y.-J.

2011-02-24

88

CW blue laser emission by second harmonic generation of 900-nm oscillation of Nd-doped strontium and lanthanum aluminate (ASL)  

NASA Astrophysics Data System (ADS)

Nd-doped strontium and lanthanum (ASL) crystals Sr1-xLax-yNdyMgxAl12-xO19 (0.05 ? x ? 0.5; y = 0.05) were grown by Czochralski pulling technique. Up to 1.67W of 900nm IR output laser power for an absorbed power of 2.53W was obtained under Ti:sapphire pumping at 792nm. Intracavity second harmonic generation experiments led to 320mW of blue laser power at 450nm with a 10mm-long BiB3O6 nonlinear crystal. Other nonlinear crystals were also evaluated such as LBO.

Varona, C.; Loiseau, P.; Aka, G.; Ferrand, B.; Lupei, V.

2006-05-01

89

Dielectric relaxation and alternating current conductivity of lanthanum, gadolinium, and erbium-polyvinyl alcohol doped films  

PubMed Central

Fourier transform infrared (FTIR) spectrum dielectric constant, ??, loss tangent, tan(?), electric modulus, M*, and ac conductivity, ?ac, of pure polyvinyl alcohol (PVA) as well as La-, Gd-, and Er-PVA doped samples have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 300–450?K and 1?kHz–4?MHz, respectively. FTIR measurements reveal that La3+, Gd3+, and Er3+ ions form complex configuration within PVA structure. Two relaxation processes, namely, ? and ? were observed in pure PVA sample. The first process is due to the interfacial or Maxwell-Wagner-Sillers polarization. The second one is related to the micro-Brownian motion of the main chains. For doped PVA samples, ?-relaxation process splits into ?a and ?c. This splitting is due to the segmental motion in the amorphous (?a) and crystalline (?c) phases of PVA matrix. Electric modulus analysis was discussed to understand the mechanism of the electrical transport process. The behavior of ac conductivity for all PVA samples indicates that the conduction mechanism is correlated barrier hopping.

Hanafy, Taha A.

2012-01-01

90

Dielectric relaxation and alternating current conductivity of lanthanum, gadolinium, and erbium-polyvinyl alcohol doped films  

NASA Astrophysics Data System (ADS)

Fourier transform infrared (FTIR) spectrum dielectric constant, ?', loss tangent, tan(?), electric modulus, M*, and ac conductivity, ?ac, of pure polyvinyl alcohol (PVA) as well as La-, Gd-, and Er-PVA doped samples have been carried out. The dielectric properties have been studied in the temperature and frequency ranges; 300-450 K and 1 kHz-4 MHz, respectively. FTIR measurements reveal that La3+, Gd3+, and Er3+ ions form complex configuration within PVA structure. Two relaxation processes, namely, ? and ? were observed in pure PVA sample. The first process is due to the interfacial or Maxwell-Wagner-Sillers polarization. The second one is related to the micro-Brownian motion of the main chains. For doped PVA samples, ?-relaxation process splits into ?a and ?c. This splitting is due to the segmental motion in the amorphous (?a) and crystalline (?c) phases of PVA matrix. Electric modulus analysis was discussed to understand the mechanism of the electrical transport process. The behavior of ac conductivity for all PVA samples indicates that the conduction mechanism is correlated barrier hopping.

Hanafy, Taha A.

2012-08-01

91

Superior oxygen ion conductivity of lanthanum gallate doped with strontium and magnesium  

SciTech Connect

The solid solution range of the La(Sr)Ga(Mg)O{sub 3} perovskite was investigated and the oxygen ion conductivities of corresponding compositions were measured. The solubility of strontium could be extended by the addition of magnesium ions to establish a balance in the oxygen vacancies associated with A and B sites. In this way, the Sr limit in the solid solution was increased to more than 20% of the La content. Doping with either Sr or Mg enhanced oxygen ion conductivity, but whereas Sr doping yielded decreased activation energy with increasing concentration, Mg produced a higher activation energy with increased Mg content. La{sub 0.8}Sr{sub 0.2}Ga{sub 0.9}Mg{sub 0.1}O{sub 2.85} was found to have the highest conductivity apart from CeO{sub 2}-based electrolytes at temperatures below 700 C, while La{sub 0.8}Sr{sub 0.2}Ga{sub 0.85}Mg{sub 0.15}O{sub 2.825} has the highest conductivity except for Bi{sub 2}O{sub 3} at temperatures above 700 C.

Huang, P.N.; Petric, A. [McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering

1996-05-01

92

Ion beam irradiation of lanthanum and thorium-doped yttrium titanates  

NASA Astrophysics Data System (ADS)

Y2Ti2O7 pyrochlores doped with La have been sintered at 1373 K for 12 h with the designed compositions of the (LaxY1-x)2Ti2O7 system (x = 0, 0.08, 0.5, and 1), and the phase compositions were analyzed by X-ray diffraction. Limited amounts of La were incorporated into yttrium titanate pyrochlore structure for La-doped samples; while, the end member composition of La2Ti2O7 formed a layered perovskite structure. Ion beam-induced amorphization occurred for all compositions in the (LaxY1-x)2Ti2O7 binary under 1 MeV Kr2+ irradiation at room temperature, and the critical amorphization dose decreased with increasing amounts of La3+. The critical amorphization temperatures for Y2Ti2O7, (La0.162Y0.838)2Ti2O7 and La2Ti2O7 were determined to be ˜780, 890 and 920 K, respectively. Th4+ and Fe3+-doped yttrium titanate pyrochlores were synthesized at 1373 K by sintering Y2Ti2O7 with (ThO2 + Fe2O3). Pyrochlore structures and the chemical compositions were primarily identified by the X-ray diffraction and energy dispersive X-ray (EDX) measurements. The lattice parameter and the critical amorphization dose (1 MeV Kr2+ at room temperature) increase for yttrium titanate pyrochlores with the addition of Th. The increasing ‘resistance’ to amorphization with less La and greater Th and Fe contents for (Y1-xLax)2Ti2O7 and Y2Ti2O7 Fe2O3 ThO2 systems, respectively, are consistent with the changes in the average ionic radius ratio at the A-sites and B-sites. These results suggest that the addition of lanthanides and actinides (e.g., Th, U, or Pu) will affect the structural stability, as well as the radiation response behavior of the pyrochlore structure-type.

Lian, J.; Zhang, F. X.; Peters, M. T.; Wang, L. M.; Ewing, R. C.

2007-05-01

93

The hard X-ray response of Ce-doped lanthanum halide scintillators  

NASA Astrophysics Data System (ADS)

We summarize the results of a number of hard X-ray measurements on cerium-doped LaCl3 and LaBr3 scintillators. The experiment was carried out at the HASYLAB synchrotron radiation facility using highly monochromatic pencil beams across the energy range 10.5 100 keV. Additional full-area measurements were carried out using radioactive sources. All measurements were carried out at room temperature. The measured FWHM energy resolutions (?E/E) under pencil beam illumination were 29% (LaBr3) and 32.4% (LaCl3) at 10.5 keV falling to 7.8% (LaBr3) and 9.2% (LaCl3) at 100 keV. At 662 keV, the energy resolutions were 3.9% and 3.0% FWHM. The proportionality of the energy responses shows marked deviations from linearity above and below the La edge at 39.8 keV. At the edge the energy response changes by 3%. Fine structure across the edge was also investigated using single photon count rate measurements taken in 1 eV steps across the edge. The data show considerable near-edge structure when compared to curves generated from standard atomic data tables. However, very little evidence was found for extended X-ray fine structure suggesting that the bulk of the structure arises from the local coordination environment.

Owens, Alan; Bos, A. J. J.; Brandenburg, S.; Dorenbos, P.; Drozdowski, W.; Ostendorf, R. W.; Quarati, F.; Webb, A.; Welter, E.

2007-04-01

94

Influence of the lanthanum deficit on electrical resistivity and heat capacity of silver-doped lanthanum manganites La{sub 1-x}Ag{sub y}MnO{sub 3}  

SciTech Connect

The electrical resistivity and heat capacity of the silver-doped lanthanum manganites La{sub 0.80}Ag{sub 0.15}MnO{sub 3} and La{sub 0.85}Ag{sub 0.15}MnO{sub 3} have been investigated. Despite the nonstoichiometry of the composition, the La{sub 0.80}Ag{sub 0.15}MnO{sub 3} manganite exhibits a bulk homogeneity and better physical properties from the applied point of view as compared to the La{sub 0.85}Ag{sub 0.15}MnO{sub 3} manganite, viz., the former compound has a higher spontaneous magnetoresistance and a larger jump of the heat capacity with a small width of the phase transition, and the anomalies of the heat capacity and electrical resistivity in the vicinity of the Curie point of this compound agree with the fluctuation nature of the second-order phase transition. The behavior of the properties of lanthanum-deficient manganites under investigation in the region of the phase transition is consistent with the classical theory of indirect exchange interaction. The behavior of the temperature dependence of the electrical resistivity has been analyzed in terms of two models. One of these models is based on the tunneling of charge carriers between ferrons or polarons, and the other model is based on the polaron hopping conduction. Both approaches lead to consistent results, and their combination has made it possible to estimate the tunneling distance of charge carriers. The origin of the influence of technological parameters characterizing the synthesis of La{sub 1-x}Ag{sub y}MnO{sub 3} ceramic materials on their physical properties has been elucidated.

Abdulvagidov, Sh. B., E-mail: abdulvagidov@iwt.ru; Gamzatov, A. G. [Russian Academy of Sciences, Amirkhanov Institute of Physics, Dagestan Scientific Center (Russian Federation); Mel'nikov, O. V.; Gorbenko, O. Yu. [Moscow State University (Russian Federation)

2009-12-15

95

Synthesis, Structure, and Properties of Sodium or Potassium-Doped Lanthanum Orthomanganites from NaCl or KCl Flux  

Microsoft Academic Search

Lanthanum and oxygen-deficient La1?x?yAxMnO3??(A=Na or K) ferromagnetic oxide phases have been synthesized from NaCl or KCl flux, starting from La2O3and MnCO3at 900°C. Composition of the final product could be varied by varying initial composition LayMnO3(0.7lanthanum content increased, Na or K content decreased and the

Ram Niwas Singh; C. Shivakumara; N. Y. Vasanthacharya; S. Subramanian; M. S. Hegde; H. Rajagopal; A. Sequeira

1998-01-01

96

Impact of Thermal Aging on the Microstructure Evolution and Mechanical Properties of Lanthanum-Doped Tin-Silver-Copper Lead-Free Solders  

NASA Astrophysics Data System (ADS)

An extensive study is made to analyze the impact of pure lanthanum on the microstructure and mechanical properties of Sn-Ag-Cu (SAC) alloys at high temperatures. Different compositions are tested; the temperature applied for the isothermal aging is 150°C, and aging times of 10 h, 25 h, 50 h, 100 h, and 200 h are studied. Optical microscopy with cross-polarized light is used to follow the grain size, which is refined from 8 mm to 1 mm for as-cast samples and is maintained during thermal aging. Intermetallic compounds (IMCs) present inside the bulk Sn matrix affect the mechanical properties of the SAC alloys. Due to high-temperature exposure, these IMCs grow and hence their impact on mechanical properties becomes more significant. This growth is followed by scanning electron microscopy, and energy-dispersive spectroscopy is used for elemental mapping of each phase. A significant refinement in the average size of IMCs of up to 40% is identified for the as-cast samples, and the coarsening rate of these IMCs is slowed by up to 70% with no change in the interparticle spacing. Yield stress and tensile strength are determined through tensile testing at 20°C for as-cast samples and after thermal aging at 150°C for 100 h and 200 h. Both yield stress and tensile strength are increased by up to 20% by minute lanthanum doping.

Sadiq, Muhammad; Pesci, Raphaël; Cherkaoui, Mohammed

2013-03-01

97

Chlorination of samarium sesquioxide  

Microsoft Academic Search

Samarium as either a metal or a compound has become very popular in the last years, mainly due to the applications of the metal or the fluorides as precursors in permanent magnets, the use of the oxychlorides in optics and those of the oxide in many applications such as catalysis and fuel cells. But samarium does not occur in nature

M. R. Esquivel; A. E. Bohé; D. M. Pasquevich

2005-01-01

98

Properties of lanthanum-doped Bi4Ti3O12-SrBi4Ti4O15 intergrowth ferroelectrics  

NASA Astrophysics Data System (ADS)

Lanthanum-doped intergrowth ferroelectrics, (Bi,La)4Ti3O12-Sr(Bi,La)4Ti4O15 [BLT-SBLT(x)], have been prepared. It is found that the remnant polarization (2Pr) of Bi4Ti3O12-SrBi4Ti4O15 (BIT-SBTi) is enlarged. The 2Pr of BLT-SBLT(0.50) has a maximum value of 25.6 ?C/cm2. Assuming that the Curie temperature of BLT-SBLT(x) is the average value of the two constituents, La content in both BLT and SBLT can be estimated on the basis of the fact that the crystal structure of BLT-SBLT(x) is not affected by doping. The result shows that when x is not larger than 1.25, La content in BIT is higher than that in SBTi, but when x is 1.50, La content in SBTi is higher. It coincides with the variation of d(118) and the relaxation characteristics of BLT-SBLT(1.50).

Zhu, Jun; Chen, Xiao-Bing; Lu, Wang-Ping; Mao, Xiang-Yu; Hui, Rong

2003-09-01

99

Tape method of forming a thin layer of doped lanthanum chromite particles and of bonding such on an electrode  

DOEpatents

A combustible polymer film, useful for application of an interconnection on an electrode is made by: (1) providing doped LaCro.sub.3 particles; (2) dispersing doped LaCrO.sub.3 particles in a solvent, to provide a dispersion; (3) screening the dispersion to provide particles in the range of from 30 micrometers to 80 micrometers; (4) admixing a fugitive polymer with the particles; (5) casting the dispersion to provide a film; (6) drying the film; and (7) stripping the film. The film can then be applied to a porous, preheated electrode top surface, and then electrochemical vapor depositing a dense skeletal LaCrO.sub.3 structure, between and around the doped LaCrO.sub.3 particles. Additional solid oxide electrolyte and fuel electrode layers can then be added to provide a fuel cell.

Richards, Von L. (Murrysville, PA); Singhal, Subhash C. (Murrysville, PA); Pal, Uday B. (Cambridge, MA)

1992-01-01

100

Tape method of forming a thin layer of doped lanthanum chromite particles and of bonding such on an electrode  

DOEpatents

A combustible polymer film, useful for application of an interconnection on an electrode is made by: (1) providing doped LaCro[sub 3] particles; (2) dispersing doped LaCrO[sub 3] particles in a solvent, to provide a dispersion; (3) screening the dispersion to provide particles in the range of from 30 micrometers to 80 micrometers; (4) admixing a fugitive polymer with the particles; (5) casting the dispersion to provide a film; (6) drying the film; and (7) stripping the film. The film can then be applied to a porous, preheated electrode top surface, and then a dense skeletal LaCrO[sub 3] structure is electrochemically vapor deposited between and around the doped LaCrO[sub 3] particles. Additional solid oxide electrolyte and fuel electrode layers can then be added to provide a fuel cell. 4 figs.

Richards, V.L.; Singhal, S.C.; Pal, U.B.

1992-07-21

101

Oxygen tracer diffusion in undoped lanthanum manganites  

Microsoft Academic Search

The oxygen tracer diffusion was studied in cation stoichiometric (LaMnO3±?) and A-site deficient (La0.9MnO3±?) lanthanum manganites by the isotope exchange depth profiling (IEDP) technique using SIMS depth profiling. The measured oxygen tracer diffusion coefficients were in the range of 10?12 to 10?15 cm2 s?1 and these values were comparable with the ones determined in Sr-doped lanthanum manganites. The activation energy

A. V. Berenov; J. L. MacManus-Driscoll; J. A. Kilner

1999-01-01

102

Valence electronic structure of Mn in undoped and doped lanthanum manganites from relative K X-ray intensity studies  

NASA Astrophysics Data System (ADS)

Relative K X-ray intensities of Mn in Mn, MnO2, LaMnO3 and La0.7B0.3MnO3 (B = Ca, Sr and Ce) systems have been measured following excitation by 59.54 keV /?-rays from a 200 mCi 241Am point-source. The measured results for the compounds deviate significantly from the results of pure Mn. Comparison of the experimental data with the multi-configuration Dirac-Fock (MCDF) effective atomic model calculations indicates reasonable agreement with the predictions of ionic model for the doped manganites except that the electron-doped La0.7Ce0.3MnO3 and hole-doped La0.7Ca0.3MnO3 compounds show some small deviations. The results of MnO2 and LaMnO3 deviate considerably from the predictions of the ionic model. Our measured /K?/K? ratio of Mn in La0.7Ca0.3MnO3 cannot be explained as a linear superposition of /K?/K? ratios of Mn for the end members which is in contrast to the recent proposal by Tyson et al. from their Mn /K? spectra.

Raj, S.; Padhi, H. C.; Raychaudhury, P.; Nigam, A. K.; Pinto, R.; Polasik, M.; Pawlowski, F.; Basa, D. K.

2001-04-01

103

Improvement of acid and base resistance of nickel phosphate pigment by the addition of lanthanum cation  

Microsoft Academic Search

Transition metal phosphates are used as inorganic pigments, however these materials had a weak point for acid and base resistance. Because lanthanum phosphate is insoluble in acidic and basic solution, the addition of lanthanum cation was tried for the improvement of the acid and base resistance of nickel phosphate pigment. The lanthanum-doped nickel phosphates were prepared from phosphoric acid, nickel

Hiroaki Onoda; Hironori Matsui; Isao Tanaka

2007-01-01

104

Near-infrared broadband luminescence and energy transfer in Bi-Tm-Er co-doped lanthanum aluminosilicate glasses  

NASA Astrophysics Data System (ADS)

The Bi-Tm-Er co-doped SiO2-Al2O3-La2O3 (SAL) glasses, which exhibited a broadband near-infrared (NIR) emission, were investigated by the optical absorption and photoluminescence spectra. A super broadband NIR emission extending from 0.95 to 1.6 ?m with a full-width at half-maximum (FWHM) of 430 nm which covered the whole O, E, S, C and L bands, was observed in Bi-Tm-Er co-doped samples under 808 nm excitation, as a result of the overlap of the Bi-related emission band (centered at 1270 nm) and the emission from Tm3+3H4?3F4 transition (1450 nm) as well as Er3+4I13/2?4I15/2 transition (1545 nm). In addition, a super broadband emission with amplitude relatively flat from 0.95 to 2.1 ?m has been observed. The possible energy transfer between Bi-related centers, Tm3+ ions and Er3+ ions was proposed.

Minh Hau, Tran; Wang, Rongfei; Yu, Xue; Zhou, Dacheng; Song, Zhiguo; Yang, Zhengwen; He, Xijia; Qiu, Jianbei

2012-09-01

105

Tape method of forming a thin layer of doped lanthanum chromite particles and of bonding such on an electrode  

SciTech Connect

This patent describes a method of forming a combustible polymer film containing a thin layer of doped LaCrO{sub 3} particles. It comprises providing LaCrO{sub 3} particles doped with an element selected from the group consisting of Ca, Sr, Co, Ba, Mg, and mixtures thereof; uniformly dispersing the particles in a solvent to provide a homogeneous dispersion; wet screening the dispersion to provide particles in the range of from 30 micrometers to 80 micrometers; admixing a fugitive polymer with the particles in an amount to provide homogeneous dispersion with a volume ratio of polymer plus particles:solvent of between 50:50 and 30:70 and a volume ratio of polymer:particles between 65:35 and 50:50; casting the dispersion onto a substrate, to provide a film having a wet thickness of from 80 micrometers to 150 micrometers; drying the film; and stripping the film from the substrate, to provide a particle-fugitive polymer film.

Richards, V.L.; Singhal, S.C.; Pal, U.B.

1992-07-21

106

Crystal growth of Ce2O(CO3)2·H2O in aqueous solutions: Film formation and samarium doping  

NASA Astrophysics Data System (ADS)

Crystalline cerium oxide carbonate hydrate (Ce2O(CO3)2·H2O) was grown in aqueous solutions at a low temperature of 80 °C under ambient pressure. When cerium nitrate was used as a starting material, large Ce2O(CO3)2·H2O particles were precipitated through homogeneous nucleation and subsequent fast crystal growth. In contrast, the usage of cerium chloride was found to promote the preferential precipitation of Ce2O(CO3)2·H2O on foreign substrates through heterogeneous nucleation and slow crystal growth. This phenomenon was applied to a chemical bath deposition of Ce2O(CO3)2·H2O films. Immersion of glass substrates in the solution at 80 °C for typically 24 h resulted in formation of solid films with a unique morphology like a micrometer-scale brush. It was also found that samarium could be incorporated into Ce2O(CO3)2·H2O during the crystal growth in the solutions, as evidenced by characteristic photoluminescence of Sm3+ in heating products of CeO2. These results suggest that rare-earth oxide carbonate hydrates with a variety of compositions and morphologies can be synthesized from the aqueous solutions.Graphical abstractCrystalline Ce2O(CO3)2·H2O particles and films were successfully prepared from aqueous solutions of cerium nitrate or chloride and urea.

Oikawa, Masashi; Fujihara, Shinobu

2005-06-01

107

Crystal growth of Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O in aqueous solutions: Film formation and samarium doping  

SciTech Connect

Crystalline cerium oxide carbonate hydrate (Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O) was grown in aqueous solutions at a low temperature of 80 deg. C under ambient pressure. When cerium nitrate was used as a starting material, large Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O particles were precipitated through homogeneous nucleation and subsequent fast crystal growth. In contrast, the usage of cerium chloride was found to promote the preferential precipitation of Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O on foreign substrates through heterogeneous nucleation and slow crystal growth. This phenomenon was applied to a chemical bath deposition of Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O films. Immersion of glass substrates in the solution at 80 deg. C for typically 24h resulted in formation of solid films with a unique morphology like a micrometer-scale brush. It was also found that samarium could be incorporated into Ce{sub 2}O(CO{sub 3}){sub 2}.H{sub 2}O during the crystal growth in the solutions, as evidenced by characteristic photoluminescence of Sm{sup 3+} in heating products of CeO{sub 2}. These results suggest that rare-earth oxide carbonate hydrates with a variety of compositions and morphologies can be synthesized from the aqueous solutions.

Oikawa, Masashi [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan); Fujihara, Shinobu [Department of Applied Chemistry, Faculty of Science and Technology, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522 (Japan)]. E-mail: shinobu@applc.keio.ac.jp

2005-06-15

108

Development of Lanthanum Ferrite SOFC Cathodes  

SciTech Connect

A number of studies have been conducted concerning compositional/microstructural modifications of a Sr-doped lanthanum ferrite (LSF) cathode and protective Sm-doped ceria (SDC) layer in an anode supported solid oxide fuel cell (SOFC). Emphasis was placed on achieving enhanced low temperature (700-800 degrees C) performance, and long-term cell stability. Investigations involved manipulation of the lanthanum ferrite chemistry, addition of noble metal oxygen reduction catalysts, incorporation of active cathode layer compositions containing Co, Fe and higher Sr contents, and attempts to optimize the ceria barrier layer between the LSF cathode and YSZ electrolyte.

Simner, Steve P.; Bonnett, Jeff F.; Canfield, Nathan L.; Meinhardt, Kerry D.; Shelton, Jayne P.; Sprenkle, Vince L.; Stevenson, Jeffry W.

2003-01-01

109

Effect of Hydrogen Anneals on Niobium-Doped Lead Zirconate Titanate Capacitors with Lanthanum Strontium Cobalt Oxide/Platinum Electrodes  

NASA Astrophysics Data System (ADS)

Ferroelectric capacitors, being oxide ceramics, are very sensitive to the effects of hydrogen environments at elevated temperatures [H. Ashida et al..: Integr. Ferroelectr. 21 (1998) 97]. After a capacitor has been exposed directly to a annealing hydrogen environment at low hydrogen partial pressures, the electrical properties of the device can deteriorate and leakage currents can increase. At higher hydrogen concentration gradients, such as the formidable forming gas annealing, physical failure of the inter-layer dielectric (ILD) and/or top electrode adhesion can occur. The authors have examined various structural approaches to mitigate the effects of hydrogen damage on integrated ferroelectric lead zirconate titanate (PZT) capacitors. These approaches, including the use of a titanium dioxide barrier layer above the PZT to impede the reducing effect of hydrogen on the ceramic and the use of electrode layers other than platinum to eliminate the generation of free hydrogen ions by catalyst action [S. Aggarwal et al..: Appl. Phys. Lett. 73 (1998) 1973]. The authors have found that niobium-doped PZT capacitors using LSCO/platinum electrodes passivated with titanium dioxide will recover from 1% forming gas annealing within 30 minutes at 450°C in nitrogen.

Evans, Joe; Jr., Jr.; Boyer, Leonard; Velasquez, Geri; Ramesh, Ramamoorthy; Aggarwal, Sanjeev; Keramidas, Vassillis

1999-09-01

110

Soft X-Ray Spectroscopic Study of Dense Strontium-Doped Lanthanum Manganite Cathodes for Solid Oxide Fuel Cell Applications  

SciTech Connect

The evolution of the Mn charge state, chemical composition, and electronic structure of La{sub 0.8}Sr{sub 0.2}MnO{sub 3} (LSMO) cathodes during the catalytic activation of solid oxide fuel cell (SOFC) has been studies using X-ray spectroscopy of as-processed, exposed, and activated dense thin LSMO films. Comparison of O K-edge and Mn L{sub 3,2}-edge X-ray absorption spectra from the different stages of LSMO cathodes revealed that the largest change after the activation occurred in the Mn charge state with little change in the oxygen environment. Core-level X-ray photoemission spectroscopy and Mn L{sub 3} resonant photoemission spectroscopy studies of exposed and as-processed LSMO determined that the SOFC environment (800 C ambient pressure of O{sub 2}) alone results in La deficiency (severest near the surface with Sr doping >0.55) and a stronger Mn{sup 4+} contribution, leading to the increased insulating character of the cathode prior to activation. Meanwhile, O K-edge X-ray absorption measurements support Sr/La enrichment nearer the surface, along with the formation of mixed Sr{sub x}Mn{sub y}O{sub z} and/or passive MnO{sub x} and SrO species.

L Piper; A Preston; S Cho; A DeMasi; J Laverock; K Smith; L Miara; J Davis; S Basu; et al.

2011-12-31

111

Synthesis and Studies of Semicarbazonato Lantianum(III) and Samarium(III) Coordination Complexes  

Microsoft Academic Search

Synthesis and characterization of lanthanum(III) and samarium(III) semicarbazonato complexes are reported. These derivatives of the type (OR)Ln(SCZ), Ln2(SCZ)3 and Ln(SCZ)(SCZH) [where Ln = La(III) or Sm(III), R = isopropyl or tertiary butyl and SCZ = anion of the aldimine or ketimine semicarbazones viz. salicylidinesemicarbazone, 2-hydroxy-1-naphthalidinesemicarbazone and 2-hydroxy-1-acetophenoneiminesemicarbazone] are obtained in the form of coloured solids by the reactions of tris(isopropoxy)

S. P. Mital; R. V. Singh; J. P. Tandon

1982-01-01

112

Evolution of orientation degree, lattice dynamics and electronic band structure properties in nanocrystalline lanthanum-doped bismuth titanate ferroelectric films by chemical solution deposition.  

PubMed

Ferroelectric lanthanum (La)-substituted bismuth titanate (Bi(4-x)La(x)Ti(3)O(12), BLT) nanocrystalline films with the composition range of 0 ?x? 1 have been directly deposited on n-type Si?(100) substrates by chemical solution deposition. The La substitution effects on the preferred orientation, surface morphology, phonon modes, emission bands and electronic band structures of the BLT films have been investigated by microscopy, Raman scattering, photoluminescence and spectroscopic ellipsometry at room temperature. X-Ray diffraction analysis shows that the films are polycrystalline and exhibit the pure perovskite phase structure. With increasing La composition, the (100)-orientation degree can be enhanced and the root-mean-square roughnesses slightly increase from 6.5 to 8.3 nm. It was found that the Raman-active mode A(1g)[Bi] at about 59 cm(-1) is unchanged while the B(1g) and A(1g)[Ti] phonon modes at about 648 and 853 cm(-1) are shifted towards higher frequency by about 36.6 and 8.4 cm(-1), respectively. Photoluminescence spectra show that the intensity of the peak located at about 2.3 eV increases with the La composition, except for the Bi(3)LaTi(3)O(12) film, due to the smallest grain size and oxygen vacancy defects. The optical constants of the BLT films have been uniquely extracted by fitting the measured ellipsometric spectra with a four-phase layered model (air/surface rough layer/BLT/Si) in the photon energy range of 0.73-4.77 eV. The Adachi dielectric function model has been successfully applied and reasonably describes the optical response behavior of the ferroelectric BLT films. Moreover, the film packing density decreases while the optical band gap linearly increases from 3.610 ± 0.066 to 3.758 ± 0.068 eV with increasing La composition. It is surmised that the phenomena are mainly ascribed to the variations of the electronic structure, especially for the conduction band, which is perturbed by the La doping. PMID:21743909

Zhang, Jinzhong; Chen, Xiangui; Jiang, Kai; Shen, Yude; Li, Yawei; Hu, Zhigao; Chu, Junhao

2011-07-08

113

Soft X-Ray Spectroscopic Study of Dense Strontium-Doped Lanthanum Manganite Cathodes for Solid Oxide Fuel Cell Applications  

SciTech Connect

The modification of the Mn charge-state, chemical composition and electronic structure of La0.8Sr0.2MnO3 (LSMO) cathodes for solid oxide fuel cell (SOFC) applications remains an area of interest, due to the poorly understood enhanced catalytic activity (often referred to as the "burn-in" phenomenon) observed after many hours of operation. Using a combination of core-level X-ray photoemission spectroscopy (XPS), X-ray emission/absorption spectroscopy (XES/XAS), resonant inelastic X-ray scattering (RIXS) and resonant photoemission spectroscopy (RPES), we have monitored the evolution of these properties in LSMO at various stages of fabrication and operation. By rapidly quenching and sealing in vacuum, we were able to directly compare the pristine (as-fabricated) LSMO with both "heat-treated" (800°C in air, and no bias) and "burnt-in" (800°C in air, -1 V bias) LSMO cathodes i.e. before and after the activation observed in our electrochemical impendence spectroscopy measurements. Comparison between the O K-edge XAS/XES and Mn L3,2-edge XAS of pristine and “burnt-in” LSMO cathodes revealed a severe change in the oxygen environment along with a reduced Mn2+ presence near the surface following activation. The change in the oxygen environment is attributed to SrxMnyOz formation, along with possible passive SrO and Mn3O4 species. We present evidence from our “heat-treated” samples that SrxMnyOz regions form at elevated temperatures in air before the application of a cathodic bias. Our core-level XPS, Mn L3,2-edge RIXS and Mn L3 RPES studies of “heat-treated” and pristine LSMO determined that SOFC environments result in La-deficiency (severest near the surface) and stronger Mn4+ contribution, leading to the increased insulating character of the cathode prior to activation. The passive Mn2+ species near the surface and increased hole-doping (>0.6) of the LSMO upon exposure to the operating environment are considered responsible for the initially poor performance of the SOFC. Meanwhile, the improved oxygen reduction following the application of a cathodic bias is considered to be due to enhanced bulk oxygen-ion diffusion resulting from the migration of Mn2+ ions towards the LSMO/electrolyte interface and the SrxMnyOz regions facilitating enhanced bulk oxygen reduction reaction kinetics.

Piper, L.F.J.; Preston, Andrew R.H.; Cho, Sang Wan; DeMasi, Alexander; Chen, Bin; Laverock, J.; Smith, K. E.; Miara, Lincoln J.; Davis, Jacob N.; Basu, Soumendra; Pal, Uday B.; Gopalan, Srikanth; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Matsuura, A. Y.; Glans, P.A.; Guo, Jianzhong

2010-12-02

114

Growth and barium zirconium oxide doping study on superconducting M-barium copper oxide (M = yttrium, samarium) films using a fluorine-free metal organic decomposition process  

NASA Astrophysics Data System (ADS)

We present a fluorine-free metal organic deposition (F-free MOD) process - which is possibly a rapid and economic alternative to commercial trifluoroacetates metal organic deposition (TFA-MOD) and metal organic chemical vapor deposition (MOCVD) processes - for the fabrication of high quality epitaxial high temperature superconducting YBa2Cu3O7-x (YBCO) films on both Rolling-Assisted Biaxially Textured Substrates (RABiTS) and single crystal substrates. We first studied the growth of YBCO and SmBCO films, and their resulting microstructure and superconducting properties. We produced epitaxial c-axis YBCO films with high critical current density (Jc) in excess of 106 A/cm2 at 77K in self field at the thickness of ˜1 mum. Because industrial applications demand high quality YBCO films with very high Jc, we investigated introducing BaZrO3 (BZO) nano-pinning sites in HTS thin films by our F-free MOD technique to improve Jc and the global pinning force (Fp). BZO-doped YBCO films were fabricated by adding extra Ba and Zr in the precursor solutions, according to the molar formula 1 YBCO + x BZO. We found the BZO content affects the growth of YBCO films and determined the optimum BZO content which leads to the most effective pinning enhancement and the least YBCO degradation. We achieved the maximum pinning force of ˜ 10 GN/m3 for x = 0.10 BZO-doped, 200 nm thick YBCO film on SrTiO3 single crystal substrates by modifying the pyrolysis from a one-step to a two-plateau decomposition during the F-free MOD process. For growing optimum BZO-doped YBCO films on RABiTS substrates, the F-free MOD process was also optimized by adjusting the maximum growth temperature and growth time to achieve stronger pinning forces. Through-process quenching studies indicate that BZO form 10--25 nm nanoparticles at the early stage of the process and are stable during the following YBCO growth, demonstrating that chemically doping YBCO films with BZO using the F-free MOD process is a very effective way to enhance pinning for YBCO coated conductors.

Lu, Feng

115

Synthesis of samarium- and nitrogen-co-doped TiO 2 by modified hydrothermal method and its photocatalytic performance for the degradation of 4-chlorophenol  

Microsoft Academic Search

Sm- and nitrogen-co-doped TiO2 (Sm–N–TiO2) catalysts were prepared via the modified hydrothermal method using tetrabutyl titanate as the precursor and calcination at 200°C. The microstructure of the sample was characterized by X-ray diffraction (XRD), ultraviolet–visible diffuse reflection spectroscopy (UV–vis-DRS), Fourier transform infrared (FTIR) spectra and X-ray photoelectron spectroscopy (XPS). The average particle size was ca. 16.0nm as calculated from XRD

D. G. Huang; S. J. Liao; W. B. Zhou; S. Q. Quan; L. Liu; Z. J. He; J. B. Wan

2009-01-01

116

Laser spectroscopy of atomic samarium.  

National Technical Information Service (NTIS)

Samarium spectrum was studied with a purpose to find transitions to be used in experiments on parity nonconservation. Macaluso-Corbino effect - Faraday rotation near resonance was used for the search and study of spectral lines. We have identified previou...

L. M. Barkov D. A. Melik-Pashaev M. S. Zolotorev

1988-01-01

117

Studies of oxygen transport mechanism in electrolytes based on doped lanthanum silicate with apatite structure using techniques of oxygen isotopic heteroexchange and impedance spectroscopy  

Microsoft Academic Search

The work presents the results of studying the mechanism of oxygen transport for a new promising class of oxygen-containing\\u000a electrolytes based on lanthanum silicate with an apatite structure using impedance spectroscopy and isotopic oxygen heteroexchange.\\u000a At 1000 K, in the case of samples with an optimum composition including codoped Fe and Al, ? ? 3 × 10?3 to 10?2 S\\/cm

V. A. Sadykov; T. S. Kharlamova; N. V. Mezentseva; S. N. Pavlova; E. M. Sadovskaya; V. S. Muzykantov; Yu. N. Bespalko; V. V. Usol’tsev; E. G. Zevak; T. A. Kriger; A. V. Ishchenko; N. F. Uvarov; A. S. Ulikhin; M. V. Chaikina; C. Argirusis

2011-01-01

118

Influence of lanthanum addition on preparation and powder properties of cobalt phosphates  

Microsoft Academic Search

Transition metal phosphates are used as inorganic pigments; however, these materials had a weak point for acid and base resistance.\\u000a Because lanthanum phosphate is insoluble in acidic and basic solution, the addition of lanthanum cation was tried to improve\\u000a the acid and base resistance of cobalt phosphate pigment. The lanthanum doped cobalt phosphates were prepared from phosphoric\\u000a acid, cobalt nitrate,

Hiroaki Onoda; Keisuke Tange; Isao Tanaka

2008-01-01

119

LASERS Tunable quasi-cw two-micron lasing in diode-pumped crystals of mixed Tm3+-doped sodium — lanthanum — gadolinium molybdates and tungstates  

NASA Astrophysics Data System (ADS)

Two-micron lasing is obtained for the first time on the 3F4 ? 3H6 transition of Tm3+ ions in diode-pumped crystals of mixed sodium — lanthanum — gadolinium tungstate Tm:NaLa1/2Gd1/2(WO4)2 (CTm = 3.6 at %) (3.6Tm : NLGW) and molybdate Tm:NaLa1/3Gd2/3(MoO4)2 (CTm = 4.8 at %) (4.8Tm : NLGM). For the 3.6Tm : NLGW crystal, the quasi-cw laser output power exceeded 200 mW and the slope efficiency (with respect to absorbed pump power) for the ?- and ?-polarisations at wavelengths of 1908 and 1918 nm was 34% and 30%, respectively. The laser wavelength of this crystal was continuously tuned within the spectral range of 1860 — 1935 nm. For the 4.8Tm : NLGM crystal, the slope efficiency for the ?- and ?-polarisations at wavelengths of 1910 and 1918 nm was 27% and 23%, respectively, and the laser wavelength was tunable within the spectral range of 1870 — 1950 nm.

Bol'shchikov, F. A.; Zharikov, Evgeny V.; Lis, Denis A.; Zakharov, N. G.; Ryabochkina, P. A.; Subbotin, Kirill A.; Antipov, Oleg L.

2010-12-01

120

Tunable quasi-cw two-micron lasing in diode-pumped crystals of mixed Tm{sup 3+}-doped sodium - lanthanum - gadolinium molybdates and tungstates  

SciTech Connect

Two-micron lasing is obtained for the first time on the {sup 3}F{sub 4} {yields} {sup 3}H{sub 6} transition of Tm{sup 3+} ions in diode-pumped crystals of mixed sodium - lanthanum - gadolinium tungstate Tm:NaLa{sub 1/2}Gd{sub 1/2}(WO{sub 4}){sub 2} (C{sub Tm} = 3.6 at %) (3.6Tm : NLGW) and molybdate Tm:NaLa{sub 1/3}Gd{sub 2/3}(MoO{sub 4}){sub 2} (C{sub Tm} = 4.8 at %) (4.8Tm : NLGM). For the 3.6Tm : NLGW crystal, the quasi-cw laser output power exceeded 200 mW and the slope efficiency (with respect to absorbed pump power) for the {pi}- and {sigma}-polarisations at wavelengths of 1908 and 1918 nm was 34% and 30%, respectively. The laser wavelength of this crystal was continuously tuned within the spectral range of 1860 - 1935 nm. For the 4.8Tm : NLGM crystal, the slope efficiency for the {pi}- and {sigma}-polarisations at wavelengths of 1910 and 1918 nm was 27% and 23%, respectively, and the laser wavelength was tunable within the spectral range of 1870 - 1950 nm. (lasers)

Bol'shchikov, F A; Ryabochkina, P A [N.P. Ogarev Mordovian State University, Saransk (Russian Federation); Zharikov, Evgeny V; Lis, Denis A; Subbotin, Kirill A [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Zakharov, N G; Antipov, Oleg L [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2010-12-09

121

Samarium-promoted cyclopropanation of allylic alcohols  

SciTech Connect

The use of samarium/mercury amalgam in conjunction with diiodomethane or chloroiodomethane to generate samarium carbenoids for the efficient cyclopropanation of allylic alcohols is discussed. These hydroxyl-directed cyclopropanations occur under mild conditions and allow a wide range of substitution about both the olefin and the carbinol carbon in allylic alcohol substrates. High yields and high diastereoselectivities are observed for many substrates.

