Sample records for samarium doped lanthanum

  1. Specific Heat of Lanthanum, Praseodymium, Neodymium, and Samarium Metals between 3 and 25K

    Microsoft Academic Search

    O. V. Lounasmaa; Lorna J. Sundstrm

    1967-01-01

    Results of specific-heat measurements are reported for lanthanum, praseodymium, neodymium, and samarium metals in the temperature range between 3 and 25K. The observed anomalies in the specific heat can generally be related to those found in several other physical properties of the metals. Analysis of the total specific heat Cp into its component parts is based on the assumptions that

  2. Sprayed lanthanum doped zinc oxide thin films

    NASA Astrophysics Data System (ADS)

    Bouznit, Y.; Beggah, Y.; Ynineb, F.

    2012-01-01

    Lanthanum doped zinc oxide thin films were deposited on soda-lime glass substrates using a pneumatic spray pyrolysis technique. The films were prepared using different lanthanum concentrations at optimum deposition parameters. We studied the variations in structural, morphological and optical properties of the samples due to the change of doping concentration in precursor solutions. X-ray diffraction (XRD) patterns show that pure and La-doped ZnO thin films are highly textured along c-axis perpendicular to the surface of the substrate. Scanning electron micrographs show that surface morphology of ZnO films undergoes a significant change according to lanthanum doping. All films exhibit a transmittance higher than 80% in the visible region.

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

    Microsoft Academic Search

    Gary F. Hartnell; Larry D. Satter

    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

  4. Removal of phosphate from polluted water by lanthanum doped vesuvianite.

    PubMed

    Li, Heng; Ru, Jingyu; Yin, Wen; Liu, Xiaohai; Wang, Jiaqiang; Zhang, Wudi

    2009-08-30

    The adsorption capacities of vesuvianite and lanthanum doped vesuvianite were studied. The effects of different mass ratios of La/vesuvianite at different contact times, pHs, and temperatures on adsorption capacity were also studied. It was found that lanthanum doped vesuvianite exhibited higher adsorption capacity than undoped one due to the reaction of bounded lanthanum with phosphate. The adsorption capacity of lanthanum doped vesuvianite for phosphate removal increased with the increase of La/vesuvianite mass ratio. The Freundlich and Langmuir models were used to simulate the sorption equilibrium, and the results indicate that the Langmuir model had a better correlation with the experimental data than the Freundlich model did. When the initial phosphate concentration was 1mgP/L, the adsorptive capacity rate would be 1.32 mg P/g lanthanum doped vesuvianite (La/vesuvianite mass ratio >or=0.14) at pH between 6 and 9 after 40h. The concentrations of residual lanthanum ions in solution at different conditions were measured. Lanthanum doped vesuvianite was also used for the removal of phosphate in a polluted river water and it could be easily recycled once without losing its activity to a greater extent. PMID:19297092

  5. Electrical properties of lanthanum doped barium titanate ceramics

    SciTech Connect

    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

    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.

  6. Reaction mechanism between lanthanum manganite and yttria doped cubic zirconia

    Microsoft Academic Search

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

    1999-01-01

    The reactivity between lanthanum deficient lanthanum manganite, La0.9MnO3, and yttria doped cubic zirconia (YSZ) has been examined at the temperature range between 1250C and 1400C. 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

  7. Influence of annealing temperature on the grain growth of samarium-doped ceria

    Microsoft Academic Search

    Hong-Hsin Huang; Hung-Peng Chang; Yu-Tsang Chien; Ming-Chih Huang; Jenn-Shing Wang

    2006-01-01

    Samarium-doped ceria (SDC) can be used as electrolyte of solid oxide fuel cells (SOFCs). In this study, SDC films have been deposited by E-beam evaporation at room temperature (RT) and 200C, and then annealed at 500, 600, 700, and 800C. The structure and morphology of samples were analyzed by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). Initial temperature for

  8. The properties of samarium doped ceria oxide thin films grown by e-beam deposition technique

    Microsoft Academic Search

    Giedrius Laukaitis; Mindaugas Jauneika; Julius Dudonis; Oresta Katkauske; Darius Milcius

    2009-01-01

    One of the main challenges in today's solid oxide fuel cell (SOFC) technology is the reduction of their operating temperature. New types of oxygen ion conducting materials are currently under investigation to overcome the problems which SOFC faces at high temperatures. Samarium doped ceria oxide (SDC) was the material of investigation in this work. Optical quartz (SiO2) and FeNiCr alloy

  9. Thermal conductivity analysis of lanthanum doped manganites

    SciTech Connect

    Mansuri, Irfan, E-mail: dr.irfan.mansuri@gmail.com [Indore Institute of Science and Technology, Pithampur Road Rau, Indore-453331 India and School of Physics, Devi Ahilya University, Khandwa Road Campus, Indore-452001 (India); Shaikh, M. W. [School of Physics, Devi Ahilya University, Khandwa Road Campus, Indore-452001, India and Acropolis Technical Campus, Village Tillore, Indore-453331 (India); Khan, E.; Varshney, Dinesh [School of Physics, Devi Ahilya University, Khandwa Road Campus, Indore-452001 (India)

    2014-04-24

    The temperature-dependent thermal conductivity of the doped manganites La{sub 0.7}Ca{sub 0.3}MnO{sub 3} is theoretically analyzed within the framework of Kubo formulae. The Hamiltonian consists of phonon, electron and magnon thermal conductivity contribution term. In this process we took defects, carrier, grain boundary, scattering process term and then calculate phonon, electron and magnon thermal conductivity.

  10. Photoluminescence of samarium-doped TiO{sub 2} nanotubes

    SciTech Connect

    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

    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.

  11. Creep and Fatigue Behavior of SnAg Solders With Lanthanum Doping

    Microsoft Academic Search

    Min Pei; Jianmin Qu

    2008-01-01

    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

  12. Chemical Preparation of Pure and Strontium-and/or Magnesium-Doped Lanthanum Gallate Powders

    E-print Network

    Tas, A. Cuneyt

    Chemical Preparation of Pure and Strontium- and/or Magnesium-Doped Lanthanum Gallate Powders A. Cu) ceramics that have been doped with strontium and/or magnesium are known to have superior oxygen re- cently synthesized strontium- and magnesium-doped LaGaO3 ceramics, using the conventional "solid

  13. Altering the equilibrium condition in Sr-doped lanthanum manganite.

    SciTech Connect

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

    1999-05-28

    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.

  14. Europium doped lanthanum zirconate nanoparticles with high concentration quenching

    SciTech Connect

    Alaparthi, Suresh B.; Lu, Long; Tian, Yue; Mao, Yuanbing, E-mail: maoy@utpa.edu

    2014-01-01

    Graphical abstract: - Highlights: Eu:La{sub 2}Zr{sub 2}O{sub 7} nanoparticles were prepared facilely by a kinetically modified molten salt method. High color purity and concentration quenching were achieved in these La{sub 2}Zr{sub 2}O{sub 7}:Eu nanoparticles. Concentration quenching mechanism was discussed for Eu{sup 3+} in these Eu:La{sub 2}Zr{sub 2}O{sub 7} nanoparticles. - Abstract: A series of Eu{sup 3+} doped lanthanum zirconate (La{sub 2}Zr{sub 2}O{sub 7}) nanoparticles (NPs, 20 5 nm in diameter) with cubic fluorite structure were facilely synthesized by a kinetically modified molten salt synthetic (MSS) process and characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM) and photoluminescence spectra (PL). Under the excitation of 405 nm, intense red emission with high color purity can be observed in the Eu{sup 3+} doped La{sub 2}Zr{sub 2}O{sub 7} NPs. Moreover, the as-prepared Eu:La{sub 2}Zr{sub 2}O{sub 7} NPs possess high concentration quenching, which is as high as ?32.5 mol% of europium dopants in the La{sub 2}Zr{sub 2}O{sub 7} host. The corresponding concentration quenching mechanism was discussed as well. Our results confirm that the kinetically modified MSS process is a promising approach for preparing rare earth (RE) ions doped A{sub 2}B{sub 2}O{sub 7} nanoparticles with uniform RE doping and high concentration quenching.

  15. Improved chemical stability and conductivity of barium cerate nanopowders by Lanthanum doping.

    PubMed

    Lee, Hunhyeong; Park, Inyu; Shin, Dongwook

    2013-09-01

    Despite of the highest proton conductivity, barium cerate electrolytes are well known for the deficiency of chemical stability at elevated temperature under CO2 atmosphere. This work is focused on improving chemical stability of lanthanum doped barium cerate (BCL) powder for electrolyte. Although lanthanum doping causes distortion of perovskite structure lattice, immoderate doping could stabilize structure due to increasing symmetry of structure lattices. The thermogravimetric analysis and AC impedance measurements revealed that the lanthanum doping suppresses the reaction between barium and carbonate and this effect results in sufficient improvement in ionic conductivity in operating temperatures range. It was confirmed that BaCe0.7La0.3O3-delta (BCL30) was the most stable composition and the conductivity of BCL30 is high as 3.8 S x cm(-1) x K at 700 degrees C. PMID:24205607

  16. Structural studies of lithium boro tellurite glasses doped with praseodymium and samarium oxides

    SciTech Connect

    Damas, Pedro [Departamento de Fsica, Faculdade de Cincias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)] [Departamento de Fsica, Faculdade de Cincias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Coelho, Joo [INESC Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)] [INESC Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); Hungerford, Graham [HORIBA Jobin Yvon IBH Ltd., Skypark 5, 45 Finnieston Street, Glasgow G3 8JU (United Kingdom)] [HORIBA Jobin Yvon IBH Ltd., Skypark 5, 45 Finnieston Street, Glasgow G3 8JU (United Kingdom); Hussain, N. Sooraj, E-mail: nandyala.sooraj@fc.up.pt [Departamento de Fsica, Faculdade de Cincias, Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal); INESC Porto, Rua do Campo Alegre, 687, 4169-007 Porto (Portugal)

    2012-11-15

    Graphical abstract: [TeO{sub 4}] trigonal bipyramid structural unit, which is formed by two unequivalent pair of oxygen atoms: two equatorial oxygens (O{sub eq}) and two axial oxygens (O{sub ax}). Highlights: ? Pr{sup 3+} and Sm{sup 3+} doped LBT glasses have been prepared and characterized. ? LBT glasses present normal surfaces without metallic clusters. ? Raman spectra revealed the network modifying behaviour of dopant ions. -- Abstract: This paper reports the preparation and structural studies of praseodymium and samarium (0.5, 2 and 4 mol%) oxide doped lithium boro tellurite glasses. These materials were prepared by the quenching technique in a ceramic crucible at 950 C. Structural characterization was performed by Raman spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy techniques. Results from Raman analysis are in good agreement with those reported in the literature, revealing a normal glass structure for the host material. Understanding on how the glasses internal structure changed when the doping concentration increases was also assessed.

  17. The pyroelectric properties of the lanthanum-doped ferroelectric plzt ceramics

    Microsoft Academic Search

    S. T. Liu; J. D. Heaps; O. N. Tufte

    1972-01-01

    The pyroelectric properties of hot-pressed lanthanum doped PZT X\\/65\\/35 ferroelectric ceramics have been studied to evaluate their potential as pyroelectric infrared detector materials. The pyroelectric coefficients ranged from 3.5 10-8 to 17.0 10-8 (coul\\/cm2 C) for lanthanum compositions from X = 0 to 8. The dielectric properties have also been measured over this compositional range. Thermal noise is

  18. Transport properties of silver-calcium doped lanthanum manganite

    NASA Astrophysics Data System (ADS)

    Cherif, B.; Rahmouni, H.; Smari, M.; Dhahri, E.; Moutia, N.; Khirouni, K.