Molander, G.A.; Harring, L.S. (Univ. of Colorado, Boulder (USA))

1989-07-21

122

Oxygen Reduction Activity of Lanthanum Strontium Nickel Ferrite  

SciTech Connect

The reduction of oxygen on nickel-doped lanthanum strontium ferrite was studied by current interrupt cyclic voltammetry. Nickel doped on the B site of the perovskite ranged from 0% to 40%. Nickel strongly influenced the sintering of the films. The minimum temperature at which a stable adherent robust film could be formed was found to increase with nickel content. The electrochemical performance for reduction of oxygen was compared with nickel content. Undoped lanthanum strontium ferrite consistently showed greater activity than the doped materials. The data were further analyzed to obtain the activation energy and pre-exponential factor. These values did not correlate with nickel composition but did correlate with one another. The variation in performance was tentatively attributed to subtle variations in microstructure.

Coffey, Greg W.; Hardy, John S.; Pederson, Larry R.; Rieke, Peter C.; Thomsen, Ed C.

2003-06-01

123

Energy stabilization of the s-symmetry superatom molecular orbital by endohedral doping of C82 fullerene with a lanthanum atom  

NASA Astrophysics Data System (ADS)

Energy stabilization of the superatom molecular orbitals (SAMOs) in fullerenes is investigated with the goal of involving their nearly free-electron bands in practical charge transport applications. Combining low-temperature scanning tunneling microscopy-based spectroscopic methods and density functional theory calculations on an endohedral metallofullerene La@C82, we confirm that the s-SAMO of C82 fullerene is stabilized by as much as 2 eV with respect to that of C60 by endohedral doping with the La atom. On the copper metal substrate, the s-SAMO energy is further lowered to just 1 eV above the Fermi level, making the applications of s-SAMO state in transport more plausible. We conclude that in an endohedral metallofullerene, the s-SAMO state is stabilized through the hybridization with the s-symmetry valence state of the metal atom and the stabilization energy correlates with the ionization potential of the free atom.

Feng, Min; Shi, Yongliang; Lin, Chungwei; Zhao, Jin; Liu, Fupin; Yang, Shangfeng; Petek, Hrvoje

2013-08-01

124

ZIRCONIA-BASED MIXED POTENTIAL CARBON MONOXIDE/HYDROCARBON SENSORS WITH LANTHANUM MAGNESIUM OXIDE, AND TERBIUM-DOPED YTTRIUM STABILIZED ZIRCONIA ELECTRODES  

SciTech Connect

We have investigated the performance of dual metal oxide electrode mixed potential sensors in an engine-out, dynamometer environment. Sensors were fabricated by sputtering thin films of LaMnO{sub 3} and Tb-doped YSZ onto YSZ electrolyte. Au gauze held onto the metal oxide thin films with Au ink was used for current collection. The exhaust gas from a 4.8L, V8 engine operated in open loop, steady-state mode around stoichiometry at 1500 RPM and 50 Nm. The sensor showed a stable EMF response (with no hysteresis) to varying concentrations of total exhaust gas HC content. The sensor response was measured at 620 and 670 C and shows temperature behavior characteristic of mixed potential-type sensors. The results of these engine-dynamometer tests are encouraging; however, the limitations associated with Au current collection present the biggest impediment to automotive use.

E. L. BROSHA; R. MUKUNDAN; ET AL

2000-10-01

125

Radiative lifetimes of neutral samarium  

NASA Astrophysics Data System (ADS)

Radiative lifetimes of 120 odd-parity levels of neutral samarium, ranging in energy from 17?190 to 33?507 cm?1, are measured using the technique of time-resolved laser-induced fluorescence on a slow atomic beam. This work is part of an ongoing study of radiative properties of rare earth neutral atoms, and is motivated by research needs in astrophysics and lighting technology. This set of Sm i lifetimes substantially increases the available published lifetime data, with 49 of the 120 level lifetimes measured for the first time. These data, most of which are accurate to ±5%, will be combined with branching fractions determined from Fourier transform spectroscopy to produce a large set of measured Sm i transition probabilities.

Den Hartog, E. A.; Lawler, J. E.

2013-09-01

126

First Principle Quantum Description of the Energetics Associated with LaBr3, LaCl3, and Ce Doped Scintillators.  

National Technical Information Service (NTIS)

Considerable interest is given to the excellent scintillation properties of cerium doped lanthanum chloride (LaCl3) and lanthanum bromide (LaBr3). The scintillation efficiencies are much greater than other materials, even those containing cerium. This hig...

D. Gao M. E. McIlwain N. Thompson

2007-01-01

127

Radioactive Isotopes of Lanthanum  

Microsoft Academic Search

The radioactive isotope La140, known to be produced by deuteron and slow neutron bombardments of lanthanum is found to have a half-life of 40.0+\\/-0.3 hours. This isotope has now been produced by the reaction Ce140(n,p)La140. Evidence for the occurrence of a d, y reaction has been obtained through the formation of La140 by the reaction Ba138(d,y)La140. The 40-hour isotope decays

Katherine E. Weimer; M. L. Pool; J. D. Kurbatov

1943-01-01

128

Plasma Anodized Lanthanum Titanate Films  

Microsoft Academic Search

This paper discusses the application of plasma anodization to the pyrochlore, lanthanum titanate (La2Ti2O7), and the use of this material as a thin film dielectric. The process involves co-evaporation of the metals, lanthanum and titanium, followed by plasma anodization. Evaporation and anodization techniques are fully discussed as are the electrical properties of the resulting films.

R. E. Whitmore; J. L. Vossen

1965-01-01

129

Hyperfine interactions of tin atoms in samarium  

Microsoft Academic Search

The hyperfine interactions of 119Sn impurity atoms in samarium at temperatures from 5 to 70 K are investigated by Mssbauer spectroscopy. The distributions\\u000a P of magnetic hyperfine fields B\\u000a hf for tin atoms at sites of the hexagonal [P\\u000a h(B\\u000a hf)] and cubic [P\\u000a c(B\\u000a hf)] samarium sublattices are determined from the experimental absorption spectra. Ion ordering in pairs of

I. N. Rozantsev; V. P. Gor’kov

2002-01-01

130

Modified doping at cuprate / lanthanum manganite interfaces  

NASA Astrophysics Data System (ADS)

Oxide heterostructures allow combining materials with similar structure but with very different ground states, which may compete at the interface to yield novel behaviors and functionalities. We explore the YBa2Cu3O7 (YBCO) / La1-xCaxMnO3 (LCMO) interface in thin film heterostructures. For x=0.3 the manganite is ferromagnetic which causes a strong depression of the superconductivity at the YBCO side. There is also a depression of the ferromagnetic moment at the interface suggesting electron transfer from the manganite into the YBCO. This is confirmed from superlattices alternating YBCO and LaMnO3 (LMO), an A- type AF insulator. While for thin LMO layers (< 6 unit cells) there is little effect on YBCO superconductivity, thicker LMO layers result in reduced Tc values and induced ferromagnetism at the interface, thus providing a firm indication of charge transfer. The occurrence of charge transfer over length scales much longer than the Thomas Fermi screening length (1 nm) is a novel behavior which, we hope, will stimulate future theoretical studies. Work supported by CICYT MAT2005 06024 C02-02.

Santamaria, Jacobo; Garcia Barriocanal, J.; Rivera, A.; Leon, C.; Varela, M.; Pennycook, S. J.; Sefrioui, Z.

2007-03-01

131

Second phases in doped lanthanum gallate perovskites  

Microsoft Academic Search

Synthesis of Lal ? xSrxGal ? yMgyO3 ? ? with 0.098 ? xmol% ? 0.100 and 0.196 ? ymol% ? 0.200 was performed in three ways: according to the solid state route either from oxides, or from oxides and carbonates and from powders prepared by ultrasonic spray pyrolysis. The samples were heterogeneous with a ‘crust’ of a darker color. Impurity

E. Djurado; M. Labeau

1998-01-01

132

Sol–gel Eu 3+\\/Tm 3+ doped transparent glass–ceramic waveguides  

Microsoft Academic Search

Eu3+ and Tm3+ doped lanthanum fluoride and lanthanum oxyfluoride are obtained from Eu3+, Tm3+ containing lanthanum fluoracetate solutions. The nature of the crystal phase obtained could be controlled by the temperature of heat treatment. Spectral characteristics of Eu3+ doped crystal phases were sufficiently different to allow utilization of Eu3+ as structural probes. Tm3+ emission at the technologically important spectral region

S. J. L. Ribeiro; C. C. Araújo; L. A. Bueno; R. R. Gonçalves; Y. Messaddeq

2004-01-01

133

Thermodynamic properties of higher lanthanum silicide  

SciTech Connect

The thermodynamic properties of lanthanum disilicide were examined for the first time in the 960-1050/sup 0/K range by measuring the electromotive force of a galvanic cell based on LaSn, the chlorides of potassium, sodium, and lanthanum, and lanthanum silicide and silicon. Reference electrodes were used to prevent lanthanum interaction with the electrolyte. The alloys were melted in an electric arc furnace in purified argon from lanthanum and silicon and followed by two-stage annealing. It was found that the resulting value of the enthalpy formation differed from the estimated value for lanthanum disilicide calculated by Miedema's model.

Polotskaya, R.I.

1988-07-01

134

Growth and characterization of rare earths doped triglycine sulfate crystals  

Microsoft Academic Search

Ferroelectric triglycine sulfate (TGS) single crystals have been grown by a temperature-lowering technique from the aqueous solution by doping with samarium sulfate, ytterbium sulfate and terbium sulfate in the ferroelectric phase. The effects of these different dopants on the morphology, growth and various properties such as dielectric, pyroelectric and piezoelectric of doped TGS crystals have been investigated. The decrease in

A. K. Batra; Padmaja Guggilla; Dewanna Cunningham; M. D. Aggarwal; R. B. Lal

2006-01-01

135

[Lanthanum carbonate in clinical practice].  

PubMed

Lanthanum is an element belonging to the group called rare earths. Due to its low solubility, lanthanum carbonate has been widely studied as an intestinal phosphate binder. The results of different clinical trials show that it is an effective and well-tolerated phosphate binder used in monotherapy. Serum phosphate levels are controlled in approximately 70% of patients at 5 years without causing hypercalcemia. The only significant adverse effects observed are a low percentage of gastrointestinal disturbances (6%). Lanthanum carbonate does not alter serum values of liposoluble vitamins or affect the pharmacokinetics of digoxin, warfarin, furosemide, phenytoin, ACE inhibitors or beta-blockers. However, it does alter the pharmacokinetics of ciprofloxacin (quinolones in general), tetracyclines and doxycycline. Lanthanum carbonate (Fosrenol) is available in Spain as 500 mg, 750 mg, and 1,000 mg chewable tablets, which should not be swallowed without chewing to avoid loss of efficacy. The initial dose recommended by the WHO is 2,250 mg/day, which is equivalent to one 750 mg at each meal. Lanthanum carbonate or lanthanum phosphate can be clearly visualized on a plain x-ray of the abdomen in patients who have recently ingested it. In summary, lanthanum carbonate is a widely studied potent phosphate binder, which offers the possibility of improving control of serum phosphate in patients with chronic kidney disease, without significant side effects. The fact that it is available as chewable tablets and that the number of daily tablets required has been significantly reduced will probably facilitate better patient compliance. PMID:18847414

Torregrosa Prats, V

2008-01-01

136

Sintering mechanism of samarium--cobalt alloys  

Microsoft Academic Search

The sintering mechanism of samarium-cobalt alloys was investigated ; employing isothermal shrinkage measurements on pre-alloyed powders and powder ; mixtures in the concentration range from 23 to 42 wt.% Sm. The sintering ; temperatures were varied from 1,020 to 1,160 deg C. The three stoichiometric ; compounds SmâCO, SmCoâ and SmâCoââ are characterized by ; com paratively slow sintering behavior,

G. H. Gessinger; E. de Lamotte

1973-01-01

137

Zur Isotopieverschiebung im Spektrum des Samariums  

Microsoft Academic Search

Zusammenfassung Es wurde die Hyperfeinstruktur einer Reihe von Samarium-Linien zwischen 4300 und 7200 Å mit einemFabry-Pérot-Interferometer photographiert und vor allem im Hinblick auf die Isotopieverschiebung der geraden Isotope untersucht. Für die ungeraden Isotope ließ sich nur entnehmen, daß der Kernspin des Sm 147 und Sm 149 ? 3\\/2 sein muß. Aus fünf photometrisch besonders genau analysierten Sm I-Linien wurden die

Peter Brix; Hans Kopfermann

1949-01-01

138

Effect of lanthanum doping on the structural, ferroelectric, and strain properties of Bi1/2(Na0.82K0.18)1/2TiO3 lead-free ceramics  

NASA Astrophysics Data System (ADS)

To clarify the effect of A-site donor doping on the phase transition and the strain enhancement, we investigated the crystal structure, as well as the piezoelectric, ferroelectric and electric-field-induced strain (EFIS) properties of La-doped Bi1/2(Na0.82K0.18)1/2TiO3 (BNKT) ceramics. Similarly to our previous studies on BNKT doped with B-site donors such as Nb and Ta, La doping was found to induce a ferroelectric-to-nonpolar (FE-NP) phase transition, leading to a large enhancement in EFIS just after the transition. The result provides strong evidence that a close relationship exists between the Goldschumidt's tolerance factor and the FE-NP transition in BNKT, which has been observed in B-site-donor or isovalent impurity-doped BNKT.

Dinh, Thi Hinh; Lee, Hyun-Young; Yoon, Chang-Ho; Malik, Rizwan Ahmed; Kong, Young-Min; Lee, Jae-Shin; Tran, Vu Diem Ngoc

2013-04-01

139

Infrared evolved gas analysis during thermal investigation of lanthanum, europium and samarium carbonates  

Microsoft Academic Search

The characterisation of rare earth elements carbonates (REECs) was performed by thermal analysis (TG–DTG) combined with simultaneous infrared evolved gas analysis–Fourier transform infrared (EGA–FTIR) spectroscopy. The TG–DTG curves were obtained using the Perkin-Elmer PC series TGA-7 thermogravimetric analyser in the temperature range 25–800°C both in dynamic air and nitrogen atmosphere.La2(CO3)3·nH2O, Eu2(CO3)3·nH2O and Sm2(CO3)3·nH2O were analysed, the dehydration and decarbonation steps

Lilli Paama; Ilkka Pitkänen; Helena Halttunen; Paavo Perämäki

2003-01-01

140

Fission ?-RAY Measurements with Lanthanum Halide Scintillation Detectors  

NASA Astrophysics Data System (ADS)

In a recent experiment, performed at the 10 MW research reactor at the Institute of Isotopes (IKI) in Budapest, the emission of prompt ?-rays from the cold-neutron induced fission of 236U* was measured. For that purpose four cerium-doped lanthanum halide scintillation detectors were employed and found very useful in order to distinguish between ?-rays from different reactions. Although data analysis is not completed yet, we could show that these novel detectors indeed provide the means towards new and more precise input data necessary for the modeling of ?-heating in nuclear reactors.

Oberstedt, A.; Billnert, R.; Karlsson, J.; Göök, A.; Oberstedt, S.; Hambsch, F.-J.; Ledoux, X.; Marmouget, J.-G.; Belgya, T.; Kis, Z.; Szentmiklosi, L.; Takács, K.; Martinez-Perez, T.; Cano-Ott, D.

2011-10-01

141

Ambi-site substitution of Mn in lanthanum germanate apatites  

Microsoft Academic Search

A neutron diffraction study at 4K of the Mn doped lanthanum germanate apatite-type oxide ion conductor of nominal starting composition “La9.5Mn0.5(GeO4)6O2.75” is reported. The structure was refined in space group P63\\/m, although high thermal displacement parameters were observed for the oxide ion sites (particularly O3, and O4). Reduced thermal displacement parameters were obtained by splitting the O3 site, and allowing

E. Kendrick; K. S. Knight; P. R. Slater

2009-01-01

142

Optical properties of samarium doped zinc-tellurite glasses  

Microsoft Academic Search

Glasses with the composition, (Sm2\\u000a O\\u000a 3)\\u000a x\\u000a (ZnO)(40-x)(TeO\\u000a 2)(60), were prepared by conventional melt quenching method. The density, molar volume, and optical energy band gap of these glasses\\u000a have been measured. The refractive index, molar refraction and polarizability of oxide ion have been calculated by using Lorentz-Lorentz\\u000a relations. Optical absorption spectra of these glasses were recorded in the range

B. Eraiah

2006-01-01

143

High-temperature spectral hole burning on samarium(II) in single crystals of the lead fluorohalide structure family and in thin films of calcium fluoride  

Microsoft Academic Search

When modern spectral hole burning applications for high-density information storage under noncryogenic temperatures are envisioned, it is necessary to develop new frequency-selective photoactive materials for this purpose. Mixed compounds of the PbFCl family, doped with samarium (II) ions, exhibits promising and true room-temperature hole burning capabilities. We investigate this class of systems (and related ones) by combining material synthesis and

Hans Bill; R. Jaaniso; Hans Hagemann; Dominique Lovy; Alain Monnier; Marc Schnieper

1995-01-01

144

DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES  

DOEpatents

A plutonium separatory ore concentration procedure involving the use of a fluoride type of carrier is presented. An improvement is given in the derivation step in the process for plutonium recovery by carrier precipitation of plutonium values from solution with a lanthanum fluoride carrier precipitate and subsequent derivation from the resulting plutonium bearing carrier precipitate of an aqueous acidic plutonium-containing solution. The carrier precipitate is contacted with a concentrated aqueous solution of potassium carbonate to effect dissolution therein of at least a part of the precipitate, including the plutonium values. Any remaining precipitate is separated from the resulting solution and dissolves in an aqueous solution containing at least 20% by weight of potassium carbonate. The reacting solutions are combined, and an alkali metal hydroxide added to a concentration of at least 2N to precipitate lanthanum hydroxide concomitantly carrying plutonium values.

Fries, B.A.

1959-11-10

145

Radiation effects in lanthanum pyrozirconate  

NASA Astrophysics Data System (ADS)

The present paper reviews recent results on radiation resistance of lanthanum pyrozirconate La2Zr2O7 obtained through molecular dynamic simulations using empirical potentials. Detailed studies of displacement cascades carried out with a 6 keV U4+ cation, representing the a-recoil nucleus, have shown only point-defects formation, Frenkel pairs and cation antisites, indicating that in this material amorphization does not occur by a direct impact mechanism. In a more enhanced simulation study, the consequences of point-defect accumulation have been analyzed. The results show that cation Frenkel pair accumulation is the driving force for lanthanum zirconate amorphization. It is demonstrated that under cation Frenkel pair accumulation, the crystal undergoes a transition from the pyrochlore to the disordered fluorite structure, with the oxygen atoms simply rearranging around cations and next to the amorphous state. Consequently, these results provide atomic-level interpretation to experimental observations of a two-step phase transition under irradiation.

Chartier, A.; Crocombette, J.-P.; Meis, C.; Weber, W. J.; Corrales, L. R.

2006-09-01

146

Radiation Effects in Lanthanum Pyrozirconate  

SciTech Connect

The present paper reviews recent results on radiation resistance of lanthanum pyrozirconate obtained using empirical potentials molecular dynamic simulations. First, displacement cascades (DCs) with a 6 keV U4+ cation representing the ?- recoil nucleus have been performed in the lanthanum pyrozirconate La2Zr2O7. Only point defects are observed after each DC. They represent on average only 10% of the total number of displaced atoms during the cascade, with two times more cation anti-sites than Frenkel pairs. These calculations indicate that amorphization does not occur by a direct impact mechanism in pyrozirconate. Second, consequences of point defects accumulation have been simulated by introducing different types--either cation anti-sites or Frenkel pairs--and concentrations of point defects in pyrochlore. Results show that cation Frenkel pairs accumulation is the driving force for lanthanum zirconate amorphization. Under cation Frenkel pair accumulation, the crystal transits first from the pyrochlore to the disordered fluorite structure, with the oxygen atoms simply rearranging around cations. Amorphization occurs as a second step. These results consequently provide atomic-level interpretation to experimental irradiation observations of a two-step phase transition.

Chartier, Alan; Crocombette, J.-P.; Meis, Constantin; Weber, William J.; Corrales, Louis R.

2006-09-01

147

Samarium(III) catalyzed one-pot construction of coumarins  

Microsoft Academic Search

Samarium(III) nitrate hexahydrate as a catalyst is used as an alternative to conventional acid catalysts in the von Pechmann condensation of phenols with ethyl acetoacetate leading to the formation of coumarin derivatives.

Sushilkumar S. Bahekar; Devanand B. Shinde

2004-01-01

148

Untersuchungen zum polarographischen Verhalten des Samarium(III)-Cupferron-Chelats  

Microsoft Academic Search

In aqueous solutions of samarium(III), cupferron and ammonium chloride a high sensitive polarographic wave is observed, which is suitable for the trace determination of samarium. The investigation of the electrode mechanism indicates that the polarographic process belongs to the adsorptive complex waves, which results from the reduction of the ligands of the Sm(III)-cupferron-chelate. The experimental results indicate that the electroactive

X. G. Yang; E. Jackwerth

1986-01-01

149

Electrochemical extraction of samarium from molten chlorides in pyrochemical processes  

Microsoft Academic Search

This work concerns the electrochemical extraction of samarium from molten chlorides. In this way, the electrochemical behaviour of samarium ions has been investigated in the eutectic LiCl–KCl at the surface of tungsten, aluminium and aluminium coated tungsten electrodes. On a W inert electrode the electro-reduction of Sm(III) takes place in only one soluble–soluble electrochemical step Sm(III)\\/Sm(II). The electrochemical system Sm(II)\\/Sm(0)

Y. Castrillejo; P. Fernández; J. Medina; P. Hernández; E. Barrado

2011-01-01

150

Samarium-neodymium direct dating of fluorite mineralization  

Microsoft Academic Search

The direct dating of many styles of hydrothermal mineralization has proved difficult, limiting understanding of the geological processes that lead to crustal fluid flow and the formation of major ore deposits. The hydrothermal mineral fluorite (CaFâ) displays large variations in rare earth element (REE) abundance and samarium\\/neodymium ratios within a single vein. Samarium-neodymium dating of fluorite from the classic granite-hosted

J. T. Chesley; A. N. Halliday; R. C. Scrivener

1991-01-01

151

The magnetic anisotropy of samarium-alnico pseudobinary alloys  

NASA Astrophysics Data System (ADS)

The anisotropy properties of samarium-Alnico V pseudobinary alloys have been investigated. With alloys containing less than 12.0 mol% samarium, the K1 values are negative at 77 K and increase with increasing temperature to approximately zero at room temperature. The K2 values remain positive at all temperatures. We do not find the easy cone that has long been thought to be existed in those alloys with K1 < 0 and K2 #62; 0. In alloys with samarium contents between 13.3 and 19.0 mol%, the K1 and K2 values are positive at all temperatures. The anisotropy fields are not changed monotonically in the whole range of 10.1 to 19.0 mol% of samarium. It is concluded that the alloys are characteristics in thermodynamically of first-order transition. We have found that the ``hard cone'' exists in each of those alloys with samarium content more than 16.0 mol% and at temperatures above 77 K. The alloys with samarium less that 13.4 mol% also have ``hard cone'' under 77 K. However, the observed ``hard cone'' is different from the well known one in the first-order magnetization process, and it will collapse to the easy axis when the measuring field and temperature increase while under room temperature.

Chang, Y. H.; Weng, C. I.; Hsu, T. K.

1984-01-01

152

The Isotopic Constitution of Lanthanum and Cerium  

Microsoft Academic Search

The isotopic abundances of lanthanum and cerium have been determined by means of a mass spectrometer. In addition to the known lanthanum isotope of mass 139, a new isotope of mass 138 and abundance 0.089 percent has been discovered. Since this isotope is isobaric with two neighboring stable isotopes it should be radioactive. No activity was observed. Upper limits for

Mark G. Inghram; Richard J. Hayden; David C. Hess

1947-01-01

153

Determination of strontium and lanthanum zirconates in YPSZ–LSM mixtures for SOFC  

Microsoft Academic Search

Mixtures of 3% yttria- and partially-stabilized zirconia with LSMx (strontium-doped lanthanum manganite, x=0, 0.15 and 0.2) were prepared and heat treated at temperatures between 1000 and 1300°C to recreate the cathode–electrolyte interface interactions taking place during preparation and operation of solid oxide fuel cells (SOFC). Such interactions include the formation of La2Zr2O7 and SrZrO3, which are undesirable for SOFC. The

Claudia Alicia Cortés-Escobedo; Juan Muñoz-Saldaña; Ana María Bolarín-Miró; Félix Sánchez-de Jesús

2008-01-01

154

Concentration dependence of the fluorescence decay profile in transition metal doped chalcogenide glass  

Microsoft Academic Search

In this paper we present the fluorescence decay profiles of vanadium and titanium doped gallium lanthanum sulphide (GLS) glass at various doping concentrations between 0.01 and 1% (molar). We demonstrate that below a critical doping concentration the fluorescence decay profile can be fitted with the stretched exponential function: exp(-(t\\/?) ? ), where ? is the fluorescence lifetime and ? is

M. Hughes; D. W. Hewak; R. J. Curry

155

Induced assembly and photoluminescence of lanthanum (Tb, Eu, Dy) complexes/ZnO/polyethylene glycol hybrid phosphors  

NASA Astrophysics Data System (ADS)

Some novel kinds of hybrid phosphors were assembled with lanthanum (Tb, Eu, Dy) complexes (with four kinds of terbium complexes is 2,4-dihydroxybenzonic acid (DHBA), 1,10-phenanthroline (phen), acetylacetone (AA) and nicotinic acid (Nic), respectively) doped ZnO/PEG particles by co-precipitation approach derived from Zn(CH3COO)2 (Zn(AC)2), NaOH, PEG as precursors at room temperature. The characteristic luminescence spectra for f f transitions of Tb3+, Eu3+, Dy3+ were observed. It is worthy to point out that ZnO is the excellent host for lanthanum ions by the assembly of PEG matrices.

Yan, Bing; Chen, Xi; Wu, Jianhua

2007-08-01

156

Improved Sinterability and Performance of Lanthanum Ferrite SOFC Cathodes  

SciTech Connect

Strontium-doped lanthanum ferrite (LSF) materials have shown considerable promise as solid oxide fuel cell (SOFC) cathodes. When used in conjunction with an anode-supported yttria-stabilized zirconia (YSZ) electrolyte assembly, power densities of 0.7-0.9 W/cm2 at 750 C and 0.7V can be achieved. However, this performance relies on the incorporation of a doped ceria interlayer between the YSZ electrolyte and LSF cathode. In the case of Sr-doped lanthanum manganites and cobaltites the ceria interlayer acts as a reaction barrier and prevents the formation of poorly conducting Sr- and La- zirconate phases. LSF, on the other hand, does not appear to react with YSZ to form the aforementioned zirconate phases even if reacted at 1400 C ({approx}250 C above the typical firing temperature for LSF). Instead, when sintered in direct contact with YSZ, Zr4+ cations diffuse into the perovskite where they occupy B-site positions, and result in decreased electrical (and possibly ionic) conductivity of the cathode. As expected the Zr diffusion exhibits thermal dependence, and is typically observed at temperatures ?1000 C. The current cathode of choice, La0.8Sr0.2FeO3-? (LSF-20), has an optimized (in terms of adherence and microstructure) sintering temperature of {approx}1150 C. Therefore, application of this cathode directly on YSZ results in the aforementioned LSF-YSZ interaction, and subsequently relatively poor performance. Hence, the need for the protective ceria interlayer. Recently, the authors have considered changes in the LSF-20 chemistry to facilitate enhanced cathode sintering <1000 C in an attempt to avoid the LSF-YSZ reaction. Modifications must be subtle in nature since high cation dopant levels can result in the formation of poorly conducting zirconate phases, typically observed with manganites and cobaltites. A composition that appears somewhat promising is a slightly A-site deficient lanthanum ferrite with a marginal amount of Cu dopant on the B-site, (La0.8Sr0.2)0.98Fe0.98Cu0.02O3-?. This composition can be sintered onto YSZ at 950 C, and to date has indicated power densities of 1.3-1.8 W/cm2 at 750 C and 0.7V ({approx}1.5-2.0 times greater than the performance exhibited for a cell with an LSF-20 cathode and ceria interlayer). Other transition metal dopants and degrees of non-stoichiometry are also under investigation.

Simner, Steve P.; Anderson, Michael D.; Stevenson, Jeffry W.

2003-10-01

157

GMR thin films deposited by a new MOCVD-injection method. Preparation, transport properties and magnetic behaviour of self-doped lanthanum manganites La1-xMnO3-? (0 <= x <= 0.3)  

NASA Astrophysics Data System (ADS)

A new liquid-source metal organic chemical vapour deposition process, using liquid injection, has been developed in order to control precisely the amount of precursor vapours to be produced. Films of self-doped La1-xMnO3-? (0 <= x <= 0.3) have been deposited on MgO (1 0 0) and LaAlO3 (0 1 2) substrates. X-ray diffraction measurements reveal an epitaxial growth. The as-deposited films exhibit both a ferromagnetic and metal-semiconductor transition at various temperatures depending on the x value. Post-annealing experiments greatly improve their magnetic and transport characteristics: the resistivity is considerably reduced and transition temperature substantially increased. For the x = 0.2 lacunar compound, the transition temperature raised up to 320 K and a magnetoresistance ??/?0 = 20%/T is obtained at 300 K in the [0T, 2T] range.

Vincent, H.; Pignard, S.; Sénateur, J. P.; Pierre, J.

1998-01-01

158

Absolute bioavailability and disposition of lanthanum in healthy human subjects administered lanthanum carbonate.  

PubMed

Lanthanum carbonate [La2(CO3)3] is a noncalcium, non-aluminum phosphate binder indicated for hyperphosphatemia treatment in end-stage renal disease. A randomized, open-label, parallel-group, phase I study was conducted to determine absolute bioavailability and investigate excretory routes for systemic lanthanum in healthy subjects. Twenty-four male subjects were randomized to a single lanthanum chloride (LaCl3) intravenous infusion (120 microg elemental lanthanum over a 4-hour period), a single 1-g oral dose [chewable La2(CO3)3 tablets; 4 x 250 mg elemental lanthanum], or no treatment (control). Serial blood, urine, and fecal samples were collected for 7 days postdosing. The absolute bioavailability of lanthanum [administered as La2(CO3)3] was extremely low (0.00127% +/- 0.00080%), with individual values in the range of 0.00015% to 0.00224%. Renal clearance was negligible following oral administration (1.36 +/- 1.43 mL/min). Intravenous administration confirmed low renal clearance (0.95 +/- 0.60 mL/min), just 1.7% of total plasma clearance. Fecal lanthanum excretion was not quantifiable after intravenous administration owing to high and variable background fecal lanthanum and constraints on the size of the intravenous dose. These findings demonstrate that lanthanum absorption from the intestinal tract into the systemic circulation is extremely low and that absorbed drug is cleared predominantly by nonrenal mechanisms. PMID:16809799

Pennick, Michael; Dennis, Kerry; Damment, Stephen J P

2006-07-01

159

Lanthanum Chloride Scintillator for X-ray Detection  

NASA Astrophysics Data System (ADS)

In this presentation we describe the testing of a new cerium doped Lanthanum Chloride crystal (LaCl3:Ce), which makes an excellent scintillation material for X-ray counting applications. Detailed measurements were taken to determine the properties of the scintillator over an energy range of 5 to 60KeV; the results demonstrate that, when used with an appropriate PMT, the crystal sustains high count rates, minimal dead time and good energy resolution. For example an energy resolution of 35% (FWHM) was achieved at 22KeV and count rates of up to 1MHz are possible without dead-time correction. A comparison of LaCl3:Ce with two conventional scintillation materials, YAP:Ce and NaI(Tl) is also presented, which shows that that LaCl3:Ce offers a good balance of performance parameters for X-ray experiments.

Martin, T.; Allier, C.; Bernard, F.

2007-01-01

160

Lanthanum Chloride Scintillator for X-ray Detection  

SciTech Connect

In this presentation we describe the testing of a new cerium doped Lanthanum Chloride crystal (LaCl3:Ce), which makes an excellent scintillation material for X-ray counting applications.Detailed measurements were taken to determine the properties of the scintillator over an energy range of 5 to 60KeV; the results demonstrate that, when used with an appropriate PMT, the crystal sustains high count rates, minimal dead time and good energy resolution. For example an energy resolution of 35% (FWHM) was achieved at 22KeV and count rates of up to 1MHz are possible without dead-time correction.A comparison of LaCl3:Ce with two conventional scintillation materials, YAP:Ce and NaI(Tl) is also presented, which shows that that LaCl3:Ce offers a good balance of performance parameters for X-ray experiments.

Martin, T.; Allier, C.; Bernard, F

2007-01-19

161

Samarium Ion Exchanged Montmorillonite for High Temperature Cumene Cracking Reaction  

NASA Astrophysics Data System (ADS)

Montmorillonite clay is cation exchanged with samarium and its catalytic influence in cumene cracking reaction is investigated. Effect of exchange with sodium ions on further exchange with samarium ions is also noted. Acidity measurements are done using Temperature Programmed Desorption (TPD) of ammonia. The retention of basic structure is proved from FTIR spectra and XRD patterns. Elemental analysis result shows that samarium exchange has occurred, which is responsible for the higher catalytic activity. Surface area and pore volume remains more or less unaffected upon exchange. Thermogravimetric analysis indicates the enhanced thermal stability on exchanging. Cumene cracking reaction is carried out at atmospheric pressure in a fixed bed glass reactor at 673 K. The predominance of Brønsted acidity is confirmed from high selectivity to benzene.

Binitha, N. N.; Silija, P. P.; Suraj, V.; Yaakob, Z.; Sugunan, S.

2011-02-01

162

Field free, directly heated lanthanum boride cathode  

DOEpatents

A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic fields which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

Leung, Ka-Ngo (Hercules, CA); Moussa, David (San Francisco, CA); Wilde, Stephen B. (Pleasant Hill, CA)

1991-01-01

163

New Synthesis for Lanthanum Hexaboride Nanocrystals.  

National Technical Information Service (NTIS)

Although lanthanum hexaboride has been used for many years as a cathode material, new applications exploiting its unusual electron emission properties are now being investigated. Nanocrystalline LaB6 materials have been predicted to provide important adva...

L. Pfefferie

2008-01-01

164

Electron Emission Characteristics of Sputtered Lanthanum Hexaboride.  

National Technical Information Service (NTIS)

Metallic filaments were coated with lanthanum hexaboride deposited by rf magnetron sputter deposition. A simple diode system was designed to measure the work function of the filaments and to study the emission behavior. It was found that under some condit...

S. J. Mroczkowski

1988-01-01

165

Field free, directly heated lanthanum boride cathode  

DOEpatents

A directly heated cylindrical lanthanum boride cathode assembly is disclosed which minimizes generation of magnetic field which would interfere with electron emission from the cathode. The cathode assembly comprises a lanthanum boride cylinder in electrical contact at one end with a central support shaft which functions as one electrode to carry current to the lanthanum boride cylinder and in electrical contact, at its opposite end with a second electrode which is coaxially position around the central support shaft so that magnetic fields generated by heater current flowing in one direction through the central support shaft are cancelled by an opposite magnetic field generated by current flowing through the lanthanum boride cylinder and the coaxial electrode in a direction opposite to the current flow in the central shaft.

Leung, Ka-Ngo; Moussa, D.; Wilde, S.B.

1987-02-02

166

Thermodynamic representation of nonstoichiometric lanthanum manganite  

Microsoft Academic Search

The thermodynamic properties of the lanthanum manganites, La1 ? xMn1 ? y,O3 ? z, have been reevaluated within the ideal association model to simultaneously account for excess oxygen and lanthanum nonstoichiometry of LaMnO3 + ?, La0.95MnO3 + ? and La0.9MnO3 + ?. It has been found that a new set of parameters can reproduce the essential features of the thermogravimetric

Harumi Yokokawa; Teruhisa Horita; Natsuko Sakai; Masayuki Dokiya; Tatsuya Kawada

1996-01-01

167

Compact lanthanum hexaboride hollow cathode  

NASA Astrophysics Data System (ADS)

A compact lanthanum hexaboride hollow cathode has been developed for space applications where size and mass are important and research and industrial applications where access for implementation might be limited. The cathode design features a refractory metal cathode tube that is easily manufactured, mechanically captured orifice and end plates to eliminate expensive e-beam welding, graphite sleeves to provide a diffusion boundary to protect the LaB6 insert from chemical reactions with the refractory metal tube, and several heater designs to provide long life. The compact LaB6 hollow cathode assembly including emitter, support tube, heater, and keeper electrode is less than 2 cm in diameter and has been fabricated in lengths of 6-15 cm for different applications. The cathode has been operated continuously at discharge currents of 5-60 A in xenon. Slightly larger diameter versions of this design have operated at up to 100 A of discharge current.

Goebel, Dan M.; Watkins, Ronald M.

2010-08-01

168

Basis for developing samarium AMS for fuel cycle analysis  

NASA Astrophysics Data System (ADS)

Modeling of nuclear reactor fuel burnup indicates that the production of samarium isotopes can vary significantly with reactor type and fuel cycle. The isotopic concentrations of 146Sm, 149Sm, and 151Sm are potential signatures of fuel reprocessing, if analytical techniques can overcome the inherent challenges of lanthanide chemistry, isobaric interferences, and mass/charge interferences. We review the current limitations in measurement of the target samarium isotopes and describe potential approaches for developing Sm-AMS. AMS sample form and preparation chemistry will be discussed as well as possible spectrometer operating conditions.

Buchholz, Bruce A.; Biegalski, Steven R.; Whitney, Scott M.; Tumey, Scott J.; Jordan Weaver, C.

2010-04-01

169

The Basis for Developing Samarium AMS for Fuel Cycle Analysis  

SciTech Connect

Modeling of nuclear reactor fuel burnup indicates that the production of samarium isotopes can vary significantly with reactor type and fuel cycle. The isotopic concentrations of {sup 146}Sm, {sup 149}Sm, and {sup 151}Sm are potential signatures of fuel reprocessing, if analytical techniques can overcome the inherent challenges of lanthanide chemistry, isobaric interferences, and mass/charge interferences. We review the current limitations in measurement of the target samarium isotopes and describe potential approaches for developing Sm-AMS. AMS sample form and preparation chemistry will be discussed as well as possible spectrometer operating conditions.

Buchholz, B A; Biegalski, S R; Whitney, S M; Tumey, S J; Weaver, C J

2008-10-13

170

Pharmacology of the phosphate binder, lanthanum carbonate.  

PubMed

Studies were conducted to compare the phosphate-binding efficacy of lanthanum carbonate directly with other clinically used phosphate binders and to evaluate any potential adverse pharmacology. To examine the phosphate-binding efficacy, rats with normal renal function and chronic renal failure received lanthanum carbonate, aluminum hydroxide, calcium carbonate, or sevelamer hydrochloride in several experimental models. Lanthanum carbonate and aluminum hydroxide markedly increased excretion of [(32)P]-phosphate in feces and reduced excretion in urine in rats with normal renal function (p < 0.05), indicating good dietary phosphate-binding efficacy. In rats with chronic renal failure, lanthanum carbonate and aluminum hydroxide reduced urinary phosphate excretion to a greater degree and more rapidly than calcium carbonate, which in turn was more effective than sevelamer hydrochloride. The potential to induce adverse pharmacological effects was assessed systematically in mice, rats, and dogs with normal renal function using standard in vivo models. There was no evidence of any adverse secondary pharmacological effects of lanthanum carbonate on the central nervous, cardiovascular, respiratory, or gastrointestinal systems. These studies indicate that lanthanum carbonate is the more potent of the currently available dietary phosphate binders. No adverse secondary pharmacological actions were observed in vivo in a systematic evaluation at high doses. PMID:21332344

Damment, Stephen J P

2011-01-01

171

The oxygen migration in the apatite-type lanthanum silicate with the cation substitution.  

PubMed

A theoretical model is proposed to determine the effects of Si substitution with Al on the oxygen diffusion in apatite-type lanthanum silicates based on density-functional theory (DFT) calculations for La10(SiO4)4(AlO4)2O2. Substitution changes the stable configuration for excess oxygen from the split interstitial to a new cluster form with the original cluster. Al doping completely changes the migration mechanism from the interstitialcy one, which was proposed for the La9.33(SiO4)6O2 starting material, to a mechanism which contains an interstitial process. Nevertheless, the migration barrier is calculated to be 0.81 eV, which indicates small changes in oxygen conduction and is consistent with the observations. The present study indicates that the cation substitution on silicon site alone does not promise the improvement of the oxide ion conduction in the lanthanum silicate. PMID:24030438

Liao, Ting; Sasaki, Taizo; Sun, Ziqi

2013-09-25

172

Analysis and first order correction of signal saturation effects in photomultiplier tubes for improved estimation of interacting radiation energy in Lanthanum bromide scintillators  

Microsoft Academic Search

The huge amount of optical photons emitted in burst by Cerium doped Lanthanum bromide scintillators poses a severe constraint on the specifications of photomultipliers, namely they must operate at very large instantaneous current values with minimum saturation of output pulse signals. Acquisition in shape and processing of photomultipliers output pulses by means of high-speed free-running analog to digital converters and

Nives Blasi; Sergio Brambilla; Ciro Boiano; Franco Camera; A. Camplani; Fabio C. L. Crespi; Agnese Giaz; Benedicte Million; Roberto Nicolini; Luna Pellegri; Stefano Riboldi; Oliver Wieland

2010-01-01

173

Co-Cu-Sm (Cobalt-Copper-Samarium)  

Microsoft Academic Search

This document is part of Subvolume C2 'Non-Ferrous Metal Systems. Part 2: Selected Copper Systems' of Volume 11 'Ternary Alloy Systems - Phase Diagrams, Crystallographic and Thermodynamic Data critically evaluated by MSIT®' of Landolt-Börnstein - Group IV 'Physical Chemistry'. It provides data of the ternary system Cobalt-Copper-Samarium.