    2015-01-01

    Electrical properties of silver-calcium doped lanthanum manganite (La0.5Ca0.5-xAgxMnO3 with 0.0

  19. Preparation and propertyperformance relationships in samarium-doped ceria nanopowders for solid oxide fuel cell electrolytes

    Microsoft Academic Search

    Marcin R. Kosinski; Richard T. Baker

    2011-01-01

    In a systematic study, Samarium doped ceria (SDC) nanopowders, SmxCe1?xO2?x\\/2 (x=0.1, 0.2 or 0.3), were prepared by a low temperature citrate complexation route. The synthesis and crystallisation of the SDC powders were followed by thermochemical techniques (TGA\\/DTA), X-ray diffraction, elemental analysis, specific surface area determination (BET) and electron microscopy (SEM and TEM). Mean crystallite sizes were found to be around

  20. Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

    NASA Astrophysics Data System (ADS)

    Morrell, B.; Okada, G.; Vahedi, S.; Koughia, C.; Edgar, A.; Varoy, C.; Belev, G.; Wysokinski, T.; Chapman, D.; Sammynaiken, R.; Kasap, S. O.

    2014-02-01

    Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm3+) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405 nm to erase the recorded dose information in Sm3+-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm3+-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm2+ to Sm3+ reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm2+ to Sm3+ reconversion process, the capture of these electrons by POHC (and hence their disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT.

  1. Optically erasable samarium-doped fluorophosphate glasses for high-dose measurements in microbeam radiation therapy

    SciTech Connect

    Morrell, B.; Okada, G.; Vahedi, S.; Koughia, C., E-mail: cyril.koughia@usask.ca; Kasap, S. O. [Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada); Edgar, A.; Varoy, C. [School of Chemical and Physical Sciences and MacDiarmid Institute, Victoria University of Wellington, Wellington 6140 (New Zealand); Belev, G.; Wysokinski, T.; Chapman, D. [Canadian Light Source, Inc., University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9 (Canada); Sammynaiken, R. [Saskatchewan Structural Sciences Centre, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9 (Canada)

    2014-02-14

    Previous work has demonstrated that fluorophosphate (FP) glasses doped with trivalent samarium (Sm{sup 3+}) can be used as a dosimetric detector in microbeam radiation therapy (MRT) to measure high radiation doses and large dose variations with a resolution in the micrometer range. The present work addresses the use of intense optical radiation at 405?nm to erase the recorded dose information in Sm{sup 3+}-doped FP glass plates and examines the underlying physics. We have evaluated both the conversion and optical erasure of Sm{sup 3+}-doped FP glasses using synchrotron-generated high-dose x-rays at the Canadian Light Source. The Sm-ion valency conversion is accompanied by the appearance of x-ray induced optical absorbance due to the trapping of holes and electrons into phosphorus-oxygen hole (POHC) and electron (POEC) capture centers. Nearly complete Sm{sup 2+} to Sm{sup 3+} reconversion (erasure) may be achieved by intense optical illumination. Combined analysis of absorbance and electron spin resonance measurements indicates that the optical illumination causes partial disappearance of the POHC and the appearance of new POEC. The suggested model for the observed phenomena is based on the release of electrons during the Sm{sup 2+} to Sm{sup 3+} reconversion process, the capture of these electrons by POHC (and hence their disappearance), or by PO groups, with the appearance of new and/or additional POEC. Optical erasure may be used as a practical means to erase the recorded data and permits the reuse of these Sm-doped FP glasses in monitoring dose in MRT.

  2. X-ray Induced Luminescence Spectroscopy of Samarium Doped Barium Sulfate Prepared by Sintering Method

    NASA Astrophysics Data System (ADS)

    Kumeda, T.; Maeda, K.; Shirano, Y.; Fujiwara, K.; Sakai, K.; Ikari, T.

    2015-06-01

    X-ray induced luminescence (XL) properties of phosphor materials made of samarium doped barium sulfate have been investigated. The samples were prepared by sintering method heated at 900-1250 C for 3 hours in air from the mixture of BaSO4 and Sm2O3. The concentration of Sm were prepared from 0.01-6 at.%. In as-prepared sample, the Sm3+ was detected by photoluminescence (PL). The PL intensity is maximum about 2 at.% with Sm, and then starts decreasing. The PL intensity showed concentration quenching. The XL observed Sm2+ and Sm3+ ions. The XL was shown from the sample sintered up to 1200 C. The XL intensity increased with Sm concentration up to 1 at.%. The intensity was almost constant larger than 1 at.% Sm. These concentration dependences is different since the X-ray energy absorbed to the host material at once, and the energy transferred to both Sm3+ and Sm2+ ions. Sm doped BaSO4 is found a host for XL phosphor materials.

  3. Investigation of the influence of strontium carbonate on fluorescence spectra of oxy-fluoride glasses doped with samarium oxide and samarium fluoride

    NASA Astrophysics Data System (ADS)

    Pashova, Teodora; Eftimov, Tinko; Kostova, Irena; Tonchev, Dancho

    2015-01-01

    Oxy-fluoride glasses containing strontium carbonate doped with samarium have been prepared. The glasses are sorted with respect to the quantity of strontium carbonate. The fluorescence spectra recorded for different pumping wavelengths are presented. We have investigated the influence of the excitation on the efficiency of the fluorescence, depending on the quantity of strontium carbonate in the samples for a variety of excitation wavelengths. The results of optical pumping in the range 370 - 490 nm show a typical fluorescence spectrum of Sm3+. When pumped with wavelengths above 500 nm a new peak that has not been reported appeared in the fluorescence spectrum. From the data analysis the range of appearance of the fluorescence peak was determined and the most efficient source for its excitation was found.

  4. Photocatalytic activity of lanthanum and sulfur co-doped TiO 2 photocatalyst under visible light

    Microsoft Academic Search

    Huili Xia; Huisheng Zhuang; Dongchang Xiao; Tao Zhang

    2008-01-01

    A novel lanthanum and sulfur co-doped TiO2 photocatalyst was synthesized by precipitation-dipping method, and characterized by X-ray diffraction(XRD), transmission\\u000a electron microscopy(TEM) and UV-Vis diffuse reflectance spectroscopy. Compared with the S-doped TiO2, La-doped TiO2 and the standard Degussa P25 photocatalysts, the lanthanum and sulfur co-doped TiO2 photocatalyst (the molar percentage of La is 3.0%) calcined at 450 C for 2 h

  5. Spray pyrolytic synthesis of samarium doped ceria (Ce 0.8Sm 0.2O 1.9) films for solid oxide fuel cell applications

    Microsoft Academic Search

    B. B. Patil; S. H. Pawar

    2007-01-01

    Uniform, adherent, single phase samarium doped ceria films have been successfully deposited by spray pyrolysis technique for their application in solid oxide fuel cell. These films have been deposited at different substrate temperatures on glass substrate and subsequently heat treated in tube furnace. Effect of substrate temperature and annealing temperature on phase formation was studied with thermo-gravimetric analysis and differential

  6. Strontium-doped lanthanum manganite coatings crystallised after air annealing of amorphous co-sputtered films

    Microsoft Academic Search

    F. Capon; D. Horwat; J. F. Pierson; V. Chapusot; A. Billard

    2009-01-01

    Strontium-doped lanthanum manganite films were deposited on steel, silicon and yttria stabilised zirconia substrates by reactive co-sputtering of La0.85Sr0.15 and Mn targets in a ArO2 gas mixture. In this study, the discharge current applied to the manganese target was varied to adjust the film composition whereas that of the LaSr target was maintained at a constant value of 1A. The

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

    Microsoft Academic Search

    Lum-Ngwegia Ngwa Nforbi

    2010-01-01

    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 500C. Several preliminary syntheses were carried out in order to obtain the correct fuel-to-oxidizer ratio necessary for the production

  8. Identification of O 2 reduction processes at yttria stabilized zirconia|doped lanthanum manganite interface

    Microsoft Academic Search

    X. J Chen; K. A Khor; S. H Chan

    2003-01-01

    Oxygen reduction processes at a yttria stabilized zirconia|doped lanthanum manganite (LSM|YSZ) interface are investigated by ac impedance spectroscopy. Three semi-arcs are clearly observed at an oxygen partial pressure (pO2) of 0.001atm. The constant-phase element of frequency arc and the pO2-dependence of 1\\/R (R: resistance) are correlated to interpret the reaction processes associated with the frequency arcs. It is found that

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

    Microsoft Academic Search

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

    2004-01-01

    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 23 times that of La0.7Sr0.3FeO3 and 10

  10. Solgel auto-combustion synthesis of samarium-doped TiO 2 nanoparticles and their photocatalytic activity under visible light irradiation

    Microsoft Academic Search

    Qi Xiao; Zhichun Si; Zhiming Yu; Guanzhou Qiu

    2007-01-01

    High photocatalytic activity of Sm3+-doped TiO2 nanocrystalline under visible light has been successfully prepared by solgel auto-combustion technique. The samples were characterized by X-ray diffraction, UVvis diffuse reflectance spectroscopy and photoluminescence (PL) spectra. UVvis diffuse reflectance spectra showed a slight shift to longer wavelengths and an extension of the absorption in the visible region for almost all the samarium-doped samples,

  11. Doping of ceria surfaces with lanthanum: a DFT + U study

    Microsoft Academic Search

    Irene Yeriskin; Michael Nolan

    2010-01-01

    In this paper we use density functional theory corrected for on-site Coulomb interactions (DFT + U) to study the defects formed in the ceria (111) and (110) surfaces doped with La. To describe consistently the defect formed with substitutional La3 + doping at a Ce4 + site we use DFT and DFT + U, with U = 5 eV for

  12. Synthesis of Sm{sup 3+}-doped strontium barium niobate crystals in glass by samarium atom heat processing

    SciTech Connect

    Chayapiwut, Nakorn [Department of Chemistry, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Honma, Tsuyoshi [Department of Chemistry, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Benino, Yasuhiko [Department of Chemistry, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Fujiwara, Takumi [Department of Chemistry, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Komatsu, Takayuki [Department of Chemistry, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan)]. E-mail: komatsu@chem.nagaokaut.ac.jp

    2005-11-15

    New glasses giving the crystallization of Sm{sup 3+}-doped Sr {sub x} Ba{sub 1-} {sub x} Nb{sub 2}O{sub 6} (SBN) ferroelectrics have been developed in the Sm{sub 2}O{sub 3}-SrO-BaO-Nb{sub 2}O{sub 5}-B{sub 2}O{sub 3} system, and the formation of SBN crystal dots and lines by continuous wave Nd:YAG laser (wavelength:1064 nm, power: 1 W) irradiations, i.e., samarium atom heat processing, has been examined. The formation of Sm{sup 3+}-doped SBN non-linear optical crystals is confirmed from X-ray diffraction analyses, micro-Raman scattering spectra, second harmonic generations, and photoluminescence spectra. Sm{sup 3+}-doped SBN crystal dots with the diameters of 20-70 {mu}m and lines with the widths of 20-40 {mu}m are written at the surface of some glasses such as 10Sm{sub 2}O{sub 3}.10SrO.10BaO.20Nb{sub 2}O{sub 5}.50B{sub 2}O{sub 3} (mol%) by Nd:YAG laser irradiations with the irradiation times of 20-70 s for the dots and with the scanning speeds of 1-5 {mu}m/s for the lines. The present study suggests that the samarium atom heat processing has a potential for the patterning of optical waveguides consisting of ferroelectric SBN crystals in glass substrates.

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

    SciTech Connect

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

    2005-09-15

    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.