2007-01-01

174

Über eine neue Erscheinung bei den Isotopen des Samariums  

Microsoft Academic Search

Zusammenfassung Hyperfeinstrukturuntersuchungen am Samarium zeigen einen Isotopenverschiebungseffekt, und zwar sind hier im Gegensatz zu den bisherigen Beobachtungen an anderen Elementen die Verschiebungen zwischen den einzelnen geraden Isotopen nicht mehr konstant, vielmehr sind die Isotope 150 und 152 etwa doppelt so weit getrennt wie 152 und 154. Die Beobachtungen lassen den Schluß zu, daß beim Aufbau des Atomkerns zwischen Sm150 und

H. Schüler; Th. Schmidt

1934-01-01

175

METHOD FOR DISSOLVING LANTHANUM FLUORIDE CARRIER FOR PLUTONIUM  

DOEpatents

A method is described for dissolving lanthanum fluoride precipitates which is applicable to lanthanum fluoride carrier precipitation processes for recovery of plutonium values from aqueous solutions. The lanthanum fluoride precipitate is contacted with an aqueous acidic solution containing dissolved zirconium in the tetravalent oxidation state. The presence of the zirconium increases the lanthanum fluoride dissolved and makes any tetravalent plutonium present more readily oxidizable to the hexavalent state. (AEC)

Koshland, D.E. Jr.; Willard, J.E.

1961-08-01

176

Laser Spectroscopic Studies of Samarium Monoxide  

NASA Astrophysics Data System (ADS)

The results of various laser spectroscopic experiments using Resolved Fluorescence Spectra (RFS), high resolution Wavelength Selected Excitation Spectroscopy (WSES), intermodulated fluorescence, and sub-Doppler Zeeman spectroscopy have been combined to investigate the structure and properties of the low-lying electronic states of samarium monoxide (SmO) in this research. Fifteen low-lying electronic states have been observed and linked together in a single energy diagram. Conclusive Omega assignments have been determined for those states. A detailed examination of the ground state shows that it is an Omega = 0 state (X0^{-}). The order and energies of the observed low-lying states are shown to be in fair agreement with those calculated from a detailed ligand field fit to the Sm^{2+ } (4f^5(^6H)6s) O^{2-} supermultiplet. Twelve of the observed low-lying states have been excited through more than twenty high resolution electronic transitions which have been rotationally analyzed. Global fits to all the transitions for the two most abundant isotopes (^{154}SmO, ^ {152}SmO) and some transitions for the four lighter isotopes (^{150} SmO, ^{149}SmO, ^{148}SmO, ^ {147}SmO) have yielded electronic term energies, rotational constants, and Omega doubling parameters for twelve low-lying and seven upper states. This is the first systematic rotational analysis for the SmO molecule. Several perturbations have been assigned and analyzed. The local perturbations have been frequently used to confirm the assignment of the spectra. Perturbation mechanisms have been proposed and the matrix elements have been calculated from the experimental results. The intensity distribution of the main and extra lines seems to support the proposed mechanisms. The Omega doubling constants and the Lande g_{rm e} factor in Zeeman spectra are obtained from the experiment and used to test the eigenfunctions of the ligand field Hamiltonian. The observed Omega doubling constants show a very good agreement with those calculated from the predicted eigenfunctions for the first few low-lying states but point to a need for revision of the eigenfunctions for higher states. The g_ {rm e} factor of (1)1 state measured from Zeeman experiment agreed with the calculated one and proved to be very sensitive to small perturbations. For the (1)2 state, the g_{rm e} factor indicates a need to modify the eigenfunctions.

Guo, Bujin

177

Strontium and samarium diffusion in diopside  

NASA Astrophysics Data System (ADS)

The volume chemical diffusion of trace amounts of Sr in diopside has been measured as a function of temperature (1100-1300°C), pressure (1 bar-20 kbar), crystallographic direction, and composition. Three experimental/analytical techniques were employed: radiotracer and sectioning; stable tracer and ion microprobe; and Rutherford back-scattering spectroscopy. Comparison of the three yielded excellent agreement. Both natural and synthetic single crystal samples were used with results in the natural diopside giving diffusivities approximately two orders of magnitude greater than those in the man-made crystals. Samarium diffusion in the synthetic crystals was also examined with the ion probe technique with results similar to Sr. Arrhenius relations for diffusion ( D = D0exp[- ?Ha/ RT]) were calculated for different pressures and analytical techniques, and activation volumes (gD Va) were derived from the equation D = D' exp[- P?Va/ RT]. Values of ? Va were negative for Sr diffusion. An empirical relation describing the temperature and pressure dependence of D for Sr in the c direction of the synthetic samples is: D( P, T) = 1200 ( cm2/ sec) exp[-122 ( Kcal/ mol)/ RT (° K)] exp[- P ( bar)/(2.94 T - 4640) R]. The expression for DSr in the natural samples ( c direction) at one atmosphere is: D(0, T) = 54 ( cm2/ sec) exp[-97 ( Kcal/ mol)/ RT (° K)]. A single compensation trend for all the data was evident for all values of D0 and ? Ha in the synthetic crystals. A number of models of geologic processes were investigated in light of the present data. Closure temperatures ( Tc) were calculated for examples of mineral-mineral age-dating and trace element geothermometry. High values of Tc indicate that pyroxenes record emplacement events and are generally not disturbed unless a fluid enters the system. Isotopic equilibration times were examined for lower crustal xenoliths and the mantle source region for MORB using the formula of Hofmann and Hart (1978). Equilibration was shown to be too fast for production of isotopic anomalies in MORB via disequilibrium melting. Also. reasonable residence times at lower crustal temperatures were shown to produce the mineralogical-scale isotopic homogeneity observed in a crustal xenolith from Kilbourne Hole, New Mexico.

Sneeringer, Mark; Hart, Stanley R.; Shimizu, Nobumichi

1984-08-01

178

Investigation into nanostructured lanthanum halides and CeBr3 for nuclear radiation detection  

NASA Astrophysics Data System (ADS)

Nanocomposites may enable the use of scintillator materials such as cerium-doped lanthanum fluoride (LaF3:Ce) and cerium bromide (CeBr3) without requiring the growth of large crystals. Nanostructured detectors may allow us to engineer immensely sized detectors of flexible form factors that will have a broad energy range and an energy resolution sufficient to perform isotopic identification. Furthermore, nanocomposites are easy to prepare and very low in cost. It is much less costly to use nanocomposites rather than grow large whole crystals of scintillator materials; with nanocomposites fabricated on an industrial scale, costs are even less. Nanostructured radiation scintillator detectors may improve quantum efficiency and provide vastly improved detector form factors. Quantum efficiencies up to 60% have been seen in photoluminescence from silicon nanocrystals in a densely packed ensemble. We have fabricated nanoparticles with sizes <10 nm and characterized their nanocomposite radiation detector properties. This work investigates the properties of the nanostructured radiation scintillator in order to extend the gamma energy response on both low- and high-energy regimes by demonstrating the ability to detect low-energy x-rays and relatively high-energy activation prompt gamma rays simultaneously using nanostructured lanthanum bromide, lanthanum fluoride, or CeBr3. Preliminary results of this investigation are consistent with a significant response of these materials to nuclear radiation.

Guss, Paul; Guise, Ronald; Mukhopadhyay, Sanjoy; Yuan, Ding

2011-09-01

179

Synthesis and luminescence properties of the lithium-containing lanthanum-oxycarbonate-like borates  

NASA Astrophysics Data System (ADS)

The lithium-containing lanthanum-oxycarbonate-like borate, Li0.6La2O2.25(BO3)0.7, has been synthesized by solid-state reactions and was found to be isostructural with the type II lanthanum-oxycarbonate La2O2(CO3). The new compound, lithium-containing lanthanum-oxycarbonate-like borate Li0.6La2O2.25(BO3)0.7 has been synthesized and its structure characterized by the Rietveld method using powder X-ray diffraction data. It crystallizes in space group P63/mmc with lattice parameters of a=b=4.03396(3) Å, c=16.5863(2) Å, V=233.746(4) Å3. The mechanism of the lithium incorporation in the borate is that four Li+ cations replace one (B2O)4+ group, i.e. Li0.6La2O2.25(BO3)0.7 can be described as Li2xLa2O1.5+2.5x(BO3)1-x, x=0.3 and the lithium incorporation stabilized the type II borate. The luminescent properties of Li0.6La2O2.25(BO3)0.7 doped with Eu3+ were studied, indicating a potential application in white light emitting diodes (WLEDs).

Kang, Youjun; Liu, Chunmeng; Kuang, Xiaojun; Mi, Jinxiao; Liang, Hongbin; Su, Qiang

2012-10-01

180

Self-activating and doped tantalate phosphors.  

SciTech Connect

An ideal red phosphor for blue LEDs is one of the biggest challenges for the solid-state lighting industry. The appropriate phosphor material should have good adsorption and emission properties, good thermal and chemical stability, minimal thermal quenching, high quantum yield, and is preferably inexpensive and easy to fabricate. Tantalates possess many of these criteria, and lithium lanthanum tantalate materials warrant thorough investigation. In this study, we investigated red luminescence of two lithium lanthanum tantalates via three mechanisms: (1) Eu-doping, (2) Mn-doping and (3) self-activation of the tantalum polyhedra. Of these three mechanisms, Mn-doping proved to be the most promising. These materials exhibit two very broad adsorption peaks; one in the UV and one in the blue region of the spectrum; both can be exploited in LED applications. Furthermore, Mn-doping can be accomplished in two ways; ion-exchange and direct solid-state synthesis. One of the two lithium lanthanum tantalate phases investigated proved to be a superior host for Mn-luminescence, suggesting the crystal chemistry of the host lattice is important.

Nyman, May Devan; Rohwer, Lauren Elizabeth Shea

2011-01-01

181

Synthesis of nano-pore samarium (III)-imprinted polymer for preconcentrative separation of samarium ions from other lanthanide ions via solid phase extraction.  

PubMed

A batch process was developed to separate samarium ions from some lanthanide ions by a novel solid phase which was prepared via the ion-imprinting technique. The samarium (III) ion-imprinted polymer (IIP) particles were synthesized by preparing the ternary complex of samarium ions with 5,7-dichloroquinoline-8-ol (DCQ) and 4-vinylpyridine (VP). Then, thermally copolymerization with styrene (functional monomer, STY) and divinylbenzene (cross-linking monomer, DVB) followed in the presence of 2-methoxy ethanol (porogen) and 2,2'-azobisisobutyronitrile (initiator, AIBN). The imprinted ion was removed by stirring the above particles with 50% (v/v) HCl to obtain the leached IIP particles. Moreover, control polymer (CP) particles were similarly prepared without the samarium ions. The unleached and leached IIP particles were characterized by X-ray diffraction (XRD), infra-red spectroscopy (IR), thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM). Finally, preconcentration and selectivity studies for samarium and the other lanthanide ions were carried out. The preconcentration of the samarium (III) traces was studied during rebinding with the leached IIP particles as a function of pH, the weight of the polymer material, the preconcentration and the elution times, the eluent volume and the aqueous phase volume. These studies indicated that the samarium (III) amount as low as 1 microg, present in 200 mL, could be preconcentrated into 25 mL of 1.0 M HCl. PMID:18611461

Shirvani-Arani, Simindokht; Ahmadi, Seyed Javad; Bahrami-Samani, Ali; Ghannadi-Maragheh, Mohammad

2008-06-05

182

Isotope effects in the lanthanum dihydrides  

Microsoft Academic Search

Equilibrium pressures of protium, deuterium, and tritium over lanthanum metal at atomic ratios up to 2.2 have been measured for temperatures ranging from approx. 800 K to slightly over 1000 K. The equilibrium pressures in the plateau regins increased as expected from the protide to the deuteride to the tritide. Sieverts' constants were determined at the higher temperature and decreased

Dean H. W. Carstens

1981-01-01

183

Electron emission characteristics of sputtered lanthanum hexaboride  

SciTech Connect

Magnetron sputtering was used to deposit a thin film of lanthanum hexaboride for cathode structures. The chemistry of the coatings was studied with x-ray diffraction, Auger electron spectroscopy, and x-ray photoelectron spectroscopy. The work function and electron emission characteristics of the coating have been studied in a diode test cell using tungsten and rhenium as substrates and controls. After optimization of sputtering parameters such as sample bias, forward power, base pressure, and argon flow rates, coatings were obtained with a work function of 2.4--2.6 eV. At 1200 K, the emission density of a lanthanum hexaboride coated tungsten filament was 8.8 mA/cm{sup 2} while the emission density of a clean tungsten filament was 9.7{times}10{sup {minus}12} A/cm{sup 2}. Coated tungsten filaments ran over 1000 h without any reduction in the emission current in a vacuum of 10{sup {minus}7} Torr. Coated filaments were flexed with moderate severity without microcracking, spalling, or a detectable difference in emission characteristics. After an initial activation, the lanthanum hexaboride-coated filaments were exposed to the atmosphere without a subsequent reduction in emission current density. Surface analysis indicated that the surface of the cathode was primarily lanthanum oxide.

Mroczkowski, S.J. (Midwest Research Technologies, Inc., Milwaukee, Wisconsin 53218 (US))

1991-05-01

184

Electron emission characteristics of sputtered lanthanum hexaboride  

Microsoft Academic Search

Magnetron sputtering was used to deposit a thin film of lanthanum hexaboride for cathode structures. The chemistry of the coatings was studied with x-ray diffraction, Auger electron spectroscopy, and x-ray photoelectron spectroscopy. The work function and electron emission characteristics of the coating have been studied in a diode test cell using tungsten and rhenium as substrates and controls. After optimization

Susan J. Mroczkowski

1991-01-01

185

Glasslike thermal conductivity in ytterbium-doped lanthanum zirconate pyrochlore  

Microsoft Academic Search

Glass-like thermal conductivity is observed in (La1?xYbx)2Zr2O7 (1\\/6?x?1\\/3), which exhibits great potential as a high-temperature thermal barrier coating material. In the pyrochlore-type La2Zr2O7, the large 16c-site La3+ is weakly bonded by its surrounding 48f-site oxygen ions, and substitution of La3+ with smaller and heavier Yb3+ gives rise to a large atomic displacement parameter (ADP) of Yb3+ which behaves as a

Chunlei Wan; Wei Zhang; Yifeng Wang; Zhixue Qu; Aibing Du; Ruifen Wu; Wei Pan

2010-01-01

186

Cobalt-Mischmetal-Samarium Permanent Magnet Alloys: Process and Properties  

Microsoft Academic Search

Several authors have reported successful fabrication of high-energy product (15–20 MGOe) Co5R-type cobalt-samarium permanent magnets. In earlier papers we have described preparation of such magnets by a liquid-phase sintering process sequence which includes powder preparation, magnetic alignment, pressing, sintering, and magnetizing. We have also described preparation of ternary compositions, primarily Co&sngbnd;Sm&sngbnd;Pr, by this process. In an effort to utilize more

M. G. Benz; D. L. Martin

1971-01-01

187

Initial Observations: Cobalt-Mischmetal-Samarium Permanent Magnet Alloys  

Microsoft Academic Search

Several authors have reported successful fabrication of high-energy-product (20 MG Oe) Co5R-type cobalt-samarium permanent magnets. In earlier papers we have described preparation of such magnets by a liquid-phase sintering process sequence which includes powder preparation, magnetic alignment, pressing, sintering, and magnetizing. We have also described preparation of ternary compositions, primarily Co&sngbnd;Sm&sngbnd;Pr, by this process. In an effort to utilize more

M. G. Benz; D. L. Martin

1971-01-01

188

Recent developments in samarium diiodide promoted organic reactions.  

PubMed

In the early eighties, we introduced samarium diiodide for the transformation of various functional groups. Since then, this reducing agent has been extensively used for the reductive cleavage of single bonds, C-C bond formations, C-N bond formations, and ?-elimination reactions. In this Personal Account, we highlight our initial results, as well as some of the contributions from various research groups. Because of space limitations, we arbitrarily select some useful results that have recently been described in literature. PMID:23468168

Gopalaiah, Kovuru; Kagan, Henri B

2013-03-07

189

Colossal magnetoresistance properties of samarium based manganese perovskites  

Microsoft Academic Search

The study of the samarium manganites Sm1?x(Sr,Ca)xMnO3 has shown the magnetoresistance properties of this kind of compounds. It allowed us to evidence the effect of the two antagonist effects, interpolated cation size and Mn(IV) : Mn(III) ratio, on the transition temperature Tmax. By varying these two factors, we were able to get RR ratio of 105 at 75K under 5T

F. Damay; N Nguyen; A Maignan; M Hervieu; B Raveau

1996-01-01

190

Microstructures and Properties of Molybdenum Wires Doped with La.  

National Technical Information Service (NTIS)

The structures and properties of the La-doped molybdenum (La-Mo) powder, compact, rods and wires annealed at different temperatures were investigated. The experimental results show that the La exists in the powders in the forms of lanthanum nitrate, lanth...

M. L. Zhou J. Li T. Zuo

1995-01-01

191

Effects of sintering temperature and composition variations on the magnetic properties of samarium cobalt magnets  

Microsoft Academic Search

A systemic study has been made of the effects of various sintering temperatures and variations in composition on the magnetic properties of samarium cobalt magnets. Residual induction, coercive force, and energy product were measured. Samarium content was varied between 35.0% to 36.5% at temperatures 1116, 1126, and 1136 degrees Celcius. A study was also made of the effect of the

L. Wolverton; L. R. Falce

2008-01-01

192

Scintillation Properties of Praseodymium Doped LuAG Scintillator Compared to Cerium Doped LuAG, LSO and  

Microsoft Academic Search

Properties of praseodymium and cerium doped Lutetium Aluminum Garnet (LuAG) were compared with cerium doped Lutetium Oxyorthosilicate (LSO) and Lanthanum Bromide (LaBr3). Light yield, its non-proportionality relative to 662 keV gamma -rays and the dependence of the energy resolution on energy of the detected gamma -rays were measured. LuAG:Pr turned out to have good proportionality, with deviation from unity around

Lukasz Swiderski; Marek Moszynski; Antoni Nassalski; Agnieszka Syntfeld-Kazuch; Tomasz Szczesniak; Kei Kamada; K. Tsutsumi; Yoshiyuki Usuki; Takayuki Yanagida; Akira Yoshikawa; Weerapong Chewpraditkul; Marcin Pomorski

2009-01-01

193

Concentration dependence of the fluorescence decay profile in transition metal doped chalcogenide glass  

Microsoft Academic Search

In this paper we present the fluorescence decay profiles of vanadium and titanium doped gallium lanthanum sulphide (GLS) glass at various doping concentrations between 0.01 and 1% (molar). We demonstrate that below a critical doping concentration the fluorescence decay profile can be fitted with the stretched exponential function: exp[-(t\\/tau)beta], where tau is the fluorescence lifetime and beta is the stretch

M. Hughes; D. W. Hewak; R. J. Curry

2007-01-01

194

Structural analysis, magnetic and electrical properties of samarium substituted lithium-nickel mixed ferrites  

NASA Astrophysics Data System (ADS)

A series of Sm-doped Li-Ni ferrites with formula of (Li0.5Fe0.5)0.4Ni0.6SmyFe2-yO4, where 0.0?y?0.1 were prepared by double sintering ceramic technique. The structure was characterized by X-ray diffraction, which has confirmed the formation of single-phase spinel structure. The samarium concentration dependence of lattice parameters obeys Vegard's law. The octahedral site radii increased with Sm content while the tetrahedral site radii decreased. Deviation from the ideal crystal structure (?) is found to decrease with Sm substitution, and the hopping length on the octahedral site is found to increase with Sm content. Hall measurement confirmed p-type conductivity behavior for Sm-doped ferrite and the main charge transport mechanism is hopping of halls between Ni2+ and Ni3+. Sintering at 1300 °C resulted in low resistivity ferrite, which was found to increase with Sm content. Resistivity is governed by both charge carrier mobility and carrier concentration. It decreases with frequency, and this behavior with frequency is discussed according to Koop's theorem. The dielectric constant is found to decrease more rapidly at low frequencies than at higher frequencies while the dielectric constant increases with Sm content. The decrease in ?? with frequency agrees with Deby's type relaxation process. Maximum in ?? is observed when the hopping frequency is equal to the external electric field frequency. The variation in tan ? with frequency shows a similar nature to that of ?? with frequency. The magnetization under applied magnetic field for the samples exhibits a clear hysteretic behavior. The scanning electron microscope (SEM) studies showed that the domain walls may tend to be trapped (pinned) by non-magnetic inclusions, precipitates and voids. The saturation magnetization (MS) increases with the sintering temperature, while the coercivity (HCi) is found to decrease.

Al-Hilli, Muthafar F.; Li, Sean; Kassim, Kassim S.

2012-03-01

195

Superconductivity in lanthanum cuprates: A layered-electron-gas model  

SciTech Connect

The nature of the superconducting state of lanthanum cuprate superconductor is discussed using strong-coupling theory, when electron-electron, electron-phonon, and electron-plasmon mechanisms are simultaneously present within a layered-electron-gas model. Treating the system as a two-component plasma, the effect of two-dimensional (2D) acoustic phonons as well as plasmons has been investigated. The approach is developed for one conducting copper oxide layer, which is an isolated free-electron layer and is well separated from insulating layers in a unit cell. A pair potential is constructed and the model parameters deduced are used to evaluate the transition temperature ({ital T}{sub {ital c}}) as a function of Ba and Sr doping. The approach is further applied to estimate the oxygen isotope coefficient {alpha} and the energy gap parameter {beta}. From these results it is argued that both 2D acoustic phonons and plasmons generated along the CuO{sub 2} layer play a significant role in copper oxide superconductors. In particular, 2D acoustic plasmons strongly influence {ital T}{sub {ital c}} and there is 60% enhancement over the phonon contribution to {ital T}{sub {ital c}}. The computed values of {ital T}{sub {ital c}}, {alpha}, and {beta} are consistent with the reported experimental data.

Varshney, D. [School of Physics, Devi Ahilya University, Indore 452001 (India); Singh, R.K. [School of Physics, Barkatullah University, Bhopal 462026 (India)

1995-09-01

196

Influence of structure on infrared emissivity of lanthanum manganites  

NASA Astrophysics Data System (ADS)

The lanthanum manganites La1-xSrxMnO3 (0.1?x?0.3) were prepared by standard solid-state reaction and sol-gel method, respectively. The structure, magnetization curves, infrared absorption and infrared normal emissivity (?N) in the 3-5 and 8-14 ?m wavebands of the samples were systematically investigated. The samples prepared by solid-state reaction are rhombohedral, and the samples obtained by sol-gel method are orthorhombic with irregularities in size and shape. The slight shoulder appearing on the peak of orthorhombic sample may be due to the asymmetric vibration in distorted lattice, and no infrared absorption occurs in the 3-5 and 8-14 ?m wavebands. The ?N of both samples decreases with increasing doping level, and due to stronger metallic character suggested by magnetization results, rhombohedral samples exhibit lower ?N values than orthorhombic ones. The ?N values in the 8-14 ?m waveband are higher than those in the 3-5 ?m waveband, and the ?N of rhombohedral sample changes significantly in the temperature range 293-328 K. For orthorhombic sample, the ?N increases slightly in the whole temperature range due to the weakening of the double-exchange interaction between Mn3+ and Mn4+.

Shen, Xingmei; Xu, Guoyue; Shao, Chunming

2010-02-01

197

Adsorption of lanthanum to goethite in the presence of gluconate  

SciTech Connect

Adsorption of Lanthanum to Goethite in the Presence of Gluconic Acid L. C. HULL,1 S. E. PEPPER2 AND S. B. CLARK2 1Idaho National Engineering and Environmental Laboratory, Idaho Falls, ID (hulllc@inel.gov) 2Washington State University, Pullman, WA (spepper@wsu.edu), (s_clark@wsu.edu) Lanthanide and trivalent-actinide elements in radioactive waste can pose risks to humans and ecological systems for many years. Organic complexing agents, from natural organic matter or the degradation of waste package components, can alter the mobility of these elements. We studied the effect of gluconic acid, as an analogue for cellulose degradation products, on the adsorption of lanthanum, representing lanthanide and trivalent-actinide elments, to goethite, representing natural iron minearals and degradation products of waste packages. Batch pH adsorption edge experiments were conducted with lanthanum alone, and with lanthanum and gluconate at a 1:1 mole ratio. Lanthanum concentrations studied were 0.1, 1, and 10 mM, covering a range from 10% to 1000% of the calculated available adsorption sites on goethite. In the absence of gluconate, lanthanum was primarily present in solution as free lanthanum ion. With gluconate present, free lanthanum concentration in solution decreased with increasing pH as step-wise deprotonation of the gluconate molecule increased the fraction lanthanum complexed with gluconate. Adsorption to the goethite surface was represented with the diffuse double-layer model. The number of adsorption sites and the intrinsic binding constants for the surface complexes were estimated from the pH adsorption edge data using the computer code FITEQL 4.0. Two surface reactions were used to fit the adsorption data in the absence of gluconate. A strong binding site with no proton release and a much higher concentration of weak binding sites with release of two protons per lanthanum adsorbed. The adsorption of lanthanum was not measurably affected by the presence of gluconate below pH 7. At pH values above 7, however, gluconate doubled the maximum amount of lanthanum adsorbed. This was modeled by including a ternary complex with a lanthanum-gluconate complex binding to a lanthanum bound on the surface. No spectroscopic data were obtained to verify the identify of the surface complexes. The presence of gluconate did not appear to affect the formation of solid lanthanum hydroxide at elevated pH and millimolar lanthanum concentrations. The effect of organic molecules on the mobility of lanthanides and trivalent-actinides cannot be simply described with equilibrium thermodynamic models based on currently available data.

Hull, Laurence C.; Sarah Pepper; Sue Clark

2005-05-01

198

Uptake of Lanthanum by a Yeast  

Microsoft Academic Search

IN the course of studies of the barium metabolism of larval Drosophila which it is planned to report in full elsewhere, we have found that larvæ on a medium containing barium-140 showed lanthanum-140 enrichment if the medium had been inoculated with Texas Y-2 strain of yeast1 twenty-four hours before adding the larvæ, but barium-140 enrichment if the larvæ had been

V. T. Bowen; Ann C. Rubinson

1951-01-01

199

Effects of lanthanum and lanthanum-modified clay on growth, survival and reproduction of Daphnia magna.  

PubMed

The novel lanthanum-modified clay water treatment technology (Phoslock seems very promising in remediation of eutrophied waters. Phoslock is highly efficient in stripping dissolved phosphorous from the water column and in intercepting phosphorous released from the sediments. The active phosphorous-sorbent in Phoslock is the Rare Earth Element lanthanum. A leachate experiment revealed that lanthanum could be released from the clay, but only in minute quantities of 0.13-2.13microgl(-1) for a worst-case Phoslock dosage of 250mgl(-1). A life-history experiment with the zooplankton grazer Daphnia magna revealed that lanthanum, up to the 1000microgl(-1) tested, had no toxic effect on the animals, but only in medium without phosphorous. In the presence of phosphorous, rhabdophane (LaPO(4).nH(2)O) formation resulted in significant precipitation of the food algae and consequently affected life-history traits. With increasing amounts of lanthanum, in the presence of phosphate, animals remained smaller, matured later, and reproduced less, resulting in lower population growth rates. Growth rates were not affected at 33microgLal(-1), but were 6% and 7% lower at 100 and 330microgl(-1), respectively, and 20% lower at 1000microgl(-1). A juvenile growth assay with Phoslock tested in the range 0-5000mgl(-1), yielded EC(50) (NOEC) values of 871 (100) and 1557 (500)mg Phoslock l(-1) for weight and length based growth rates, respectively. The results of this study show that no major detrimental effects on Daphnia are to be expected from Phoslock or its active ingredient lanthanum when applied in eutrophication control. PMID:19801159

Lürling, Miquel; Tolman, Yora

2009-09-17

200

Influence of samaria doping on the resistance of ceria thin films and its implications to the planar oxygen sensing devices  

Microsoft Academic Search

In order to evaluate and analyze the effect of samarium (Sm) doping on the resistance of cerium oxide, we have grown highly oriented samaria doped ceria (SDC) thin films on sapphire, Al2O3 (0001) substrates by using oxygen plasma-assisted molecular beam epitaxy (OPA-MBE). The film growth was monitored using reflection high-energy electron diffraction (RHEED) which shows two-dimensional growth throughout the deposition.

Shilpi Gupta; Satyanarayana V N T Kuchibhatla; Mark H. Engelhard; V. Shutthanandan; Ponnusamy Nachimuthu; Weilin Jiang; Laxmikant V. Saraf; Suntharampillai Thevuthasan; Shalini Prasad

2009-01-01

201

Novel samarium(III) selective membrane sensor based on glipizid  

Microsoft Academic Search

We found that N-[2-[4-[[[(cyclohexyl amino)carbonyl]amino]sulfonyl]phenyl]ethyl]-5-methyl pyrazine carboxamide (glipizid) can be used as an excellent ionophore to make a novel samarium-selective membrane sensor. The electrode based on glipizid, containing sodium teraphenyl borate as lipophilic salt and benzyl acetate as a plasticiser, gave the best performance. The electrode exhibits a good Nernstian response towards Sm3+ions in the range of 1.0×10?1 to 1.0×10?6M

Mohammad Reza Ganjali; Mohammad Reza Pourjavid; Morteza Rezapour; Soheila Haghgoo

2003-01-01

202

Selective reductive transformations using samarium diiodide-water.  

PubMed

Samarium diiodide (SmI(2)) is one of the most important reductive electron transfer reagents available in the laboratory. Key to the popularity of SmI(2) is the ability of additives and co-solvents to tune the properties of the reagent. Over the last decade water has emerged as a particularly valuable additive, opening up new chemical space and leading to the discovery of unprecedented selectivity and new reactions promoted by SmI(2). In this Feature Article we review recent progress in the application of SmI(2)-H(2)O systems, with an emphasis on mechanistic considerations and the development of new transformations. PMID:21879049

Szostak, Michal; Spain, Malcolm; Parmar, Dixit; Procter, David J

2011-08-30

203

Novel electro-strain-effect in La-doped Pb(Zr,Ti)O3 relaxor ferroelectrics  

Microsoft Academic Search

Lanthanum doped lead zirconate titanate [(Pb,La)(Zr,Ti)O3] transparent ceramics show relaxor behavior when the content of Lanthanum is 4-14% and molar ratio of Zr\\/Ti is 65\\/35. They were known as important electro-optical materials, but few researches had been focused on their electromechanical behavior. In the present work, we report a large recoverable electrostrain of about 0.2% at 1.0 kV\\/mm in (Pb,La)

L. X. Zhang; X. Ren; Y. Wang; X. Q. Ke; X. D. Ding; J. Sun

2009-01-01

204

Lutetium-doped EuO films grown by molecular-beam epitaxy  

SciTech Connect

The effect of lutetium doping on the structural, electronic, and magnetic properties of epitaxial EuO thin films grown by reactive molecular-beam epitaxy is experimentally investigated. The behavior of Lu-doped EuO is contrasted with doping by lanthanum and gadolinium. All three dopants are found to behave similarly despite differences in electronic configuration and ionic size. Andreev reflection measurements on Lu-doped EuO reveal a spin-polarization of 96% in the conduction band, despite non-magnetic carriers introduced by 5% lutetium doping.

Melville, A.; Heeg, T. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Mairoser, T.; Schmehl, A. [Zentrum fuer elektronische Korrelationen und Magnetismus, Universitaet Augsburg, Universitaetsstrasse 1, D-86159 Augsburg (Germany); Shai, D. E.; Monkman, E. J.; Harter, J. W. [Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Hollaender, B.; Schubert, J. [Peter Gruenberg Institute, PGI 9-IT, JARA-FIT, Research Centre Juelich, D-52425 Juelich (Germany); Shen, K. M. [Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States); Mannhart, J. [Max Planck Institute for Solid State Research, D-70569 Stuttgart (Germany); Schlom, D. G. [Department of Materials Science and Engineering, Cornell University, Ithaca, New York 14853 (United States); Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853 (United States)

2012-05-28

205

Cathodic polarization of nickel in lanthanum-containing salt melts  

Microsoft Academic Search

The thermodynamic characteristics of lanthanum deposition into a solid nickel cathode from molten electrolytes were investigated using polarization curves with a galvanostatic pulse technique. The experiments were performed under argon using a lead reference electrode and encased auxiliary electrode of spectroscopically pure graphite. The lanthanum deposition potential required to calculate Gibbs energy changes was determined experimentally during electrolysis of the

A. G. Morachevskii; E. G. Klebanov; D. U. Yan

1988-01-01

206

COPRECIPITATION OF Pu(IV) WITH LANTHANUM OXALATE  

Microsoft Academic Search

Plutonium coprecipitation with lanthanum oxalate forms anomalous mixed ; crystals with a lower miscibility boundary at micro component concentrations from ; 10⁻⁶ to 10⁻⁹ M. The distribution of Pu(IV) between the lanthanium ; oxalate and the solution follows the Khlopin or logarithmic law, depending on the ; conditions of coprecipitation. A strong plutonium enrichment of lanthanum ; oxalate crystals was

V. I. Grebenshchikova; R. V. Bryzgalova

1960-01-01

207

Search for parity nonconserving optical rotation in atomic samarium  

NASA Astrophysics Data System (ADS)

We have searched for parity nonconserving (PNC) optical rotation in five optical transitions within the 4f66s2 ground configuration of atomic samarium using laser polarimetry. It had been suggested that these transitions might be favorable for studying electroweak effects because the upper levels have close-lying levels of opposite parity which might give rise to strong mixing by the PNC Hamiltonian HPNC. In terms of the usual parameter R[=Im(EPNC/M)], we obtain (in units of 10-8) R662=2.1(1.8), R628=-7(16), R611=-6(8), R569=-17(30), and R558=-6(12), where the subscripts give the wavelengths of the transitions. The values of R are not significantly greater than those already reported for the heavy elements bismuth, lead, and thallium, and we conclude that the samarium transitions do not offer the prospect of a critical test of electroweak theory. Upper limits on the matrix elements of HPNC between the upper levels of the transitions and their close-lying opposite-parity neighbors are derived from the results.

Lucas, D. M.; Warrington, R. B.; Stacey, D. N.; Thompson, C. D.

1998-11-01

208

Isotope effects in the lanthanum dihydrides  

SciTech Connect

Equilibrium pressures of protium, deuterium, and tritium over lanthanum metal at atomic ratios up to 2.2 have been measured for temperatures ranging from approx. 800 K to slightly over 1000 K. The equilibrium pressures in the plateau regins increased as expected from the protide to the deuteride to the tritide. Sieverts' constants were determined at the higher temperature and decreased in this same order. Within experimental error the terminal solubilities of the three isotopes in the metal, defined by the separation of the dihydride phase from the metal, are the same.

Carstens, D.H.W.

1981-04-02

209

Seventh Spectrum of Lanthanum: La VII  

Microsoft Academic Search

The spectra of lanthanum ions were photographed in the 90Å-1220Å region on a 3-m normal incidence spectrograph at the Antigonish laboratory and a 10.7m grazing incidence spectrograph at the NIST laboratory. The source used in both laboratories was a triggered spark. The 5s25p3-(5s5p4+5s25p25d+5s25p26s) transitions of La VII were analysed. All five levels of the ground state and 37 of 44

R. R. Gayasov; Y. N. Joshi; A. Tauheed

1998-01-01

210

Scintillation properties of praseodymium doped LuAG scintillator compared to cerium doped LuAG, LSO and LaBr  

Microsoft Academic Search

Properties of praseodymium and cerium doped Lutetium Aluminum Garnet (LuAG) were compared with cerium doped Lutetium Oxyorthosilicate (LSO) and Lanthanum Bromide (LaBr3). Light yield, its non-proportionality relative to 662 keV ?-rays and the dependence of the energy resolution on energy of the detected ?-rays were measured. LuAG:Pr turned out to have good proportionality, with deviation from unity around 10% at

L. Swiderski; M. Moszyilski; A. Nassalski; A. Syntfeld-Kazuch; T. Szczesniak; K. Kamada; K. Tsutsumi; Y. Usuki; T. Yanagida; A. Yoshikawa; W. Chewpraditkul

2008-01-01

211

Resonances of coherent population trapping in samarium vapours  

SciTech Connect

Resonances of coherent population trapping were detected in atomic vapours of the rare-earth element samarium. The coherent population trapping was produced by two external-cavity diode lasers (672 and 686 nm) in a {Lambda}-system formed by the three levels of {sup 154}Sm: the 4f{sup 6}6s{sup 2}({sup 7}F{sub 0}) ground state, the first fine-structure 4f{sup 6}6s{sup 2}({sup 7}F{sub 1}) sublevel of the ground state and the 4f{sup 6}({sup 7}F)6s6p({sup 3}P{sup o}){sup 9}F{sup o}{sub 1} upper level. The dependence of the spectral shapes and resonance contrasts on the polarisation of the laser beams and the direction of the applied magnetic field was studied. The obtained results were analysed. (nonlinear optical phenomena)

Kolachevsky, Nikolai N; Akimov, A V; Kiselev, N A; Papchenko, A A; Sorokin, Vadim N; Kanorskii, S I [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2001-01-31

212

Thermal stability of lanthanum scandate dielectrics on Si(100)  

NASA Astrophysics Data System (ADS)

The authors have examined the thermal stability of amorphous, molecular beam deposited lanthanum scandate dielectric thin films on top of Si (100) after a 1000 °C, 10 s rapid thermal anneal. After the anneal, crystallization of LaScO3 is observed. Excellent suppression of lanthanum and scandium diffusion into the substrate silicon is indicated by the back-side secondary ion mass spectrometry (SIMS) analyses. In contrast, front-side SIMS and high-resolution electron energy loss analyses of the amorphous Si/LaScO3/Si (100) stack indicated the outdiffusion of lanthanum and scandium into the silicon capping layer during the anneal.

Sivasubramani, P.; Lee, T. H.; Kim, M. J.; Kim, J.; Gnade, B. E.; Wallace, R. M.; Edge, L. F.; Schlom, D. G.; Stevie, F. A.; Garcia, R.; Zhu, Z.; Griffis, D. P.

2006-12-01

213

Infrared luminescence of Tm3+/Yb3+ codoped lanthanum aluminum germanate glasses  

NASA Astrophysics Data System (ADS)

Tm3+ doped and Tm3+/Yb3+ codoped lanthanum aluminum germanate (LAG) glasses are prepared by melt-quenching method and characterized optically. Based on the measurement of absorption spectrum, Judd-Ofelt intensity parameters (?2,?4,?6) are calculated. The radiation emission rates, branching ratios, and lifetimes of Tm3+ are calculated to evaluate the spectroscopic properties of Tm3+ in LAG glass. The infrared emission properties of the samples are investigated and the results show that the 1.8 ?m emission can be greatly enhanced by adding proper amount of Yb3+ under the excitation of 980 nm. The energy transfer processes of Yb3+-Yb3+ and Yb3+-Tm3+ are analyzed, and the results show that Yb3+ ions can transfer their energy to Tm3+ ions with high efficiency and large energy transfer coefficient.