  14. Cobalt doped lanthanum chromite material suitable for high temperature use

    DOEpatents

    Ruka, Roswell J. (Churchill, PA)

    1986-01-01

    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.

  15. Site selective spectroscopy and crystal field analysis of Eu3 + doped lanthanum-calcium-zirconium-silicon borate

    Microsoft Academic Search

    J. A. Capobianco; P. P. Proulx; N. Raspa; D. J. Simkin; D. Krashkevich

    1989-01-01

    The fluorescence of Eu3+ doped lanthanumcalciumzirconiumsilicon borate ceramic was studied at 77 and 300 K using laser excited site selective spectroscopy. The fluorescence spectrum excited at 514.532 nm reveals the presence of three distinct sites for Eu3+. The sites were assigned to Eu3+ substituting for lanthanum in a ninefold coordination site in LaBO3 and Eu3+ substituting for Ca2+ in six-

  16. Dielectric investigations of polycrystalline samarium bismuth ferrite ceramic

    NASA Astrophysics Data System (ADS)

    Palaimiene, E.; Macutkevic, J.; Karpinsky, D. V.; Kholkin, A. L.; Banys, J.

    2015-01-01

    Results of broadband dielectric investigations of samarium doped bismuth ferrite ceramics are presented in wide temperature range (20-800 K). At temperatures higher than 400 K, the dielectric properties of samarium bismuth ferrite ceramics are governed by Maxwell-Wagner relaxation and electrical conductivity. The DC conductivity increases and activation energy decreases with samarium concentration. In samarium doped bismuth ferrite, the ferroelectric phase transition temperature decreases with samarium concentration and finally no ferroelectric order is observed at x = 0.2. At lower temperatures, the dielectric properties of ferroelectric samarium doped bismuth ferrite are governed by ferroelectric domains dynamics. Ceramics with x = 0.2 exhibit the relaxor-like behaviour.

  17. Photocatalytic degradation of 2,4,6-trichlorophenol using lanthanum doped ZnO in aqueous suspension

    Microsoft Academic Search

    S. Anandan; A. Vinu; T. Mori; N. Gokulakrishnan; P. Srinivasu; V. Murugesan; K. Ariga

    2007-01-01

    La-doped ZnO nano particles with different La contents were prepared by co-precipitation method using the precursors of zinc and lanthanum. The XRD results indicated that the particle size of La-doped ZnO is much smaller as compared to that of pure ZnO and decreases with increasing La loading. The effect of La loading on the photocatalytic activity of La-doped ZnO in

  18. Magnetic and transport properties of lanthanum perovskites with B-site half doping

    NASA Astrophysics Data System (ADS)

    Dho, Joonghoe; Hur, N. H.

    2006-04-01

    We have synthesized various half doped lanthanum perovskites LaBB0.5'O (BB'=MnV, MnCr, MnCo, MnNi, FeCr, FeMn, FeCo, FeNi) by solid state reaction method. The crystal structure was orthorhombic in all samples, but the magnetic and transport properties showed a large variation with the composition. A ferromagnetic feature was quite strong in the Mn-based perovskites but weak or non-existent in the Fe-based ones. The resistivity of Ni-doped ones was much smaller than those of the others. For all half doped perovskits, remarkably, the temperature dependent transport was well explained by variable range hopping model with different localization lengths.

  19. Lanthanum-doped Bi4Ti3O12 ceramics prepared by high-pressure technique

    NASA Astrophysics Data System (ADS)

    Lin, Xue; Guan, Qing-Feng; Liu, Yang; Li, Hai-Bo

    2010-10-01

    We present an effective way in this paper to increase the density of lanthanum doped bismuth titanate ceramics, Bi4xLaxTi3O12 (BLT), thereby significantly improving the performance of the BLT ceramics. Dense BLT ceramicses, Bi4xLaxTi3O12 (x = 0.25, 0.5, 0.75, 1.0), are prepared by using nanocrystalline powders fabricated by a gel method and high-pressure technique. The microstructures of the BLT ceramicses prepared separately by conventional-pressure and high-pressure techniques are investigated by using x-ray diffraction and transmission electron microscope. The influence of La-doping on the densification of bismuth titanate ceramics is investigated. The experimental results indicate that the phase compositions of all samples with various lanthanum dopings sintered at 900 C possess layer-structure of Bi4Ti3O12. The green compacts are pressed under 2.5 GPa, 3.0 GPa, 3.5 GPa and 4.0 GPa, separately. It is found that the density of BLT ceramics is significantly increased due to the decreasing of porosity in the green compacts by high-pressure process.

  20. Effects of magnetization on hole localization and MnO octahedra disorder in hole-doped lanthanum manganese perovskites

    Microsoft Academic Search

    C. H. Booth; E. L. Brosha; G. H. Kwei; F. Bridges; J. J. Neumeier

    1998-01-01

    The authors review the distortions of the MnO octahedra reduced by magnetization in hole-doped lanthanum manganese perovskites. The systems they consider include the colossal magnetoresistance (CMR) samples La{sub 1-x}CaMnO (x = 0.21, 0.25, 0.30), La{sub 0.76}Ba{sub 0.33}MnO, and a poorer quality La{sub 0.76}Pb{sub 0.33}MnO sample. They also report preliminary work on three samples of oxygen-doped LaMnO{sub 3+δ} and a lanthanum-deficient

  1. Two dielectric relaxation mechanisms observed in lanthanum doped barium strontium titanate glass ceramics

    NASA Astrophysics Data System (ADS)

    Zhang, Yong; Ma, Tao; Wang, Xiangrong; Yuan, Zongbao; Zhang, Qian

    2011-04-01

    The dielectric relaxation at temperatures ranging from 100 C to 550 C in lanthanum-doped barium strontium titanate glass ceramics has been investigated by measurements of both dielectric temperature curve and complex impedance spectroscopy. The temperature dependence of dielectric properties reveals two regimes. In the first regime, at temperatures lower than 350 C, the charge carrier contributed to interfacial polarization is conduction electrons. In contrast, in the second regime, at temperatures higher than 350 C, the dielectric relaxation was attributed to the thermally activated movement of oxygen vacancies. Thus, two relaxation mechanisms could be explained on the basis of defect chemistry and impedance analysis.

  2. Magnetic and transport properties of lanthanum perovskites with B-site half doping

    Microsoft Academic Search

    Joonghoe Dho; N. H. Hur

    2006-01-01

    We have synthesized various half doped lanthanum perovskites LaB0.5B0.5?O3 (BB?=MnV, MnCr, MnCo, MnNi, FeCr, FeMn, FeCo, FeNi) by solid state reaction method. The crystal structure was orthorhombic in all samples, but the magnetic and transport properties showed a large variation with the composition. A ferromagnetic feature was quite strong in the Mn-based perovskites but weak or non-existent in the Fe-based

  3. Optical assessment on a new self-frequency doubling crystal: neodymium-doped lanthanum calcium borate

    Microsoft Academic Search

    Rui Guo; Yicheng Wu; Peizhen Fu; Fangli Jing

    2005-01-01

    A new, to our knowledge, neodymium-doped lanthanum calcium borate crystal (Nd3+:La2CaB10O19, Nd:LCB) has been grown by the flux method. The spectroscopic parameters for Nd:LCB crystal have also been calculated based on Judd-Ofelt theory. The intensity parameters Omegat are Omega2=4.9610-20 cm2, Omega4=3.94 10-20 cm2, and Omega6=3.7110-20 cm2. The radiative lifetime taur is 349 mus. The absorption band at 800 nm has

  4. Synthesis of lanthanum-doped MCM-48 molecular sieves and its catalytic performance for the oxidation of styrene.

    PubMed

    Zhan, Wangcheng; Guo, Yanglong; Wang, Yanqin; Liu, Xiaohui; Guo, Yun; Wang, Yunsong; Zhang, Zhigang; Lu, Guanzhong

    2007-10-25

    Lanthanum-doped MCM-48 molecular sieves with different La contents were synthesized hydrothermally and characterized by X-ray diffraction (XRD), nitrogen sorption, transmission electron microscopy (TEM), UV-visible spectroscopy, and Fourier transform infrared (FT-IR) spectroscopy. The results show that the majority of La cations have been incorporated into the framework of MCM-48 molecular sieves. When the molar ratio of La/Si is >0.039 in the sample, some of lanthanum species exist in the extraframework. Compared with pure silicate MCM-48, lanthanum-doped MCM-48 samples show the medium strong acidity that is due to the incorporation of La in the framework of silica. In the oxidation of styrene with H(2)O(2) as the oxidant over the lanthanum-doped MCM-48 catalysts, benzaldehyde is the main product with a small amount of styrene oxide. The La content in the catalysts, reaction temperature, reaction time, and solvent affect greatly the catalytic oxidation of styrene. The conversion of styrene and the selectivity to styrene oxide increase noticeably when a small amount of NaOH aqueous solution is added into the reaction mixture. Ln-doped MCM-48 catalysts with 14 kinds of rare earth elements were synthesized hydrothermally and evaluated for the oxidation of styrene. The results show that their catalytic performance is tremendously different and depends on the nature of rare earth elements doped in the MCM-48 mesoporous materials. PMID:17914798

  5. Optical and magnetic properties of zinc oxide quantum dots doped with cobalt and lanthanum.

    PubMed

    Yu, Shiyong; Zhao, Jing; Su, Hai-Quan

    2013-06-01

    Cobalt and Lanthanum-doped ZnO QDs are synthesized by a modified sol-gel method under atmospheric conditions. The as-prepared quantum dots are characterized by X-ray powder diffraction (XRD), energy dispersive X-ray (EDX) analysis and high resolution transmission electron microscopy (HRTEM). The optical properties of the products are studied by fluorescent spectroscopy. With a proper Co and La doping, these nanoparticles possess exceptionally small size and enhanced fluorescence. Hysteresis loops of un-doped ZnO QDs and Co and La-doped ZnO QDs indicate that both the samples show ferromagnetic behavior at room temperature. Finally, these nanoparticles can label the BGC 803 cells successfully in short time and present no evidence of toxicity or adverse affect on cell growth even at the concentration up to 1 mM. We expect that the as-prepared Co and La-doped ZnO QDs can provide a better reliability of the collected data and find promising applications in biological, medical and other fields. PMID:23862449

  6. Intrinsic inhomogeneities of low-doped lanthanum manganites in the paramagnetic temperature range

    SciTech Connect

    Solin, N. I., E-mail: solin@imp.uran.ru [Russian Academy of Sciences, Ural Branch, Institute of Metal Physics (Russian Federation)

    2012-01-15

    The nature of the electrical resistivity for low-doped lanthanum manganites is elucidated. The electrical resistivity is described by the Efros-Shklovskii law (ln{rho} {radical} (T{sub 0}/T){sup -1/2}, where T{sub 0} {radical} 1/R{sub ls}) in the temperature range from T* Almost-Equal-To 300 K Almost-Equal-To T{sub C} (T{sub C} is the Curie temperature for conducting manganites) to their T{sub C} and is explained by the tunneling of carriers between localized states. The magnetoresistance is explained by a change in the size of localized states R{sub ls} in a magnetic field. The patterns of change in R{sub ls} with temperature and magnetic field strength determined from magnetotransport properties are satisfactorily described in the model of phase separation into small-radius metallic droplets in a paramagnetic matrix. The sizes R{sub ls} and their temperature dependence have been estimated through magnetic measurements. The results confirm the existence of a Griffith phase. The intrinsic inhomogeneities produced by thermodynamic phase separation determine the electrical resistivity and magnetoresistance of lanthanum manganites.