Zhang, Qiang; Chen, Guorong; Zhang, Guang; Qiu, Jianrong; Chen, Danping

2010-01-01

214

The energetics of lanthanum tantalate materials  

SciTech Connect

Lanthanum tantalates are important refractory materials with application in photocatalysis, solid oxide fuel cells, and phosphors. Soft-chemical synthesis utilizing the Lindqvist ion, [Ta{sub 6}O{sub 19}]{sup 8-}, has yielded a new phase, La{sub 2}Ta{sub 2}O{sub 7}(OH){sub 2}. Using the hydrated phase as a starting material, a new lanthanum orthotantalate polymorph was formed by heating to 850 {sup o}C, which converts to a previously reported LaTaO{sub 4} polymorph at 1200 {sup o}C. The stabilities of La{sub 2}Ta{sub 2}O{sub 7}(OH){sub 2} (LaTa-OH), the intermediate LaTaO{sub 4} polymorph (LaTa-850), and the high temperature phase (LaTa-1200) were investigated using high-temperature oxide melt solution calorimetry. The enthalpy of formation from the oxides were calculated from the enthalpies of drop solution to be -87.1{+-}9.6, -94.9{+-}8.8, and -93.1{+-}8.7 kJ/mol for LaTa-OH, LaTa-850, and LaTa-1200, respectively. These results indicate that the intermediate phase, LaTa-850, is the most stable. This pattern of energetics may be related to cation-cation repulsion of the tantalate cations. We also investigated possible LnTaO{sub 4} and Ln{sub 2}Ta{sub 2}O{sub 7}(OH){sub 2} analogues of Ln=Pr, Nd to examine the relationship between cation size and the resulting phases. - Graphical abstract: The energetics of three lanthanum tantalates were investigated by the high-temperature oxide melt solution calorimetry. The enthalpies of formation from the oxides were calculated from the enthalpies of drop solution to be -87.1{+-}9.6, -94.9{+-}8.8, and -93.1{+-}8.7 kJ/mol for La{sub 2}Ta{sub 2}O{sub 7}(OH){sub 2}, LaTaO{sub 4} (850 {sup o}C), and LaTaO{sub 4} (1200 {sup o}C), respectively. These results indicate that the intermediate phase, LaTaO{sub 4} (850 {sup o}C), is the most stable in energy. Display Omitted

Forbes, Tori Z., E-mail: tmforbes@ucdavis.ed [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, CA 95616 (United States); Nyman, May, E-mail: mdnyman@sandia.go [Sandia National Laboratory, POB 5800, Albuquerque, NM 87185 (United States); Rodriguez, Mark A., E-mail: marodri@sandia.go [Sandia National Laboratory, POB 5800, Albuquerque, NM 87185 (United States); Navrotsky, Alexandra, E-mail: anavrotsky@ucdavis.ed [Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, CA 95616 (United States)

2010-11-15

215

Lanthanum isotopic composition of meteoritic and terrestrial matter  

Microsoft Academic Search

Mass spectrometric techniques were used to measure the lanthanum isotopic composition of meteoritic and terrestrial whole rock samples weighing about 150 mg each. Measurement results are reported, and their cosmochemical implications are discussed.

Jason J.-S. Shen; Typhoon Lee; Chau-Ting Chang

1994-01-01

216

Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions  

PubMed Central

Lanthanum tricyanide efficiently catalyzes a benzoin-type coupling between acyl silanes and ketones. Yields range from moderate to excellent over a broad substrate scope encompassing aryl, alkyl, electron-rich, and sterically hindered ketones.

Tarr, James C.; Johnson, Jeffrey S.

2009-01-01

217

Emission from a bismuth doped chalcogenide glass spanning from 1 mum to 2.7 mum  

Microsoft Academic Search

In this paper we report emission from Bi doped gallium lanthanum sulphide (Bi:GLS) glass with a full width at half maximum (FWHM) of 600 nm which is flattened and covers the entire telecommunications window. The excitation wavelength of this emission was 1020 nm, the quantum efficiency (QE) was 17%, the lifetime was 160 mus and product of the emission cross

M. A. Hughes; T. Suzuki; Y. Ohishi

2011-01-01

218

Giant negative thermal expansion in La-doped CaFe2As2  

NASA Astrophysics Data System (ADS)

Lanthanum doping for calcium in CaFe2As2 results in negative thermal expansion that can be exceptionally large. The behavior is unusual among Fe-As materials, and is presumably associated with the close proximity of CaFe2As2 to a structural phase instability.

Rebello, A.; Neumeier, J. J.; Gao, Zhaoshun; Qi, Yanpeng; Ma, Yanwei

2012-09-01

219

Effect of lanthanide-doping into NaTaO 3 photocatalysts for efficient water splitting  

Microsoft Academic Search

The activities of water splitting over NiO\\/NaTaO3 photocatalysts were improved by doping of lanthanides, La, Pr, Nd, Sm, Gd, Tb and Dy into NaTaO3. Lanthanum was the most effective as a dopant. The apparent quantum yield at 270 nm amounted to ?50%. Moreover, the deactivation observed for a non-doped NiO\\/NaTaO3 photocatalyst was suppressed. SEM observation suggests that these effects on

Akihiko Kudo; Hideki Kato

2000-01-01

220

Improvement in electrical characteristics of graded manganese doped barium strontium titanate thin films  

Microsoft Academic Search

Highly (100) textured graded manganese (Mn) doped Ba0.5Sr0.5TiO3 [BST (50\\/50)] thin films were deposited on lanthanum aluminate substrates using sol-gel technique. We have demonstrated that the graded acceptor doping is a promising technique to reduce the temperature coefficient of capacitance (TCC), loss tangent, and leakage current of BST thin films. In the temperature range between 175 and 260 K the

M. Jain; S. B. Majumder; R. S. Katiyar; F. A. Miranda; F. W. Van Keuls

2003-01-01

221

Seventh Spectrum of Lanthanum: La VII  

NASA Astrophysics Data System (ADS)

The spectra of lanthanum ions were photographed in the 90Å-1220Å region on a 3-m normal incidence spectrograph at the Antigonish laboratory and a 10.7m grazing incidence spectrograph at the NIST laboratory. The source used in both laboratories was a triggered spark. The 5s25p3-(5s5p4+5s25p25d+5s25p26s) transitions of La VII were analysed. All five levels of the ground state and 37 of 44 levels of the 5s5p4+5s25p25d+5s25p26s configurations have been established. 102 lines have been classified in the 307-1005Å region. Hartree-Fock (HFR) and Least-Squares-Fit (LSF) calculations were carried out to interpret the spectrum.

Gayasov, R. R.; Joshi, Y. N.; Tauheed, A.

1998-05-01

222

Phases in lanthanum-nickel-aluminum alloys  

SciTech Connect

Lanthanum-nickel-aluminum (LANA) alloys will be used to pump, store and separate hydrogen isotopes in the Replacement Tritium Facility (RTF). The aluminum content (y) of the primary LaNi{sub 5}-phase is controlled to produce the desired pressure-temperature behavior for adsorption and desorption of hydrogen. However, secondary phases cause decreased capacity and some may cause undesirable retention of tritium. Twenty-three alloys purchased from Ergenics, Inc. for development of RTF processes have been characterized by scanning electron microscopy (SEM) and by electron microprobe analysis (EMPA) to determine the distributions and compositions of constituent phases. This memorandum reports the results of these characterization studies. Knowledge of the structural characteristics of these alloys is a useful first step in selecting materials for specific process development tests and in interpreting results of those tests. Once this information is coupled with data on hydrogen plateau pressures, retention and capacity, secondary phase limits for RTF alloys can be specified.

Mosley, W.C.

1992-01-01

223

Protonic conduction in lanthanum strontium aluminate and lanthanum niobate-based oxides at elevated temperatures  

Microsoft Academic Search

Ionic conduction behaviors in aluminum containing oxides, Lan?xSr1+xAlnO3n+1?? (n=1 and 2), and in lanthanum niobate-based oxides, La3?xSrxNbO7??, were investigated using electrochemical methods at elevated temperatures.In La1?xSr1+xAlO4??, single-phase was confirmed at 0?x?0.10. The highest conductivity in this solution appeared when x=0.10 (2.4×10?4S cm?1 at 1000 °C in H2). Electromotive forces (emfs) of gas concentration cells and H\\/D isotope effect on conductivity

Tetsuo Shimura; Yuzuru Tokiwa; Hiroyasu Iwahara

2002-01-01

224

Samarium Hexaboride - First True 3D Topological Insulator  

NASA Astrophysics Data System (ADS)

Although many important breakthroughs in the study of topological states of matter have been achieved within the last few years, a very important link still remains missing--the experimental discovery of a true 3D topological insulator. Materials currently known to have topological surface states (e.g. Bi1-xSbx, Bi2Se3 and Bi2Te3) are also bulk conductors, and thus do not have a well-defined topological index. Recent calculations of the heavy-fermion Kondo insulator Samarium Hexaboride (SmB6) have predicted the possibility of in-gap topological surface states in this material. Meanwhile, the conjectured existence of a topologically-protected surface state in SmB6 could resolve many of the long-standing puzzles surrounding its low-temperature transport properties. Here we study the transport properties of SmB6 with a novel configuration designed to distinguish bulk-dominated conduction from surface-dominated conduction. We find that SmB6 is a true topological insulator with an insulating bulk and a metallic surface. This discovery resolves the standing puzzles about the strange transport behavior of this material, and it provides the first material in which transport properties of a 3D topological state can be studied.

Wolgast, Steven; Kurdak, ?a?liyan; Sun, Kai; Allen, James; Fisk, Zachary

2013-03-01

225

Electrical properties of complex perovskite samarium nickel titanate  

NASA Astrophysics Data System (ADS)

The complex perovskite oxide samarium nickel titanate, Sm(Ni1/2Ti1/2)O3 (SNT) is synthesized by solid-state reaction technique. The x-ray diffraction pattern of the sample at room temperature shows monoclinic phase. The microstructure analysis of the sample is performed using scanning electron microscope. Alternating current impedance spectroscopy is used to investigate the electrical properties of SNT in a temperature range from 313 K to 673 K and in a frequency range from 100 Hz to 1 MHz. A peak is observed in the frequency dependence of imaginary part of electric modulus ( M?( ?)) indicating a non-Debye type of relaxation. The relaxation peak of M?( ?) moves towards higher frequencies with the increase of temperature showing the thermally activated nature of the relaxation time. The relaxation times for M?( ?) at different temperatures are found to obey Arrhenius law with an activation energy of 0.57 eV. The scaling behaviour of M?( ?) shows that the relaxation describes the same mechanism at various temperatures. The complex impedance plane plots show that the relaxation mechanism in SNT is purely a bulk effect arising from the semiconductive grains of the sample. The frequency dependent conductivity is found to obey the power law.

Kumar, Nishant; Dutta, Alo; Prasad, S.; Sinha, T. P.

2013-09-01

226

Effect of Palladium Overlayer on Samarium Hydride Thin Film Switchable Mirror: Electrochemical and Topographical Study  

NASA Astrophysics Data System (ADS)

Samarium films with a typical thickness of 55 nm deposited by vacuum evaporation and covered with Pd overlayers with thicknesses of 5, 8, 11, and 15 nm were loaded with hydrogen and deloaded in a 1 M KOH solution galvanostatically at room temperature. Our study showed that palladium overlayer thickness plays the most crucial role in observing the fast transition between an as-deposited metallic state and a semiconducting nearly samarium trihydride state as well as in obtaining a very high optical contrast. The desorption of hydrogen from palladium-capped SmH3-? films was studied by in situ transmission measurement during the electrochemical loading/unloading of hydrogen. It was shown that palladium cap layer thickness affects the deloading of hydrogen from the hydrided films. The effect of a palladium overlayer on the surface morphology of metallic and hydrogen-desorbed samarium films showed the sequence of nucleation and growth.

Kumar, Pushpendra; Malhotra, Lalit Kumar

2006-12-01

227

Synthesis of LaB 6 from BN and lanthanum-citrate-hydrate  

Microsoft Academic Search

Lanthanum hexaboride was synthesized by reacting a powdered mixture of hexagonal boron nitride and lanthanum-citrate-hydrate carbonized substance which had been prepared by heating lanthanum-citrate-hydrate at 1000° C in a nitrogen atmosphere. The optimum conditions for the synthesis were a ratio of boron to lanthanum in the starting mixture between 5.0 and 6.0 with heating in the temperature range 1480 and

M. Shiota; M. Tsutsumi; K. Uchida

1980-01-01

228

White light emission characteristics of europium doped fluoride crystals  

NASA Astrophysics Data System (ADS)

Under 405 nm diode laser excitation Europium doped Lanthanum fluoride glows bright white and revealed numerous wavelengths in the blue, green and red regions of the electromagnetic spectrum. These lines were emitted from 5DJ (J=0, 1, 2 and 3) to 7FJ (J=0, 1, 2, 3, 4, 5, and 6) levels. For the same excitation conditions Europium doped Calcium fluoride glows white with abundant blue emission and some yellow light. These materials appear to be promising candidates for solid state white light sources. Emission characteristics are described in detail.

Reddy, B. Rami; Colon, Tomeka

2013-03-01

229

40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).  

Code of Federal Regulations, 2013 CFR

...Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1). 721.10370 Section 721...Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1). (a) Chemical substance...phosphinic acid, p-octyl-, lanthanum (3+) salt (2:1) (PMN P-10-99; CAS...

2013-07-01

230

Comparison of the sorption properties of crystalline and amorphous samarium(III) oxohydroxides  

Microsoft Academic Search

The influence of the pH of precipitation (pH1) and the ionic medium on the sorption properties of as-precipitated samarium(III) oxohydroxides,i.e., the pH of zero charge point and the rate of heterogeneous hydrolysis of the IrCl6\\u000a 2?, RhCl6\\u000a 3?, and PtCl4\\u000a 2? complexes, was studied. The composition of precipitates was studied by the drop titration of solutions of samarium nitrate\\u000a and

S. I. Pechenyuk; L. F. Kuz'mich; E. V. Kalinkina; S. I. Matveenko

1998-01-01

231

A spectrophotometric study of samarium (III) speciation in chloride solutions at elevated temperatures  

Microsoft Academic Search

The speciation of samarium (III) in chloride-bearing solutions was investigated spectrophotometrically at temperatures of 100–250°C and a pressure of 100bars. The simple hydrated ion, Sm3+, is predominant at ambient temperature, but chloride complexes are the dominant species at elevated temperatures. Cumulative formation constants for samarium chloride species were calculated for the following reactions:Sm3++Cl-=SmCl2+?1Sm3++2Cl-=SmCl2+?2Within experimental error, the values for the first

Art. A. Migdisov; A. E. Williams-Jones; C. Normand; S. A. Wood

2008-01-01

232

Beyond samarium diiodide: vistas in reductive chemistry mediated by lanthanides(II).  

PubMed

Reactions proceeding through open-shell, single-electron pathways offer attractive alternative outcomes to those proceeding through closed-shell, two-electron mechanisms. In this context, samarium diiodide (SmI(2)) has emerged as one of the most important and convenient-to-use electron-transfer reagents available in the laboratory. Recently, significant progress has been made in the reductive chemistry of other divalent lanthanides which for many years had been considered too reactive to be of value to synthetic chemists. Herein, we illustrate how new samarium(II) complexes and nonclassical lanthanide(II) reagents are changing the landscape of modern reductive chemistry. PMID:22893612

Szostak, Michal; Procter, David J

2012-08-15

233

Methyl chloride production from methane over lanthanum-based catalysts.  

PubMed

The mechanism of selective production of methyl chloride by a reaction of methane, hydrogen chloride, and oxygen over lanthanum-based catalysts was studied. The results suggest that methane activation proceeds through oxidation-reduction reactions on the surface of catalysts with an irreducible metal-lanthanum, which is significantly different from known mechanisms for oxidative chlorination. Activity and spectroscopic measurements show that lanthanum oxychloride (LaOCl), lanthanum trichloride (LaCl3), and lanthanum phases with an intermediate extent of chlorination are all active for this reaction. The catalyst is stable with no noticeable deactivation after three weeks of testing. Kinetic measurements suggest that methane activation proceeds on the surface of the catalyst. Flow and pulse experiments indicate that the presence of hydrogen chloride is not required for activity, and its role appears to be limited to maintaining the extent of catalyst chlorination. In contrast, the presence of gas-phase oxygen is essential for catalytic activity. Density-functional theory calculations suggest that oxygen can activate surface chlorine species by adsorbing dissociatively and forming OCl surface species, which can serve as an active site for methane activation. The proposed mechanism, thus, involves changing of the formal oxidation state of surface chlorine from -1 to +1 without any changes in the oxidation state of the underlying metal. PMID:17295483

Podkolzin, Simon G; Stangland, Eric E; Jones, Mark E; Peringer, Elvira; Lercher, Johannes A

2007-02-13

234

Cytocompatibility of a free machining titanium alloy containing lanthanum.  

PubMed

Titanium alloys like Ti6Al4V are widely used in medical engineering. However, the mechanical and chemical properties of titanium alloys lead to poor machinability, resulting in high production costs of medical products. To improve the machinability of Ti6Al4V, 0.9% of the rare earth element lanthanum (La) was added. The microstructure, the mechanical, and the corrosion properties were determined. Lanthanum containing alloys exhibited discrete particles of cubic lanthanum. The mechanical properties and corrosion resistance were slightly decreased but are still sufficient for many applications in the field of medical engineering. In vitro experiments with mouse macrophages (RAW 264.7) and human bone-derived cells (MG-63, HBDC) were performed and revealed that macrophages showed a dose response below and above a LaCl3 concentration of 200 microM, while MG-63 and HBDC tolerated three times higher concentrations without reduction of viability. The viability of cells cultured on disks of the materials showed no differences between the reference and the lanthanum containing alloy. We therefore propose that lanthanum containing alloy appears to be a good alternative for biomedical applications, where machining of parts is necessary. PMID:18646202

Feyerabend, Frank; Siemers, Carsten; Willumeit, Regine; Rösler, Joachim

2009-09-01

235

Parameters estimation for passively all-fiber Q-switched erbium- and samarium-doped laser  

NASA Astrophysics Data System (ADS)

We present a heuristic method for fitting the parameter values of the theoretical model underlying the experimental passively all-fiber Q-switched laser behavior. We use genetic algorithms (GA) to obtain an agreement between the experimental data and the theoretical model throughout simulations of the laser response for several values of the continuous-wave pumping.

Elena Preda, Cristina; Mégret, Patrice

2013-05-01

236

Syntesis of lanthanum zirconate hydrosols by the ion exchange method  

NASA Astrophysics Data System (ADS)

Ion exchange of LaCl3 and ZrOCl2 aqueous solutions with anion-exchanger AV-17-8 was used to synthesize finely dispersed hydrosol of amorphous lanthanum zirconate La2Zr2O7. Heat treatment of dried La2Zr2O7 hydrosols at 700°C and 1100°C resulted in the formation of powders with fluorite and pyrochlore type structures, respectively. Epitaxial La2Zr2O7 films were obtained on SrTiO3 (001) single crystals. The substrate has an influence on the lanthanum zirconate crystal orientation, as well as strong inhibitory effect on sintering processes.

Bovina, E. A.; Tarasova, J. V.; Chibirova, F. Kh

2011-04-01

237

Axial effects of xenon-samarium poisoning in the advanced test reactor  

Microsoft Academic Search

The paper details an analytical study of the time-dependent behavior in the spatial distributions of xenon and samarium fission product poisons in the Advanced Test Reactor (ATR) during operation and after shutdown. The results of this study provide insight into the behavior and significance of the changing spatial distributions of fission product poisons with respect to the prediction of shim

D. J. Auslander; A. C. Smith; R. T. McCracken

1990-01-01

238

Phase transformations and the development of magnetic coercivity in samarium-cobalt based permanent magnet alloys  

Microsoft Academic Search

An experimental investigation of the microstructures of precipitation-hardening samarium-cobalt based magnets has been undertaken in order to determine the nature of the microstructural features critical for the development of high intrinsic coercivity in these permanent magnet alloys. In alloys aged near peak coercivity, three microstructural features are commonly observed. The bulk of the material consists of a modulated structure of

Rabenberg

1983-01-01

239

Magnetization of powder particles of highly coercive multicomponent samarium-cobalt base alloys  

Microsoft Academic Search

We studied the particle distribution of powders of highly coercive multicomponent alloys on the basis of the compound samarium-cobalt as to shape, dimensions, and intensity of magnetization; we examined the dependences of the grain size distribution of the powders on the time of comminution. It was established that the particles have predominantly the shape of parallelepipeds, cubes, tetrahedrons (approximately 30,

Yu. F. Sapelkina; G. I. Yaglo; A. A. Pavlyukov; L. N. Tul'chinskii

1987-01-01

240

Solar Nebula Heterogeneity in p-Process Samarium and Neodymium Isotopes  

Microsoft Academic Search

Bulk carbonaceous chondrites display a deficit of ~100 parts per million (ppm) in 144Sm with respect to other meteorites and terrestrial standards, leading to a decrease in their 142Nd\\/144Nd ratios by ~11 ppm. The data require that samarium and neodymium isotopes produced by the p process associated with photodisintegration reactions in supernovae were heterogeneously distributed in the solar nebula. Other

Rasmus Andreasen; Mukul Sharma

2006-01-01

241

Scintillators with potential to supersede lanthanum bromide  

SciTech Connect

New scintillators for high-resolution gamma ray spectroscopy have been identified, grown and characterized. Our development efforts have focused on two classes of high light yield materials: Europium-doped alkaline earth halides and Cerium-doped garnets. Of the halide single crystals we have grown by the Bridgman method - SrI{sub 2}, CaI{sub 2}, SrBr{sub 2}, BaI{sub 2} and BaBr{sub 2} - SrI{sub 2} is the most promising. SrI{sub 2}(Eu) emits into the Eu{sup 2+} band, centered at 435 nm, with a decay time of 1.2 {micro}s and a light yield of up to 115,000 photons/MeV. It offers energy resolution better than 3% FWHM at 662 keV, and exhibits excellent light yield proportionality. Transparent ceramics fabrication allows production of Gadolinium- and Terbium-based garnets which are not growable by melt techniques due to phase instabilities. While scintillation light yields of Cerium-doped ceramic garnets are high, light yield non-proportionality and slow decay components appear to limit their prospects for high energy resolution. We are developing an understanding of the mechanisms underlying energy dependent scintillation light yield non-proportionality and how it affects energy resolution. We have also identified aspects of optical design that can be optimized to enhance energy resolution.

Cherepy, Nerine; Payne, Steven; Aszatlos, Steve; Hull, Giulia; Kuntz, J.; Niedermayr, Tom; Pimputkar, S.; Roberts, J.; Sanner, R.; Tillotson, T.; van Loef, Edger; Wilson, Cody; Shah, Kanai; Roy, U.; Hawrami, R.; Burger, Arnold; Boatner, Lynn; Choong, Woon-Seng; Moses, William

2009-06-01

242

Sm3+ doped lithium aluminoborate glasses for orange coloured visible laser host material  

NASA Astrophysics Data System (ADS)

Samarium doped lithium aluminium borate glasses have been prepared by conventional melt quench technique and their detailed spectroscopic analysis has been done. The structural analysis has been done by using FTIR studies and density is measured by Archimedes method. The UV-vis-NIR absorption spectra show an increase in intensity of different transitions from the ground level 6H5/2 to various 2S+1LJ levels with an increase in samarium concentration at the expense of aluminium. The fluorescence spectra show several transitions from 4G5/2 to various 6HJ levels along with 4F3/2 to 6HJ and 4G7/2 to 6H5/2.

Kaur, Parvinder; Kaur, Simranpreet; Singh, Gurinder Pal; Singh, D. P.

2013-10-01

243

Electronic Structure Study of Cerium Doped Scintillators  

NASA Astrophysics Data System (ADS)

The interest shown in recent years related to cerium doped lanthanum halides, such as LaCl3, LaBr3, and LaI3, is mainly due to their potential applicability as gamma ray scintillation detectors. We have performed a comprehensive theoretical study of these materials to better understand the scintillation process and define the nature of the self trapped exciton (STE) associated with thermally dependent scintillation process. The present work focuses on the study of the luminescence properties of cerium doped lanthanum halide scintillators from the point view of solid state band structure calculations. Our calculated band structures are in good agreement with experimental values. For example, LaCl3 band gap is calculated to be 6.85 eV as compared to approximately 7.0 eV for the experimentally determined value. The theoretically calculated excitation spectra are also compared with the experimental spectra. We find that scintillation efficiencies are dependent on the location of the of Ce^3+ ground 4f and excited 5d levels with respect to the fundamental band gap of the host materials.

Gao, Da; McIlwain, Michael

2008-03-01

244

Neurotoxicological consequence of long-term exposure to lanthanum  

Microsoft Academic Search

Lanthanides, because of their diversified physical and chemical effects, have been widely used in a number of fields. As a result, more and more lanthanides are entering into the environment and eventually accumulated in human body. Recently, a new medicine, lanthanum carbonate (Fosrenol), has been used to treat chronic renal failure (CRF), and the dosage is much higher than the

Liuxing Feng; Haiqing Xiao; Xiao He; Zijie Li; Fuliang Li; Nianqing Liu; Yuliang Zhao; Yuying Huang; Zhiyong Zhang; Zhifang Chai

2006-01-01

245

Thorium adsorption behaviour on mixed ammonium lanthanum oxalate, LAOX  

Microsoft Academic Search

The cation-exchange properties of mixed ammonium lanthanum oxalate, LAOX, were studied by batch equilibration as a function of the concentration of some cations, such as alkaline earths or ammonium and of some anions and acids. The distribution coefficients for thorium are high, while U(VI) is not adsorbed over a large acidity range. Thus, the separation of thorium from uranium may

M. T Valentini Ganzerli; L Maggi; V Crespi Caramella

1999-01-01

246

The isotopic composition and atomic weight of lanthanum  

Microsoft Academic Search

The isotopic composition of lanthanum has been measured with high precision using a thermal ionization mass spectrometer, equipped with a Daly collector, whose linearity was verified by measuring an isotopically certified reference material for potassium (NIST 985), whose isotopes span a wide range of isotope ratios. The abundance sensitivity of the mass spectrometer in the vicinity of the measured LaO+

John R. de Laeter; Nino Bukilic

2005-01-01

247

Discovery of cesium, lanthanum, praseodymium and promethium isotopes  

NASA Astrophysics Data System (ADS)

Currently, forty-one cesium, thirty-five lanthanum, thirty-two praseodymium, and thirty-one promethium isotopes have been observed and the discovery of these isotopes is described here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

May, E.; Thoennessen, M.

2012-09-01

248

LANTHANUM ISOTOPES IN A POSSIBLE NEW REGION OF NUCLEAR DEFORMATION  

Microsoft Academic Search

The discovery and further characterization of several neutron deficient ; lanthanum isotopes are reported. These isotopes occur in what was previously ; postulated as a possible new region of nuclear deformation. Heavy ion ; bombardments of natural indium foil were used to produce the neutron deficient La ; isotopes by means of In(O¹⁶,xn)La reactions. Two procedures were then ; used:

I. L. Preiss; P. M. Strudler; R. Wolfgang

1962-01-01

249

Negative-parity states in odd-mass lanthanum isotopes  

Microsoft Academic Search

A semimicroscopic calculation is done to obtain the negative-parity states of odd-mass lanthanum isotopes. In agreement with a recently published calculation we find that a positive deformation is needed to explain the experimental data. NUCLEAR STRUCTURE 129La; calculated levels as a function of deformation.

S. Das Gupta; N. de Takacsy

1974-01-01

250

Discovery of Cesium, Lanthanum, Praseodymium and Promethium Isotopes  

Microsoft Academic Search

Currently, forty-one cesium, thirty-five lanthanum, thirty-two praseodymium, and thirty-one promethium, isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.

E. May; M. Thoennessen

2011-01-01

251

Low-temperature mechanical energy dissipation phenomena in lanthanum superconductors  

Microsoft Academic Search

The anelastic properties of ceramics which belong to the lanthanum family of superconductors were studied. The internal friction and Young's modulus measurements were carried out by the vibrating reed technique in the temperature range from 20 to 300 K. The measurement frequency was in the range of 90-760 Hz. A large internal friction, corresponding to a maximum of the relaxation,

M. Gazda; B. Kusz; R. Barczynski; O. Gzowski; L. Murawski; I. Davoli; S. Stizza

1993-01-01

252

METHOD OF SEPARATING PLUTONIUM FROM LANTHANUM FLUORIDE CARRIER  

Microsoft Academic Search

An improvement in oxidation-reduction type methods of separating ; plutoniunn from elements associated with it in a neutron-irradiated uranium ; solution is described. The method relates to the separating of plutonium from ; lanthanum ions in an aqueous 0.5 to 2.5 N nitric acid solution by 'treating the ; solution, at room temperature, with ammonium sulfite in an amount sufficient

G. W. Watt; R. H. Goeckermann

1958-01-01

253

Lanthanum manganites and other giant-magnetoresistance magnetic conductors  

Microsoft Academic Search

A review is given of crystallographic, magnetic and electric properties of lanthanum manganites and related materials with a giant magnetoresistance (GMR). An analysis of experimental data for partially substituted manganites shows that if the spontaneous magnetic moment is unsaturated, the material is being in a phase-separated ferro-antiferromagnetic state. One possible GMR mechanism consists in a change of such a state

E L Nagaev

1996-01-01

254

LANTHANUM STAINING OF THE SURFACE COAT OF CELLS  

PubMed Central

Among the techniques which have been reported to stain the surface coat of cells, for electron microscopy, is lanthanum staining en bloc. Similarly, the presence of the cationic dye, Alcian blue 8GX, in a primary glutaraldehyde fixative has been reported to improve the preservation of the surface coat of cells of many types; however, the preserved coat is not very electron opaque unless thin sections are counterstained. The present paper shows that for several rat tissues lanthanum staining en bloc is an effective electron stain for the cell surface, giving excellent contrast, if combined sequentially with prefixation in an aldehyde fixative containing Alcian blue. The cationic substance cetylpyridinium chloride was found to have a similar effect to that of Alcian blue in enhancing the lanthanum staining of the surface coat material of the brush border of intestinal epithelial cells. The patterns of lanthanum staining obtained for the tissues studied strikingly resemble those reported in the literature where tissues are stained by several standard methods for demonstrating mucosubstances at the ultrastructural level. This fact and the reproduction of the effect of Alcian blue by cetylpyridinium chloride constitute a persuasive empirical argument that the material visualized is a mucopolysaccharide or mucopolysaccharide-protein complex.

Shea, Stephen M.

1971-01-01

255

Gas phase chemistry of bis(pentamethylcyclopentadienyl)samarium  

SciTech Connect

The gas phase chemistry of bis(pentamethylcyclopentadienyl)samarium, (C{sub 5}Me{sub 5}){sub 2}Sm, was studied by Fourier transform ion cyclotron resonance mass spectrometry (FTICR/MS). Positive electron impact (EI) spectra showed the formation of (C{sub 5}Me{sub 5}){sub 2} Sm{sup +}, (C{sub 5}Me{sub 5})Sm{sup +}, and Sm{sup +}. All three ions reacted with (C{sub 5}Me{sub 5}){sub 2}Sm by charge transfer, as verified by double-resonance techniques, and (C{sub 5}Me{sub 5})Sm{sup +} also formed the (C{sub 5}Me{sub 5}){sub 3}Sm{sub 2}{sup +} ion in a condensation reaction with neutral (C{sub 5}Me{sub 5}){sub 2}Sm. The laser desorption/ionization (LDI) spectra showed, in addition to (C{sub 5}Me{sub 5}){sub 2}Sm{sup +}, (C{sub 5}Me{sub 5})Sm{sup +}, and Sm{sup +}, the formation of (C{sub 5}Me{sub 4}H)Sm{sup +} and (C{sub 5}Me{sub 4}CH{sub 2})Sm{sup +}. The latter species most probably involves a tetramethylfulvenide ligand. Access to all of the ionic species cited here could also be obtained by reacting laser-desorbed Sm{sup +} ions with pentamethylcyclopentadiene, C{sub 5}Me{sub 5}H. (C{sub 5}Me{sub 4}CH{sub 2})Sm{sup +}, (C{sub 5}Me{sub 4}H)Sm{sup +}, and (C{sub 5}Me{sub 5})Sm{sup +} were formed as primary products, and the metallocene ion (C{sub 5}Me{sub 5}){sub 2}Sm{sup +} resulted from the rapid addition of C{sub 5}Me{sub 5}H to (C{sub 5}Me{sub 4}CH{sub 2})Sm{sup +}. 34 refs., 4 figs.

Marcalo, J.; Matos, A.P. de [Instituto Technologico e Nuclear, Sacavem (Portugal); Evans, W. [Univ. of California, Irvine, CA (United States)

1996-01-09

256

Optimal treatment of painful bone metastases with Samarium EDTMP in a haemodialysis patient: effectiveness and safety of internal radiotherapy.  

PubMed

One of the current therapeutic approaches in the treatment of osteoblastic bone metastases uses the affinity of Samarium ((153)Sm) ethylene-diamine-tetramethylene phosphonic acid (EDTMP) for bone areas of bone turnover. As Samarium EDTMP is a beta-emitter, the radiotherapy contributes to osteoblastic bone lesion control over time. To date, the safety and effectiveness of Samarium therapy have not been established in patients with renal impairment. In this first report, we describe our experience of use of Samarium EDTMP in conjunction with biphosphonates in a haemodialysis patient for treatment of painful bone metastasis. Encouraging results were obtained in achieving pain control. The use of this radioisotope could be more widely applied to treat haemodialysis patients. PMID:19369693

Skalli, Saadia; Desruet, Marie-Dominique; Bourre, Jean-Cyril; Caravel, Jean-Pierre; Vuillez, Jean-Philippe

2009-04-15

257

Structural Characterization of Methanol Substituted Lanthanum Halides  

PubMed Central

The first study into the alcohol solvation of lanthanum halide [LaX3] derivatives as a means to lower the processing temperature for the production of the LaBr3 scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(µ-Br)(H2O)7](Br)2}2 (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H2O)7(MeOH)2](Br)3 (2) compound was isolated where the La metal center retains its original 9-coordination through the binding of two additional MeOH solvents but necessitates the transfer of the innersphere Br to the outersphere. In an attempt to in situ dry the reaction mixture of 1 in MeOH over CaH2, crystals of [Ca(MeOH)6](Br)2 (3) were isolated. Compound 1 dissolved in MeOH at reflux temperatures led to the isolation of an unusual arrangement identified as the salt derivative {[LaBr2.75•5.25(MeOH)]+0.25 [LaBr3.25•4.75(MeOH)]?0.25} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr3 in MeOH forming the 8-coordinated [LaBr3(MeOH)5] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX3 derivatives were isolated as [(MeOH)4(Cl)2La(µ-Cl)]2 (6) and [La(MeOH)9](I)3•MeOH (7). Beryllium Dome XRD analysis indicated that the bulk material for 5 appear to have multiple solvated species, 6 is consistent with the single crystal, and 7 was too broad to elucidate structural aspects. Multinuclear NMR (139La) indicated that these compounds do not retain their structure in MeOD. TGA/DTA data revealed that the de-solvation temperatures of the MeOH derivatives 4 – 6 were slightly higher in comparison to their hydrated counterparts.

Boyle, Timothy J.; Ottley, Leigh Anna M.; Alam, Todd M.; Rodriguez, Mark A.; Yang, Pin; Mcintyre, Sarah K.

2010-01-01

258

Electronic Excitations in Lanthanum Cuprates Measured by Resonant Inelastic X-ray Scattering  

NASA Astrophysics Data System (ADS)

Excitations of the valence electrons in the high-temperature superconducting cuprate La2--xSr xCuO4 were measured by Resonant Inelastic X-ray Scattering (RIXS). Several types of electronic excitations resonant at the Cu 1s?4p transition were studied over a wide range of dopings 0 ? x ? 0.35. A 500 meV excitation was observed at a reduced momentum transfer q=(pi 0) corresponding to the zone boundary, whose temperature and doping dependence was the same as the two-magnon Raman scattering mode. The momentum dependence of this 2-magnon excitation agrees with recent theoretical calculations. Momentum resolved measurements of the x=0 sample revealed a broad range of excitations above and below the main charge transfer peak, and their dispersions were measured across the Brillouin zone. These include a dispersionless ˜1.8 eV peak, which is either a local crystal field ( d-d excitation) or dipole-forbidden charge transfer excitation, and a dispersive 2.2 eV peak identified as a Zhang-Ng type charge-transfer exciton. The 2.2 eV peak was less dispersive than predicted from the theoretical models, due to electron-phonon coupling, as illustrated by the temperature dependent shift in the peak position. With increased hole doping, the RIXS spectral weight transfers from higher to lower energies, analogous to earlier optical conductivity studies. At the finite momentum of q=(pi 0), however, the changes are most systematic: an isosbestic point was observed at 2.2 eV where the spectra of all dopings cross, and spectral weight is transferred from high to low energies, with near-linear dependence on x, in a manner suggesting that the integrated RIXS intensity is preserved. The intensity and energy variations of the spectral peaks, as well as the isosbestic point and possible sum rule, could be explained qualitatively by a rigid three-band model which includes the non-bonding oxygen, upper Hubbard, and Zhang-Rice singlet bands. The estimated properties of the bands, such as width and energy separation, are in reasonably quantitative agreement with current theoretical models and angle-resolved photoemission measurements. Moreover, anomalies in the doping dependence are similar to those observed in other types of spectroscopies. These results underscore the relevance of the RIXS method in understanding the electronic behavior of the Lanthanum cuprates.

Ellis, David Shai

259

Tissue uptake and intracellular distribution of 140-lanthanum after oral intake by the rat  

SciTech Connect

The ability of lanthanum to stabilize hydroxyapatite against acid dissolution is well known. It is possible to use lanthanum to experimentally alter hard tissues in vivo and in vitro. It was, therefore, of interest to determine the tissue distribution of lanthanum following oral ingestion of a LaCl/sub 3/ solution. Oral intake of 140-lanthanum (as LaCl/sub 3/ in drinking water) in adult rats over a 3-d period was voluntary and amounted to 0.27 mmol LaCl/sub 3/ per animal per day. The teeth sowed increases in 140-lanthanum uptake with time. Distribution of 140-lanthanum within the incisors of animals drinking the LaCl/sub 3/ solution showed that the highest specific activity of 140-lanthanum was associated with the outer layer of the tooth (that portion exposed to the oral environment). The soft tissues, such as lung, kidney, and liver, maintained a constant 140-lanthanum concentration after the first day of intake. The intracellular distribution of 140-lanthanum was measured in liver, with the soluble fraction showing the highest content. No histological changes were observed in the rat tissues after 3 d of oral intake (0.27 mmol/d) of lanthanum.

Rabinowitz, J.L.; Fernandez-Gavarron, F.; Brand, J.G.

1988-01-01

260

Phase behavior of lanthanum strontium manganites  

SciTech Connect

The phase stability of Sr-doped LaMnO{sub 3} (LSM) perovskite in the La-Sr-Mn-O system was investigated as a function of Sr content and A/B cation ratio. The perovskite structure changed with both Sr content and A/B cation ratio. As the Sr content was increased to 0.2 mol, the perovskite structure adopted an orthorhombic distortion. This changed to a monoclinic or hexagonal structure for 0.2 {le} Sr {le} 0.3 mol. When the Sr content increased to 0.3 mol, the structure reverted to orthorhombic symmetry. Data from X-ray powder diffractometry, scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray emission spectroscopy, showed that secondary phases in the La-Sr-Mn-O system were underdeveloped with respect to changes of the doped Sr content, A/B cation ratio, and thermal history. X-ray detectable minor phases present in the LSM material were Mn{sub 3}O{sub 4}, (La, Sr)Mn{sub 2}O{sub 4}, La{sub 2}O{sub 3}, La(OH){sub 3}, (La, Sr){sub 3}Mn{sub 2}O{sub 7}, and (La, Sr){sub 2}MnO{sub 4}.

Zheng, F.; Pederson, L.R.

1999-08-01

261

Anthropogenic dissolved and colloid/nanoparticle-bound samarium, lanthanum and gadolinium in the Rhine River and the impending destruction of the natural rare earth element distribution in rivers  

NASA Astrophysics Data System (ADS)

The strong increase in the consumption of rare earth elements (REE) in high-tech products and processes is accompanied by increasing amounts of REE released into the environment. Following the first report of Gd contamination of the hydrosphere in 1996, anthropogenic Gd originating from contrast agents has now been reported worldwide from river and estuarine waters, coastal seawater, groundwater and tap water. Recently, microcontamination with La, that is derived from a point source where catalysts for petroleum refining are produced, has been detected in the Rhine River in Germany and the Netherlands. Here we report the occurrence of yet another REE microcontamination of river water: in addition to anthropogenic Gd and La, the Rhine River now also shows significant amounts of anthropogenic Sm. The anthropogenic Sm, which enters the Rhine River north of Worms, Germany, with the same industrial wastewater that carries the anthropogenic La, can be traced through the Middle and Lower Rhine to the Netherlands. At Leverkusen, Germany, some 250 km downstream from the point source at Worms, anthropogenic Sm still contributes up to 87% of the total dissolved Sm concentration of the Rhine River. Results from ultrafiltration suggest that while the anthropogenic Gd is not particle-reactive and hence exclusively present in the truly dissolved REE pool (<10 kDa), the anthropogenic La and Sm are also present in the colloidal/nanoparticulate REE pool (between 10 kDa and 0.2 ?m). Though difficult to quantify, our data suggest that the Rhine River may carry up to 5700 kg of anthropogenic La, up to 584 kg of anthropogenic Sm, and up to 730 kg of anthropogenic Gd per year toward the North Sea. There exist no regulatory limits for dissolved REE in natural waters, but total REE and Y (?REY) concentrations of up to 0.14 mg/kg in the plume downstream of and 52.2 mg/kg at the head of an effluent pipe at Rhine-km 447.3 at Worms get close to and well-above, respectively, the levels at which ecotoxicological effects have been documented. Because of the increasing use of REE and other formerly “exotic” trace elements in high-tech applications, these critical metals have now become emerging contaminants that should be monitored, and it appears that studies of their biogeochemical behavior in natural freshwaters might soon no longer be possible.