  7. Room temperature optical and dielectric properties of Sr and Ni doped lanthanum ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Naseem, Swaleha; Khan, Wasi; Singh, B. R.; Naqvi, A. H.

    2015-06-01

    Strontium and nickel doped lanthanum ferrite (LaFeO3) nanoparticles (NPs) were prepared reverse micelle (RM) and calcinated at 700C. Microstructural studies were carried by XRD and SEM/EDS techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible spectroscopy and band gap energy was estimated 3.89 eV. Room temperature dielectric constant (?') decreases abruptly at lower frequencies owing to the charge transport relaxation time. The observed behavior of the dielectric properties can be attributed on the basis of Koop's theory based on Maxwell-Wagner's two layer model in studied nanoparticles.

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

    Microsoft Academic Search

    Hiroyuki Yamaura; Tetsuya Ikuta; Hidenori Yahiro; Genji Okada

    2005-01-01

    The cathodic polarization of strontium-doped lanthanum ferrite, La1?xSrxFeO3??, was studied in the hydrogenoxygen 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 773973 K. The best cathodic performance was obtained for La0.7Sr0.3FeO3?? heat-treated at 1173 K. The cathode resistance of

  9. Photoinduced hydroxyl radical and photocatalytic activity of samarium-doped TiO 2 nanocrystalline

    Microsoft Academic Search

    Qi Xiao; Zhichun Si; Jiang Zhang; Chong Xiao; Xiaoke Tan

    2008-01-01

    Sm3+-doped TiO2 nanocrystalline has been prepared by solgel auto-combustion technique and characterized by X-ray diffraction (XRD), BrunauerEmmettTeller (BET) method, and also UVvis diffuse reflectance spectroscopy (DRS). These Sm3+-doped TiO2 samples were tested for methylene blue (MB) decomposition and OH radical formation. The analysis of OH radical formation on the sample surface under UV irradiation was performed by fluorescence technique with

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

    SciTech Connect

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

    2004-11-30

    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 23 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.

  11. Bismuth doped lanthanum ferrite perovskites as novel cathodes for intermediate-temperature solid oxide fuel cells.

    PubMed

    Li, Mei; Wang, Yao; Wang, Yunlong; Chen, Fanglin; Xia, Changrong

    2014-07-23

    Bismuth is doped to lanthanum strontium ferrite to produce ferrite-based perovskites with a composition of La(0.8-x)Bi(x)Sr0.2FeO(3-?) (0 ? x ? 0.8) as novel cathode material for intermediate-temperature solid oxide fuel cells. The perovskite properties including oxygen nonstoichiometry coefficient (?), average valence of Fe, sinterability, thermal expansion coefficient, electrical conductivity (?), oxygen chemical surface exchange coefficient (K(chem)), and chemical diffusion coefficient (D(chem)) are explored as a function of bismuth content. While ? decreases with x due to the reduced Fe(4+) content, D(chem) and K(chem) increase since the oxygen vacancy concentration is increased by Bi doping. Consequently, the electrochemical performance is substantially improved and the interfacial polarization resistance is reduced from 1.0 to 0.10 ? cm(2) at 700 C with Bi doping. The perovskite with x = 0.4 is suggested as the most promising composition as solid oxide fuel cell cathode material since it has demonstrated high electrical conductivity and low interfacial polarization resistance. PMID:24971668

  12. Lanthanum and zirconium co-doped ZnO nanocomposites: synthesis, characterization and study of photocatalytic activity.

    PubMed

    Moafi, Hadi Fallah; Zanjanchi, Mohammad Ali; Shojaie, Abdollah Fallah

    2014-09-01

    Nanocomposits of zinc oxide co-doped with lanthanum and zirconium were prepared using the modified sol-gel method. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), diffuse reflectance spectroscopy (DRS), and BET surface area measurement. For comparison, the La and Zr mono doped ZnO have also been prepared under the same conditions. The XRD results revealed that all the materials showed a hexagonal wurtzite crystal structure. It was found that the particle size of La-Zr-doped ZnO is much smaller as compared to that of pure ZnO. The effect of operational parameters such as, doping concentration, catalyst loading, pH and initial concentration of methylene blue on the extent of degradation was investigated. The photocatalytic activity of the undoped ZnO, mono-doped and La-Zr-ZnO photocatalysts was evaluated by the photocatalytic degradation of methylene blue in aqueous solution. The presence of lanthanium and/or zirconium causes a red shift in the absorption band of ZnO. The results show that the photocatalytic activity of the La-Zr-ZnO photocatalyst is much higher than that of undoped and mono-doped ZnO, resulting from the La and Zr synergistic effect. The co-operation of the lanthanum and zirconium ion leads to the narrowing of the band gap and greatly improves the photocatalytic activity. The photocatalyst co-doped with lanthanum and zirconium 4 mol% shows the best photoactivity and photodecomposition efficiencies were improved by 92% under UV-Vis irradiation at the end of 30 min, compared with the pure and mono doped samples. PMID:25924382

  13. Intermediate-temperature electrochemical performance of a polycrystalline PrBaCo 2O 5+ ? cathode on samarium-doped ceria electrolyte

    Microsoft Academic Search

    Dengjie Chen; Ran Ran; Kun Zhang; Jun Wang; Zongping Shao

    2009-01-01

    A-site cation-ordered PrBaCo2O5+? (PrBC) double perovskite oxide was synthesized and evaluated as the cathode of an intermediate-temperature solid-oxide fuel cell (IT-SOFC) on a samarium-doped ceria (SDC) electrolyte. The phase reaction between PrBC and SDC was weak even at 1100C. The oxygen reduction mechanism was investigated by electrochemical impedance spectroscopy characterization. Over the intermediate-temperature range of 450700C, the electrode polarization resistance

  14. Synthesis and cationic ordering structure of samarium-doped lead magnesium niobate ceramics

    SciTech Connect

    Kim, B.K.; Cha, S.B. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Ceramics] [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Ceramics

    1997-06-01

    The pyrochlore-free 10 mol% Sm{sub 2}O{sub 3}-doped/undoped Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3} ceramics were fabricated and their cationic ordering structures were investigated by X-ray/electron diffraction techniques. In the X-ray diffraction patterns, only fundamental diffraction peaks were observed for the undoped Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}, while the (h + 1/2 k + 1/2 l + 1/2) superlattice reflections were also observed for the 10 mol% Sm{sub 2}O{sub 3}-doped Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}. In the electron diffraction patterns, the (h + 1/2 k + 1/2 l + 1/2) superlattice reflections as well as the fundamental diffraction spots were observed for the undoped and the 10 mol% Sm{sub 2}O{sub 3}-doped Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}, but the intensities of the superlattice reflections were stronger for the 10 mol% Sm{sub 2}O{sub 3}-doped Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}. It has been experimentally assured that Sm-doping enhances the 1:1 ordering of Mg{sup 2+} and Nb{sup 5+} ions in Pb(Mg{sub 1/3}Nb{sub 2/3})O{sub 3}.

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

    NASA Astrophysics Data System (ADS)

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

    2011-01-01

    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 scattering data reveal a fractal type correlation of building blocks in virgin powders. Increase in fractal dimension and reduction in upper cutoff vis--vis the densification of agglomerates were found with increasing calcination temperature. Calcination, beyond 900 C, results in breaking down of the fractal morphology almost completely. Such shrinkage event also results in a modification of the microscopic structure. These changes have been attributed to the compaction of agglomerates of both Ca- and Sr-doped lanthanum chromites, assisted via liquid state sintering by the melting of the intermediate phases at intermediate calcination stages.

  16. Effects of Magnetization on Hole Localization and MnO6 Octahedra Disorder in Hole-Doped Lanthanum Manganese Perovskites

    Microsoft Academic Search

    C. H. Booth; F. Bridges; J. J. Neumeier; E. L. Brosha; T. H. Geballe; G. J. Snyder; G. H. Kwei

    1999-01-01

    We review the distortions of the MnO6 octahedra reduced by magnetization in hole-doped lanthanum manganese perovskites. The systems we consider include the colossal magnetoresistance (CMR) samples La1-xCaxMnO3 (x=0.21, 0.25, 0.30), La0.67Ba0.33MnO3, and a poorer quality La0.67Pb0.33MnO3 sample. We also report preliminary work on three samples of oxygen-doped LaMnO3+d and a lanthanum-deficient La0.9MnO3 sample. We find the same exponential relationship between

  17. Piezoelectric, pyroelectric and dielectric properties of La and Sm-doped PZT ceramics

    Microsoft Academic Search

    C. Pramila; T. C. Goel; P. K. C. Pillai

    1993-01-01

    Pair-doped lead zirconate titanate (PZT) samples were prepared by introducing lanthanum (La) and samarium (Sm) into the PZT lattice. Three compositions of pair-doped PZT were prepared by a conventional method. The dielectric, piezoelectric and pyroelectric properties of these samples were studied and compared with that of PLZT(8\\/65\\/35) samples prepared under the same conditions. The piezoelectric and pyroelectric figures of merit

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

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

    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.

  19. Portable gamma spectrometry with cerium-doped lanthanum bromide scintillators: Suitability assessments for luminescence and electron spin resonance dating applications

    Microsoft Academic Search

    L. J. Arnold; M. Duval; C. Falgures; J.-J. Bahain; M. Demuro

    Cerium-doped lanthanum bromide (LaBr3:Ce) crystals offer a range of improved scintillation properties over traditional NaI:Tl crystals for in situ gamma spectrometry. At present, however, it remains unclear whether the internal radioactivity of LaBr3:Ce detectors compromises their suitability for low-level activity radioisotope measurements of natural sedimentary deposits, such as those required in luminescence and electron spin resonance (ESR) dating. In this

  20. Engineered hydrochar composites for phosphorus removal/recovery: Lanthanum doped hydrochar prepared by hydrothermal carbonization of lanthanum pretreated rice straw.

    PubMed

    Dai, Lichun; Wu, Bo; Tan, Furong; He, Mingxiong; Wang, Wenguo; Qin, Han; Tang, Xiaoyu; Zhu, Qili; Pan, Ke; Hu, Qichun

    2014-06-01

    Engineered hydrochar composites (EHC) were synthesized by hydrothermal carbonization (HTC) of lanthanum pretreated rice straw. The as-prepared composite with about 30% lanthanum content showed greater P removal potential than La(OH)3, indicating the synergistic effect of hydrochar and lanthanum in P removal. The adsorption results showed that EHC showed great P adsorption capacities (>50mgPg(-1)) in the pH range of 2.5-10.5, and the presence of competing anions had little negative effects on P adsorption on EHC. The equilibrium time for P adsorption on EHC was considerably reduced under acid condition (12h) compared to alkaline condition (48h). The maximum adsorption capacity was 61.57mgPg(-1) according to Langmuir isotherms. These results suggested that EHC was highly effective in P adsorption in a wide range of pH and the presence of competing anions, thus EHC could be a promising adsorbent for phosphorus removal/recovery from wastewater. PMID:24727355

  1. Optical assessment on a new self-frequency doubling crystal: neodymium-doped lanthanum calcium borate

    NASA Astrophysics Data System (ADS)

    Guo, Rui; Wu, Yicheng; Fu, Peizhen; Jing, Fangli

    2005-04-01

    A new, to our knowledge, neodymium-doped lanthanum calcium borate crystal (Nd3+:La2CaB10O19, Nd:LCB) has been grown by the flux method. The spectroscopic parameters for Nd:LCB crystal have also been calculated based on Judd-Ofelt theory. The intensity parameters ?t are ?2=4.9610-20 cm2, ?4=3.94 10-20 cm2, and ?6=3.7110-20 cm2. The radiative lifetime ?r is 349 ?s. The absorption band at 800 nm has a FWHM of 12 nm. The absorption cross section is ?a=2.4010-20 cm2, and the emission cross sections at 1070 nm are ?X=3.0210-19 cm2, ?Y=2.3310-19 cm2, and ?Z=2.6810-19 cm2. The measured fluorescence lifetime ?f is 64 ?s, and the quantum efficiency ? is 18.3%. In comparison with other Nd-doped laser crystals, the calculated parameters show that Nd:LCB crystal satisfies the fundamental spectral condition for laser emission.

  2. Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

    Microsoft Academic Search

    Go Okada; Brian Morrell; Cyril Koughia; Andy Edgar; Chris Varoy; George Belev; Tomasz Wysokinski; Dean Chapman; Safa Kasap

    2011-01-01

    The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm3+ --> Sm2+ valence conversion in Sm3+ doped fluorophosphates glasses has been tested for use in x-ray dosimetry for

  3. Anomalous Hall effect in calcium-doped lanthanum cobaltite and gadolinium

    NASA Astrophysics Data System (ADS)

    Baily, Scott Alan

    The physical origin of the anomalous (proportional to magnetization) Hall effect is not very well understood. While many theories account for a Hall effect proportional to the magnetization of a material, these theories often predict effects significantly smaller than those found in ferromagnetic materials. An even more significant deficiency of the conventional theories is that they predict an anomalous Hall resistivity that is proportional to a power of the resistivity, and in the absence of a metal insulator transition cannot account for the anomalous Hall effect that peaks near TC. Recent models based on a geometric, or Berry, phase have had a great deal of success describing the anomalous Hall effect in double-exchange systems (e.g., lanthanum manganite and chromium dioxide). In gadolinium, as in double-exchange magnets, the exchange interaction is mediated by the conduction electrons and the anomalous Hall effect may therefore resemble that of CrO2 and other metallic double-exchange ferromagnets. Lanthanum cobaltite is similar to manganite in many ways, but a strong double-exchange interaction is not present. Calcium-doped lanthanum cobaltite films were found to have the largest anomalous Hall effect of any ferromagnetic metal. The primary purpose of this study is to gain insight into the origin of the anomalous Hall effect with the hope that these theories can be extended to account for the effect in other materials. The Hall resistivity, magnetoresistance, and magnetization of a Gadolinium single crystal were measured in fields up to 30 T. Cobaltite films were grown via laser ablation and characterized by a variety of techniques. Hall resistivity, magnetoresistance, magnetization, and magnetothermopower of L 1-xCaxCoO3 samples with 0.15 < x < 0.4 were measured in fields up to 7 T. The Gd results suggest that Berry's phase contributes partially to the Hall effect near TC. Berry's phase theories hold promise for explaining the large anomalous Hall effect in La1-xCaxCoO3 near T C, but the material presents many additional complexities, including a unique low temperature magnetoresistance. At low temperature, the Hall effect may be best explained by spin-polarized carriers scattering off of orbital disorder in spin-ordered clusters.

  4. Crystal structures and magnetic properties of strontium and copper doped lanthanum ferrites

    SciTech Connect

    Sora, Isabella Natali, E-mail: isabella.natali-sora@unibg.it [INSTM R.U. and Department of Industrial Engineering, University of Bergamo, Dalmine, BG, I-24044 (Italy); Caronna, Tullio; Fontana, Francesca [INSTM R.U. and Department of Industrial Engineering, University of Bergamo, Dalmine, BG, I-24044 (Italy); Julian Fernandez, Cesar de [INSTM R.U. Firenze and Department of Chemistry, University of Florence, I-50019 Sesto Fiorentino (Italy); CNR-Istituto di Scienze e Tecnologie Molecolari (ISTM), 20133 Milano (Italy); Caneschi, Andrea [INSTM R.U. Firenze and Department of Chemistry, University of Florence, I-50019 Sesto Fiorentino (Italy); Green, Mark [Center for Neutron Research, NIST, Gaithersburg, MD (United States); Department of Materials Science and Engineering, University of Maryland, College Park, MD 20742-2115 (United States)

    2012-07-15

    The crystal and magnetic structures of La{sub 0.8}Sr{sub 0.2}Fe{sub 1-x}Cu{sub x}O{sub 3-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 LaFeO{sub 3}, 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)O{sub 6} 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 {mu}{sub x}=2.66(3){mu}{sub B} and 2.43(3){mu}{sub 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. - Graphical abstract: Hysteresis loops measured at room temperature of the sample with x=0.05. Highlights: Black-Right-Pointing-Pointer Iron based perovskites with the largest coercive fields. Black-Right-Pointing-Pointer Sr and Cu lanthanum ferrites as magnetic materials. Black-Right-Pointing-Pointer Doped lanthanum ferrites show antiferromagnetic and weak ferromagnetic interactions. Black-Right-Pointing-Pointer Sr and Cu lanthanum ferrites show distorted perovkite structure.

  5. 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)

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

    2011-07-01

    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.

  6. The effect of Pr co-dopant in samarium doped ceria

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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 30-1000C and it was observed that the thermal expansion increased linearly with increasing temperature for all the samples.

  7. Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

    SciTech Connect

    Okada, Go; Morrell, Brian; Koughia, Cyril; Kasap, Safa [Department of Electrical and Computer Engineering, University of Saskatchewan, Saskatoon, SK S7N 5A9 (Canada); Edgar, Andy; Varoy, Chris [School of Chemical and Physical Sciences and MacDiarmid Institute, Victoria University of Wellington, Kelburn Parade (New Zealand); Belev, George; Wysokinski, Tomasz [Canadian Light Source Inc., University of Saskatchewan, Saskatoon, SK S7N 0X4 (Canada); Chapman, Dean [Department of Anatomy and Cell Biology, University of Saskatchewan, Saskatoon, SK S7N 5E5 (Canada)

    2011-09-19

    The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm{sup 3+}{yields} Sm{sup 2+} valence conversion in Sm{sup 3+} doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to {approx}5 Gy and saturates at doses exceeding {approx}80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high ''peak-to-valley'' contrast have been observed by means of confocal photoluminescence microscopy.

  8. Spatially resolved measurement of high doses in microbeam radiation therapy using samarium doped fluorophosphate glasses

    NASA Astrophysics Data System (ADS)

    Okada, Go; Morrell, Brian; Koughia, Cyril; Edgar, Andy; Varoy, Chris; Belev, George; Wysokinski, Tomasz; Chapman, Dean; Kasap, Safa

    2011-09-01

    The measurement of spatially resolved high doses in microbeam radiation therapy has always been a challenging task, where a combination of high dose response and high spatial resolution (microns) is required for synchrotron radiation peaked around 50 keV. The x-ray induced Sm3+ ? Sm2+ valence conversion in Sm3+ doped fluorophosphates glasses has been tested for use in x-ray dosimetry for microbeam radiation therapy. The conversion efficiency depends almost linearly on the dose of irradiation up to 5 Gy and saturates at doses exceeding 80 Gy. The conversion shows strong correlation with x-ray induced absorbance of the glass which is related to the formation of phosphorus-oxygen hole centers. When irradiated through a microslit collimator, a good spatial resolution and high "peak-to-valley" contrast have been observed by means of confocal photoluminescence microscopy.

  9. Doping controlled spin reorientation in dysprosium-samarium orthoferrite single crystals

    NASA Astrophysics Data System (ADS)

    Cao, Shixun; Zhao, Weiyao; Kang, Baojuan; Zhang, Jincang; Ren, Wei

    2015-03-01

    As one of the most important phase transitions, spin reorientation (SR) in rare earth transition metal oxides draws much attention of emerging materials technologies. The origin of SR is the competition between different spin configurations which possess different free energy. We report the control of spin reorientation (SR) transition in perovskite rare earth orthoferrite Dy1-xSmxFeO3, a whole family of single crystals grown by optical floating zone method from x =0 to 1. Temperature dependence of the magnetizations under zero-field-cooling (ZFC) and field-cooling (FC) processes are studied. We have found a remarkable linear change of SR transition temperature in Sm-rich samples for x>0.2, which covers an extremely wide temperature range including room temperature. The a-axis magnetization curves under FCC process bifurcate from and then jump down to that of warming process (ZFC and FCW curves) in single crystals when x =0.5-0.9, suggesting complicated 4f-3d electron interactions among Dy3+-Sm3+, Dy3+-Fe3+, and Sm3+-Fe3+ sublattices of diverse magnetic configurations for materials physics and design. The magnetic properties and the doping effect on SR transition temperature in these single crystals might be useful in the spintronics device application. This work is supported by the National Key Basic Research Program of China (Grant No. 2015CB921600), and the National Natural Science Foundation of China (NSFC, Nos. 51372149, 50932003, 11274222).

  10. Adsorption behavior of phosphate on lanthanum(III) doped mesoporous silicates material.

    PubMed

    Zhang, Jianda; Shen, Zhemin; Shan, Wenpo; Chen, Ziyan; Mei, Zhijian; Lei, Yangming; Wang, Wenhua

    2010-01-01

    A series of lanthanum doped meosoporous MCM-41 (LaxM41, x is Si/La molar ratio) was prepared by sol-gel method. The surface structure of the materials was investigated with X-ray diffraction and N2 adsorption/desorption technique. The content of La in the materials was determined by ICP. It was found that the La content of La25M41, La50M41 and La100M41 was 7.53%, 3.89% and 2.32%, respectively. The phosphate adsorption capacities increased with increasing amount of La incorporation. With 0.40 g La25M41 99.7% phosphate could be removed. The effects of Si/La molar ratio, LaxM41 dose, pH, initial concentration of phosphate solution, co-ions on phosphate adsorption were also evaluated. The phosphate adsorption kinetics of LaxM41 could be well-described by the pseudo second-order model, and Langmuir isotherm fit equilibrium data much better than the Freundlich isotherm. PMID:20617725

  11. The influence of lanthanum doping on the physical and electrical properties of BTV ferroelectric thin films

    NASA Astrophysics Data System (ADS)

    Chen, Kai-Huang; Cheng, Chien-Min; Shih, Chia-Chi; Tsai, Jen-Hwan

    2011-06-01

    In this study, the ferroelectricity of as-deposited Bi3.9La0.1Ti2.9V0.1O12 (BLTV), Bi3.9Ti2.9V0.1O12 (BTV), and Bi4Ti3O12 (BIT) thin films was prepared and compared by rf magnetron sputtering technology. For the BLTV, BTV, and BIT thin films deposited on Pt/Ti/SiO2/Si and SiO2/Si substrate, the physical and electrical characteristics of lanthanum doped BTV (BLTV) were better than those of BIT and BTV thin films. Regarding the physical properties, the micro-structure of as-deposited BTV and BLTV thin films were obtained and compared by XRD patterns and SEM images. The BLTV and BTV thin films were also exhibited clear the ferroelectricity. The remanent polarization ( P r ) of as-deposited BLTV thin films was 11 C/cm2 as the measured frequency of 100 kHz. It was higher than those of BTV thin films. Finally, the polarization of BLTV thin film capacitor decreased by 9%, while that of the BTV decreased by 15% after the fatigue test with 109 switching cycles.

  12. Solid oxide fuel cells with doped lanthanum gallate electrolyte and LaSrCoO cathode, and Ni-samaria-doped ceria cermet anode

    Microsoft Academic Search

    Radenka Maric; Satoshi Ohara; Takehisa Fukui; Hiroyuki Yoshida; Masayoshi Nishimura; Toru Inagaki; Kazuhiro Miura

    1999-01-01

    The electrode performance of a single solid-oxide fuel cell (SOFC) was evaluated using a 500 μm 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-δ} 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

  13. [Study on preparation of lanthanum-doped TiO2 nanometer thin film materials and its photocatalytic activity].