Kulaks?z, Serkan; Bau, Michael

2013-01-01

262

A comparative study of the oxides of lanthanum, cerium, praseodymium, and samarium as catalysts for the oxidative dehydrogenation of methane in the presence and absence of carbon tetrachloride  

Microsoft Academic Search

The catalytic oxidative coupling of methane to ethane and ethene has been investigated on the rare earth oxides, i.e., La[sub 2]O[sub 3], CeO[sub 2], Pr[sub 6]O[sub 11], and Sm[sub 2]O[sub 3]. Addition of a small amount of tetrachloromethane (TCM) to the reactant stream improves the catalytic activity of these oxides. In particular, the praseodymium catalyst yields high selectivity to the

Shigeru Sugiyama; Yasuyuki Matsumura; J. B. Moffat

1993-01-01

263

A comparative study of the oxides of lanthanum, cerium, praseodymium, and samarium as catalysts for the oxidative dehydrogenation of methane in the presence and absence of carbon tetrachloride  

SciTech Connect

The catalytic oxidative coupling of methane to ethane and ethene has been investigated on the rare earth oxides, i.e., La[sub 2]O[sub 3], CeO[sub 2], Pr[sub 6]O[sub 11], and Sm[sub 2]O[sub 3]. Addition of a small amount of tetrachloromethane (TCM) to the reactant stream improves the catalytic activity of these oxides. In particular, the praseodymium catalyst yields high selectivity to the C[sub 2] compounds comparable to La[sub 2]O[sub 3] or Sm[sub 2]O[sub 3] when TCM is present in the feedstream. The X-ray diffraction patterns for these catalysts after the reaction with TCM show the presence of the oxychlorides in the catalysts except for the cerium catalyst, for which the selectivity to C[sub 2] compounds is very low even in the presence of TCM. The oxychlorides can be generated on La[sub 2]O[sub 3], Sm[sub 2]O[sub 3], or Pr[sub 6]O[sub 11] by preheating under a stream including TCM. The product distribution of the reaction with these catalysts in the absence of TCM is similar to that with the oxides in the presence of TCM, while Pr[sub 6]O[sub 11] pretreated with TCM is unstable with no TCM in the feedstream. It appears that the improvement of the activity of the rare earth catalysts with TCM in the feedstream is primarily due to the formation of the oxychlorides during the reaction. 49 refs., 6 figs., 5 tabs.

Sugiyama, Shigeru; Matsumura, Yasuyuki; Moffat, J.B. (Univ. of Waterloo, Ontario (Canada))

1993-02-01

264

Radiotracer study of the preparation of high-purity lanthanum fluoride  

SciTech Connect

This paper reports that the behavior of the impurities iron, cobalt, yttrium, and cerium is determined via radiotracer techniques for the preparation of high-purity lanthanum fluoride. The behavior of nickel and copper during the coprecipitation of a lanthanum nitrate solution is determined by graphite furnace atomic absorption spectrometric (GFAAS) analysis. There is no commercially available radiotracer for neodymium, a key impurity associated with absorption losses in fluoride glasses. However, the chemical behavior of neodymium and that of yttrium are very similar and, therefore, it is reasonable to assume that the behavior of yttrium throughout the processing is indicative of the behavior of neodymium. The concentrations of impurities in lanthanum nitrate, carbonate, and fluoride are estimated using the radiotracer and GFAAS data for each processing step. Results indicate that while high-purity lanthanum carbonate can be prepared, any impurities present in the lanthanum carbonate will be carried quantitatively into lanthanum fluoride upon hydrofluorination.

Ewing, K.J.; Jaganathan, J.; Peitersen, L.; Aggarwal, I.D. (Naval Research Lab., Code 6505, Washington, DC (US)); Sommers, J.A.; Fahey, J.V. (Teledyna Wah Chang Albany, Albany, OR (US))

1992-06-01

265

Investigation into Nanostructured Lanthanum Halides and CeBr{sub 3} for Nuclear Radiation Detection  

SciTech Connect

This slide-show presents work on radiation detection with nanostructured lanthanum halides and CeBr{sub 3}. The goal is to extend the gamma energy response on both low and high-energy regimes by demonstrating the ability to detect low-energy x-rays and relatively high-energy activation prompt gamma rays simultaneously using the nano-structured lanthanum bromide, lanthanum fluoride, cerium bromide, or other nanocrystal material. Homogeneous and nano structure cases are compared.

Guss, P., Guise, R., Mukhopadhyay, S., Yuan, D.

2011-06-22

266

Stimulation of taxol production and excretion in Taxus spp cell cultures by rare earth chemical lanthanum  

Microsoft Academic Search

The trivalent ion of a rare earth element, lanthanum, was tested for elicitor-like effects on taxol production in suspension cultures of four different Taxus spp cells. In T. yunnanensis cell cultures, the lanthanum ion at concentrations from 1.15 to 23.0 ?M stimulated taxol production. The lanthanum ion also promoted taxol excretion by the T. yunnanensis cells considerably. The maximum stimulation

Jianyong Wu; Chuangui Wang; Xingguo Mei

2001-01-01

267

Highly substituted benzannulated cyclooctanol derivatives by samarium diiodide-induced cyclizations  

PubMed Central

Summary A series of ?-oxo esters suitably substituted with various styrene subunits was subjected to samarium diiodide-induced 8-endo-trig cyclizations. Efficacy, regioselectivity and stereoselectivity of these reactions via samarium ketyls strongly depend on the substitution pattern of the attacked alkene moiety. The stereoselectivity of the protonation of the intermediate samariumorganyl is also influenced by the structural features of the substrates. This systematic study reveals that steric and electronic factors exhibited by the alkene and ketone subunits are of high importance for the outcome of these cyclization reactions leading to highly substituted benzannulated cyclooctanol derivatives. In exceptional cases, 7-exo-trig cyclizations to cycloheptanol derivatives have been observed. In examples with high steric hindrance the ketyl–aryl coupling can be a competing process.

Saadi, Jakub; Brudgam, Irene

2010-01-01

268

Develop techniques for ion implantation of (lead-lanthanum-zirconate-titanate) for adaptive optics  

NASA Astrophysics Data System (ADS)

Research was conducted at Pacific Northwest Laboratory to develop high photosensitivity adaptive optical elements utilizing ion implanted lanthanum-doped lead-zirconate-titanate (PLZT). One centimeter square samples were prepared by implanting ferroelectric and anti-ferroelectric PLZT with a variety of species or combinations of species. These included Ne, O, Ni, Ne/Cr, Ne/Al, Ne/Ni, Ne/O, and Ni/O, at a variety of energies and fluences. An indium-tin oxide (ITO) electrode coating was designed to give a balance of high conductivity and optical transmission at near uv to near ir wavelengths. Samples were characterized for photosensitivity; implanted layer thickness, index of refraction, and density; electrode (ITO) conductivity; and in some cases, residual stress curvature. Thin film anti-ferroelectric PLZT was deposited in a preliminary experiment. The structure was amorphous with x-ray diffraction showing the beginnings of a structure at substrate temperatures of approximately 550 C. This report summarizes the research and provides a sampling of the data taken during the report period.

Batishko, C. R.; Brimhall, J. L.; Pawlewicz, W. T.; Stahl, K. A.; Toburen, L. H.

1987-09-01

269

Develop techniques for ion implantation of PLZT (lead-lanthanum-zirconate-titanate) for adaptive optics  

SciTech Connect

Research was conducted at Pacific Northwest Laboratory to develop high photosensitivity adaptive optical elements utilizing ion implanted lanthanum-doped lead-zirconate-titanate (PLZT). One centimeter square samples were prepared by implanting ferroelectric and anti-ferroelectric PLZT with a variety of species or combinations of species. These included Ne, O, Ni, Ne/Cr, Ne/Al, Ne/Ni, Ne/O, and Ni/O, at a variety of energies and fluences. An indium-tin oxide (ITO) electrode coating was designed to give a balance of high conductivity and optical transmission at near uv to near ir wavelengths. Samples were characterized for photosensitivity; implanted layer thickness, index of refraction, and density; electrode (ITO) conductivity; and in some cases, residual stress curvature. Thin film anti-ferroelectric PLZT was deposited in a preliminary experiment. The structure was amorphous with x-ray diffraction showing the beginnings of a structure at substrate temperatures of approximately 550/sup 0/C. This report summarizes the research and provides a sampling of the data taken during the report period.

Batishko, C.R.; Brimhall, J.L.; Pawlewicz, W.T.; Stahl, K.A.; Toburen, L.H.

1987-07-01

270

Infrared luminescence of Tm{sup 3+}/Yb{sup 3+} codoped lanthanum aluminum germanate glasses  

SciTech Connect

Tm{sup 3+} doped and Tm{sup 3+}/Yb{sup 3+} codoped lanthanum aluminum germanate (LAG) glasses are prepared by melt-quenching method and characterized optically. Based on the measurement of absorption spectrum, Judd-Ofelt intensity parameters ({Omega}{sub 2},{Omega}{sub 4},{Omega}{sub 6}) are calculated. The radiation emission rates, branching ratios, and lifetimes of Tm{sup 3+} are calculated to evaluate the spectroscopic properties of Tm{sup 3+} in LAG glass. The infrared emission properties of the samples are investigated and the results show that the 1.8 {mu}m emission can be greatly enhanced by adding proper amount of Yb{sup 3+} under the excitation of 980 nm. The energy transfer processes of Yb{sup 3+}-Yb{sup 3+} and Yb{sup 3+}-Tm{sup 3+} are analyzed, and the results show that Yb{sup 3+} ions can transfer their energy to Tm{sup 3+} ions with high efficiency and large energy transfer coefficient.

Zhang Qiang; Zhang Guang [Key Laboratory of Material Science and Technology for High Power Lasers, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China); Chen Guorong [Key Laboratory for Ultrafine Materials of Ministry of Education, School of Materials Science and Engineering, East China University of Science and Technology, Shanghai 200237 (China); Qiu Jianrong [State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027 (China); Chen Danping [Key Laboratory of Material Science and Technology for High Power Lasers, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800 (China)

2010-01-15

271

Synthesis of new steroid analogues by samarium diiodide induced cyclisations of ?-naphthyl 1,3-diones  

Microsoft Academic Search

We present the synthesis of new steroid analogues via samarium diiodide mediated intramolecular ketyl–aryl coupling reactions of ?-naphthyl-substituted 1,3-diones. From previous experiments with ?-naphthyl monoketones high stereoselectivities with the ‘unnatural’cis\\/cis annulation of rings B\\/C\\/D were expected. Surprisingly, we observed the formation of two diastereomers with cis- and trans-fused rings B and C of the tetracyclic skeleton. The diastereoselectivity proved to

Ulrike K. Wefelscheid; Hans-Ulrich Reissig

2010-01-01

272

Matrix effect in soft metal-bonded samarium-cobalt (SmCo 5 ) permanent magnets  

Microsoft Academic Search

This paper discusses the preparation of samarium-cobalt (SmCo5) alloy powders by reduction-diffusion process. These powders were blended with equal weight percentages of soft metal\\/alloy\\u000a powders, such as indium, tin and solder alloy (Pb-17Sn), to prepare bonded magnets. Important magnetic properties such as\\u000a remanence, coercivity and energy product of these magnets were measured. Effect of matrix metal\\/alloy on the magnetic properties

A Verma; P Verma; R K Sidhu

1996-01-01

273

Bismuth replacement by samarium in strontium bismuth niobate and its multiferroic nature  

NASA Astrophysics Data System (ADS)

Strontium bismuth niobate (SBN) is a ferroelectric material. This research reports the effects of the total replacement of bismuth in SBN by the rare-earth element, samarium. X-ray-diffraction measurement with Rietveld analysis shows that the tetragonal crystal structure of SBN is essentially retained but is distorted to an orthorhombic form. The new phase shows a ferromagnetic response in addition to its inherent ferroelectric property at room temperature.

Srinivas, A.; Sritharan, T.; Boey, F. Y. C.

2005-08-01

274

Bismuth replacement by samarium in strontium bismuth niobate and its multiferroic nature  

Microsoft Academic Search

Strontium bismuth niobate (SBN) is a ferroelectric material. This research reports the effects of the total replacement of bismuth in SBN by the rare-earth element, samarium. X-ray-diffraction measurement with Rietveld analysis shows that the tetragonal crystal structure of SBN is essentially retained but is distorted to an orthorhombic form. The new phase shows a ferromagnetic response in addition to its

A. Srinivas; T. Sritharan; F. Y. C. Boey

2005-01-01

275

Chondrite Barium, Neodymium, and Samarium Isotopic Heterogeneity and Early Earth Differentiation  

Microsoft Academic Search

Isotopic variability in barium, neodymium, and samarium in carbonaceous chondrites reflects the distinct stellar nucleosynthetic contributions to the early solar system. We used 148Nd\\/144Nd to correct for the observed s-process deficiency, which produced a chondrite 146Sm-142Nd isochron consistent with previous estimates of the initial solar system abundance of 146Sm and a 142Nd\\/144Nd at average chondrite Sm\\/Nd ratio that is lower

Richard W. Carlson; Maud Boyet; Mary Horan

2007-01-01

276

YAG laser-induced crystalline dot patterning in samarium tellurite glasses  

Microsoft Academic Search

A CW YAG laser with a wavelength of 1064 nm and with a power of 1 W has been used to irradiate samarium tellurite glasses with the compositions of 10RO·10Sm2O3·80TeO2 (R=Mg, Ba) at room temperature for 30–60 s. It is found from polarized optical microscopy and from X-ray diffraction (XRD) analyses that crystalline dot patterns with sharp refractive index changes

Ryuji Sato; Yasuhiko Benino; Takumi Fujiwara; Takayuki Komatsu

2001-01-01

277

Radiation dose calculations in persons receiving injection of samarium-153 EDTMP  

Microsoft Academic Search

Samarium-153 EDTMP has been proposed as a radionuclide therapeutic agent to treat malignant bone tissue disorders. Data obtained from laboratory rats has been used to calculate the radiation dose for humans following the administration of (¹⁵³Sm)EDTMP. The data reveal that the highest doses are present in the skeleton and the urinary bladder wall (bladder dose varies with frequency of voiding).

K. W. Logan; W. A. Volkert; R. A. Holmes

1987-01-01

278

Evaluation of samarium-153 and holmium-166-EDTMP in the normal baboon model  

Microsoft Academic Search

Bone-seeking radiopharmaceuticals such as ethylenediaminetetramethylene phosphonate (EDTMP) complexes of samarium-153 and holmium-166 are receiving considerable attention for therapeutic treatment of bone metastases. In this study, using the baboon experimental model, multicompartmental analysis revealed that with regard to pharmacokinetics, biodistribution, and skeletal localisation, 166Ho-EDTMP was significantly inferior to 153Sm-EDTMP and 99mTc-MDP. A more suitable 166Ho-bone-seeking agent should thus be sought for

W. K. A. Louw; I. C. Dormehl; A. J. van Rensburg; N. Hugo; A. S. Alberts; O. E. Forsyth; G. Beverley; M. A. Sweetlove; J. Marais; M. G. Lötter; A. van Aswegen

1996-01-01

279

Electrochemical study of Pd capped samarium hydride thin film switchable mirror  

Microsoft Academic Search

A 55-nm samarium film capped with a 15-nm palladium overlayer switched from a metallic reflecting to a semiconducting, transparent in visible state during ex-situ hydrogen loading via electrochemical means in 1 M KOH electrolytic aqueous solution at room temperature. The optical transmittance exhibits a hysteresis effects on loading and unloading of hydrogen in SmHx thin film between x=2 and 3.

Pushpendra Kumar; L. K. Malhotra

2005-01-01

280

Efficacy and Toxicity of 153Samarium-EDTMP in Painful Breast Cancer Bone Metastases  

Microsoft Academic Search

SummaryAim: The aim of this study was to assess the usefulness of 153samarium-ethylene-diamino-tetramethylene phosphonic acid (153Sm-EDTMP, a beta and gamma emitter) treatment in the palliation of painful bone metastases from breast cancer. Patients and Methods: 43 women (aged 41–79, mean 60 years) with bone-disseminated breast cancer and bone pain refractory to opioid analgesics received 153Sm-EDTMP. Karnofsky performance status, pain score

Jiri Dolezal

2009-01-01

281

Adverse Events in the Long-Term Follow-Up of Patients Treated With Samarium Sm 153 Lexidronam for Osseous Metastases  

SciTech Connect

Purpose: To investigate adverse events after samarium Sm 153 lexidronam and the effect of pre- and post-samarium Sm 153 lexidronam external beam radiation therapy (EBRT) and/or chemotherapy on myelosuppression in patients who received samarium Sm 153 lexidronam for osseous metastases. Methods and Materials: We performed a single-institution retrospective review of 139 patients treated with samarium Sm 153 lexidronam between November 1997 and February 2008. New-onset adverse events after samarium Sm 153 lexidronam were reported. The effect of samarium Sm 153 lexidronam on platelet and peripheral white blood cell counts and the duration of myelosuppression after samarium Sm 153 lexidronam plus EBRT and/or chemotherapy were calculated. Differences in the prevalence of adverse events among patients with varying treatment histories were evaluated with the Pearson chi-square test. Results: Hematologic follow-up was available for 103 patients. Chemotherapy and/or EBRT had no effect on the magnitude or duration of myelosuppression. The most common nonhematologic adverse events were acute lower extremity edema (n = 27) and acute and transient neuropathy (n = 29). Patients treated with chemotherapy after samarium Sm 153 lexidronam had a higher prevalence of lower extremity edema (9 of 18 [50%]) than those who were not treated with chemotherapy after samarium Sm 153 lexidronam (18 of 85 [21.2%]) (p = 0.01, chi-square test). No adverse events were correlated with EBRT. Conclusions: Our observation of new-onset, acute and transient edema and neuropathy after samarium Sm 153 lexidronam and of a relationship between edema and post-samarium Sm 153 lexidronam chemotherapy suggests the need for re-examination of patients in past series or for a prospective investigation with nonhematologic adverse events as a primary endpoint.

Paravati, Anthony J., E-mail: Anthony.J.Paravati@dartmouth.edu [Dartmouth Medical School, Hanover, NH (United States); Russo, Andrea L. [Dartmouth Medical School, Hanover, NH (United States); Aitken, Candice [Dartmouth Medical School, Hanover, NH (United States); Department of Medicine, Section of Radiation Oncology, Dartmouth-Hitchcock Medical Center, Lebanon, NH (Lebanon)

2011-10-01

282

Thermal behaviour of the basic carbonates of lanthanum-europium  

Microsoft Academic Search

The basic carbonates of lanthanum with 10%, 20%, 50% and 80% of europium were prepared by precipitation from homogeneous solutions via the hydrolysis of urea, without the addition of an auxiliary anion, at two different temperatures. Elemental analysis, complexometric methods, X-ray diffraction patterns, solid state IR absorption, thermogravimetry\\/derivative thermogravimetry (TG\\/DTG) and differential thermal analysis (DTA) were used to characterise the

J. M. Luiz; J. R. Matos; I. Giolito; M. Ionashiro

1995-01-01

283

Heptamethylindenyl lanthanide(III) complexes of lanthanum, neodymium, and erbium  

Microsoft Academic Search

Both the steric bulk and the electronic character of this ligand resulting from the seven methyl groups favor the stabilization of the lanthanide-carbon bonds. Alkali metal salts of heptamethylindenide(Hmi) were used as precursors of the lanthanide complexes. Lanthanum, erbium or neodymium chlorides were added to a stoichiometric amount of potassium Hmi, allowing the mixture to stand at 25°C ca 2

Minoru Tsutsui; Li Ban Chen; David E. Bergbreiter; T. Ken Miyamoto

1982-01-01

284

Graphs for Isotopes of 57-La(Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides a graphic representation of nucleon separation energies and residual interaction parameters for isotopes of the chemical element 57-La (Lanthanum, atomic number Z = 57).

Sukhoruchkin, S. I.; Soroko, Z. N.

285

Lanthanum Isotopes in a Possible New Region of Nuclear Deformation  

Microsoft Academic Search

New neutron-deficient lanthanum isotopes have been produced by heavy-ion bombardments of indium, and identified by means of chemical separations and genetic relationships. The proposed mass assignments and corresponding half-lives are: La124, 7.2+\\/-0.5 min; La128, 4.2+\\/-0.5 min; La127, 3.8+\\/-0.5 min; La126, 1.0+\\/-0.3 min; and La125, <1 min.

Ivor L. Preiss; Paul M. Strudler; Richard Wolfgang

1963-01-01

286

Nanostructured Lanthanum Zirconate Coating and Its Thermal Stability Properties  

Microsoft Academic Search

In this paper, nano-La2Zr2O7 thermal barrier coatings (MCrAlY+ La2Zr2O7) were prepared by atmospheric plasma sprayed (APS). The microstructures and thermal stability properties were systematically studied to compare with their conventional counterparts by Scanning Electric Microscopy (SEM) transmission electron microscope (TEM) and X-Ray diffraction(XRD). The results showed that the nanostructured lanthanum zirconate coatings were typical lamellar structure which was composed of

Xiao-dong ZHAO; Ke-li ZENG; Jian-gang XIE; Zhen-duo LI

2007-01-01

287

Back bombardment for dispenser and lanthanum hexaboride cathodes  

Microsoft Academic Search

The back bombardment (BB) effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode's temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC) and lanthanum hexaboride (LaB6) thermionic rf

Mahmoud Bakr; R. Kinjo; Y. W. Choi; M. Omer; K. Yoshida; S. Ueda; M. Takasaki; K. Ishida; N. Kimura; T. Sonobe; T. Kii; K. Masuda; H. Ohgaki; H. Zen

2011-01-01

288

Electrochemical behaviour of lanthanum fluoride in molten fluorides  

Microsoft Academic Search

The electrochemical behaviour of lanthanum fluoride dissolved in molten lithium fluoride and in eutectic mixture LiF-CaF2 was investigated by cyclic voltammetry and laboratory electrolysis. The cyclic voltammetry experiments were carried out at\\u000a 900°C and 800°C, respectively, in a graphite crucible (counter electrode). Several types of working electrodes (Mo, W, Ni\\u000a and Cu) were used. Ni\\/Ni(II) was used as a reference

Marta Ambrová; Jana Jurišová; Vladimír Danielik

2008-01-01

289

Transition-metal-doped chalcogenide glasses for broadband near-infrared sources  

Microsoft Academic Search

In this paper we report the spectroscopic data for samples of 0.031% iron, 0.017% nickel, 0.01% chromium and 0.017% cobalt (molar) doped gallium lanthanum sulphide (GLS) glass. Photoluminescence (PL) with a full width half maximum (FWHM) of around 500 nm and peaking between 1120 nm and 1460 nm is observed when excited using wavelengths of 850 nm and 1064 nm.

Mark A. Hughes; Jonathan E. Aronson; William S. Brocklesby; David P. Shepherd; Daniel W. Hewak; Richard J. Curry

2004-01-01

290

Infrared to visible frequency upconversion temperature sensor based on Er 3+-doped PLZT transparent ceramics  

Microsoft Academic Search

Infrared to visible upconversion in erbium doped lead lanthanum zirconate titanate (PLZT) transparent ceramic is reported for the first time. Intense green upconversion emissions around 534 and 565nm originating from the thermally coupled levels 2H11\\/2 and 4S3\\/2 are observed. The mechanism responsible for excitation of these emitting levels is sequential two photon absorption based on the temperature dependence of the

Andrea S. S. de Camargo; João Fernando Possatto; Luiz Antonio de O. Nunes; Ériton R. Botero; Érika R. M. Andreeta; Ducinei Garcia; José Antonio Eiras

2006-01-01

291

Strontium-Doped Perovskites Rival Platinum Catalysts for Treating NOx in Simulated Diesel Exhaust  

Microsoft Academic Search

The high cost and poor thermal durability of current lean nitrogen oxides (NOx) aftertreatment catalysts are two of the major barriers to widespread adoption of highly fuel-efficient diesel engines. We demonstrated the use of strontium-doped perovskite oxides as efficient platinum substitutes in diesel oxidation (DOC) and lean NOx trap (LNT) catalysts. The lanthanum-based perovskite catalysts coated on monolith substrates showed

Chang Hwan Kim; Gongshin Qi; Kevin Dahlberg; Wei Li

2010-01-01

292

Domain switching energies: Mechanical versus electrical loading in La-doped bismuth ferrite-lead titanate  

Microsoft Academic Search

The mechanical stress-induced domain switching and energy dissipation in morphotropic phase boundary (1-x)(Bi1 - yLay)FeO3-xPbTiO3 during uniaxial compressive loading have been investigated at three different temperatures. The strain obtained was found to decrease with increasing lanthanum content, although a sharp increase in strain was observed for compositions doped with 7.5 and 10 at. % La. Increased domain switching was found

T. Leist; K. G. Webber; W. Jo; T. Granzow; E. Aulbach; J. Suffner; J. Rödel

2011-01-01

293

Will Lanthanum Halide Scintillators Make NaI(Tl) Obsolete?  

NASA Astrophysics Data System (ADS)

The commercial availability of lanthanum halide scintillators (LaCl3:Ce and LaBr3:Ce) has been much anticipated due to their significantly better resolution (3-4% at 662 keV) relative to NaI(Tl). Unfortunately, our initial investigation of these scintillators revealed significant alpha contamination quite apparent in background spectra. Using measurements of the detector in coincidence with a HPGe detector, we identified the alpha-contaminant as Ac-227. Since this time, the alpha contamination has been substantially reduced so that a second contaminant, La-138 (a beta, gamma, and x-ray source) has become the dominant contaminant in the material. Commercially-available sizes of lanthanum halide scintillators have now reached sizes suitable for handheld Radioactive Isotope Identification Devices (RIIDs). To study the potential of this new material for RIIDs we performed a series of measurements comparing a 1.5'' x 1.5'' LaBr3 detector with an Exploranium GR-135 RIID, which contains a 1.5'' x 2.2'' NaI(Tl) detector. Measurements were taken for short timeframes of seconds to minutes, as typifies RIID usage. Measurements included examples of naturally occurring radioactive material (NORM) typically found in cargo. Of particular interest was the extent to which interference between the La-138 contaminant and K-40, a radioisotope commonly found in NORM, compromise the lanthanum halide performance. Example spectra, detector comparisons and results will be shown.

Milbrath, Brian

2006-05-01

294

Infrared Spectroscopic Studies on Amorphous and Crystalline Lanthanum Aluminoborates  

NASA Astrophysics Data System (ADS)

The development of lanthanum aluminoborate crystalline phase of LaAl2.03B4O10.5 (124) composition from the amorphous xerogels prepared by sol-gel technique has been characterized by thermal analysis and infrared spectroscopy. Thermal analysis evidenced continuous weight losses up to 800°C as a result of nitrates decomposition, glycerol combustion and dehydroxylation. The crystallization of amorphous xerogels occurs between 760 and 860°C. The IR data indicate that the local structure dramatically modifies as crystalline phases are developed from the amorphous xerogels. The major changes occur in the boron surrounding where, from the most borons which are three-coordinated in amorphous xerogels, almost only tetra-coordinated species appear in the crystalline samples. While in amorphous xerogels, aluminum occurs as hexa-, penta- and tetra-coordinated by oxygen, in the crystalline samples obtained from lanthanum aluminoborates, amorphous precursors of composition corresponding to 124-lanthanum aluminoborate phase aluminum, it is preponderantly penta- and hexa-coordinated.

Simon, S.; Grecu, R.; Simon, V.

295

Magnetoresistance of lanthanum manganites with activation-type conductivity  

NASA Astrophysics Data System (ADS)

The temperature dependence of the resistivity and magnetic moment of La0.85Ba0.15MnO3 and La0.85Sr0.15MnO3 manganite single crystals in magnetic fields up to 90 kOe is investigated. Analysis of the experimental results shows that the magnetoresistance of lanthanum manganites far from the Curie temperature T C can be described quantitatively by the s- d model normally used for ferromagnets and taking into account only the exchange interaction between the spins of charge carriers and magnetic moments. These data also show that the features of lanthanum manganites responsible for colossal magnetoresistance (CMR) are manifested in a narrow temperature interval ? T ? 20 K near T C. Our results suggest a CMR mechanism analogous to the mechanism of giant magnetoresistance (GMR) observed in Fe/Cr-type multilayers with nanometer layer thickness. The nanostratification observed in lanthanum manganites and required for GMR can be described taking into account the spread in T C in the CMR range ? T.

Kurkin, M. I.; Neifeld, E. A.; Korolev, A. V.; Ugryumova, N. A.; Gudin, S. A.; Gapontseva, N. N.

2013-05-01

296

Waveshifting fiber readout of lanthanum halide scintillators  

NASA Astrophysics Data System (ADS)

Newly developed high-light-yield inorganic scintillators coupled to waveshifting optical fibers provide the capability of efficient X-ray detection and millimeter scale position resolution suitable for high-energy cosmic ray instruments, hard X-ray/gamma ray astronomy telescopes and applications to national security. The CASTER design for NASA's proposed Black Hole Finder Probe mission, in particular, calls for a 6 8 m2 hard X-ray coded aperture imaging telescope operating in the 20 600 keV energy band, putting significant constraints on cost and readout complexity. The development of new inorganic scintillator materials (e.g., cerium-doped LaBr3 and LaCl3) provides improved energy resolution and timing performance that is well suited to the requirements for national security and astrophysics applications. LaBr3 or LaCl3 detector arrays coupled with waveshifting fiber optic readout represent a significant advance in the performance capabilities of scintillator-based gamma cameras and provide the potential for a feasible approach to affordable, large area, extremely sensitive detectors. We describe some of the applications and present laboratory test results demonstrating the expected scintillator performance.

Case, G. L.; Cherry, M. L.; Stacy, J. G.

2006-07-01

297

Effects of lanthanum on calcium-dependent phenomena in human red cells.  

PubMed

Lanthanum (0.25 mM) does not penetrate into fresh or Mg2+-depleted cells, whereas it does into ATP-depleted or ATP + 2,3-diphosphoglycerate-depleted cells, into cells containing more than 3 mM calcium, or cells stored for more than 4 weeks in acid/citrate/dextrose solution. In fresh cells loaded with calcium, extracellular lanthanum blocks the active Ca2+-efflux completely and inhibits (Ca2+ + Mg2+)-ATPase (ATP phosphohydrolase, EC 3.6.1.3) activity to about 50%. In Mg2+-depleted cells Ca2+-Ca2+ exchange is inhibited by lanthanum. Ca2+-leak is unaffected by lanthanum up to 0.25 mM concentration; higher lanthanum concentrations reduce leak rate. In NaCl medium Ca2+-leak +/ S.D. amounts to 0.28 +/ 0.08 mumol/1 of cells per min, whereas in KC1 medium to 0.15 +/ 0.04 mumol/1 of cells per min at 2.5 mM [Ca2+]e and 0.25 mM [La3+]e pH 7.1. Lanthanum inhibits Ca2+-dependent rapid K+ transport in ATP-depleted and propranolol-treated red cells, i.e. whenever intracellular calcium is below a critical level. The inhibition of the rapid K+ transport can be attributed to protein-lanthanum interactions on the cell surface, since lanthanum is effectively detached from the membrane lipids by propranolol. Lanthanum at 0.2--0.25 mM concentration has no direct effect on the morphology of red cells. The shape regeneration of Ca2+-loaded cells, however, is blocked by lanthanum owing to Ca2+-pump inhibition. Using lanthanum the transition in cell shape can be quantitatively correlated to intracellular Ca2+ concentrations. PMID:152127

Szász, I; Sarkadi, B; Schubert, A; Gárdos, G

1978-09-22

298

Comparison Between Features and Performance Characteristics of Fifteen HP Samarium Cobalt and Ferrite Based Brushless DC Motors Operated by Same Power Conditioner  

Microsoft Academic Search

The impact of samarium-cobalt and ferrite magnet materials on the design and performance characteristics of electronically commutated brushless dc motors of equal horsepower output is presented. This is accomplished through the design, construction and testing of two 15 hp, 120 volt brushless dc motors built for propulsion of electric vehicles, and similar applications. In one of these motors, samarium-cobalt (Sm

N. A. Demerdash; R. H. Miller; T. W. Nehl; B. P. Overton; C. J. Ford

1983-01-01

299

RADIOCHEMICAL INVESTIGATION OF PRODUCTS RESULTING FROM A DIVISION OF LANTHANUM BY 660 Mev ENERGY PROTONS  

Microsoft Academic Search

According to the experimental data and calculations of the cross ; sections the fission of lanthanum results in formation of isotopes wlth surplus ; neutrons. The isotopes are distributed over a wide range of atomic numbers from ; Z = 15 to Z = 40. The yields from fission of lanthanum by 660-Mev protons ; distributed according to their atomic

A. K. Lavrukhina; L. D. Krasavina; A. A. Pozdnyaikov

1958-01-01

300

Thermodynamic Stabilities of Lanthanum Tungstates Using a Calcium Fluoride Solid Electrolyte Galvanic Cell  

Microsoft Academic Search

A knowledge of the thermodynamic stabilities of the lanthanum tungstates measured as the Gibbs energies of formation from the free oxides is important as lanthanum is used as a powerful desulphurizing agent and tungsten as a special alloying element in the production of clean steels and special steels. These data will also be useful as the system La2O3 WO3 can

S. RAGHAVAN

2001-01-01

301

Factors Affecting Lanthanum and Cerium Biosorption on Pinus brutia Leaf Powder  

Microsoft Academic Search

The biosorption behavior of lanthanum and cerium ions from aqueous solution by leaf powder of Pinus brutia was separately studied in a batch system as a function of initial pH, contact time, initial metal ion concentration, temperature, and adsorbent amount. The uptake of lanthanum and cerium was increased when the initial pH of the solution was increased. Thermodynamic parameters such

Ceren Kütahyali; ?enol Sert; Berkan Çetinkaya; Süleyman Inan; Meral Eral

2010-01-01

302

Synthesis, characterization, and antimicrobial properties of Cu-inorganic antibacterial material containing lanthanum  

Microsoft Academic Search

In this paper a kind of new inorganic antibacterial material: Cu-antibacterial white carbon black containing lanthanum was synthesized. The characterization and antimicrobial effect of the Cu-antibacterial white carbon black containing lanthanum was investigated. Inorganic antibiotic materials comprised the carrier, the antibacterial ion and the additive. In this study, we choosed white carbon black as the carrier, which was compound by

Bin ZHANG; Yan LIN; Xiaoning TANG; Suqiong HE; Gang XIE

2010-01-01

303

A confusional state associated with use of lanthanum carbonate in a dialysis patient: a case report.  

PubMed

A 75-year-old woman was admitted with febrile confusion and abdominal pain. She was taking medications that included lanthanum carbonate. Examination, biology, a cerebral scan, and a review of her medications could not explain the confusion. The plain film of the abdomen revealed multiple diffuse calcium-like deposits throughout the digestive tract. The plasma levels of lanthanum were higher than normal. The confusion resolved after discontinuation of the lanthanum carbonate. This case raises the problem of the potential role played by lanthanum tablet residue in the genesis or aggravation of diverticular flare-up and the problem of the potential permeability of the blood-brain barrier with lanthanum use in case of its digestive accumulation, leading to increased serum concentrations. PMID:19596740

Muller, Clotilde; Chantrel, Francois; Faller, Bernadette

2009-07-13

304

X-ray spectrum in the range (6-12) A emitted by laser-produced plasma of samarium  

SciTech Connect

A detailed analysis of the x-ray spectrum emitted by laser-produced plasma of samarium (6-12 A) is presented, using ab initio calculations with the HULLAC relativistic code and isoelectronic considerations. Resonance 3d-nf (n=4 to 7), 3p-4d, 3d-4p, and 3p-4s transitions in Ni samarium ions and in neighboring ionization states (from Mn to Zn ions) were identified. The experiment results show changes in the fine details of the plasma spectrum for different laser intensities.

Louzon, Einat; Henis, Zohar; Levi, Izhak; Hurvitz, Gilad; Ehrlich, Yosi; Fraenkel, Moshe; Maman, Shlomo [Soreq Research Center, Yavne 81800 (Israel); Mandelbaum, Pinchas [Jerusalem College of Engineering, Ramat Beth Hakerem, Jerusalem 91035 (Israel)

2009-05-15

305

The effect of field strength on the resonance structure of three-photon ionization spectra of the samarium atom  

NASA Astrophysics Data System (ADS)

Amplitude ratios of resonance maxima caused by two-photon transitions from different levels of the ground term of the samarium atom are studied experimentally and theoretically as functions of the laser-radiation field strength. The results of these studies are shown to be promising for identifying the resonance structure of three-photon ionization spectra of the samarium atom. A not yet observed excited even-parity state with energy E ? 36789.1 cm-1 and hypothetical values of total angular momentum J = 5, 6 has been discovered.

Gomonai, A. I.; Remeta, E. Yu.

2013-03-01

306

Spectroscopic valence of cerium in cerium-lanthanum-iron compounds  

NASA Astrophysics Data System (ADS)

In Ce2Fe14B and Ce2Fe17, cerium is mixed valent and nonmagnetic. Any structural or compositional modification of these intermetallics which induces cerium to become trivalent and develop a local 4f moment should result in compounds with enhanced magnetostrictions, magnetocrystalline anisotropies, and net magnetic moments. Due to the dependence of cerium valence on steric volume, one approach for manipulating the valence is to increase the cell volume of these phases by forming pseudoternaries or pseudobinaries of these compounds with lanthanum. In this work, we report the spectroscopic valence of cerium obtained from the cerium L3 edge of La2-xCexFe14B, La2-xCexFe17, and selected hydrides and nitrides of these intermetallics. In La2-xCexFe14B the average cerium valence is found to decrease only slightly with increasing lanthanum content. Analysis of the extended x-ray absorption fine structure of the cerium and lanthanum L3 edges from the La2-xCexFe14B series is only consistent with cerium preferentially occupying the small 4f rare-earth site in the tetragonal Nd2Fe14B structure. In La2-xCexFe17 the shift of cerium towards the trivalent state with decreasing x is more pronounced, but the shift is incomplete over the range of compositions investigated (x>=1). Although these results do not exclude the possibility of trivalent cerium in some of these compounds, none of the compounds provided unambiguous evidence of trivalent cerium.

Capehart, T. W.; Mishra, R. K.; Fuerst, C. D.; Meisner, G. P.; Pinkerton, F. E.; Herbst, J. F.

1997-05-01

307

Synthesis and characterization of rare-earth doped SrBi{sub 2}Nb{sub 2}O{sub 9} phase in lithium borate based nanocrystallized glasses  

SciTech Connect

Glass composites comprising of un-doped and samarium-doped SrBi{sub 2}Nb{sub 2}O{sub 9} nanocrystallites are fabricated in the glass system 16.66SrO-16.66[(1-x)Bi{sub 2}O{sub 3}-xSm{sub 2}O{sub 3}]-16.66Nb{sub 2}O{sub 5}-50Li{sub 2}B{sub 4}O{sub 7} (0<=x<=0.5, in mol%) via the melt quenching technique. The glassy nature of the as-quenched samples is established by differential thermal analyses. Transmission electron microscopic studies reveal the presence of about 15 nm sized spherical crystallites of the fluorite-like SrBi{sub 1.9}Sm{sub 0.1}Nb{sub 2}O{sub 9} phase in the samples heat treated at 530 deg. C. The formation of layered perovskite-type un-doped and samarium-doped SrBi{sub 2}Nb{sub 2}O{sub 9} nanocrystallites with an orthorhombic structure through the intermediate fluorite phase is confirmed by X-ray powder diffraction and micro-Raman spectroscopic studies. The influence of samarium doping on the lattice parameters, lattice distortions, and the Raman peak positions of SrBi{sub 2}Nb{sub 2}O{sub 9} perovskite phase is clarified. The dielectric constants of the perovskite SrBi{sub 2}Nb{sub 2}O{sub 9} and SrBi{sub 1.9}Sm{sub 0.1}Nb{sub 2}O{sub 9} nanocrystals are relatively larger than those of the corresponding fluorite-like phase and the precursor glass. - Graphical Abstract: This figure shows the XRD patterns at room temperature for the as-quenched and heat treated samples in Sm{sub 2}O{sub 3}-doped (x=0.1) glass. Based on these results, it is concluded that the formation of samarium-doped perovskite SBN phase takes place via an intermediate fluorite-like phase in the crystallization of this glass.

Harihara Venkataraman, B. [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Fujiwara, Takumi [Department of Applied Physics, Graduate School of Engineering, Tohoku University, Sendai 980-8579 (Japan); Komatsu, Takayuki, E-mail: komatsu@mst.nagaokaut.ac.j [Department of Materials Science and Technology, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan)

2009-06-15

308

Atomic Mass and Nuclear Binding Energy for La-172 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-172 (Lanthanum, atomic number Z = 57, mass number A = 172).

Sukhoruchkin, S. I.; Soroko, Z. N.

309

New neutron-deficient isotopes of lanthanum and cerium  

Microsoft Academic Search

The short-lived neutron-deficient isotopes of lanthanum and cerium were produced in the 32S+96, 98Ru reactions and separated according to their masses. Seven isotopes 123-125La and 124-127Ce have been first observed and their half-lives and low-energy gamma-ray data are reported. In addition, low-energy gamma-ray data are given for the 122-125Ba and 127La decays. The beta-decay probabilities for Ce, La and Ba

D. D. Bogdanov; A. V. Demyanov; V. A. Karnaukhov; M. Nowick; L. A. Petrov; J. Voboril; A. Plochocki

1978-01-01

310

Atomic Mass and Nuclear Binding Energy for La-162 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-162 (Lanthanum, atomic number Z = 57, mass number A = 162).

Sukhoruchkin, S. I.; Soroko, Z. N.

311

Atomic Mass and Nuclear Binding Energy for La-177 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-177 (Lanthanum, atomic number Z = 57, mass number A = 177).

Sukhoruchkin, S. I.; Soroko, Z. N.

312

Atomic Mass and Nuclear Binding Energy for La-187 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-187 (Lanthanum, atomic number Z = 57, mass number A = 187).

Sukhoruchkin, S. I.; Soroko, Z. N.

313

Atomic Mass and Nuclear Binding Energy for La-198 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-198 (Lanthanum, atomic number Z = 57, mass number A = 198).

Sukhoruchkin, S. I.; Soroko, Z. N.

314

Atomic Mass and Nuclear Binding Energy for La-179 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-179 (Lanthanum, atomic number Z = 57, mass number A = 179).

Sukhoruchkin, S. I.; Soroko, Z. N.

315

Atomic Mass and Nuclear Binding Energy for La-160 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-160 (Lanthanum, atomic number Z = 57, mass number A = 160).

Sukhoruchkin, S. I.; Soroko, Z. N.

316

Atomic Mass and Nuclear Binding Energy for La-184 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-184 (Lanthanum, atomic number Z = 57, mass number A = 184).

Sukhoruchkin, S. I.; Soroko, Z. N.

317

Atomic Mass and Nuclear Binding Energy for La-169 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-169 (Lanthanum, atomic number Z = 57, mass number A = 169).

Sukhoruchkin, S. I.; Soroko, Z. N.

318

Atomic Mass and Nuclear Binding Energy for La-199 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-199 (Lanthanum, atomic number Z = 57, mass number A = 199).

Sukhoruchkin, S. I.; Soroko, Z. N.

319

Atomic Mass and Nuclear Binding Energy for La-204 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-204 (Lanthanum, atomic number Z = 57, mass number A = 204).

Sukhoruchkin, S. I.; Soroko, Z. N.

320

Atomic Mass and Nuclear Binding Energy for La-183 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-183 (Lanthanum, atomic number Z = 57, mass number A = 183).

Sukhoruchkin, S. I.; Soroko, Z. N.

321

Atomic Mass and Nuclear Binding Energy for La-150 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-150 (Lanthanum, atomic number Z = 57, mass number A = 150).

Sukhoruchkin, S. I.; Soroko, Z. N.

322

Atomic Mass and Nuclear Binding Energy for La-193 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-193 (Lanthanum, atomic number Z = 57, mass number A = 193).

Sukhoruchkin, S. I.; Soroko, Z. N.

323

Atomic Mass and Nuclear Binding Energy for La-188 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-188 (Lanthanum, atomic number Z = 57, mass number A = 188).

Sukhoruchkin, S. I.; Soroko, Z. N.

324

Atomic Mass and Nuclear Binding Energy for La-167 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-167 (Lanthanum, atomic number Z = 57, mass number A = 167).

Sukhoruchkin, S. I.; Soroko, Z. N.

325

Atomic Mass and Nuclear Binding Energy for La-159 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-159 (Lanthanum, atomic number Z = 57, mass number A = 159).

Sukhoruchkin, S. I.; Soroko, Z. N.

326

Atomic Mass and Nuclear Binding Energy for La-181 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-181 (Lanthanum, atomic number Z = 57, mass number A = 181).

Sukhoruchkin, S. I.; Soroko, Z. N.

327

Atomic Mass and Nuclear Binding Energy for La-196 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-196 (Lanthanum, atomic number Z = 57, mass number A = 196).

Sukhoruchkin, S. I.; Soroko, Z. N.

328

Atomic Mass and Nuclear Binding Energy for La-165 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-165 (Lanthanum, atomic number Z = 57, mass number A = 165).

Sukhoruchkin, S. I.; Soroko, Z. N.

329

Atomic Mass and Nuclear Binding Energy for La-178 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-178 (Lanthanum, atomic number Z = 57, mass number A = 178).

Sukhoruchkin, S. I.; Soroko, Z. N.

330

Atomic Mass and Nuclear Binding Energy for La-205 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-205 (Lanthanum, atomic number Z = 57, mass number A = 205).

Sukhoruchkin, S. I.; Soroko, Z. N.

331

Atomic Mass and Nuclear Binding Energy for La-195 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-195 (Lanthanum, atomic number Z = 57, mass number A = 195).

Sukhoruchkin, S. I.; Soroko, Z. N.

332

Atomic Mass and Nuclear Binding Energy for La-200 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-200 (Lanthanum, atomic number Z = 57, mass number A = 200).

Sukhoruchkin, S. I.; Soroko, Z. N.

333

Atomic Mass and Nuclear Binding Energy for La-174 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-174 (Lanthanum, atomic number Z = 57, mass number A = 174).

Sukhoruchkin, S. I.; Soroko, Z. N.

334

Atomic Mass and Nuclear Binding Energy for La-153 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-153 (Lanthanum, atomic number Z = 57, mass number A = 153).

Sukhoruchkin, S. I.; Soroko, Z. N.

335

Atomic Mass and Nuclear Binding Energy for La-168 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-168 (Lanthanum, atomic number Z = 57, mass number A = 168).

Sukhoruchkin, S. I.; Soroko, Z. N.

336

Atomic Mass and Nuclear Binding Energy for La-186 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-186 (Lanthanum, atomic number Z = 57, mass number A = 186).

Sukhoruchkin, S. I.; Soroko, Z. N.

337

Atomic Mass and Nuclear Binding Energy for La-197 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-197 (Lanthanum, atomic number Z = 57, mass number A = 197).

Sukhoruchkin, S. I.; Soroko, Z. N.

338

Atomic Mass and Nuclear Binding Energy for La-171 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-171 (Lanthanum, atomic number Z = 57, mass number A = 171).

Sukhoruchkin, S. I.; Soroko, Z. N.

339

Atomic Mass and Nuclear Binding Energy for La-202 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-202 (Lanthanum, atomic number Z = 57, mass number A = 202).

Sukhoruchkin, S. I.; Soroko, Z. N.

340

Atomic Mass and Nuclear Binding Energy for La-161 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-161 (Lanthanum, atomic number Z = 57, mass number A = 161).

Sukhoruchkin, S. I.; Soroko, Z. N.

341

Atomic Mass and Nuclear Binding Energy for La-175 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-175 (Lanthanum, atomic number Z = 57, mass number A = 175).

Sukhoruchkin, S. I.; Soroko, Z. N.

342

Nuclear Spins of Neutron-deficient Lanthanum and Cerium Isotopes  

Microsoft Academic Search

Nuclear spins of some neutron-deficient lanthanum and cerium isotopes have been measured by the atomic-beam magnetic resonance method. The results are: 131La (59 min) I=3\\/2, 132La (4.5 h) I=2, 132mLa (25 min) I=6, 133La (4.0 h) I=5\\/2, 135La (19.4 h) I=5\\/2, 136La (10 min) I=1, 130Ce (25 min) I=0, 132Ce (4.2 h) I=0, 133Ce (5.4 h) I=9\\/2, 133mCe (97 min)

S. Ingelman; C. Ekstroem; M. Olsmats; B. Wannberg

1973-01-01

343

Atomic Mass and Nuclear Binding Energy for La-180 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-180 (Lanthanum, atomic number Z = 57, mass number A = 180).

Sukhoruchkin, S. I.; Soroko, Z. N.

344

Atomic Mass and Nuclear Binding Energy for La-203 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-203 (Lanthanum, atomic number Z = 57, mass number A = 203).

Sukhoruchkin, S. I.; Soroko, Z. N.

345

Atomic Mass and Nuclear Binding Energy for La-182 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-182 (Lanthanum, atomic number Z = 57, mass number A = 182).

Sukhoruchkin, S. I.; Soroko, Z. N.

346

Atomic Mass and Nuclear Binding Energy for La-190 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-190 (Lanthanum, atomic number Z = 57, mass number A = 190).

Sukhoruchkin, S. I.; Soroko, Z. N.

347

Atomic Mass and Nuclear Binding Energy for La-192 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-192 (Lanthanum, atomic number Z = 57, mass number A = 192).

Sukhoruchkin, S. I.; Soroko, Z. N.

348

Atomic Mass and Nuclear Binding Energy for La-154 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-154 (Lanthanum, atomic number Z = 57, mass number A = 154).

Sukhoruchkin, S. I.; Soroko, Z. N.

349

Atomic Mass and Nuclear Binding Energy for La-201 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-201 (Lanthanum, atomic number Z = 57, mass number A = 201).

Sukhoruchkin, S. I.; Soroko, Z. N.

350

Atomic Mass and Nuclear Binding Energy for La-155 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-155 (Lanthanum, atomic number Z = 57, mass number A = 155).

Sukhoruchkin, S. I.; Soroko, Z. N.

351

Atomic Mass and Nuclear Binding Energy for La-170 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-170 (Lanthanum, atomic number Z = 57, mass number A = 170).

Sukhoruchkin, S. I.; Soroko, Z. N.

352

Atomic Mass and Nuclear Binding Energy for La-189 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-189 (Lanthanum, atomic number Z = 57, mass number A = 189).

Sukhoruchkin, S. I.; Soroko, Z. N.

353

Atomic Mass and Nuclear Binding Energy for La-151 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-151 (Lanthanum, atomic number Z = 57, mass number A = 151).

Sukhoruchkin, S. I.; Soroko, Z. N.

354

Atomic Mass and Nuclear Binding Energy for La-191 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-191 (Lanthanum, atomic number Z = 57, mass number A = 191).

Sukhoruchkin, S. I.; Soroko, Z. N.

355

Atomic Mass and Nuclear Binding Energy for La-157 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-157 (Lanthanum, atomic number Z = 57, mass number A = 157).

Sukhoruchkin, S. I.; Soroko, Z. N.

356

Atomic Mass and Nuclear Binding Energy for La-163 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-163 (Lanthanum, atomic number Z = 57, mass number A = 163).

Sukhoruchkin, S. I.; Soroko, Z. N.

357

Atomic Mass and Nuclear Binding Energy for La-156 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-156 (Lanthanum, atomic number Z = 57, mass number A = 156).

Sukhoruchkin, S. I.; Soroko, Z. N.

358

Atomic Mass and Nuclear Binding Energy for La-152 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-152 (Lanthanum, atomic number Z = 57, mass number A = 152).

Sukhoruchkin, S. I.; Soroko, Z. N.

359

Atomic Mass and Nuclear Binding Energy for La-164 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-164 (Lanthanum, atomic number Z = 57, mass number A = 164).

Sukhoruchkin, S. I.; Soroko, Z. N.

360

Atomic Mass and Nuclear Binding Energy for La-176 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-176 (Lanthanum, atomic number Z = 57, mass number A = 176).

Sukhoruchkin, S. I.; Soroko, Z. N.

361

Atomic Mass and Nuclear Binding Energy for La-194 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-194 (Lanthanum, atomic number Z = 57, mass number A = 194).

Sukhoruchkin, S. I.; Soroko, Z. N.

362

Atomic Mass and Nuclear Binding Energy for La-185 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-185 (Lanthanum, atomic number Z = 57, mass number A = 185).

Sukhoruchkin, S. I.; Soroko, Z. N.

363

Atomic Mass and Nuclear Binding Energy for La-158 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-158 (Lanthanum, atomic number Z = 57, mass number A = 158).

Sukhoruchkin, S. I.; Soroko, Z. N.

364

Atomic Mass and Nuclear Binding Energy for La-173 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-173 (Lanthanum, atomic number Z = 57, mass number A = 173).

Sukhoruchkin, S. I.; Soroko, Z. N.

365

Atomic Mass and Nuclear Binding Energy for La-166 (Lanthanum)  

NASA Astrophysics Data System (ADS)

This document is part of the Supplement containing the complete sets of data of Subvolume B `Nuclei with Z = 55 - 100' of Volume 22 `Nuclear Binding Energies and Atomic Masses' of Landolt-Börnstein - Group I `Elementary Particles, Nuclei and Atoms', and additionally including data for nuclei with Z = 101 - 130. It provides atomic mass, mass excess, nuclear binding energy, nucleon separation energies, Q-values, and nucleon residual interaction parameters for atomic nuclei of the isotope La-166 (Lanthanum, atomic number Z = 57, mass number A = 166).

Sukhoruchkin, S. I.; Soroko, Z. N.

366

Syntesis of lanthanum zirconate hydrosols by the ion exchange method  

Microsoft Academic Search

Ion exchange of LaCl3 and ZrOCl2 aqueous solutions with anion-exchanger AV-17-8 was used to synthesize finely dispersed hydrosol of amorphous lanthanum zirconate La2Zr2O7. Heat treatment of dried La2Zr2O7 hydrosols at 700°C and 1100°C resulted in the formation of powders with fluorite and pyrochlore type structures, respectively. Epitaxial La2Zr2O7 films were obtained on SrTiO3 (001) single crystals. The substrate has an

E. A. Bovina; J. V. Tarasova; F. Kh Chibirova

2011-01-01

367

METHOD OF SEPARATING PLUTONIUM FROM LANTHANUM FLUORIDE CARRIER  

DOEpatents

An improvement in oxidation-reduction type methods of separating plutoniunn from elements associated with it in a neutron-irradiated uranium solution is described. The method relates to the separating of plutonium from lanthanum ions in an aqueous 0.5 to 2.5 N nitric acid solution by 'treating the solution, at room temperature, with ammonium sulfite in an amount sufficient to reduce the hexavalent plutonium present to a lower valence state, and then treating the solution with H/sub 2/O/sub 2/ thereby forming a tetravalent plutonium peroxide precipitate.

Watt, G.W.; Goeckermann, R.H.

1958-06-10

368

Fabrication of lanthanum copper oxide nanofibers by electrospinning  

NASA Astrophysics Data System (ADS)

For about 75 years electrospinning has been explored as a simple and versatile method to produce nanofibers. Since electrospinning was introduced in the 1930s, most researchers have focused on fabrication and theoretical work for polymer nanofibers. Recently, more than 40 ceramic nanofibers were produced by electrospinning. However, few theoretical works have been performed on ceramic electrospinning. The objectives of this dissertation were to study the relationships among variables and responses using response surface methodology and to applying this to ceramic electrospinning theory. The theory was applied in the fabrication of ceramic nanofibers. Lanthanum nitrate/copper nitrate/polyacrylamide composite nanofibers were prepared by combining a sol-gel process and electrospinning. Porous lanthanum copper oxide nanofibers with diameters ranging from 75 nm to 175 nm were obtained by calcination of composite fibers. Responses dependent on experimental conditions were studied in polymer electrospinning and ceramic electrospinning, independently. In both types of electrospinning, solution parameters were found to be more important than process parameters in determining responses (fiber diameters, bead density). With varying ceramic precursor concentrations, fiber diameters decrease first, then increase though the conductivities increase continuously. Bead density shows the opposite trend. Regression analysis shows that bead density is inversely proportional to (fiber diameter)3 (sigmaBead ? 1h3 where sigmaBead is the bead density and h is the fiber diameter) Polymer (polyacrylamide) electrospinning and ceramic (lanthanum copper oxide) electrospinning was compared using the same parameters (pH, voltage). Ceramic electrospinning showed similar trends compared to polymer electrospinning although the electrospinning solution contained ceramic precursors. A higher conductivity of ceramic electrospinning solution produced thinner fibers. Additionally, it was verified experimentally that the proposed model in the polymer system could be applied to a ceramic system. Using the lanthanum copper oxide nanoparticles, three planar sensors were fabricated over tape-cast yttria-stabilized zirconia substrate with screen-printed electrodes. Sensing characteristics such as sensitivity, stability, signal to noise ratio, and response time were studied with varying NO gas concentration and temperature. At 450°C, sensitivity was 6.44 mV/log (ppm) and response time was 29.2 seconds. Electrospinning was found to be an effective route for the preparation of dispersible nanoparticles.

Park, Hyun

369

Conditions of formation of lanthanum, praseodymium, and neodymium aluminates  

Microsoft Academic Search

1.In the systems La2O3-Al2O3, Pr2O3-Al2O3, and Nd2O3-Al2O3, two types of compounds are formed: Ln2O3 · Al2O3 and Ln2O3 · 11Al2O3. The compound Nd2O3 · 11Al2O3 was produced for the first time.2.The conditions of the formation of compounds in the interaction of the oxides of lanthanum, praseodymium, and neodymium with a-alumina, aluminum nitrate, and in the coprecipitation of solutions containing aluminum

N. A. Godina; É. K. Keler

1966-01-01

370

Distant functionalization via incorporation of thiophene moieties in electrophilic reactions promoted by samarium diiodide  

PubMed

Methyl thiophene-2-carboxylate, methyl 3-(thien-2-yl)acrylate, and methyl 5,2'-bithiophene-2-carboxylate were utilized as the synthetic equivalents of pentanoate 5-anion, pentanoate 4,5-dianion, heptanoate 7-anion, and nonanoate-8,9-dianion. By the promotion of samarium diiodide, these thiophene-incorporating compounds reacted with aldehydes, ketones, and conjugated esters regioselectively at the thienyl rings. Long-chain esters with remote hydroxyl and carboxyl groups, including an antiarthritis agent, a shellac component, and an inhibitory agent of spore germination, were prepared after reductive desulfurization on Raney nickel. PMID:11073684

Yang; Nandy; Selvakumar; Fang

2000-11-16

371

Oxygen ion conductivity of the ceria-samarium oxide system with fluorite structure  

Microsoft Academic Search

Ionic conduction of oxygen in the ceria-samarium oxide system was investigated as a function of temperature, partial pressure of oxygen and the oxide composition, together with its crystal structure, density and defect structure. The ionic conductivity of (CeO2)1-x(SmO1.5)x was the highest in ZrO2-, ThO2- and CeO2-based oxide systems. The system CeO2-SmO1.5 consisted of the solid solution with a fluorite structure

Hidenori Yahiro; Yukari Eguchi; Koichi Eguchi; Hiromichi Arai

1988-01-01

372

NONLINEAR OPTICAL PHENOMENA: Resonances of coherent population trapping in samarium vapours  

Microsoft Academic Search

Resonances of coherent population trapping were detected in atomic vapours of the rare-earth element samarium. The coherent population trapping was produced by two external-cavity diode lasers (672 and 686 nm) in a Lambda-system formed by the three levels of 154Sm: the 4f66s2(7F0) ground state, the first fine-structure 4f66s2(7F1) sublevel of the ground state and the 4f6(7F)6s6p(3Po)9Fo1 upper level. The dependence

Nikolai N. Kolachevsky; A. V. Akimov; N. A. Kiselev; A. A. Papchenko; Vadim N. Sorokin; S. I. Kanorskii

2001-01-01

373

Chelating Ligand-Mediated Hydrothermal Synthesis of Samarium Orthovanadate with Decavanadate as Vanadium Source  

PubMed Central

A new ethylenediaminetetraacetic acid- (EDTA-) mediated hydrothermal route to prepare chrysanthemum-shaped samarium orthovanadate (SmVO4) nanocrystals with decavanadate (K6V10O28·9H2O) as vanadium source has been developed. The present hydrothermal approach is simple and reproducible and employs a relatively mild reaction temperature. The EDTA, pH value, and temperature of the reaction systems play important roles in determining the morphologies and growth process of the SmVO4 products. The products have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectra (PL), and UV-Vis spectroscopy.

Zuo, Wenli

2013-01-01

374

Blast from the past: the aluminum's ghost on the lanthanum salts.  

PubMed

Hyperphosphatemia is a common serious complication of chronic renal diseases, which needs appropriate continuous treatment in order to avoid ominous side effects. Therefore, oral chelating agents able to avoid phosphate absorption by the gut are mandatory. In the past, Aluminium salts, and more recently Calcium and Magnesium salts, and a synthetic resin polyallylamine hydrochloride have been employed, but Aluminium was later abandoned, because it has been a silent killer of many uremic patients, due to subtle absorption eventually leading to toxicity on Central Nervous System and bone, with allucinations, seizures, dementia, and osteomalacia, bone pain, fracturing osteodystrophy, and death. Recently, a new chelating agent able to bind dietary phosphate, namely Lanthanum carbonate has been introduced, with a proven efficacy profile for short-term treatment. However, after careful examination of the very few scientific papers available to date, we strongly advise caution before adopting, at present, lanthanum carbonate as a phosphate binder in uremic patients. In fact, notwithstanding minimized, some data are worrying: first, Lanthanum ions are absorbed, though at a minimal extent, by human gut; 2) pharmacokinetic evaluations show a greater exposure to Lanthanum in uremic patients;3) Lanthanum concentration is increased tenfold in blood and fivefold in bone after short-term supplementation in uremic patients; 4) there is no proofs that Lanthanum cannot cross the blood brain barrier in uremic patients; 5)Lanthanum has many biological effects and is potentially highly toxic. The Aluminum story should serve as cautionary tale when considering the use of new metal ions. PMID:16022663

Canavese, Caterina; Mereu, Cristina; Nordio, Maurizio; Sabbioni, Enrico; Aime, Silvio

2005-01-01

375

PERMEABILITY OF SERTOLI CELL TIGHT JUNCTIONS TO LANTHANUM AFTER LIGATION OF DUCTUS DEFERENS AND DUCTULI EFFERENTES  

PubMed Central

The permeability of Sertoli cell tight junctions to lanthanum administered during fixation has been compared in rats after ligation of the ductus deferens and after ligation of the ductuli efferentes. In both control and vasoligated testes, lanthanum penetrated only short distances into the Sertoli cell tight junctions before stopping abruptly. The tight junction, consisting of numerous pentalaminar fusions of contiguous Sertoli cell membranes, prevented diffusion of lanthanum into the adluminal compartment of the seminiferous epithelium. In rats with ligated ductuli efferentes, lanthanum completely permeated many Sertoli cell tight junctions and occupied intercellular spaces of the adluminal compartment. In spite of their newly acquired permeability to lanthanum, tight junctions retained characteristic ultrastructural features, including numerous membrane fusions. When lanthanum-filled tight junctions were sectioned en face, membrane fusions appeared as pale lines in lakes of electron-opaque tracer. These linearly extensive fasciae occludentes occasionally ended blindly, suggesting that lanthanum may have traversed the junction by diffusing around such incomplete barriers. The increased permeability of Sertoli cell tight junctions after efferent ductule ligation, which caused rapid testicular weight gain followed by atrophy, indicates that tight junctions are sensitive to enforced retention of testicular secretions inside the seminiferous tubules. The apparent normalcy of Sertoli cell tight junctions after vasoligation, which had no effect on testis weight, supports the view that blockage of testicular secretions distal to the epididymis is relatively innocuous.

Neaves, William B.

1973-01-01

376

Thermodynamic properties of Sr-doped LaMnOâ perovskite in the La-Sr-Mn-O system  

Microsoft Academic Search

Thermodynamic properties of Sr-doped perovskite-type lanthanum manganites (LSM) were generated by measuring the electromotive force (EMF) of test materials, using the solid galvanic cell technique. The cell consisted of an anode (SrO\\/SrFâ), an electrolyte (CaFâ or SrFâ) and a cathode (LSM\\/SrFâ). Two types of cells were tested in which type 1 used a CaFâ electrolyte and type 2 used a

Feng Zheng; L. R. Pederson

1999-01-01

377

Structural characteristics and UV-light enhanced gas sensitivity of La-doped ZnO nanoparticles  

Microsoft Academic Search

La-doped ZnO nanoparticles were synthesized by sol–gel method starting from zinc acetate dihydrate, lanthanum sesquioxide, alcohol and nitric acid. The crystal structure and morphology of the nanoparticles were characterized by XRD, FESEM, respectively. The thermal decomposition behavior of the the ZnO-based xerogel was detected by TG-DSC. The results show that as-prepared nanoparticles with the hexagonal wurtzite contain the adsorbed water

Chunqiao Ge; Changsheng Xie; Mulin Hu; Yanghai Gui; Zikui Bai; Dawen Zeng

2007-01-01

378

Computational removal of lanthanum-cerium bromide self-activity  

NASA Astrophysics Data System (ADS)

It has been reported that detectors made of lanthanum-cerium halides, such as LaBr3(Ce) and CeBr3 have superior energy resolution for gamma-radiation detection compared to that offered by conventional sodium iodide [NaI(T1)] detectors. However, it has also been observed that the lanthanum-cerium halides contain certain amount of self-activity caused by the radioactive isotope 138La. Additionally, LaBr3(Ce) and CeBr3 crystals have also been reported to be affected by ?-contamination in the low-energy and ?-contamination in the high-energy regions. This paper presents a computational approach to reduce self-activity and contamination for LaBr3(Ce) and CeBr3 detectors using a third reference NaI(T1) detector. This procedure can be implemented as an automatic self-calibration module for gamma-radiation detectors made of LaBr3(Ce) and/or CeBr3 crystals.

Yuan, Ding; Guss, Paul; Mukhopadhyay, Sanjoy

2011-07-01

379

Radio-opaque fecal impaction and pseudo-occlusion in a dialyzed patient taking lanthanum carbonate.  

PubMed

Lanthanum therapy is an efficient therapy of hyperphosphoremia by chelating phosphore in the digestive tract. Lanthanum is a silvery white metallic element that belongs to group 3 of the periodic table. This drug is lightly absorbed and has low water solubility. It should be borne in mind that abdominal X-rays of patients taking lanthanum carbonate may have a radio-opaque appearance typical of imaging agents. This characteristic is suggested to confirm adherence of the patient by doing an abdominal X-ray. We describe in our case a particular good compliant patient with slow digestive transit, which ends by pseudo-occlusion. PMID:22118504

Muller, Clotilde; Muller, Sandrine; Sissoko, Aicha; Klein, Alexandre; Faller, Bernadette; Chantrel, Francois

2011-11-28

380

Lanthanum-hexaboride carbon composition for use in corrosive hydrogen-fluorine environments  

DOEpatents

The present invention relates to a structural composition useful in corrosive hydrogen-fluorine environments at temperatures in excess of 1400/sup 0/K. The composition is formed of a isostatically pressed and sintered or a hot-pressed mixture of lanthanum hexaboride particles and about 10 to 30 vol% carbon. The lanthanum-hexaboride reacts with the high-temperature fluorine-containing gases to form an adherent layer of corrosion-inhibiting lanthanum trifluoride on exposed surfaces of the composition. The carbon in the composite significantly strengthens the composite, enhances thermal shock resistance, and significantly facilitates the machining of the composition.

Holcombe, C.E. Jr.; Kovach, L.; Taylor, A.J.

1980-01-22

381

Lanthanum-hexaboride carbon composition for use in corrosive hydrogen-fluorine environments  

DOEpatents

The present invention relates to a structural composition useful in corrosive hydrogen-fluorine environments at temperatures in excess of 1400.degree. K. The composition is formed of a isostatically pressed and sintered or a hot-pressed mixture of lanthanum hexaboride particles and about 10-30 vol. % carbon. The lanthanum-hexaboride reacts with the high-temperature fluorine-containing bases to form an adherent layer of corrosion-inhibiting lanthanum trifluoride on exposed surfaces of the composition. The carbon in the composite significantly strengthens the composite, enhances thermal shock resistance, and significantly facilitates the machining of the composition.

Holcombe, Cressie E. (Knoxville, TN); Kovach, Louis (Oak Ridge, TN); Taylor, Albert J. (Ten Mile, TN)

1981-01-01

382

Determination of the Nuclear Electric Charge Distribution of Samarium Isotopes 144, 148, 150, 152, 154 by the Muonic Atom Method.  

National Technical Information Service (NTIS)

The theory of the nucleus-negative muon system in the case of electrical interactions is discussed. The interactions of muons with the samarium isotopes 152, 154, 144, 148, 150 are investigated. After a description of the experimental device, from muon be...

P. Barreau

1977-01-01

383

Cyclizations producing hydrindanones with two methyl groups at the juncture positions mediated by samarium diiodide and electrolysis.  

PubMed

One-electron reductive intramolecular cyclization of enones with ketones or aldehydes mediated by samarium diiodide and electrolysis to afford cis-trimethyl- hydrindanolones. The reactions gave selectivities ranging from 1:1 to 100:0 depending on the conditions. PMID:22976471

Sono, Masakazu; Ise, Natsuko; Shoji, Tsutomu; Tori, Motoo

2012-09-13

384

Samarium153-EDTMP:Pharmacokinetic, Toxicity and Pain Response Using an Escalating Dose Schedule in Treatment of Metastatic Bone Cancer  

Microsoft Academic Search

Samarium-153 emitsmedium-energy beta particlesand an imageable gammaphotonwith a physicalhalf-lifeof 46.3hr. Whenchelatedto ethylenediaminetetramethylenephosphonic acid(EDTMP), it is remarkably stablein vitro andin vivo.In this study, we administered escalating amounts of 1@Sm EDTMP, from 0.1 to 1.0 mCi\\/kg (3.7â€\\

Mehdi Farhanghi; Richard A. Holmes; Wynn A. Volkert; K. William Logan; Amolak Singh

385

Trace Element Partitioning Determined by Beta Track Mapping: An Experimental Study Using Carbon and Samarium as Examples  

Microsoft Academic Search

A technique for experimental determination of concentrations and distribution of trace elements is described. The technique employs nuclear emulsions to register ; particles from spontaneous decay ot a radioactive isotope. At least 58 elements in the periodic system can be studied experimentally in this way. A detailed description of the technique using carbon 14 and samarium 151 as examples in

Bjørn O. Mysen; Martin G. Seitz

1975-01-01

386

Microstructure-properties relationships in samarium modified lead titanate piezoceramics—II. Dielectric, piezoelectric and mechanical properties  

Microsoft Academic Search

The influence of the microstructural parameters on the extrinsic contributions to the electromechanical behavior of samarium modified lead titanate piezoceramics is studied. A complete structural, compositional and microstructural characterization has been carried out to this purpose.The electromechanical coupling factors kp and k31 show strong dependence on the microstructure. There is not any important microstructural dependence of the electromechanical properties related

J. Ricote; C. Alemany; L. Pardo; C. E. Millar

1996-01-01

387

Neutron and Charged-Particle Induced Cross Sections for Radiochemistry in the Region of Samarium, Europium, and Gadolinium  

SciTech Connect

We have developed a set of modeled nuclear reaction cross sections for use in radiochemical diagnostics. Systematics for the input parameters required by the Hauser-Feshbach statistical model were developed and used to calculate neutron and proton induced nuclear reaction cross sections in the mass region of samarium, europium and gadolinium (62 {le} Z {le} 64, 82 {le} N {le} 96).

Hoffman, R D; Kelley, K; Dietrich, F S; Bauer, R; Mustafa, M

2004-11-30

388

Synthesis and theoretical analysis of samarium nanoparticles: perspectives in nuclear medicine.  

PubMed

The use of lanthanides as radionuclides in nuclear medicine is well-known, because they can be used for detecting and treating cancerous tumors. Due to the fact that the doses are directly related to the number of unstable atoms involved, the possibility of obtaining controlled-size lanthanide nanoparticles opens a wide scope for their application in nuclear medicine. In this work, we report the synthesis of anew samarium nanoparticle by using the bioreduction method, where the pH conditions play an important role in the size control of the produced clusters. The nanoparticles were characterized by using an transmission electron microscope, in addition to the use of a quantum mechanical method to relate the atomic and electronic structures to the chemical selectivity, which allows us to predict a direct coordination between the DTPA-bis-biotin molecules with the samarium nanoparticles larger than 55 atoms. This work involves experimental and theoretical methods to propose a totally new application for nanotechnology in nuclear medicine. PMID:16852046

Ascencio, Jorge A; Rincon, Ana C; Canizal, Gerardo

2005-05-12

389

Polarization Characteristics of High Valence Ion Doped Bismuth Lanthanum Titanate Ceramics  

Microsoft Academic Search

Bi3.25La0.75Ti3?3xNb3xO12 (BLTN) and Bi3.25La0.75Ti3?3xV3xO12 (BLTV) ceramics (x = 0, 0.01, 0.03, 0.05, 0.07 and 0.1) were prepared by a solid state reaction method. For all BLTN and BLTV compositions, bismuth-layered perovskite structures were confirmed using X-ray diffraction. The remanent polarization increases and reaches to the maximum value at x = 0.05 for BLTN and at x = 0.01–0.03 for BLTV

JIN SOO KIM; HAI JOON LEE; SUN HEE KANG; SUN YOUNG LEE; ILL WON KIM

2004-01-01

390

Interphase exchange and diffusion of oxygen in lanthanum-strontium cobaltites doped with iron  

NASA Astrophysics Data System (ADS)

Oxides La0.4Sr0.6Co1 - x Fe x O3 - ? ( x = 0.2 and 0.4) were synthesized by the ceramic technology. The kinetics of exchange and diffusion of oxygen in these oxides were studied by the isotopic exchange method over the temperature range 600-900°C at an oxygen pressure of 10 torr. The temperature dependences of interphase exchange rate and oxygen diffusion coefficient in the bulk and near-surface region were obtained, and the effective activation energies of exchange and oxygen diffusion were calculated. The concentration of iron ions was shown to have no substantial influence on the exchange rate and oxygen diffusion. Ratio between the values of exchange rate and diffusion coefficient were shown to influent on the precision of the values estimation.

Ananyev, M. V.; Kurumchin, E. Kh.

2010-06-01

391

Electron-microscope study of lanthanum-doped lead zirconate-titanate solid solutions  

SciTech Connect

This paper examines the structure of specimens of lanthanumdoped lead zirconate-titanate solid solutions in the hysteresis region of the phase diagram, using transmission electron microscopy. The electron-microscopic images of PLZT ceramic of composition display an unusual diffraction contrast. An analysis of the images obtained for different orientations of the cleavages of specimens of composition indicate that the second-phase inclusions are cylindrical in the main. The authors hypothesize that the inclusions are a ferroelectric phase in an antiferroelectric matrix.

Ishchuk, V.M.; Presnyakova, O.V.

1985-12-01

392

Effect of fluorination on the lanthanum-doped AB 2-type metal hydride electrodes  

Microsoft Academic Search

The effect of fluorination on the surface of an AB2-type hydrogen-storage alloy with the composition Zr0.7Ti0.3V0.4Mn0.4Ni1.2 is investigated. Electron probe microanalysis (EPMA), scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and X-ray diffraction (XRD) techniques show that the fluorinated AB2-type alloys have a unique surface morphology and high reactivity with a protective film. The treatment is found to be effective

H. Y Park; W. I Cho; B. W Cho; S. R Lee; K. S Yun

2001-01-01

393

Chemical Preparation of Pure and Strontium and\\/or Magnesium-Doped Lanthanum Gallate Powders  

Microsoft Academic Search

Powder compositions of LaGaO3 ,L a 0.9Sr0.1GaO2.95, and La0.8Sr0.2Ga0.83Mg0.17O2.815 were prepared via a Pechini-type process that uses citric acid and ethylene glycol. The calcina- tion behavior of the precursor powders of the above- mentioned phases was studied in the temperature range of 200°-1400°C in an air atmosphere. Characterization of the powder samples were performed using several processes, including X-ray diffractometry,

A. Cüneyt Ta?; Peter J. Majewski; Fritz Aldinger

2000-01-01

394

Sodium doped lanthanum manganites thin films: Influence of the oxygen content on the structural parameters  

NASA Astrophysics Data System (ADS)

We report the structural characterisation of La1-xNaxMnO{3+?} thin films deposited by Rf-magnetron sputtering onto SrTiO{3} (100) single crystal substrates. In particular, we focussed our attention on a series of samples annealed at different pO{2}, ranging from 1 to 10-6 atm. XRD and microRaman data show an expansion of the perovskite lattice for samples annealed in reducing conditions. This results agree with general manganite gas-solid equilibrium involving the formation of Mn4+as the oxygen content increases. For pO{2} < 10-6 atm the structure rearranges because of the increasing the oxygen vacancies and the volume of the unit cell shrinks.

Alessandri, I.; Bontempi, E.; Sangaletti, L.; Pagliara, S.; Malavasi, L.; Parmigiani, F.; Flor, G.; Depero, L. E.

2004-11-01

395

Crystal structures and magnetic properties of strontium and copper doped lanthanum ferrites  

NASA Astrophysics Data System (ADS)

The crystal and magnetic structures of La0.8Sr0.2Fe1-xCuxO3-w compounds, which exhibit coercive fields larger than any others reported for iron-based perovskites, have been analyzed at room temperature with the neutron powder diffraction technique and the Rietveld method of profile fitting. For x in the range 0.05-0.10 the material is monophasic with orthorhombic symmetry (space group Pnma), and crystallizes in the perovskite-like cell of LaFeO3, Fe/Cu cations occupy octahedral sites, La/Sr cations are twelve-fold coordinated. For x=0.20 the material is biphasic, with a main orthorhombic phase (space group Pnma) and a secondary rhombohedral phase with space group R-3c (hexagonal setting). The structural transition from the orthorhombic to the rhombohedral phase reduces the structural distortion of the (Fe/Cu)O6 octahedron. The average bond distance (Fe/Cu)-O and the pseudo-cubic unit cell volume decrease with increasing Cu content in accordance with the presence of higher valence states of the transition metals. The magnetic structure was modeled for the monophasic samples (x=0.05 and 0.10) assuming an antiferromagnetic interaction between Fe/Cu neighboring cations (G-type): the magnetic moments order antiferromagnetically along the b-axis, with the spin direction along a-axis. The magnetic moments of the Fe/Cu atoms are ?x=2.66(3)?B and 2.43(3)?B for the compositions x=0.05 and 0.10, respectively. By measuring the first magnetization curve and the hysteresis loops, coexisting antiferromagnetic and weak ferromagnetic interactions were observed for all samples.

Natali Sora, Isabella; Caronna, Tullio; Fontana, Francesca; de Julián Fernández, César; Caneschi, Andrea; Green, Mark

2012-07-01

396

Enhanced Low Temperature Sintering of (Sr, Cu) Doped Lanthanum Ferrite SOFC Cathodes  

SciTech Connect

This study details subtle compositional modifications (marginal A-site deficiencies and Cu B-site dopant additions) to a La0.8Sr0.2FeO3 (LSF-20) cathode material to enhance sintering below 1000 C. The interaction of the modified LSF-20 compounds with YSZ below 1000 C was also investigated. Initial single cell studies utilizing a (La0.8Sr0.2)0.98Fe0.98Cu0.02O3 cathode material on an anode supported YSZ cell have indicated power densities in the range 1.35-1.75 W/cm2 at 750 C and 0.7V.

Simner, Steve P.; Anderson, Michael D.; Bonnett, Jeff F.; Stevenson, Jeffry W.

2004-11-30

397

Enhanced Low Temperature Sintering of (Sr, Cu) Doped Lanthanum Ferrite SOFC Cathodes  

SciTech Connect

This study details subtle compositional modifications (marginal A-site deficiencies and Cu B-site dopant additions) to a La0.8Sr0.2FeO3 (LSF-20) cathode to enhance sintering below 1000 degrees C. The interaction of the modified LSF-20 compounds with YSZ below 1000 degrees C was also investigated. Initial single cell studies utilizing a (La0.8Sr0.2)0.98Fe0.98Cu0.02O3 cathode on an anode-supported YSZ cell have indicated power densities in the range 1.35-1.75 W/cm2 at 750 degrees C and 0.7V.