    PubMed

    Zheng, Huai-li; Tang, Ming-fang; Gong, Ying-kun; Deng, Xiao-jun; Wu, Bang-hua

    2003-04-01

    In this paper, lanthanum-doped TiO2 nanometer film materials coated on glass were prepared in Ti(OBu)4 precursor solutions by sol-gel processing. Transmittance and photocatalytic activity were respectively investigated and tested for these nanometer thin films prepared with different amount of lanthanum (La), different amount of polyethylene glycol (PEG), and different coating layer times. Some reactive mechanisms were also discussed. For one layer La-addition had little effect on the film transmissivity; but the photocatalytic activity was significantly improved due to La-addition. With increasing PEG, the transmittance of the film decreased for one layer film; but its photocatalytic activity did not rise. Increasing layer number did not affect the transmissivity of multilayer film. After coating two times, increasing layer number did not significantly improve the photocatalytic activity. The highest photocatalytic activity and best transmissivity were obtained for two layer TiO2 film when the dosage of lanthanum was 0.5 g and the dosage of polyethylene was 0.2 g in the precursor solutions. These materials will probably be used in the protection of environment, waste water treatment, and air purification. PMID:12961861

  14. Photoluminescence and visible diffuse-reflection spectroscopic evidence of samarium reduction in air-fired samples of mixed samarium: strontium tetraborate precipitates.

    PubMed

    Brown, Telvin M; Jeffreys, Mareo C; Pehaire, Mario; Stump, Nathan A

    2013-03-01

    Photoluminescence and visible diffuse-reflection spectroscopies have provided evidence of the reduction of samarium to the divalent state in samarium-doped strontium borate and pure samarium borate samples. The samples were prepared by the air firing of homogeneous precipitates of divalent strontium and trivalent samarium ions from aqueous solutions with saturated sodium tetraborate. The use of this method in the preparation of divalent lanthanide ions has not been reported previously. Reduced samarium was observed in fired tetraborate precipitates prepared with solutions containing 1, 5, 10, 25, 50, 75, and 90 mole percent samarium versus strontium. Divalent samarium also was identified in fired precipitates of trivalent samarium solutions precipitated with tetraborate. Sm(2+) was identified as the primary emitting species in each of the eight compositions. However, diffuse-reflection spectroscopy indicated the presence of trivalent samarium in the studied samples, ranging from minimal for samples prepared with low samarium concentrations to nearly exclusive when pure samarium was studied. Quenching of the characteristic emission associated with the trivalent species is believed to result in the absence of the emission features arising from residual samarium(III) in the products. Although the absence of trivalent samarium emission enhanced the ability of emission spectroscopy to identify small amounts of divalent samarium, indicating that reduction had occurred, it limited the ability of this method to determine the extent of the reduction. Diffuse-reflection spectroscopy's ability to look at both species provided a much better analysis of the extent of samarium reduction. PMID:23452491

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

    SciTech Connect

    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

    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.

  16. Optical and transport properties of lanthanum-doped stannate BaSnO3

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

    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 Mssbauer 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.

  17. Joining of highly aluminum-doped lanthanum strontium manganese oxide with tetragonal zirconia by plastic deformation

    E-print Network

    Dutta, Prabir K.

    , Argonne, IL 60439, United States c The Center for Industrial Sensors and Measurement, 177 Watts Hall, 2041; LSAM; LSM; Ceramic conductor; Fuel cell; Sensor; Raman microscopy 1. Introduction Yttria sensors that exploit its high ionic conductivity [1]. Lanthanum stron- tium manganese oxide, LaxSr1 - x

  18. Thermal lens and Auger upconversion losses' effect on the efficiency of Nd3+-doped lead lanthanum zirconate titanate transparent ceramics

    NASA Astrophysics Data System (ADS)

    de Camargo, Andrea S. S.; Jacinto, Carlos; Catunda, Tomaz; Nunes, Luiz Antonio De O.; Garcia, Ducinei; Eiras, Jos Antonio

    2006-10-01

    A thorough investigation of optical losses for the 1064nm emission in Nd3+-doped lead lanthanum zirconate titanate (PLZT) transparent ceramics is presented. Thermal lens experiments were carried out to evaluate thermo-optical properties and the fluorescence quantum efficiency of the emitting level 4F3/2. Excited-state absorption losses were measured in the emitting wavelength region, and the Auger upconversion energy transfer parameter ? was calculated. By using ?, the pump-intensity dependence of the optical gain at 1064nm, the fluorescence quantum efficiency, and the generation of heat in the ceramic were simulated for a high 803nm pump-power regime. Since the radiative and nonradiative losses in Nd:PLZT were verified to be considerably lower than in various commercial laser crystals and glasses, it is suggested that this material might become an interesting alternative for high-power laser emission.

  19. Samarium-doped mesoporous TiO2 nanoparticles with improved photocatalytic performance for elimination of gaseous organic pollutants

    NASA Astrophysics Data System (ADS)

    Tang, Jianting; Chen, Xiaomiao; Liu, Yu; Gong, Wei; Peng, Zhenshan; Cai, Tiejun; Luo, Lianjing; Deng, Qian

    2013-01-01

    Mesoporous TiO2 doped with different amounts of Sm were prepared via a sol-gel route with Pluronic P123 as template. The materials were characterized by X-ray diffraction, transmission electron microscopy, and N2 sorption experiments, etc. The photocatalytic activity of the mesoporous TiO2 was tested in elimination of gaseous methanol and acetone. The Sm doped mesoporous TiO2 have higher activity than those of the commercial photocatalyst (Degussa, P25) and Sm doped TiO2 counterparts without mesopore structure under ultraviolet light irradiation. A possible mechanism was proposed to account for the high photocatalytic activity of the Sm doped mesoporous TiO2. The superior activity of the Sm doped mesoporous TiO2 may be attributed to the synergic effect of the high surface area, mesopore structure and doped Sm species.

  20. Doped lanthanum ferrite cathode development for use in single-step co-fired solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Zink, Peter Andrew

    A major obstacle to the commercialization of solid oxide fuel cells (SOFCs) is the high operating temperature range (800 to 1000C). Lowering the operating temperature to approximately 600C allows for cost reduction through the use of inexpensive stack housing and sealing materials, but conventional SOFC cathode materials have high charge transfer resistance at those temperatures which results in poor performance. This research focused on developing an SOFC cathode material with low charge transfer resistance at low operating temperatures and a porous microstructure that would not impede mass transfer when synthesized using the single-step co-firing process. Towards this goal, mixed ionic and electronic conducting lanthanum ferrite perovskite cathode materials were synthesized using calcium and cerium as dopants. A specific stoichiometry of calcium doped lanthanum ferrite, La0.78Ca0.16FeO3+/-delta (LCF), proved to be a superior cathode compared to state-of-the-art conventional cathode materials across a range of measures. In order to understand the LCF cathode performance, the defect model structure was determined using thermogravimetric (TGA) measurements, oxygen-ion permeability and four-probe conductivity measurements as a function of temperature and oxygen partial pressure (pO2). The results were analyzed to determine defect concentrations and mobility. The electrochemical performance of LCF was characterized using electrochemical impedance spectroscopy measurements on symmetrical cells which compared favorably to conventional lanthanum manganite cathode materials. Reactivity of LCF with yttria-stabilized zirconia (YSZ) electrolyte was confirmed and prevented using a gadolinium doped ceria (GDC) barrier layer. Microstructural analysis showed evidence of a small amount (2--5 wt%) of secondary phase that precipitated from LCF as a liquid during sintering at approximately 1220C. The secondary phase was a poor n-type oxide (Ca-Fe-O), present within both the LCF cathode and GDC barrier layer microstructures. In spite of the presence of the liquid phase, LCF symmetrical cells yielded adequate microstructures and satisfactory electrochemical performance. To understand the reasons for the superior electrochemical performance of LCF, the chemical oxygen ion diffusivity and surface exchange coefficient were determined using conductivity relaxation measurements. Both of these parameters in LCF were found to be an order of magnitude greater than conventional cathode materials.

  1. Highly active lanthanum doped ZnO nanorods for photodegradation of metasystox.

    PubMed

    Korake, P V; Dhabbe, R S; Kadam, A N; Gaikwad, Y B; Garadkar, K M

    2014-01-01

    La-doped ZnO nanorods with different La contents were synthesized by microwave assisted method and characterized by various sophisticated techniques such as XRD, UV-Vis., EDS, XPS, SEM and TEM. The XRD patterns of the La-doped ZnO indicate hexagonal crystal structure with an average crystallite size of 30nm. It was found that the crystallite size of La-doped ZnO is much smaller as compared to pure ZnO and decreases with increasing La content. The photocatalytic activity of 0.5mol% La-doped ZnO in the degradation of metasystox was studied. It was observed that degradation efficiency of metasystox over La-doped ZnO increases up to 0.5mol% doping then decreases for higher doping levels. Among the catalyst studied, the 0.5mol% La-doped ZnO was the most active, showing high photocatalytic activity for the degradation of metasystox. The maximum reduction of concentration of metasystox was observed under static condition at pH 8. Reduction in the Chemical Oxygen Demand (COD) of metasystox was observed after 150min. The cytotoxicological studies of meristematic root tip cells of Allium cepa were studied. The results obtained indicate that photocatalytically degraded products of metasystox were less toxic as compared to metasystox. PMID:24231392

  2. Effect of samarium doped ceria nanoparticles impregnation on the performance of anode supported SOFC with (Pr 0.7Ca 0.3) 0.9MnO 3? ? cathode

    Microsoft Academic Search

    Lin XIONG; Shaorong WANG; Zhenrong WANG; Tinglian WEN

    2010-01-01

    Solid oxide fuel cell (SOFC) electrodes, after a high temperature sintering, may be impregnated to deposit nanoparticles within their pores to enhance the catalytic function. Samarium doped CeO2 (SDC) nanoparticles were infiltrated into (Pr0.7Ca0.3)0.9MnO3?? (PCM) cathode of anode supported SOFC cells. The cell with 2.6 mg\\/cm2 SDC impregnated in cathode showed the maximum power density of 580 mW\\/cm2 compared with

  3. Electrical properties and thermal expansion of cobalt doped apatite-type lanthanum silicates based electrolytes for IT-SOFC

    SciTech Connect

    Shi, Qingle; Lu, Lihua; Jin, Hongjian [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)] [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China); Zhang, Hua, E-mail: huazhang@njut.edu.cn [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)] [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China); Zeng, Yanwei [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)] [College of Materials Science and Engineering, Nanjing University of Technology, No.5 Xinmofan Road, Nanjing, Jiangsu (China)

    2012-03-15

    Graphical abstract: The figure shows the dependence of conductivity on the Co content. It can be seen that La{sub 10}Si{sub 5.2}Co{sub 0.8}O{sub 26.6} exhibits the highest ionic conductivity of 3.33 Multiplication-Sign 10{sup -2} S/cm at 800 Degree-Sign C. When x {<=} 0.8, as doping Co weakens the binding energy and aids the migration of the interstitial oxide ions, the ionic conductivity improves. On the other hand, excess dopant of Co (0.8 < x {<=} 1.5) can decrease the number of interstitial oxide ions and reduce the ionic conductivity. Highlights: Black-Right-Pointing-Pointer The unit volumes of La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} increase with increasing cobalt content. Black-Right-Pointing-Pointer Doping Co can increase the thermal expansion because of the larger radius of Co{sup 3+} ion. Black-Right-Pointing-Pointer Conductivities of La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} first increase and then decrease with cobalt content. Black-Right-Pointing-Pointer Above 550 Degree-Sign C, La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} shows low activation energies of around 0.7 eV. -- Abstract: The thermal expansion and conductivities have been investigated for Co{sup 3+} doped lanthanum silicates. The apatite-type lanthanum silicates with formula La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} (x = 0.2, 0.4, 0.6, 0.8, 1.0, 1.5) were synthesized by sol-gel process. The thermal expansion coefficient (TEC) of La{sub 10}Si{sub 6-x}Co{sub x}O{sub 27-x/2} was improved with increasing cobalt content because of the lower valence and larger radius of Co{sup 3+} ion compared to Si{sup 4+}. Analysis of AC impedance spectroscopy showed that conductivity increased first and then decreased with increasing cobalt content. There is an optimum doping amount of cobalt and La{sub 10}Si{sub 5.2}Co{sub 0.8}O{sub 26.6} exhibits the highest conductivity of 3.33 Multiplication-Sign 10{sup -2} S/cm at 800 Degree-Sign C. When x {<=} 0.8, the local distortion caused by doping with Co{sup 3+} can significantly affect the oxygen channels and assist the migration of the interstitial oxide ions, resulting in the improvement of ionic conductivity. However, excess Co{sup 3+} dopant (0.8 < x {<=} 1.5) reduced the number of interstitial oxide ions and decreased the conductivity.

  4. Fabrication of Sr- and Co-doped lanthanum chromite interconnectors for SOFC

    SciTech Connect

    Setz, L.F.G. [Departamento de Engenharia de Materiais, Universidade Federal de Sao Carlos - DEMa/UFSCar (Brazil) [Departamento de Engenharia de Materiais, Universidade Federal de Sao Carlos - DEMa/UFSCar (Brazil); Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil); Santacruz, I. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain)] [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Universidad de Malaga, 29071 Malaga (Spain); Colomer, M.T., E-mail: tcolomer@icv.csic.es [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain); Mello-Castanho, S.R.H. [Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil)] [Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN (Brazil); Moreno, R. [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain)] [Instituto de Ceramica y Vidrio, ICV (CSIC), 28049 Madrid (Spain)

    2011-07-15

    Graphical abstract: FESEM micrographs of the fresh fracture surfaces for the La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} sintered specimens cast from optimised suspensions with 13.5, 15 and 17.5 vol.% solids loading. Aqueous suspensions were prepared using ammonium polyacrylate (PAA) as dispersant and tetramethylammonium hydroxide (TMAH) to assure a basic pH and providing stabilization. Sintering of the green discs was performed in air at 1600 {sup o}C for 4 h. Highlights: {yields} Optimum casting slips were achieved with 3 wt.% of ammonium polyacrylate and 1 wt.% of tetramethylammonium hydroxide. -- Abstract: Many studies have been performed dealing with the processing conditions of electrodes and electrolytes in solid oxide fuel cells (SOFCs). However, the processing of the interconnector material has received less attention. Lanthanum chromite (LaCrO{sub 3}) is probably the most studied material as SOFCs interconnector. This paper deals with the rheology and casting behaviour of lanthanum chromite based materials to produce interconnectors for SOFCs. A powder with the composition La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} was obtained by combustion synthesis. Aqueous suspensions were prepared to solids loading ranging from 8 to 17.5 vol.%, using ammonium polyacrylate (PAA) as dispersant and tetramethylammonium hydroxide (TMAH) to assure a basic pH and providing stabilization. The influence of the additives concentrations and suspension ball milling time were studied. Suspensions prepared with 24 h ball milling, with 3 wt.% and 1 wt.% of PAA and TMAH, respectively, yielded the best conditions for successful slip casting. Sintering of the green discs was performed in air at 1600 {sup o}C for 4 h leading to relatively dense materials.

  5. Low-temperature high-pressure spectroscopy of lanthanum lutetium gallium garnet crystals doped with Cr3+ and Nd3+

    NASA Astrophysics Data System (ADS)

    Kami?ska, A.; Kaczor, P.; Durygin, A.; Suchocki, A.; Grinberg, M.

    2002-03-01

    Low-temperature luminescence measurements under high pressures in diamond-anvil cell of nonstoichiometric lanthanum lutetium gallium garnet (LLGG) doped with Cr3+ ions and nonintentionally with Nd3+ ions are reported. Three nonequivalent Cr3+ centers were found in the crystal using this technique. The results also reveal information about the electronic structure of different Cr3+ centers in those crystals. Cr3+ ions in a LLGG crystal experience a very low crystal field strength. The energy differences between the 4T2 and 2E levels are negative, and equal to about -1100 cm-1 for two of those centers and about -1500 cm-1 for the third one. The spectral results were corroborated by a theoretical analysis of the luminescence decay times as a function of pressure, which allowed one to establish the exact values of the crystal-field parameter Dq at ambient pressure for those centers. The crystal exhibits a large inhomogeneous broadening of the R lines, associated with nonstoichiometry. In addition to the Cr3+ luminescence also luminescence of Nd3+ ions was detected in the LLGG crystals. One of the Nd3+ luminescence lines, associated with the 4F3/2-->4I9/2 transition, is strongly dependent on pressure, with a pressure coefficient equal to 0.96+/-0.02 cm-1/kbar, which makes this system interesting as a pressure gauge in the infrared region.

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

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

    X-ray diffraction (XRD), dielectric constant (?'), dielectric loss factor (??), 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.

  7. Phase stability and processing of strontium and magnesium doped lanthanum gallate

    NASA Astrophysics Data System (ADS)

    Zheng, Feng

    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 and Mg doped LaGaO3 (LSGM) perovskite is a new oxygen-ionic conductor with higher conductivity than yttria-stabilized zirconia (YSZ). This material is a candidate for a wide variety of electrochemical devices. In order to realize this potential, the phase stability and processing of this material needs to be investigated in detail. In this study, a systematic investigation of the LSGM materials in terms of phase stability, phase transition, sintering, microstructure and electrical conductivity as functions of temperature, doping content and A/B cation ratio has been carried out. The generalized formula of the materials investigated is (La1--xSrx)A(Ga1--yMg y)BO3--delta. Optimized processing parameters have been obtained by investigating their impact on density change and microstructure. Consequently, a suitable compositional window of the LSGM perovskite has been identified for SOFC electrolyte applications. Based on detailed diffraction analysis, it is found that the undoped LaGaO3 takes on the orthorhombic (Pbnm) symmetry at room temperature. This structure changes to rhombohedral (R3c) at 147 +/- 2C or changes to monoclinic (I2/a) when the doping level increases from 0.1 to 0.2 moles. We have optimized the compositional window to make the single perovskite phase with high oxygen ionic conductivity (x = 0.10 to 0.20 with A/B ratio between 0.98 to 1.02). The best processing condition, starting from glycine nitrate process (GNP) combustion synthesized ultra-fine LSGM powder, is sintering in air at 1500C for 2 hours. The doped material has higher oxygen ionic conductivity than YSZ at all temperatures. In addition, based on the structure and phase relations, a high temperature phase diagram for this system has been proposed. Finally, a model has been proposed to account for the high ionic conductivity of this material and to explain the effect of the doping content and the stoichiometry on the ionic conductivity. (Abstract shortened by UMI.)

  8. Microwave-assisted synthesis of Eu3+ doped lanthanum orthoborates, their characterizations and luminescent properties

    NASA Astrophysics Data System (ADS)

    Badan, Cansin; Esenturk, Okan; Y?lmaz, Ay?en

    2012-11-01

    LaBO3 with various particle sizes have been successfully prepared by microwave-assisted combustion and sol-gel synthesis methods. Urea, citric acid and glycine have been used as fuels during the synthesis process. Characterizations were done by X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) Spectroscopy, Photoluminescence Excitation and Emission Spectroscopies, Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM). The SEM micrographs show dissimilar morphologies of powders with different particle sizes. Luminescent properties of 2.5%, 5.0%, and 7.5% Eu doped LaBO3 synthesized with three different fuels were compared. The results showed that a 5% level is the critical doping amount for all, and the one synthesized with urea gives rise to the stronger emissions compared to others.

  9. Phase stability and processing of strontium and magnesium doped lanthanum gallate

    Microsoft Academic Search

    Feng Zheng

    2000-01-01

    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

  10. Effect of lanthanum doping on the electrical properties of sol-gel derived ferroelectric lead-zirconate-titanate for ultra-large-scale integration dynamic random access memory applications

    Microsoft Academic Search

    C. Sudhama; J. Kim; J. Lee; V. Chikarmane; W. Shepherd; E. R. Myers

    1993-01-01

    Thin films of lead-zirconate-titanate [(PZT) PbZr{sub 0.5}Ti{sub 0.5})O] possess demonstrably adequate charge storage densities and endurance to read\\/write cycling for ultra-large-scale integration dynamic random access memory (DRAM) applications. Lanthanum (donor) doping is expected to reduce the (p-type) conductivity to acceptable levels (<10⁻⁶ A\\/cm²). In this study, six thin films of 200 nm sol-gel derived lanthanum-doped PZT, with the [La]\\/([La] +

  11. Growth and spectroscopic properties of ytterbium-doped lanthanum calcium borate (Yb 3+:La 2CaB 10O 19) crystal

    Microsoft Academic Search

    Rui Guo; Yicheng Wu; Peizhen Fu; Fangli Jing

    2005-01-01

    A new ytterbium-doped lanthanum calcium borate crystal (Yb3+:La2CaB10O19, Yb:LCB) has been grown by the flux method. The spectroscopic properties have been investigated and the fundamental spectral parameters for Yb:LCB crystal have been calculated. Yb:LCB crystal has the strongest absorption at 976 nm with a full-width at half-maximum of 14 nm. The absorption and emission cross-sections are 1.1610?20 and 3.5110?20 cm2,

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

    PubMed Central

    Hanafy, Taha A.

    2012-01-01

    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; 300450?K and 1?kHz4?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. PMID:22933826

  13. Development of zirconia electrolyte films on porous doped lanthanum manganite cathodes by electrophoretic deposition

    SciTech Connect

    Basu, R.N.; Randall, C.A.; Mayo, M.J.

    2000-07-01

    Electrophoretic deposition (EPD) was explored as an inexpensive route for fabricating the 8 mol% yttria stabilized zirconia electrolyte in solid oxide fuel cells (SOFCs). Normally, deposition of particulate ceramic powders onto a sintered porous surface yields a non uniform coating which, after sintering, results in porosity, surface roughness and cracking in the coating. To overcome this problem, the present study used a fugitive graphite interlayer between the porous air electrode supported (AES) cathode tube (doped-LaMnO{sub 3}) and the deposited zirconia film. By this approach, a fairly dense green coating ({approximately}60%) was obtained, which yielded a smooth surface and pore-free microstructure after sintering. Preliminary results on the effect of a fugitive interlayer on the unfired (green) and fired zirconia coatings are discussed.

  14. Growth and spectroscopic properties of ytterbium-doped lanthanum calcium borate (Yb 3+:La 2CaB 10O 19) crystal

    NASA Astrophysics Data System (ADS)

    Guo, Rui; Wu, Yicheng; Fu, Peizhen; Jing, Fangli

    2005-01-01

    A new ytterbium-doped lanthanum calcium borate crystal (Yb 3+:La 2CaB 10O 19, Yb:LCB) has been grown by the flux method. The spectroscopic properties have been investigated and the fundamental spectral parameters for Yb:LCB crystal have been calculated. Yb:LCB crystal has the strongest absorption at 976 nm with a full-width at half-maximum of 14 nm. The absorption and emission cross-sections are 1.16 10 -20 and 3.51 10 -20 cm 2, respectively. The fluorescence lifetime is 0.95 ms. The ground-state energy level splitting is calculated to be 640 cm -1. In comparison with other Yb-doped laser crystals, the calculated parameters show that Yb:LCB crystal satisfies the fundamental spectral condition for laser emission.