Simner, Steve P.; Anderson, Michael D.; Bonnett, Jeff F.; Stevenson, Jeffry W.

2004-11-30

398

Accumulation and elimination of lanthanum by duckweed (Lemna minor L.) as influenced by organism growth and lanthanum sorption to glass.  

PubMed

Lanthanide emissions to the environment increase as a result of the growing industrial applications of these elements. However, robust data to evaluate the environmental fate of lanthanides are scarce. This article describes the accumulation and elimination of lanthanum (La) by common duckweed (Lemna minor L.). Speciation modeling was performed to assure that solubility products were not exceeded. It also showed that La was predominantly associated with ethylenediaminetetraacetic acid (EDTA). Lanthanum concentrations in plants and medium and the amounts sorbed to glass vessels were quantified by using the radioisotope 140La. The amount of La adsorbed on the glass reached values of 25% of the total La present. A model was formulated to describe La uptake in exponentially growing duckweed in the presence of an adsorptive surface. Growth-induced dilution appeared more efficient in lowering plant La concentrations than actual elimination. An elimination study revealed two compartments, of which the smallest eliminated 50 times faster than the bigger compartment, which eliminated mainly by growth dilution. The average bioconcentration factor was 2,000 L/kg fresh weight and 30,000 L/kg dry weight, comparable with those of other higher plants. At the applied concentration of 10 nM, no effects were observed on duckweed growth. However, the high bioconcentration factor warrants monitoring of lanthanide emissions. PMID:12109750

Weltje, Lennart; Brouwer, Anke H; Verburg, Tona G; Wolterbeek, Hubert Th; de Goeij, Jeroen J M

2002-07-01

399

Sm3+ effects in the Tm3+ doped tellurite glass for S-band amplification  

NASA Astrophysics Data System (ADS)

Thulium doped Samarium codoped tellurite-tungstate glasses were produced. Luminescence properties in the infrared region were investigated looking to observe improved properties for S-band amplification in the co doped samples. Thulium is well-known by the 3H4-3F4 radiative transition emitting around ~1.47?m, which is a self-terminating transition in tellurite hosts due the longer lifetime of the lower level in relation to the upper level of this transition. Analysis of absorption and emission spectra showed that we could quench the 3F4 level significantly, what improved the intensity of the emission at 1.49?m. However, the state 3H4 were also quenched due the cross relaxation process due the absorption bands of Sm3+ around 1.5?m.

Belançon, Marcos P.; Ferenz, Julio; Chillcce, Enver; Barbosa, Luis Carlos

2013-02-01

400

Effect of Heat Treatment Temperature on Performance of Plasma-Sprayed Apatite-Lanthanum Silicate Coatings as Electrolytes for IT-SOFC  

NASA Astrophysics Data System (ADS)

Magnesium-doped lanthanum silicate with apatite-type structure was prepared by solid state sintering, as a solid electrolyte for intermediate temperature solid oxide fuel cells. The electrolyte layers were fabricated by air plasma spraying, followed by post heat treatments, and their microstructures and phase composition were characterized by SEM and XRD. The gas permeation of electrolyte layers was measured by a specific instrument with pure H2 and O2 at room temperature. It is shown that amorphous and trace phases exist in as-sprayed electrolyte layer, and then disappear after a post heat treatment in air furnace at temperature up to 1000 °C. The permeability can be decreased by the heat treatment, especially after 4 h at 1000 °C.

Sun, Fu; Zhang, Nannan; Liao, Hanlin; Li, Jinglong

2012-12-01

401

Morphology-controlled nonaqueous synthesis of anisotropic lanthanum hydroxide nanoparticles  

SciTech Connect

The preparation of lanthanum hydroxide and manganese oxide nanoparticles is presented, based on a nonaqueous sol-gel process involving the reaction of La(OiPr){sub 3} and KMnO{sub 4} with organic solvents such as benzyl alcohol, 2-butanone and a 1:1 vol. mixture thereof. The lanthanum manganese oxide system is highly complex and surprising results with respect to product composition and morphology were obtained. In dependence of the reaction parameters, the La(OH){sub 3} nanoparticles undergo a shape transformation from short nanorods with an average aspect ratio of 2.1 to micron-sized nanofibers (average aspect ratio is more than 59.5). Although not directly involved, KMnO{sub 4} plays a crucial role in determining the particle morphology of La(OH){sub 3}. The reason lies in the fact that KMnO{sub 4} is able to oxidize the benzyl alcohol to benzoic acid, which presumably induces the anisotropic particle growth in [0 0 1] direction upon preferential coordination to the {+-}(1 0 0), {+-}(0 1 0) and {+-}(-110) crystal facets. By adjusting the molar La(OiPr){sub 3}-to-KMnO{sub 4} ratio as well as by using the appropriate solvent mixture it is possible to tailor the morphology, phase purity and microstructure of the La(OH){sub 3} nanoparticles. Postsynthetic thermal treatment of the sample containing La(OH){sub 3} nanofibers and {beta}-MnOOH nanoparticles at the temperature of 800 deg. C for 8 h yielded polyhedral LaMnO{sub 3} and worm-like La{sub 2}O{sub 3} nanoparticles as final products. - Graphical abstract: Lanthanum hydroxide nanoparticles are synthesized based on a nonaqueous sol-gel process involving the reaction of La(OiPr){sub 3} and KMnO{sub 4} with organic solvents such as benzyl alcohol, 2-butanone and a 1:1 vol. mixture thereof. In dependence of the reaction parameters, the La(OH){sub 3} nanoparticles undergo a shape transformation from short nanorods to micron-sized nanofibers.

Djerdj, Igor [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland); Department of Physics, Faculty of Science, University of Zagreb, Bijenicka 32, P.O. Box 331, 10002 Zagreb (Croatia); Garnweitner, Georg [Max Planck Institute of Colloids and Interfaces, Research Campus Golm, D-14424 Potsdam (Germany); Sheng Su, Dang [Department of Inorganic Chemistry, Fritz-Haber-Institute of the Max-Planck-Society, Faradayweg 4-6, D-14195 Berlin (Germany); Niederberger, Markus [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland)], E-mail: markus.niederberger@mat.ethz.ch

2007-07-15

402

Influence of La doping on structural and dielectric properties of SrBi2Nb2O9 ceramics  

Microsoft Academic Search

Lanthanum doped SrBi2Nb2O9 ceramics with the chemical formula SrBi2-xLaxNb2O9 (SBLN) (x=0-0.5) have been prepared through conventional solid state route. X-ray diffraction reveals the shrinkage of unit cell of strontium bismuth niobate with incorporation of La3+ dopant, having no lone pair electrons. Shifting of Raman phonon modes indicates the reduced rattling space of NbO6 octahedra with increase in La doping concentration.

Maya Verma; K. Sreenivas; Vinay Gupta

2009-01-01

403

Isolation of short-lived isotopes of lanthanum and indium by ?-diketonates sublimation  

Microsoft Academic Search

Trace amounts of lanthanum hexafluoroacetylacetonate and indium acetylacetonate were isolated by combination of methods, which includes synthesis of volatile elements -diketonates by nucleophilic ligands exchange and fractional sublimation. This method is useful for produce isotope generators.

A. V. Davidov; M. I. Isenberg; E. V. Fedoseev; S. S. Travnikov

1996-01-01

404

METAL INTERACTIONS AT SULFIDE MINERAL SURFACES. PART 2. ADSORPTION AND DESORPTION OF LANTHANUM  

EPA Science Inventory

Batch-type adsorption experiments with four sulfide minerals (chalcocite, galena, pyrite, and sphalerite) were used to investigate the adsorption and desorption behavior of lanthanum (III) in the presence of ethylenediaminetetraacetic acid (EDTA), a model humic substance. Linear ...

405

Thermodynamic properties of lanthanum in gallium-indium eutectic based alloys  

NASA Astrophysics Data System (ADS)

Activity and activity coefficients of lanthanum were determined for the first time in gallium-indium eutectic based alloys in a wide temperature range employing electromotive force method. Activity of ?-La and super cooled liquid lanthanum in Ga-In eutectic based alloys between 573 and 1073 K linearly depends on the reciprocal temperature:lga=5.660-15,352T±0.093 lga=6.074-15,839T±0.093 Activity coefficients of ?-La and super cooled liquid lanthanum in this system at 617-1073 K are described by the following equations:lg?=3.786-12,216T±0.171 lg?=4.199-12,703T±0.171 In addition activity of lanthanum in alloys with In was also determined in the same temperature range.

Shchetinskiy, A. V.; Dedyukhin, A. S.; Volkovich, V. A.; Yamshchikov, L. F.; Maisheva, A. I.; Osipenko, A. G.; Kormilitsyn, M. V.

2013-04-01

406

Study of Collective Quadrupole Excitation in Samarium 144, 148, 150, 152, and 154 Isotopes and Cerium 140 by Inelastic Electron Scattering.  

National Technical Information Service (NTIS)

The region of Samarium nuclei where spectacular variations of nuclear deformation appear was investigated. Transition charge densities of the first 2(+) states were determined by measuring the inelastic scattering cross sections of electrons on the six nu...

V. Meot

1987-01-01

407

Cerium and lanthanum promote floral initiation and reproductive growth of Arabidopsis thaliana  

Microsoft Academic Search

The effects of cerium and lanthanum on the vegetative growth, floral initiation and reproductive growth of Arabidopsis thaliana were studied. Addition of cerium nitrate (0.5–10 ?M) or lanthanum nitrate (0.5–50 ?M) to the culture medium significantly increased the lengths of primary roots, but had no significant effects on the number of rosette leaves produced per plant, plant heights and dry

Ya-Wen He; Chiang-Shiong Loh

2000-01-01

408

Lanthanum-molybdenum multilayer mirrors for attosecond pulses between 80 and 130 eV  

Microsoft Academic Search

A novel multilayer material system consisting of lanthanum and molybdenum nano-layers for both broadband and highly reflecting multilayer mirrors in the energy range between 80 and 130 eV is presented. The simulation and design of these multilayers were based on an improved set of optical constants, which were recorded by extreme ultraviolet (XUV)\\/soft-x-ray absorption measurements on freestanding lanthanum nano-films between

M. Hofstetter; A. Aquila; M. Schultze; A. Guggenmos; S. Yang; E. Gullikson; M. Huth; B. Nickel; J. Gagnon; V. S. Yakovlev; E. Goulielmakis; F. Krausz; U. Kleineberg

2011-01-01

409

Synthesis and characterization of porous chromia-pillared layered lanthanum niobic acid  

Microsoft Academic Search

The first chromia-pillared layered lanthanum niobic acid was prepared by an ion-exchange route, in which n-hexylamine-pre-expanded lanthanum niobate reacted with chromium(III) acetate [Cr(OAc)3] aqueous solution under reflux condition, and the ion-exchanged product was calcined at 450 °C in air flow. The structure of the novel pillared material was examined by means of various analytical techniques, such as powder X-ray diffraction (XRD),

Xianji Guo; Wenhua Hou; Gailing Bao; Qijie Yan

2006-01-01

410

Equilibrium distribution of lanthanum, neodymium, and thorium between lithium chloride melt and liquid bismuth  

NASA Astrophysics Data System (ADS)

The distribution of lanthanum, neodymium, and thorium between a lithium chloride melt and liquid bismuth with additions of lithium as a reducing agent are investigated at 650°C. Equilibrium values of their distribution constants are measured. It is shown that in contrast to neodymium and lanthanum, thorium cannot be extracted from bismuth into lithium chloride. This allows us to propose an efficient scheme for separating lanthanides and thorium in a system for the extraction of fuel salts in molten-salt nuclear reactors.

Zagnit'ko, A. V.; Ignat'ev, V. V.

2013-04-01

411

A simple sol–gel technique for preparing lanthanum oxide nanopowders  

Microsoft Academic Search

Nanosized lanthanum oxide powders have been prepared by a simple sol–gel technique using commercial lanthanum oxide, nitrate acid and polyethylene glycol (PEG) as the starting materials. The decomposition process of dried gel powders were investigated by differential thermal and thermogravimetric analysis(TG-DSC). The crystalline structures and morphologies of the powders were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM).

Xingang Wang; Maolin Wang; Hua Song; Bingjun Ding

2006-01-01

412

Near-electrode processes in lanthanum-gallium tantalate crystals  

SciTech Connect

The near-electrode processes on the surfaces of the polar cuts of lanthanum-gallium tantalate crystals grown in different atmospheres were investigated. The temperature dependences of short-circuit currents in the temperature range 20-700{sup o}C were measured and phase analysis of the sample surfaces after the temperature tests were performed. It is shown that short-circuit currents arise on the surfaces of polar cuts with identical conducting coatings without preliminary polarization. These currents are caused by the generation of intrinsic emf as a result of the electrochemical reactions on opposite polar cut surfaces coming in contact with a conducting coating. It is established that the crystal growth atmosphere and the conducting coating material significantly affect the temperature dependences of short-circuit currents.

Buzanov, O. A. [OAO Fomos Materials (Russian Federation); Zabelina, E. V., E-mail: e.zabelina@gmail.com; Kozlova, N. S., E-mail: kozlova_nina@mail.ru; Sagalova, T. B. [Moscow State Institute of Steel and Alloys (Russian Federation)

2008-09-15

413

Molten salt synthesis of lead lanthanum zirconate titanate ceramic powders  

Microsoft Academic Search

Lead lanthanum zirconate titanate (Pb0.95La0.03)(Zr0.52Ti0.48)O3 (PLZT) was synthesized by one step molten salt method with the starting materials of PbC2O4, La2O3, ZrO(NO3)2·2H2O and TiO2 in the NaCl–KCl eutectic mixtures in the temperature range of 700–1000°C. The single phase of (Pb0.95La0.03)(Zr0.52Ti0.48)O3 powders was prepared at a temperature as low as 850°C for 5h. The effects of process parameters, such as soaking

Zongying Cai; Xianran Xing; Lu Li; Yeming Xu

2008-01-01

414

Dielectric signature of charge order in lanthanum nickelates  

NASA Astrophysics Data System (ADS)

Three charge-ordering lanthanum nickelates La2- x A x NiO4, substituted with specific amounts of A = Sr, Ca, and Ba to achieve commensurate charge order, are investigated using broadband dielectric spectroscopy up to GHz frequencies. The transition temperatures of the samples are characterized by additional specific heat and magnetic susceptibility measurements. We find colossal magnitudes of the dielectric constant for all three compounds and strong relaxation features, which partly are of Maxwell-Wagner type arising from electrode polarization. Quite unexpectedly, the temperature-dependent colossal dielectric constants of these materials exhibit distinct anomalies at the charge-order transitions. This phenomenon is ascribed to a variation of intrinsic material properties affecting the formation of depletion layers at the electrode-sample interfaces.

Sippel, P.; Krohns, S.; Thoms, E.; Ruff, E.; Riegg, S.; Kirchhain, H.; Schrettle, F.; Reller, A.; Lunkenheimer, P.; Loidl, A.

2012-07-01

415

Oxygen vacancies in lanthanum aluminate (LaAlO3)  

NASA Astrophysics Data System (ADS)

Oxygen vacancies can affect the properties of an oxide in various manners such as increasing its ion or electronic conductivity, changing its lattice constant or causing dielectric breakdown. The aim of this research is to investigate structural changes and consequent changes in properties caused by oxygen vacancies in a model complex oxide, lanthanum aluminate, LaAlO3. We use density functional theory with the generalized gradiant approximation (GGA) and within the VASP package to calculate the structure and properties of representative oxygen vacancy profiles. We find that the presence of oxygen vacancies modifies the pattern of rotations of the oxygen octahedra. We discuss the implications of our results for understanding the correlation between epitaxial strain in oxide thin films and intrinsic defect profiles.

Sayre, Joshua; Spaldin, Nicola

2011-03-01

416

Field emission characteristics of lanthanum hexaboride coated silicon field emitters  

NASA Astrophysics Data System (ADS)

Lanthanum hexaboride(LaB6) films have been deposited on silicon tip field emitters by electron-beam evaporation. The field emission characteristics are studied in a diode test cell in a vacuum system. The experimental results show that the field emission stability of the LaB6-coated Si-tip FEA can be improved and the emission current is significantly enhanced to 75 µA, in contrast to pure Si-tip FEA of 500 nA and Mo-coated Si-tip FEA of 300 nA with 1500 V applied to the anode. Furthermore, even at low vacuum (>1.5 × 10-5 Torr) it still exhibits good emission properties and strong ability to withstand ion bombardment. This LaB6-coated Si-tip FEA is an excellent electronic candidate, in particular a fit for travelling-wave tubes, klystrons and other large vacuum apparatus.

Wang, Xiaoju; Lin, Zulun; Qi, Kangcheng; Chen, Zexiang; Wang, Zhigang; Jiang, Yadong

2007-08-01

417

Electron-emission characteristics of sputtered lanthanum hexaboride  

SciTech Connect

Metallic filaments were coated with lanthanum hexaboride deposited by rf magnetron sputter deposition. A simple diode system was designed to measure the work function of the filaments and to study the emission behavior. It was found that under some conditions, LaB6 can be sputter deposited onto filament structures with the resultant work function and stoichiometry similar to bulk LaB6. The sputtered coatings were dense and adherent. The coated filaments could be flexed with moderate severity without exhibiting microcracking, spalling, or a detected difference in emission characteristics. At 1100 C, the emission density of LaB6 coated tungsten ribbon was 0.1 amps/sq.cm. while the emission density of tungsten ribbon was 10 to the minus 7th power amps/sq.cm. Filaments ran 250 hours without any reduction in the emission current. Intermittent atmospheric exposure had no effect on the emission.

Mroczkowski, S.J.

1988-08-11

418

Phases in lanthanum-nickel-aluminum alloys. Part 2  

SciTech Connect

Lanthanum-nickel-aluminum (LANA) alloys will be used to pump, store and separate hydrogen isotopes in the Replacement Tritium Facility (RTF). The aluminum content (y) of the primary LaNi{sub 5}-phase is controlled to produce the desired pressure-temperature behavior for adsorption and desorption of hydrogen. However, secondary phases cause decreased capacity and some may cause undesirable retention of tritium. Twenty-three alloys purchased from Ergenics, Inc. for development of RTF processes have been characterized by scanning electron microscopy (SEM) and by electron microprobe analysis (EMPA) to determine the distributions and compositions of constituent phases. This memorandum reports the results of these characterization studies. Knowledge of the structural characteristics of these alloys is a useful first step in selecting materials for specific process development tests and in interpreting results of those tests. Once this information is coupled with data on hydrogen plateau pressures, retention and capacity, secondary phase limits for RTF alloys can be specified.

Mosley, W.C.

1992-08-01

419

Separation\\/preconcentration of trace heavy metals in urine, sediment and dialysis concentrates by coprecipitation with samarium hydroxide for atomic absorption spectrometry  

Microsoft Academic Search

Multi-element determination of trace elements in urine and dialysis solutions by atomic absorption spectrometry has been investigated. Coprecipitation with samarium hydroxide was used for preconcentration of trace elements and elimination of matrix elements. To 10 ml of each sample was added 500 ?l of 2 mgml?1 samarium solutions; the pH was then adjusted to 12.2 in order to collect trace

Sibel Saracoglu; Mustafa Soylak; Latif Elci

2003-01-01

420

Neutron Capture and Transmission Measurements and Resonance Parameter Analysis of Samarium  

SciTech Connect

The purpose of the present work is to accurately measure the neutron cross sections of samarium. The most significant isotope is {sup 149}Sm, which has a large neutron absorption cross section at thermal energies and is a {sup 235}U fission product with a 1% yield. Its cross sections are thus of concern to reactor neutronics. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic institute (RPI) LINAC facility using metallic and liquid Sm samples. The capture measurements were made at the 25 meter flight station with a multiplicity-type capture detector, and the transmission total cross-section measurements were performed at 15- and 25-meter flight stations with {sup 6}Li glass scintillation detectors. Resonance parameters were determined by a combined analysis of six experiments (three capture and three transmission) using the multi-level R-matrix Bayesian code SAMMY version M2. The significant features of this work are as follows. Dilute samples of samarium nitrate in deuterated water (D{sub 2}O) were prepared to measure the strong resonances at 0.1 and 8 eV without saturation. Disk-shaped spectroscopic quartz cells were obtained with parallel inner surfaces to provide a uniform thickness of solution. The diluent feature of the SAMMY program was used to analyze these data. The SAMMY program also includes multiple scattering corrections to capture yield data and resolution functions specific to the RPI facility. Resonance parameters for all stable isotopes of samarium were deduced for all resonances up to 30 eV. Thermal capture cross-section and capture resonance integral calculations were made using the resultant resonance parameters and were compared to results obtained using resonance parameters from ENDF/B-VI updated through release 3. Extending the definition of the capture resonance integral to include the strong 0.1 eV resonance in {sup 149}Sm, present measurements agree within estimated uncertainties with EnDF/B-VI release 3. The thermal capture cross-section was calculated from the present measurements of the resonance parameters and also agrees with ENDF within estimated uncertainties. The present measurements reduce the statistical uncertainties in resonance parameters compared to prior measurements.

G. Leinweber; J.A. Burke; H.D. Knox; N.J. Drindak; D.W. Mesh; W.T. Haines; R.V. Ballad; R.C. Block; R.E. Slovacek; C.J. Werner; M.J. Trbovich; D.P. Barry; T. Sato

2001-07-16

421

Gene doping.  

PubMed

Gene doping abuses the legitimate approach of gene therapy. While gene therapy aims to correct genetic disorders by introducing a foreign gene to replace an existing faulty one or by manipulating existing gene(s) to achieve a therapeutic benefit, gene doping employs the same concepts to bestow performance advantages on athletes over their competitors. Recent developments in genetic engineering have contributed significantly to the progress of gene therapy research and currently numerous clinical trials are underway. Some athletes and their staff are probably watching this progress closely. Any gene that plays a role in muscle development, oxygen delivery to tissues, neuromuscular coordination, or even pain control is considered a candidate for gene dopers. Unfortunately, detecting gene doping is technically very difficult because the transgenic proteins expressed by the introduced genes are similar to their endogenous counterparts. Researchers today are racing the clock because assuring the continued integrity of sports competition depends on their ability to develop effective detection strategies in preparation for the 2012 Olympics, which may mark the appearance of genetically modified athletes. PMID:20020377

Azzazy, Hassan M E

2010-01-01

422

A representative hard surface layer prepared and investigated on a cobalt-samarium magnet  

SciTech Connect

For investigations on the micromagnetic processes on hard magnetic materials it is imperative that the surface grains display the same magnetic hardness as the bulk of the material. In this paper the successful preparation of a nucleation type cobalt-samarium sample (Co{sub 5}Sm) with bulk coercivity in the surface for high resolution Kerr microscopy by waterfree diamond polishing technique is reported. This fact is proven by domain observations and by comparing hysteresis curves measured by VSM for the bulk and with a transverse optical magnetometer for the surface. Kerr microscopical domain observations on the remagnetizing behavior at applied fields up to 18 kOe were performed after previous saturation at 26.5 kOe. Of particular interest were the soft spots which remagnetize long before the coercive field is reached. Some examples such as strongly misoriented grains, large grains, grains damaged during polishing, foreign phases etc. are presented.

Neudecker, M.K.; Boockmann, K.; Hubert, A. (Inst. fur Werkstoffwissenshaften der Univ. Erlangen-Nurnberg, Martensstr. 7, D852 Erlang (DE))

1990-09-01

423

Chelating ligand-mediated hydrothermal synthesis of samarium orthovanadate with decavanadate as vanadium source.  

PubMed

A new ethylenediaminetetraacetic acid- (EDTA-) mediated hydrothermal route to prepare chrysanthemum-shaped samarium orthovanadate (SmVO4) nanocrystals with decavanadate (K6V10O28 ·9H2O) as vanadium source has been developed. The present hydrothermal approach is simple and reproducible and employs a relatively mild reaction temperature. The EDTA, pH value, and temperature of the reaction systems play important roles in determining the morphologies and growth process of the SmVO4 products. The products have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), photoluminescence spectra (PL), and UV-Vis spectroscopy. PMID:24068882

Li, Quanguo; Zuo, Wenli; Li, Feng

2013-08-28

424

Crystalline ?-samarium sesquisulfide nanowires: structure and electronic properties of an unusual intrinsically degenerate semiconductor  

NASA Astrophysics Data System (ADS)

We report that ?-phase samarium sesquisulfide (?-Sm2S3) intrinsically takes on an electronic structure similar to that of a heavily degenerate p-type semiconductor by means of UV-Vis absorption spectroscopy and first-principles calculations. When prepared by chemical vapor deposition, these samples were found to have a tendency to crystallize as bundles of nanowires. Additional characterizations using high-resolution electron microscopy, along with selected area electron diffraction and X-ray diffraction, were applied to verify the matching of the modeled structure of ?-Sm2S3 to that of the experimentally measured material. We expect this compound to be intrinsically well suited for potential applications in the p-type elements of diode devices such as in photovoltaic devices and thermo-electric converters.

Marin, Chris; Brewer, Joseph; Li Cheung, Chin; Wang, Lu; Mei, Wai-Ning

2013-03-01

425

Time-resolved nonlinear infrared spectroscopy of samarium ions in SmFeO3  

NASA Astrophysics Data System (ADS)

We demonstrate that resonant 32.3 THz pumping of f-f transitions in the samarium ions in SmFeO3 leads to a nonlinear regime of radiation-matter interaction. The nonlinearity arises from the photoinduced population of the excited state, the dynamics of which was studied in a pump-probe experiment. The measurements have been performed in the spectral range near the 6H(5)/(2)?6H(7)/(2) electronic transition. The observations show dynamics with a lifetime of 4 ps. The sign of the dynamics surprisingly differs in different spectral ranges: This phenomenon is interpreted as an excitation-induced shift of the spectral line. The results are described by the nonlinear optical polarization using the optical Bloch equations for an ensemble of two-level systems.

Bossini, D.; Malik, D.; Redlich, B.; van der Meer, A. F. G.; Pisarev, R. V.; Rasing, Th.; Kimel, A. V.

2013-02-01

426

Preparation and use of samarium diiodide (SmI(2)) in organic synthesis: the mechanistic role of HMPA and Ni(II) salts in the samarium Barbier reaction.  

PubMed

Although initially considered an esoteric reagent, SmI(2) has become a common tool for synthetic organic chemists. SmI(2) is generated through the addition of molecular iodine to samarium metal in THF.(1,2-3) It is a mild and selective single electron reductant and its versatility is a result of its ability to initiate a wide range of reductions including C-C bond-forming and cascade or sequential reactions. SmI(2) can reduce a variety of functional groups including sulfoxides and sulfones, phosphine oxides, epoxides, alkyl and aryl halides, carbonyls, and conjugated double bonds.(2-12) One of the fascinating features of SmI-(2)-mediated reactions is the ability to manipulate the outcome of reactions through the selective use of cosolvents or additives. In most instances, additives are essential in controlling the rate of reduction and the chemo- or stereoselectivity of reactions.(13-14) Additives commonly utilized to fine tune the reactivity of SmI(2) can be classified into three major groups: (1) Lewis bases (HMPA, other electron-donor ligands, chelating ethers, etc.), (2) proton sources (alcohols, water etc.), and (3) inorganic additives (Ni(acac)(2), FeCl(3), etc).(3) Understanding the mechanism of SmI(2) reactions and the role of the additives enables utilization of the full potential of the reagent in organic synthesis. The Sm-Barbier reaction is chosen to illustrate the synthetic importance and mechanistic role of two common additives: HMPA and Ni(II) in this reaction. The Sm-Barbier reaction is similar to the traditional Grignard reaction with the only difference being that the alkyl halide, carbonyl, and Sm reductant are mixed simultaneously in one pot.(1,15) Examples of Sm-mediated Barbier reactions with a range of coupling partners have been reported,(1,3,7,10,12) and have been utilized in key steps of the synthesis of large natural products.(16,17) Previous studies on the effect of additives on SmI(2) reactions have shown that HMPA enhances the reduction potential of SmI(2) by coordinating to the samarium metal center, producing a more powerful,(13-14,18) sterically encumbered reductant(19-21) and in some cases playing an integral role in post electron-transfer steps facilitating subsequent bond-forming events.(22) In the Sm-Barbier reaction, HMPA has been shown to additionally activate the alkyl halide by forming a complex in a pre-equilibrium step.(23) Ni(II) salts are a catalytic additive used frequently in Sm-mediated transformations.(24-27) Though critical for success, the mechanistic role of Ni(II) was not known in these reactions. Recently it has been shown that SmI(2) reduces Ni(II) to Ni(0), and the reaction is then carried out through organometallic Ni(0) chemistry.(28) These mechanistic studies highlight that although the same Barbier product is obtained, the use of different additives in the SmI(2) reaction drastically alters the mechanistic pathway of the reaction. The protocol for running these SmI(2)-initiated reactions is described. PMID:23407417

Sadasivam, Dhandapani V; Choquette, Kimberly A; Flowers, Robert A

2013-02-04

427

The Level of Europium154 Contaminating Samarium153-EDTMP Activates the Radiation Alarm System at the US Homeland Security Checkpoints  

Microsoft Academic Search

153Sm-EDTMP is a radiopharmaceutical composed of EDTMP (ethylenediamine-tetramethylenephosphonate) and Samarium-153 [1]. 153Sm-EDTMP has an affinity for skeletal tissue and concentrates in areas with increased bone turnover; thus, it is successfully used in relieving pain related to diffuse bone metastases [1]. The manufacturing process of 153Sm-EDTMP leads to contamination with 154Eu (Europium-154) [2]. A previous study only alluded to the retention

Mohammed Najeeb Al Hallak; Matt McCurdy; Nicolas Zouain; Justin Hayes

2009-01-01

428

Phase I Trial of Vertebral Intracavitary Cement and Samarium (VICS): Novel Technique for Treatment of Painful Vertebral Metastasis  

Microsoft Academic Search

Purpose: Kyphoplasty is an effective procedure to alleviate pain in vertebral metastases. However, it has no proven anticancer activity. Samarium-153-ethylene diamine tetramethylene phosphonate (¹³Sm-EDTMP) is used for palliative treatment of bone metastases. A standard dose of 1 mCi\\/kg is administrated intravenously. The present study was conducted to determine the feasibility of intravertebral administration of ¹³Sm with kyphoplasty. Methods and Materials:

Hani Ashamalla; Erico Cardoso; Mark Macedon; Adel Guirguis; Lijun Weng; Shamsah Ali; Bahaa Mokhtar; Michael Ashamalla; Nokul Panigrahi

2009-01-01

429

Synthesis, structure and luminescence properties of samarium (III) and dysprosium (III) complexes with a new tridentate organic ligand  

Microsoft Academic Search

A novel organic ligand, 6-diphenylamine carbonyl 2-pyridine carboxylic acid (HDPAP), and the corresponding lanthanide complexes, tris(6-diphenylamine carbonyl 2-pyridine carboxylato) samarium (III) (Sm-DPAP) and tris(6-diphenylamine carbonyl 2-pyridine carboxylato) dysprosium (III) (Dy-DPAP) have been designed and synthesized. The crystal structures and photoluminescence of Sm-DPAP and Dy-DPAP have been studied. The results showed that the lanthanide complexes have electroneutral structures, and the solid

Bao-Li An; Meng-Lian Gong; Ming-Xing Li; Ji-Ming Zhang

2004-01-01

430

Dose response relationship and multiple dose efficacy and toxicity of samarium-153-EDTMP in metastatic cancer to bone  

Microsoft Academic Search

Introduction: The optimal dose of samarium-153-EDTMP (153Sm-EDTMP) for effective palliation of painful metastases to bone is under investigation. It is not known whether increased doses of 153Sm EDTMP will lead to better and longer pain and tumour control and survival. Multiple dose efficacy and toxicity is of importance as most Patients will require prolonged support for pain.Methods: Twenty-eight (28) patients

Albert S. Alberts; Ben J. Smit; Werner K. A. Louw; Ado Janse van Rensburg; Alet van Beek; Veronique Kritzinger; Johan S. Nel

1997-01-01

431

Pharmacokinetics and biodistribution of samarium-153-labelled OC125 antibody coupled to CITCDTPA in a xenograft model of ovarian cancer  

Microsoft Academic Search

The use of samarium-153 in the context of radioimmunotherapy of cancers has been limited by the instability of antibody labelling, which produces high uptake concentrations in liver and bone. This study compares the pharmacokinetics and biodistribution of153Sm-labelled OC125 monoclonal antibody, in whole or F(ab')2 fragment form and with diethylene triamine penta-acetic acid (DTPA) or 6-p-isothiocyanatobenzyl diethylene triamine penta-acetic acid (CITCDTPA)

Françoise Kraeber-Bodéré; Anil Mishra; Philippe Thédrez; Alain Faivre-Chauvet; Manuel Bardiès; S. Imai; Jean Le Boterff; Jean-François Chatal

1996-01-01

432

Titania-lanthanum phosphate photoactive and hydrophobic new generation catalyst  

SciTech Connect

Titania-lanthanum phosphate nanocomposites with multifunctional properties have been synthesized by aqueous sol-gel method. The precursor sols with varying TiO{sub 2}:LaPO{sub 4} ratios were applied as thin coating on glass substrates in order to be transparent, hydrophobic, photocatalytically active coatings. The phase compositions of the composite powders were identified by powder X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM). The anatase phase of TiO{sub 2} in TiO{sub 2}-LaPO{sub 4} composite precursors was found to be stable even on annealing at 800 deg. C. The glass substrates, coated with TL1 (TiO{sub 2}-LaPO{sub 4} composition with 1 mol% LaPO{sub 4}) and TL50 (composite precursor containing TiO{sub 2} and LaPO{sub 4} with molar ratio 1:1) sols and annealed at 400 deg. C, produced contact angles of 74 deg. and 92 deg., respectively, though it is only 62 deg. for pure TiO{sub 2} coating. The glass substrates, coated with TL50 sol, produced surfaces with relatively high roughness and uneven morphology. The TL1 material, annealed at 800 deg. C, has shown the highest UV photoactivity with an apparent rate constant, k{sub app}=24x10{sup -3} min{sup -1}, which is over five times higher than that observed with standard Hombikat UV 100 (k{sub app}=4x10{sup -3} min{sup -1}). The photoactivity combined with a moderate contact angle (85.3 deg.) shows that this material has a promise as an efficient self-cleaning precursor. - Graphical abstract: Multifunctional TiO{sub 2}-LaPO{sub 4} composite stabilizes anatase phase with enhanced photocatalytic activity, and moderately higher hydrophobicity is a promising material for self-cleaning application. Highlights: > Titania-lanthanum phosphate nanocomposites were synthesized by aqueous sol-gel method. > Transparent, hydrophobic, photoactive coatings were developed on glass substrates. > The glass substrates, coated with TL1 annealed at 400 deg. C, produced a contact angle of 74 deg. > The TL1 material at 800 deg. C has shown the highest UV photoactivity (k{sub app}=24x10{sup -3} min{sup -1}). > Photoactivity and moderate contact angle show that this is an efficient self-cleaning precursor.

Jyothi, Chembolli K.; Jaimy, Kanakkanmavudi B. [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India); Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India); Sankar, Sasidharan; Smitha, V.S. [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India); Warrier, K.G.K., E-mail: wwarrierkgk@yahoo.co.in [National Institute for Interdisciplinary Science and Technology (NIIST), CSIR, Trivandrum 695019 (India)

2011-07-15

433

Low toxicity and efficacy of (153)samarium-EDTMP and melphalan as a conditioning regimen for secondary acute myelogenous leukemia.  

PubMed

We report the case of a 15-yr-old girl who developed secondary acute myelogenous leukemia (AML) 4 yr after completion of therapy for metastatic Ewing sarcoma (primary right acetabulum with metastatic disease to the lungs). Peripheral blood stem cells were collected after the second cycle of chemotherapy with the plan for future consolidation with high-dose chemotherapy and autologous stem cell rescue; however, because of the patient's excellent response to chemotherapy and surgery, therapy was completed without the need for high-dose chemotherapy. No human leukocyte antigen (HLA)-matched related donor was available for a bone marrow transplant. Because of previous lung radiation, high-dose samarium [30 mCi/kg of samarium-153 ethylenediaminetetramethylenephosphonate ((153)Sm-EDTMP) day -14] and melphalan (140 mg/m(2) day -2) were chosen as the conditioning regimen to avoid potential lung complications. The patient received an infusion of 6.1 x 10(8)/kg mononuclear autologous cells on day 0. She achieved engraftment on day +23. Three years after transplantation, she continues to have complete remission. Samarium and melphalan constitute a well-tolerated regimen with potential antileukemic activity. PMID:15667625

Rodriguez, Vilmarie; Erlandson, Linda; Arndt, Carola A S; Wiseman, Gregory A; Anderson, Peter M

2005-02-01

434

Highly Photosensitive PCFs with Extremely Germanium Doped Core  

NASA Astrophysics Data System (ADS)

We report about preparation and application of index guiding germanium doped microstructured fibers, special designed for Bragg grating inscription. Due to their maximum germanium oxide concentration of 36 mol% they show a very high photosensitivity. The core diameters of the PCFs were variied between 1.6 and 6.6 ?m by changing the fiber diameters. For small core PCF preparation we integrated an additional microstructured cane overcladding step. The cores are about at half total diameter doped with germanium. The holey silica claddings are arranged in a five ring hexagonal package with a hole-pitch ratio of about 0.9 and 0.3. So we can vary the inscription efficiency of Ge doped PCFs. In difference to other highly doped or non-silica PCFs with highly polarizable and probably photosensitive core components, e.g. PCFs with lanthanum glass core, germanium doped PCFs show beside their high photosensitivity a low spectral loss. Measured with an unstructured fiber the highly germanium doped silica core material exhibits a minimum loss of about 6.5 dB/km. Inserted in the PCF structure the attenuation is increased to about 40 dB/km at a wavelength of 1.2 ?m for the large core PCF. The small core PCF show an increased loss level in the hundred dB/km range. This effect is caused, as well as the increase of hydroxide impurification during the partial ``atmospheric'' PCF preparation procedure, by structural imperfections of the designed PCFs. The high germanium concentration in the central core region allows a suitable Bragg grating inscription.

Schuster, K.; Kobelke, J.; Wang, Y.; Schwuchow, A.; Kirchhof, J.; Bartelt, H.; Pissadakis, S.

2010-11-01

435

Performance of Lanthanum Strontium Manganite Electrodes at High Pressure  

SciTech Connect

The high-pressure performance of lanthanum strontium manganite (LSM), LSM-zirconia, and LSM/ceria composite electrodes was studied by impedance spectroscopy and dc methods. Electrode resistances decreased in proportion to P(O2)1/2 for the LSM electrode in both cathodic and anodic directions to at least 100 atm, a decrease that was attributed to dissociative oxygen adsorption, surface diffusion, and related phenomena. For the LSM-20/zirconia composite electrode, resistances decreased in proportion to P(O2)1/4 across the entire pressure range considered. Two principal features appeared in the impedance spectra, one that showed a P(O2)1/4 dependence attributed to charge transfer reactions, and one that was nearly pressure-independent, possibly due to transport in the zirconia portion of the composite. For the LSM-20/ceria composite electrode, resistances decreased as P(O2)0.3-0.4 at high pressure, depending on temperature. Two features appeared in the impedance spectra: one at low to intermediate frequency having a P(O2)1/2 dependence and one at high frequency having a P(O2)1/4 dependence. These features are attributed to dissociative oxygen adsorption and to charge transfer reactions, respectively. Results suggest that cathodic losses can be substantially lowered by operation of solid oxide fuel cells at greater than ambient pressure.

Thomsen, Edwin C.; Coffey, Greg W.; Pederson, Larry R.; Marina, Olga A.

2009-06-15

436

Ecotoxicological assessment of lanthanum with Caenorhabditis elegans in liquid medium.  

PubMed

With their widespread applications in industry, agriculture and many other fields, more and more rare earth elements (REEs) are getting into the environment, especially the aquatic systems. Therefore, understanding the aquatic ecotoxicity of REEs has become more and more important. In the present work, Caenorhabditis elegans (C. elegans) was used as a test organism and life-cycle endpoints were chosen along with elemental assay to evaluate the aquatic toxicity of lanthanum (La), a representative of REEs. The results show La³+ had significant adverse effects on the growth and reproduction of worms above a concentration of 10 ?mol L?¹. The elemental mapping by microbeam synchrotron radiation X-ray fluorescence (?-SRXRF) illustrated how La treatment disturbed the metals distribution in the whole body of a single tiny nematode at lower levels. Our results suggested that the high-level REEs in some polluted water bodies would lead to an aquatic ecological crisis. The assessment we performed in the present work could be developed as a standardized test design for aquatic toxicological research. PMID:21510015

Zhang, Haifeng; He, Xiao; Bai, Wei; Guo, Xiaomei; Zhang, Zhiyong; Chai, Zhifang; Zhao, Yuliang

2010-12-01

437

Lanthanum Molybdenum Oxide: Low Temperature Synthesis and Characterization  

SciTech Connect

A recently developed fast oxide ion conductor, namely lanthanum molybdenum oxide (La{sub 2}Mo{sub 2}O{sub 9}, LAMO), was synthesized instantaneously by a citrate-nitrate auto-ignition process at a fixed citrate to nitrate ratio of 0.3 and characterized by thermal analysis, x-ray diffraction, impedance spectroscopy, and thermal expansion measurements. Crystalline LAMO has formed instantaneously during the combustion process. The signature of the order-disorder transition of stoichiometric LAMO around 570 degrees C was evident from differential thermal analysis, differential scanning calorimetry electrical conductivity, and thermal expansion measurements. Though the in situ x-ray measurements did not indicate any clear evidence of a phase transition, a stepwise change in the lattice parameter near the vicinity of the transition temperature was apparent thereby confirming the phase transition to be of first order in nature. The thermal expansion coefficient of LAMO was calculated to be 13.92 x 10-6/ degrees K at 950 degrees C. The present method formed phase pure LAMO instantaneously and produced sintered samples with high conductivity, namely, 0.052 S/cm at 800 degrees C and 0.08 S/cm at 950 degrees C compared to LAMO prepared through various other solution routes.

Basu,S.; Devi, P.; Mati, A.; Lee, Y.; Hanson, J.

2006-01-01

438

Lanthanum reduces the excitation efficiency in fly photoreceptors  

PubMed Central

Lanthanum (La3+), a known inhibitor of Ca2+ binding proteins, was applied to the extracellular space of fly retina. Shot noise analysis indicated that a combination of intense light and La3+ caused a large (down to zero) reduction in the rate of occurrence of the quantal responses to single photons (quantum bumps) which sum to produce the photoreceptor potential. Light in the presence of La3+ also increased the effective bump duration. These effects are very similar to the effects of the mutations trp of Drosophila and nss of Lucilia flies on the quantum bump rate and duration. La3+ applied to the nss mutant caused only a small reduction in the bump rate, suggesting that La3+ may affect the nss gene product which is deficient in the mutant. The close similarity in the properties of the receptor potential of the La(3+)-treated photoreceptor of the wild type and of the nss mutant together with existing evidence for the highly reduced intracellular Ca2+ ([Ca2+]i) level in nss photoreceptors suggest that both La3+ and the mutation cause a severe reduction in [Ca2+]i. This effect may arise from an inhibition of a Ca2+ transporter protein located in the surface membrane that normally replenishes Ca2+ pools in the photoreceptors, a process essential for light excitation.

1991-01-01

439

First-principles thermodynamic modeling of lanthanum chromate perovskites  

NASA Astrophysics Data System (ADS)

Tendencies toward local atomic ordering in (A,A')(B,B')O3-? mixed composition perovskites are modeled to explore their influence on thermodynamic, transport, and electronic properties. In particular, dopants and defects within lanthanum chromate perovskites are studied under various simulated redox environments. (La1-x,Srx)(Cr1-y,Fey)O3-? (LSCF) and (La1-x,Srx)(Cr1-y,Ruy)O3-? (LSCR) are modeled using a cluster expansion statistical thermodynamics method built upon a density functional theory database of structural energies. The cluster expansions are utilized in lattice Monte Carlo simulations to compute the ordering of Sr and Fe(Ru) dopant and oxygen vacancies (Vac). Reduction processes are modeled via the introduction of oxygen vacancies, effectively forcing excess electronic charge onto remaining atoms. LSCR shows increasingly extended Ru-Vac associates and short-range Ru-Ru and Ru-Vac interactions upon reduction; LSCF shows long-range Fe-Fe and Fe-Vac interaction ordering, inhibiting mobility. First principles density functional calculations suggest that Ru-Vac associates significantly decrease the activation energy of Ru-Cr swaps in reduced LSCR. These results are discussed in view of experimentally observed extrusion of metallic Ru from LSCR nanoparticles under reducing conditions at elevated temperature.

Dalach, P.; Ellis, D. E.; van de Walle, A.

2012-01-01

440

Study of prolonged administration of lanthanum carbonate in dialysis patients.  

PubMed

Data of 36 months were accumulated regarding the effects of lanthanum carbonate (LA) on serum phosphate concentrations in dialysis patients. Fifty-three patients (average age and dialysis history 58.4 years and 9.1 years) were included in this study who have been receiving outpatient treatment since March 2009, and who have been unable to maintain serum phosphate concentrations of ?6.0?mg/dL via traditional therapeutic agents used for hyperphosphatemia. Patients were given dosage of LA in addition to, or instead of, co-hyperphosphatemia treatments already being received. Mean dosages of calcium carbonate (CC) and sevelamer hydrochloride (SH) before starting LA administration were 1301.9?mg and 2462.3?mg, respectively. Dosage of LA for all cases was 750?mg at initial dose; 1528.3?mg at 5 months; and 1416.7?mg at 30 months. Dosage of other phosphate binders were 905.7?mg of CC and 820.8?mg of SH at 5 months; and 687.5?mg of CC and 1031.3?mg of SH at 30 months. Serum phosphorus levels (P levels) were significantly decreased at 1 month of LA administration, and continued until 30 months of La treatment. These results suggest that LA successfully controlled serum P and Ca concentrations simultaneously within target ranges without affecting serum intact parathyroid hormone concentration, although further long-term prospective cohort study on LA would be required. PMID:23586507

Gotoh, Junichi; Kukita, Kazutaka; Tsuchihashi, Seiichiro; Hattori, Masahiro; Iida, Junichi; Horie, Takashi; Onodera, Kazuhiko; Furui, Hidenori; Tamaki, Toru; Meguro, Junichi; Yonekawa, Motoki; Kawamura, Akio

2013-04-01

441

The Bayo Canyon/radioactive lanthanum (RaLa) program  

SciTech Connect

LANL conducted 254 radioactive lanthanum (RaLa) implosion experiments Sept. 1944-March 1962, in order to test implosion designs for nuclear weapons. High explosives surrounding common metals (surrogates for Pu) and a radioactive source containing up to several thousand curies of La, were involved in each experiment. The resulting cloud was deposited as fallout, often to distances of several miles. This report was prepared to summarize existing records as an aid in evaluating the off-site impact, if any, of this 18-year program. The report provides a historical setting for the program, which was conducted in Technical Area 10, Bayo Canyon about 3 miles east of Los Alamos. A description of the site is followed by a discussion of collateral experiments conducted in 1950 by US Air Force for developing an airborne detector for tracking atmospheric nuclear weapons tests. All known off-site data from the RaLa program are tabulated and discussed. Besides the radiolanthanum, other potential trace radioactive material that may have been present in the fallout is discussed and amounts estimated. Off-site safety considerations are discussed; a preliminary off-site dose assessment is made. Bibliographical data on 33 persons important to the program are presented as footnotes.

Dummer, J.E.; Taschner, J.C.; Courtright, C.C.

1996-04-01

442

Combustion synthesis and photoluminescence of Eu3+ doped LaAlO3 nanophosphors  

NASA Astrophysics Data System (ADS)

Eu3+ doped LaAlO3 nanophosphors were successfully synthesized by a combustion process using concentrated solution of lanthanum nitrates and aluminate as oxidiser, and glycine acid as fuel. The powders were characterized by infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and fluorescence spectroscopy. Pure LaAlO3 phase was obtained at 800 °C heated for 4 h, without formation of any intermediate phase, with an average crystal size, as determined by TEM, of 60 nm. Intense photoluminescence emission is reported at 616 nm, allowing the use of this material as red phosphor.

Dhahri, A.; Horchani-Naifer, K.; Benedetti, A.; Enrichi, F.; Ferid, M.

2012-09-01

443

Fabrication of large-volume, low-cost ceramic lanthanum halide scintillators for gamma ray detection : final report for DHS/DNDO/TRDD project TA-01-SL01.  

SciTech Connect

This project uses advanced ceramic processes to fabricate large, optical-quality, polycrystalline lanthanum halide scintillators to replace small single crystals produced by the conventional Bridgman growth method. The new approach not only removes the size constraint imposed by the growth method, but also offers the potential advantages of both reducing manufacturing cost and increasing production rate. The project goal is to fabricate dense lanthanum halide ceramics with a preferred crystal orientation by applying texture engineering and solid-state conversion to reduce the thermal mechanical stress in the ceramic and minimize scintillation light scattering at grain boundaries. Ultimately, this method could deliver the sought-after high sensitivity and <3% energy resolution at 662 keV of lanthanum halide scintillators and unleash their full potential for advanced gamma ray detection, enabling rapid identification of radioactive materials in a variety of practical applications. This report documents processing details from powder synthesis, seed particle growth, to final densification and texture development of cerium doped lanthanum bromide (LaBr{sub 3}:Ce{sup +3}) ceramics. This investigation demonstrated that: (1) A rapid, flexible, cost efficient synthesis method of anhydrous lanthanum halides and their solid solutions was developed. Several batches of ultrafine LaBr{sub 3}:Ce{sup +3} powder, free of oxyhalide, were produced by a rigorously controlled process. (2) Micron size ({approx} 5 {micro}m), platelet shape LaBr{sub 3} seed particles of high purity can be synthesized by a vapor phase transport process. (3) High aspect-ratio seed particles can be effectively aligned in the shear direction in the ceramic matrix, using a rotational shear-forming process. (4) Small size, highly translucent LaBr{sub 3} (0.25-inch diameter, 0.08-inch thick) samples were successfully fabricated by the equal channel angular consolidation process. (5) Large size, high density, translucent LaBr{sub 3} ceramics samples (3-inch diameter, > 1/8-inch thick) were fabricated by hot pressing, demonstrating the superior manufacturability of the ceramic approach over single crystal growth methods in terms of size capability and cost. (6) Despite all these advances, evidence has shown that LaBr{sub 3} is thermally unstable at temperatures required for the densification process. This is particularly true for material near the surface where lattice defects and color centers can be created as bromine becomes volatile at high temperatures. Consequently, after densification these samples made using chemically prepared ultrafine powders turned black. An additional thermal treatment in a flowing bromine condition proved able to reduce the darkness of the surface layer for these densified samples. These observations demonstrated that although finer ceramic powders are desirable for densification due to a stronger driving force from their large surface areas, the same desirable factor can lead to lattice defects and color centers when these powders are densified at higher temperatures where material near the surface becomes thermally unstable.

Boyle, Timothy J.; Ottley, Leigh Anna M.; Yang, Pin; Chen, Ching-Fong; Sanchez, Margaret R.; Bell, Nelson Simmons

2008-10-01

444

Formation of 1,4-diketones via bis-acylation of the conjugated carbon–carbon double bonds in acrylates, acrylamides, methyl vinyl ketone and styrenes with aroyl chlorides promoted by samarium metal in DMF  

Microsoft Academic Search

Promoted by samarium in DMF, aroyl chlorides react readily with conjugated carbon–carbon double bonds in acrylates, acrylamides, methyl vinyl ketone and styrenes in a bis-acylation manner. These reactions proceed smoothly under mild conditions without the need of pretreating or activating the metallic samarium, affording the corresponding 1,4-diketones in good to excellent yields.

Yongjun Liu; Yongmin Zhang

2003-01-01

445

Spectral investigations of Sm3+ doped lead bismuth magnesium borophosphate glasses  

NASA Astrophysics Data System (ADS)

The multicomponent lead bismuth magnesium borophosphate glass systems (LBMBPS) doped with Samarium ions with the molar compositions of (50-x)PbO?xBi2O3?25MgHPO4?24B2O3?1Sm2O3 (where x=10, 20, 30, and 40) were fabricated using conventional melt quenching technique. The amorphous nature of these glass samples was confirmed with XRD studies. The spectral data from the optical absorption studies were employed to compute various spectroscopic parameters such as Judd-Ofelt intensity parameters. The Judd-Ofelt parameterization employed reflects the covalency and vibration frequencies of the ligands with Samarium ions. The radiative parameters such as radiative transition probabilities (A), the total radiative transitional probabilities (AT), radiative life times (?R), branching ratios (?) and absorption cross sections (?) were computed for certain lasing levels. The glass systems thus developed indicate their potential lasing candidature. The emission cross sections (?E) for the significant lasing transitions 4G5/2?6H5/2, 4G5/2?6H7/2, and 4G5/2?6H9/2 evaluated from the photoluminescence spectra were reported. The radiative properties obtained in our investigations suggest their lasing candidature.

Ravi Babu, Y. N. Ch.; Sree Ram Naik, P.; Vijaya Kumar, K.; Rajesh Kumar, N.; Suresh Kumar, A.

2012-09-01

446

Effects of ultraviolet excitation on the spectroscopic properties of Sm3+ and Tb3+ doped aluminophosphate glasses  

NASA Astrophysics Data System (ADS)

Li2O-BaO-Al2O3-La2O3-P2O5 glasses optically activated with rare earth ions with the 4f5, and 4f8 electronic configuration (Sm3+ and Tb3+, respectively) were analyzed by Raman spectroscopy, absorption, excitation photoluminescence, decay curves and temperature dependent photoluminescence. The spectroscopic characteristics of the as-prepared and heat treated samples at temperatures below and above Tg were studied as well as their room temperature photometric properties under ultraviolet excitation. All the doped glasses exhibit typical signatures of the lanthanides in their trivalent charge state. For the samarium doped glass heat treated at 250 °C (samarium doped glasses have much lower luminance intensity (around 0.3 Cd/m2) when compared with the 6-7 Cd/m2 observed for the terbium doped ones.

Nico, C.; Graça, M. P. F.; Elisa, M.; Sava, B. A.; Monteiro, R. C. C.; Rino, L.; Monteiro, T.

2013-10-01

447

Vertically aligned nanorods of lanthanum hexaboride with efficient field emission properties  

NASA Astrophysics Data System (ADS)

The present study describes a borothermal reduction process to obtain nanostructured lanthanum hexaboride (LaB6) particles and their films. The morphology (nanorods and nanoparticles) of the boride nanostructures could be controlled by using a lanthanum hydroxide precursor (with controlled shape and size) obtained by a microemulsion mediated process. The LaB6 films fabricated by spin coating of nanorods of LaB6 led to an assembly of vertically oriented nanorods with excellent field emission properties (field enhancement factor of 4522). This methodology does not require any template for obtaining these vertically aligned nanorods. The field emission properties can be tuned by controlling the shape and size of the lanthanum hexaboride nanostructures.

Jha, Menaka; Patra, Rajkumar; Ghosh, Santanu; Ganguli, Ashok K.

2013-01-01

448

Domain structure-property relations in lead lanthanum zirconate titanate ceramics  

SciTech Connect

The domain structure and dielectric properties as a function of lanthanum concentration and Zr/Ti ratio have been investigated in rhombohedral and tetragonal lead lanthanum zirconate titanate (PLZT) ceramics. Transmission electron microscopy revealed that, with increasing lanthanum concentration and Zr/Ti ratio, the long-range-ordered domains (macrodomains) reduced in width, initially being fine scale (20 nm) striations, but eventually forming a {open_quote}{open_quote}mottled{close_quote}{close_quote} contrast (5 nm), characteristic of a relaxor. Relative permittivity measurements as a function of temperature revealed a correlation between broadening of the dielectric maxima and the onset of relaxor-type behavior with the appearance of the striations and mottled (relaxor) contrast, respectively. {copyright} {ital 1996 Materials Research Society.}

Akbas, M.A.; Reaney, I.M.; Lee, W.E. [Department of Engineering Materials, The University of Sheffield, Sheffield, S1 3JD (United Kingdom)

1996-09-01

449

Performance Evaluation of an Oxygen Sensor as a Function of the Samaria Doped Ceria Film Thickness  

SciTech Connect

The current demand in the automobile industry is in the control of air-fuel mixture in the combustion engine of automobiles. Oxygen partial pressure can be used as an input parameter for regulating or controlling systems in order to optimize the combustion process. Our goal is to identify and optimize the material system that would potentially function as the active sensing material for such a device that monitors oxygen partial pressure in these systems. We have used thin film samaria doped ceria (SDC) as the sensing material for the sensor operation, exploiting the fact that at high temperatures, oxygen vacancies generated due to samarium doping act as conducting medium for oxygen ions which hop through the vacancies from one side to the other contributing to an electrical signal. We have recently established that 6 atom % Sm doping in ceria films has optimum conductivity. Based on this observation, we have studied the variation in the overall conductivity of 6 atom % samaria doped ceria thin films as a function of thickness in the range of 50 nm to 300 nm at a fixed bias voltage of 2 volts. A direct proportionality in the increase in the overall conductivity is observed with the increase in sensing film thickness. For a range of oxygen pressure values from 1 mTorr to 100 Torr, a tolerable hysteresis error, good dynamic response and a response time of less than 10 seconds was observed

Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Jiang, Weilin; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

2010-12-01

450

Thickness Dependency of Thin Film Samaria Doped Ceria for Oxygen Sensing  

SciTech Connect

High temperature oxygen sensors are widely used for exhaust gas monitoring in automobiles. This particular study explores the use of thin film single crystalline samaria doped ceria as the oxygen sensing material. Desired signal to noise ratio can be achieved in a material system with high conductivity. From previous studies it is established that 6 atomic percent samarium doping is the optimum concentration for thin film samaria doped ceria to achieve high ionic conductivity. In this study, the conductivity of the 6 atomic percent samaria doped ceria thin film is measured as a function of the sensing film thickness. Hysteresis and dynamic response of this sensing platform is tested for a range of oxygen pressures from 0.001 Torr to 100 Torr for temperatures above 673 K. An attempt has been made to understand the physics behind the thickness dependent conductivity behavior of this sensing platform by developing a hypothetical operating model and through COMSOL simulations. This study can be used to identify the parameters required to construct a fast, reliable and compact high temperature oxygen sensor.

Sanghavi, Rahul P.; Nandasiri, Manjula I.; Kuchibhatla, Satyanarayana V N T; Jiang, Weilin; Varga, Tamas; Nachimuthu, Ponnusamy; Engelhard, Mark H.; Shutthanandan, V.; Thevuthasan, Suntharampillai; Kayani, Asghar N.; Prasad, Shalini

2010-11-23

451

Early earth and solar system evolution - Insights from strontium, barium neodymium, and samarium isotopes  

NASA Astrophysics Data System (ADS)

Recent thermal ionization mass spectrometer advances have made it possible to determine the isotopic composition of both terrestrial and extra-terrestrial samples with unrivaled precision. The coupled long- and short-lived samarium- neodymium decay system ( 147 Sm[arrow right] 143 Nd, t ? =106 Ga, 146 Sm[arrow right] 142 Nd, t ? =103 Ma) have been used to confirm the presence of 142 Nd variations in early Archean samples, and to show that the depleted upper mantle is elevated in 142 Nd compared to chondrite meteorites. These results imply that major silicate differentiation of the Earth's mantle occurred within about 30 Ma after accretion. Furthermore, they require the presence of an enriched reservoir that has not interacted with the depleted mantle since initial differentiation. This study presents high-precision thermal ionization mass spectrometer data for strontium, barium, neodymium, and samarium isotopic compositions of meteorite and terrestrial samples in order to investigate: (i) whether the 142 Nd differences between meteorites and terrestrial samples are indeed caused by the decay of 146 Sm with variable Sm/Nd ratios, (ii) if their Nd isotopic compositions are fundamentally different due to variations in nucleosynthetic components or neutron fluences; and (iii) if traces of the early enriched reservoir can be found in deep mantle plume derived lavas carrying solar noble gas signatures. The Sm, Nd, and Ba isotopic compositions of carbonaceous chondrites are found to be different from that of ordinary chondrites, the eucrite parent body, and Earth, which are all identical. Non-radiogenic Sr isotopic compositions are identical for terrestrial samples and meteorites. Variations in nucleosynthetic components (s-, r-, and p-process) within the Solar System are evident from p- process deficits in Sm and Nd and r-process excesses in Ba for carbonaceous chondrites. The p-process deficit explains the bimodal 142 Nd distribution seen in chondrites but is insufficient to explain the difference between chondrites and the terrestrial upper mantle. No signs of the early enriched reservoir were found in deep mantle plume lavas from the Iceland hot spot and Deccan Flood basalts. However, this could be due to dilution with depleted upper mantle material. Combined, these results point to a homogenous inner Solar System with respect to heavy elements and confirm early terrestrial mantle differentiation.

Andreasen, Rasmus

2007-08-01

452

Influence of composition and pressure on the electric field-induced antiferroelectric to ferroelectric phase transformation in lanthanum modified lead zirconate titanate ceramics.  

PubMed

The electric field-induced phase transformation behavior in lanthanum-doped lead zirconate titanate ceramics was examined by polarization versus electrical field (P-E) measurements carried out from room temperature to 130 degrees C and under hydrostatic pressures from 20 to 300 MPa. The samples with composition (Pb(1-x)La(x))(Zr(0.90)Ti(0.10))(1-x/4)O(3) [PLZT x/90/10; x = 2,3,4 at%] were prepared by the standard solid-state reaction method. The analysis at room temperature under atmospheric pressure showed that the increase in the lanthanum content induces a transformation from the typical ferroelectric hysteresis, observed for PLZT 2,3/90/10, to double-hysteresis loops, typical of antiferroelectric phases, for PLZT 4/90/10 under a strong electric field. Hydrostatic pressure- induced and temperature-induced ferroelectric (FE) to antiferroelectric (AFE) phase transformations were examined. The measured hysteresis loops indicated that the FE-AFE phase transformation depends on both temperature and hydrostatic pressure for PLZT 3/90/10. This composition, which is in a ferroelectric state at room temperature under atmospheric pressure, can be transformed into the antiferroelectric phase by the application of a hydrostatic pressure of 100 MPa or by increasing the temperature to around 90 degrees C. The PLZT 2/90/10 and 4/90/10 compositions displayed predominantly ferroelectric and antiferroelectric behavior, respectively, over the ranges of temperature and hydrostatic pressure examined in the present study. PMID:19811977

Peláiz-Barranco, Aimé; Hall, David A

2009-09-01

453

Preparation of yttrium, lanthanum, cerium, and neodymium basic carbonate particles by homogeneous precipitation  

SciTech Connect

Uniform yttrium, lanthanum, cerium, and neodymium basic carbonate particles were prepared by homogeneous precipitation. Powders were characterized with respect to size, shape, crystal structure, and thermal decomposition behavior. Yttria precursor particles were spherical, monosized (0.4 {mu}m), and amorphous; whereas lanthana, neodymia, and ceria precursors were prismatic (ranging from 1 to 6 {mu}m in size) and crystalline. Crystal structure was found to be ancylite-type orthorhombic symmetry in all three cases. Upon heating in air, yttrium, lanthanum, and neodymium precursors underwent two-step decomposition to first form oxycarbonate and then oxide. Cerium hydroxycarbonate decomposed in a single step to form the oxide.

Akinc, M.; Sordelet, D. (Iowa State Univ., Ames (USA))

1987-07-01

454

Mechanism of the lanthanum bromide assisted electrochemical aldolization of. alpha. -bromo ketones  

SciTech Connect

Linear sweep voltammetry, preparative electrolyses under a variety of experimental conditions, and trapping experiments have been used to explore the mechanism of the formation of the aldol 2-benzoyl-1-phenylpropanol by electrochemical reduction of {alpha}-bromopropiophenone in the presence of benzaldehyde and lanthanum bromide. The aldol condensation occurs by reaction of the free (lithio) enolate with a lanthanum bromide-benzaldehyde-tetrahydrofuran complex. Electrochemical reduction of the bromo ketone forms the Z enolate highly stereospecifically. The erythro aldol is formed stereoselectively initially, but the condensation is reversible, and the equilibrium mixture of aldols, containing mostly the threo isomer, is isolated from the electrolysis.

Fry, A.J.; Susla, M. (Wesleyan Univ., Middletown, CT (USA))

1989-04-26

455

Synthesis, Characterization, and Cytotoxic Activity of New Lanthanum(III) Complexes of Bis-Coumarins  

PubMed Central

Complexes of lanthanum(III) with bis-coumarins: 3,3?-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one) (H2L1) and bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane (H2L2) were synthesized by reaction of lanthanum(III) salt and the ligands, in amounts equal to metal : ligand molar ratio of 1 : 2. The complexes were prepared by adding an aqueous solution of lanthanum(III) salt to an aqueous solution of the ligand subsequently raising the pH of the mixture gradually to circa 5.0 by adding dilute solution of sodium hydroxide. The lanthanum(III) complexes with bis-coumarins were characterized by different physicochemical methods—elemental analysis, IR-, 1H-, and 13C-NMR-spectroscopies, and mass spectral data. The spectral data of lanthanum(III) complexes were interpreted on the basis of comparison with the spectra of the free ligands. This analysis showed that in the La(III) complexes, the ligands coordinated to the metal ion through both deprotonated hydroxyl groups. On the basis of the ?(C=O) red shift observed, participation of the carbonyl groups in the coordination with the metal ion was also suggested. In the present study, we performed a cytotoxic-effects screening of the lanthanum complexes with H2L1 and H2L2 in a panel of human tumor cell lines, using the standard MTT-dye reduction assay for cell viability. The panel consisted of the acute myeloid leukemia-derived HL-60 and the chronic myeloid leukemia-derived BV-173. Following a 24- hour treatment of BV-173 cells with lanthanum complex of H2L1 at 100 or 200 ?M led to a DNA-laddering. The findings suggest that the observed cytotoxicity of the lanthanum complex of H2L1 on BV-173 is at least partly mediated through induction of programmed cell death.

Kostova, Irena; Momekov, Georgi; Tzanova, Tzvetomira; Karaivanova, Margarita

2006-01-01

456

LaZnB5O10, the first lanthanum zinc borate  

PubMed Central

Lanthanum zinc penta­borate, LaZnB5O10, was synthesized by flux-supported solid-state reaction. It is a member of the LnMB5O10 (Ln = rare earth ion and M = divalent metal ion) structure type. The crystal shows a three-dimensional structure constructed from two-dimensional {[B5O10]5?}n layers with the lanthanum (coordination number nine) and zinc (coordination number six) ions filling in the inter­layers.

Jiao, Zhi-Wei; Wang, Ru-Ji; Wang, Xiao-Qing; Shen, De-Zhong; Shen, Guang-Qiu

2010-01-01

457

LaZnB(5)O(10), the first lanthanum zinc borate.  

PubMed

Lanthanum zinc penta-borate, LaZnB(5)O(10), was synthesized by flux-supported solid-state reaction. It is a member of the LnMB(5)O(10) (Ln = rare earth ion and M = divalent metal ion) structure type. The crystal shows a three-dimensional structure constructed from two-dimensional {[B(5)O(10)](5-)}(n) layers with the lanthanum (coordination number nine) and zinc (coordination number six) ions filling in the inter-layers. PMID:21579905

Jiao, Zhi-Wei; Wang, Ru-Ji; Wang, Xiao-Qing; Shen, De-Zhong; Shen, Guang-Qiu

2009-12-04

458

Lanthanum carbonate is not associated with QT interval modification in hemodialysis patients  

PubMed Central

Lanthanum carbonate is an efficacious noncalcium, nonresin phosphate-binder that is being increasingly used in chronic kidney disease stage 5 (CKD-5) dialysis patients. Available evidence has indicated that QT interval changes correlate with mortality in healthy subjects and in dialysis patients. Experimental studies have suggested the possibility that lanthanum carbonate may produce prolongation of the QT interval. This is not accepted by other authors. There is no data confirming this in prospective clinical studies. The goal of this study was to verify the effect of lanthanum carbonate on the QT interval of the electrocardiogram (EKG) tracing. Material and methods We studied 25 hemodialyzed patients. After a six-month run-in period, with aluminum-hydroxide, lanthanum carbonate was administered at increasing doses: 500 mg twice a day for week 1; 750 mg, twice daily during week 2; 1000 mg twice daily during week 3; and 1000 mg three times daily during week 4. EKGs were recorded on patients prior to and 3 hours following each dialysis treatment. Assessments were made of differences in body weight; systolic blood pressure; diastolic blood pressure; length of PR and QRS complex; heart rate; QT; QT-c; QT-d; and axis of wave P, QRS complex and T using lanthanum carbonate at increasing doses. Results QT-c is before dialysis session during run-in 431 ± 20 msec with variation by ?9 to + 1 msec (P = not significant [NS]) during lanthanum use; and 437 ± 25 msec after dialysis session with variation by ?6 to ?1 msec (P = NS) during lanthanum use. Any difference was observed during study among before and after dialysis session in QT-c (difference by 0.09 to 3.2%) (P = NS); and QT-d (difference by 8.6 to 9.1%) (P = NS). Conclusion Our study shows that lanthanum carbonate administration, at increasing doses, did not modify the EKG parameters. This effect is observed both in predialysis and in postdialysis recordings. Further studies are necessary with more prolonged observations.

Di Iorio, Biagio; Cucciniello, Emanuele

2010-01-01

459

History of Doping and Doping Control  

Microsoft Academic Search

\\u000a Although attempts to enhance athletic performance are probably much older, the word “doping” was first mentioned in 1889 in\\u000a an English dictionary. It described originally a mixed remedy containing opium, which was used to “dope” horses. “Dope” was\\u000a a spirit prepared from the residues of grapes, which Zulu warriors used as a “stimulant” at fights and religious procedures\\u000a and which

Rudhard Klaus Müller

460

Lanthanum Gallium Tin Antimonides LaGaxSnySb2  

NASA Astrophysics Data System (ADS)

A series of quaternary lanthanum gallium tin antimonides LaGaxSnySb2 was elaborated to trace the structural evolution between the known end members LaGaSb2 (SmGaSb2-type) and LaSnySb2 (LaSn0.75Sb2-type). Five members of this series were characterized by single-crystal X-ray diffraction. For low Sn content, the Sn atoms disorder with Ga atoms in zigzag chains to form solid solutions LaGa1-ySnySb2 (0<=y<=0.2) adopting the SmGaSb2-type structure, as exemplified by LaGa0.92(3)Sn0.08Sb2 and LaGa0.80(3)Sn0.20Sb2 (orthorhombic, space group D52-C2221,Z=4). For higher Sn and lower Ga content, there is a segregation in which the Sn atoms appear in chains of closely spaced partially occupied sites as in the parent LaSn0.75Sb2-type structure whereas the Ga atoms remain in zigzag chains as in the parent SmGaSb2-type structure. This feature is observed in the structures of LaGa0.68(4)Sn0.31(3)Sb2, LaGa0.62(3)Sn0.32(3)Sb2, and LaGa0.43(3)Sn0.39(3)Sb2 (orthorhombic, space group D172h-Cmcm,Z=4). The last example illustrates that the combined Ga/Sn content can be substoichiometric (x+y<1). These compounds have a layered nature, with the chains of Ga or Sn atoms residing between 2?[LaSb2] slabs.

Morgan, Mark G.; Wang, Meitian; Mills, Allison M.; Mar, Arthur

2002-08-01

461

A new large area lanthanum hexaboride plasma source  

NASA Astrophysics Data System (ADS)

A new 18×18 cm2 active area lanthanum hexaboride (LaB6) plasma source for use in a dc discharge has been developed at UCLA. The cathode consists of four tiled LaB6 pieces indirectly heated to electron emission (1750 °C) by a graphite heater. A molybdenum mesh anode 33 cm in front of the LaB6 accelerates the electrons, ionizing a fill gas to create a 20×20 cm2 nearly square plasma. The source is run in pulsed operation with the anode biased up to +400 V dc with respect to the cathode for up to 100 ms at a 1 Hz repetition rate. Both the cathode and anode ``float'' electrically with respect to the chamber walls. The source is placed in a toroidal chamber 2 m wide and 3 m tall with a major radius of 5 m. Toroidal and vertical magnetic fields confine the current-free plasma which follows the field in a helix. The plasma starts on the bottom of the machine and spirals around it up to four times (120 m) and can be configured to terminate either on the top wall or on the neutral gas itself. The source typically operates with a discharge current up to 250 A in helium making plasmas with Te<30 eV, Ti<16 eV, and ne<3×1013 cm-3 in a background field of 100 G

Cooper, C. M.; Gekelman, W.; Pribyl, P.; Lucky, Z.

2010-08-01

462

Back bombardment for dispenser and lanthanum hexaboride cathodes  

NASA Astrophysics Data System (ADS)

The back bombardment (BB) effect limits wide usage of thermionic rf guns. The BB effect induces not only ramping-up of a cathode’s temperature and beam current, but also degradation of cavity voltage and beam energy during a macropulse. This paper presents a comparison of the BB effect for the case of dispenser tungsten-base (DC) and lanthanum hexaboride (LaB6) thermionic rf gun cathodes. For each, particle simulation codes are used to simulate the BB effect and electron beam dynamics in a thermionic rf gun cathode. A semiempirical equation is also used to investigate the stopping range and deposited heat power of BB electrons in the cathode material. A numerical simulation method is used to calculate the change of the cathode temperature and current density during a single macropulse. This is done by solving two differential equations for the rf gun cavity equivalent circuit and one-dimensional thermal diffusion equation. High electron emission and small beam size are required for generation of a high-brightness electron beam, and so in this work the emission properties of the cathode are taken into account. Simulations of the BB effect show that, for a pulse of 6?s duration, the DC cathode experiences a large change in the temperature compared with LaB6, and a change in current density 6 times higher. Validation of the simulation results is performed using experimental data for beam current beyond the gun exit. The experimental data is well reproduced using the simulation method.

Bakr, Mahmoud; Kinjo, R.; Choi, Y. W.; Omer, M.; Yoshida, K.; Ueda, S.; Takasaki, M.; Ishida, K.; Kimura, N.; Sonobe, T.; Kii, T.; Masuda, K.; Ohgaki, H.; Zen, H.

2011-06-01

463

The effect of electromotive-force generation on electrical properties of thin samarium sulfide films  

SciTech Connect

Electrical properties of thin SmS polycrystalline films with various values of the lattice constant at T = 300-580 K are studied. Specific features of the temperature dependences of electrical conductivity at T > 450 K are revealed. The effect of generation of the electromotive force with magnitude as large as 1.3 V at T = 440-470 K is observed when the films were subjected to the pressure of a spherical indenter. It is shown that it is possible to transform SmS films into a high-resistivity state (with the difference in the resistivity by three orders of magnitude) by applying an electric field with the strength higher than 100 V/cm. All the results obtained are accounted for using a model of the phenomenon of the electromotive-force generation in SmS under uniform heating of the sample and can also be attributed to the variable valence of samarium ions with respect to the lattice defects.

Kaminskii, V. V., E-mail: Vladimir.Kaminski@mail.ioffe.ru; Kazanin, M. M.; Solov'ev, S. M.; Sharenkova, N. V.; Volodin, N. M. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2006-06-15

464

High temperature phase transitions and critical exponents of Samarium orthoferrite determined by in situ optical ellipsometry  

NASA Astrophysics Data System (ADS)

Determining phase transitions has always been a great challenge in material science due to their important fundamental and technological aspects. Recently, iron-based perovskites (RFeO3), exhibiting phase transitions at high temperatures, have attracted much interest for their functional properties at room temperature, such as multiferroicity (BiFeO3) and ultrafast spin dynamics (TmFeO3). In this family of materials, Samarium orthoferrite (SmFeO3) is a weak ferromagnet, ordering at high temperatures and exhibiting an intrinsic spin reorientation transition above room temperature, which is ``hidden'' in macroscopic magnetization measurements in polycrystalline samples. In the present article, we show that the related magnetic high temperature phase transitions can be studied through their dielectric functions by spectroscopic ellipsometry in situ and without any need for an applied external magnetic field. The presence of this intrinsic spin reorientation transition is demonstrated for textured SmFeO3 films and we have determined a critical exponent of ? = 0.45 +/- 0.01 for the magnetic phase transition, coherently from optical, magneto-optical, and structural investigations.

Berini, B.; Fouchet, A.; Popova, E.; Scola, J.; Dumont, Y.; Franco, N.; da Silva, R. M. C.; Keller, N.

2012-03-01

465

PENTAMETHYLCYCLOPENTADIENYL DERIVATIVES OF THE TRIVALENT LANTHANIDE ELEMENTS (NEODYMIUM, SAMARIUM, AND YTTERBIUM)  

SciTech Connect

The anionic complexes of the type (ML{sub x})(Me{sub 5}C{sub 5}){sub 2}M'Cl{sub 2}, where M is lithium or sodium, L is diethyl ether or N,N,-N{prime},N{prime}-tetramethylethylenediamine, and M{prime} is neodymium, samarium, or ytterbium, have been prepared from the metal trichlorides and the pentamethylcyclopentadienide anion. The neutral species (Me{sub 5}C{sub 5}){sub 2}NdCl(THF), (Me{sub 5}C{sub 5}){sub 2}NdN(SiMe{sub 3}){sub 2}, and (Me{sub 5}C{sub 5}){sub 2}YbCl(THF) have also been prepared. The mono-ring derivatives (Na(OEt{sub 2}){sub 2})((C{sub 5}Me{sub 5})NdCl{sub 3}) and (Me{sub 5}C{sub 5})Nd(N(SiMe{sub 3}){sub 2}){sub 2} are also described.

Tilley, T. Don; Andersen, R.A.

1980-07-01

466

Cyan-white-red luminescence from europium doped Al2O3-La2O3-SiO2 glasses.  

PubMed

Aluminum-lanthanum-silicate glasses with different Eu doping concentration have been synthesized by conventional melt-quenching method at 1680 degrees C in reductive atmosphere. Under 395nm excitation, samples with low Eu doping concentration show mainly the cyan broad emission at 460nm due to 4f(6)5d(1)-4f(7) transition of Eu(2+); and the samples with higher Eu doping concentration show mainly some narrow emissions with maximum at 616nm due to (5)D(0)-(7)F(j) (J=0, 1, 2, 3, 4) transitions of Eu(3+). Cyan-white-red tunable luminescence under 395nm excitation has been obtained by changing the Eu doping concentration. PMID:18545375

Yang, Hucheng; Lakshminarayana, G; Zhou, Shifeng; Teng, Yu; Qiu, Jianrong

2008-04-28

467

Effects and safety of lanthanum carbonate in end stage renal disease patients with hyperphosphatemia: a meta-analysis - system review of lanthanum carbonate.  

PubMed

Abstract Aim: To assess the effect and safety of lanthanum carbonate (LC) for hypophosphatemia in patients with end-stage renal disease (ESRD). Methods: According to the collaborative review group search strategy, we searched MEDLINE (1996 to 2012.12); EBCO (1996 to 2012.12), and CNKI. We searched Chinese journals by hand. We conducted quality assessment and data extraction by two independent investigators. Meta-analysis was conducted by RevMan 5.0. Results were expressed as OR with 95% confidence interval for dichotomous outcomes and WMD with 95% confidence interval for continuous outcomes. Result: We identified 16 reports which might meet the inclusion criteria for our review. The meta-analysis showed that LC was superior to placebo in treating hypophosphatemia of end-stage renal disease patients (OR?=?5.46, 95% CI: 2.37 to 2.61, p?Lanthanum carbonate is well effective and tolerated in treating hyperphosphatemia of ESRD patients. Lanthanum carbonate is not likely to cause hypercalcemia compared to calcium-based phosphate binders. PMID:23992043

Guo, Hua; Zhang, Xiaojuan; Tang, Shaowen; Zhang, Shali

2013-09-02

468

Fluorescence properties and electron paramagnetic resonance studies of ?-irradiated Sm3+-doped oxyfluoroborate glasses  

NASA Astrophysics Data System (ADS)

The permanent photoinduced valence manipulation of samarium doped oxyfluoroborate glasses as a function of ?-ray irradiation has been investigated using a steady-state fluorescence and electron paramagnetic resonance techniques. An increase in SrF2 content in the glass led to the red shift of the peaks in as prepared glass, while in irradiated glasses this led to the decrease in defect formation as well as increase in photoreduction of Sm3+ to Sm2+ ion. The energy transfer mechanism of induced permanent photoreduction of Sm3+ to Sm2+ ions in oxyfluoroborate glasses has been discussed. The decay analysis shows exponential behavior before irradiation and non-exponential behavior after irradiation. The energy transfer in irradiated glasses increases with the increase in SrF2 content in the glass and also with the irradiation dose.

Babu, B. Hari; Ravi Kanth Kumar, V. V.

2012-11-01