  15. Dielectric and ferroelectric properties of lanthanum doped SrBi{sub 4}Ti{sub 4}O{sub 15} ferroelectric ceramics

    SciTech Connect

    Ashok, K.; Sarah, P., E-mail: pasala_sarah@yahoo.com [Vardhaman College of Engineering, Shamshabad (India); Raju, V.S. [National Centre for Compositional Characterization of Materials, Bhabha Atomic Research Centre, Hyderabad (India); Chandralingam, S. [Department of Physics, Jawaharlal Nehru Technological University, College of Engineering, Hyderabad (India)

    2011-07-01

    Bismuth layer structure ferroelectrics (BLSFs) have attracted intensive investigation for the potential use in non volatile ferroelectric random access memory (FeRAM) and piezoelectric devices suitable at high temperature. Bismuth layered structured compounds with general formula of (Bi{sub 2}O{sub 2}){sup 2+} (A{sub m-1}B{sub m}O{sub 3m+1}){sup 2-} are firstly found by Aurivillius. The structure of these compounds can be described as pseudo-perovskite (A{sub m-1}B{sub m}O{sub 3m+1}){sup 2-} slabs separated by (Bi{sub 2}O{sub 2}){sup 2+} layers along the crystallographic c-axis. The 12-coordinated A site can be occupied by such cations as La{sup 3+}, Bi{sup 3+}, Ba{sup 2+}, Sr{sup 2+}, Pb{sup 2+}, Ca{sup 2+}, Na{sup +}, etc. While the octahedral-coordinated B site can be occupied by W{sup 6+}, Nb{sup 5+}, Ta{sup 5+}, Ti{sup 4+} etc. Lanthanum substituted BiT (Bi{sub 4}Ti{sub 4}O{sub 12}) known as BLT has been extensively investigated. With this substitution, BLT shows relatively large P{sub r}, low synthesis temperature and good fatigue endurance which makes it a potential candidate for FeRAM application. So, lanthanum doping is an effective way to improve the ferroelectric and fatigue properties of Bi{sub 4}Ti{sub 4}O{sub 12}. Lanthanum doped Bismuth layer structure ferroelectrics (BLSFs) ceramics SrBi{sub 4-x}La{sub x}Ti{sub 4}O{sub 15} (x=0, 0.025, 0.050, 0.075, 0.1) were prepared by solid state reaction method. X-ray diffraction pattern showed that single phase was formed when x=0-0.1. Morphological studies were carried out by SEM analysis. It was found that crystal lattice constant, dielectric and electrical properties of SBT ferroelectrics varied appreciably with amount of doping. Dielectric measurements in the frequency range 100Hz-1MHz were made using an impedance analyzer (Wayne Kerr 6500P) and the measurements were carried out from RT to 600 deg C. The ferroelectric hysteresis loop was traced at room temperature by a standard P-E loop tracer based on sawyer-tower circuit. The values of 2P{sub r} and E{sub c} for pure and lanthanum doped SBT are given. The above results indicate that La{sup 3+} modification is an effective way to improve the ferro electrical properties of SrBi{sub 4}Ti{sub 4}O{sub 15}. The transition temperature (T{sub c}) and dielectric constant for SrBi{sub 4}Ti{sub 4}O{sub 15} are given. It is observed that with the increasing of lanthanum content remnant polarization increases and coercive field decreases. It is believed that these materials are potentially attractive candidates for FeRAM industry.

  16. Electronic conductivity measurement of Sm and La-doped ceria ceramics by HebbWagner method

    Microsoft Academic Search

    Taro Shimonosono; Yoshihiro Hirata; Yuka Ehira; Soichiro Sameshima; Teruhisa Horita; Harumi Yokokawa

    2004-01-01

    Samarium- and lanthanum-doped ceria powders with compositions Ce0.8Sm0.2O1.9 (SDC) and Ce0.8La0.2O1.9 (LDC) were prepared by heating the oxalate solid solution (Ce0.8R0.2)2(C2O4)3 (R=Sm, La) at 873 K in air. As-prepared powders were densified to 96.397.4% relative density by sintering in air at 1773 K for 4 h. The electronic current of disk sample was measured at 1073 K for SDC and

  17. Variation in band gap of lanthanum chromate by transition metals doping LaCr{sub 0.9}A{sub 0.1}O{sub 3} (A:Fe/Co/Ni)

    SciTech Connect

    Naseem, Swaleha, E-mail: wasiamu@gmail.com; Khan, Wasi, E-mail: wasiamu@gmail.com; Saad, A. A., E-mail: wasiamu@gmail.com; Shoeb, M., E-mail: wasiamu@gmail.com; Ahmed, Hilal, E-mail: wasiamu@gmail.com; Naqvi, A. H. [Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z.H. College of Engg. and Technology, Aligarh Muslim University, Aligarh-202002 (India); Husain, Shahid [Department of Physics, Aligarh Muslim University, Aligarh-202002 (India)

    2014-04-24

    Transition metal (Fe, Co, Ni) doped lanthanum chromate (LaCrO{sub 3}) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 800C. Microstructural studies were carried by XRD and SEM/EDS techniques. The results of structural characterization show the formation of all samples in single phase without any impurity. Optical properties were studied by UV- visible and photoluminescence techniques. The energy band gap was calculated and the variation was observed with the doping of transition metal ions. Photoluminescence spectra show the emission peak maxima for the pure LaCrO{sub 3} at about 315 nm. Influence of Fe, Co, Ni doping was studied and compared with pure lanthanum chromate nanoparticles.

  18. 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)

    Sadiq, Muhammad; Pesci, Raphal; Cherkaoui, Mohammed

    2013-03-01

    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 150C, 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 20C for as-cast samples and after thermal aging at 150C for 100 h and 200 h. Both yield stress and tensile strength are increased by up to 20% by minute lanthanum doping.

  19. Development of lanthanum ferrite SOFC cathodes

    Microsoft Academic Search

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

    2003-01-01

    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 (700800C) performance, and long-term cell stability. Investigations involved manipulation of the lanthanum ferrite chemistry, addition of noble metal oxygen reduction

  20. Study of the Durability of Doped Lanthanum Manganite and Cobaltite Cathode Materials under Real World Air Exposure Atmospheres

    SciTech Connect

    Singh, Prabhakar; Mahapatra, Manoj; Ramprasad, Rampi; Minh, Nguyen; Misture, Scott

    2014-11-30

    The overall objective of the program is to develop and validate mechanisms responsible for the overall structural and chemical degradation of lanthanum manganite as well as lanthanum ferrite cobaltite based cathode when exposed to real world air atmosphere exposure conditions during SOFC systems operation. Of particular interest are the evaluation and analysis of degradation phenomena related to and responsible for (a) products formation and interactions with air contaminants, (b) dopant segregation and oxide exolution at free surfaces, (c) cation interdiffusion and reaction products formation at the buried interfaces, (d) interface morphology changes, lattice transformation and the development of interfacial porosity and (e) micro-cracking and delamination from the stack repeat units. Reaction processes have been studied using electrochemical and high temperature materials compatibility tests followed by structural and chemical characterization. Degradation hypothesis has been proposed and validated through further experimentation and computational simulation.

  1. Stability of the Zhang-Rice Singlet with Doping in Lanthanum Strontium Copper Oxide Across the Superconducting Dome and Above.

    PubMed

    Brookes, N B; Ghiringhelli, G; Charvet, A-M; Fujimori, A; Kakeshita, T; Eisaki, H; Uchida, S; Mizokawa, T

    2015-07-10

    The spin character of the states at the top of the valence band in doped La_{2-x}Sr_{x}CuO_{4} (x=0.03, 0.07, 0.15, 0.22, and 0.30) has been investigated using spin-polarized resonant photoemission. A clear Zhang-Rice singlet (ZRS) is observed at all doping levels. Its stability and polarization are preserved as a function of doping, suggesting that the concept of the ZRS can be used across a wide doping range and up to the metallic nonsuperconducting overdoped regime. The results are significant for theoretical models that use the ZRS approximation and for the understanding of the peculiar interplay between the ZRS and the remaining localized spins. PMID:26207496

  2. X-ray radiometric determination of lanthanides (praseodymium, neodymium, and samarium) in soils

    NASA Astrophysics Data System (ADS)

    Savichev, A. T.; Vodyanitskii, Yu. N.

    2011-04-01

    A procedure of the modified energy-dispersive X-ray fluorescence method (X-ray radiometric analysis using a 241Am radionuclide source) was developed for the identification of praseodymium, neodymium, and samarium. The procedure is based on the exclusion of the disturbing effect of barium and lanthanum on the lines of praseodymium and neodymium, as well as the effect of lanthanum and cerium on the lines of samarium. On the basis of the new method, data were obtained on the geochemistry of three lanthanides in soils of the northern taiga. Praseodymium and neodymium were detected by the X-ray radiometric method even in podzols depleted of heavy metals. The method can detect samarium at the levels of the soil clarke and higher. Positive samarium (or, wider, rare-earth) anomalies can be expected in the soils located not far from the deposits of apatite-nephelines, loparites, and phosphorites and in the soils developed on alkaline granites and carbonate weathering crusts.

  3. Citrate gel synthesis of aluminum-doped lithium lanthanum titanate solid electrolyte for application in organic-type lithium-oxygen batteries

    NASA Astrophysics Data System (ADS)

    Le, Hang T. T.; Kalubarme, Ramchandra S.; Ngo, Duc Tung; Jang, Seong-Yong; Jung, Kyu-Nam; Shin, Kyoung-Hee; Park, Chan-Jin

    2015-01-01

    Aluminium doped lithium lanthanum titanate (A-LLTO) powders with various excess Li2O content are synthesized using a simple citrate gel method. The obtained A-LLTO powders show an agglomerated form, composed of nano-sized particles of 20-50 nm. The morphology and conductivity of the A-LLTO ceramics are largely affected by the content of excess Li2O. The highest total ionic conductivity of 3.17 10-4 S cm-1 is achieved for the A-LLTO sample containing 20% excess Li2O, exhibiting a vacancy content of 6%, and a total activation energy of 0.358 eV. The A-LLTO can act as a membrane to protect lithium metal from oxygen and other contaminants diffused through the oxygen electrode part. The Li-O2 cell employing the A-LLTO solid electrolyte shows a good cycle life of longer than 100 discharge-charge cycles, under the constant capacity mode of 300 mAh g-1.

  4. Electrochemical ammonia synthesis from steam and nitrogen using proton conducting yttrium doped barium zirconate electrolyte with silver, platinum, and lanthanum strontium cobalt ferrite electrocatalyst

    NASA Astrophysics Data System (ADS)

    Yun, Dae Sik; Joo, Jong Hoon; Yu, Ji Haeng; Yoon, Hyung Chul; Kim, Jong-Nam; Yoo, Chung-Yul

    2015-06-01

    Electrochemical ammonia synthesis from steam and nitrogen has been systematically investigated using a proton-conducting electrolyte supported cell based on 20 mol% yttrium doped barium zirconate (BaZr0.8Y0.2O3-?) in a temperature range of 475-600 C at atmospheric pressure. Silver (Ag), platinum (Pt), and lanthanum strontium cobalt ferrite (La0.6Sr0.4Co0.2Fe0.8O3-?) are used for both anode and cathode electrocatalysts. Maximum ammonia formation rates of 4.9 10-11 mol cm-2 s-1 and 8.5 10-11 mol cm-2 s-1 are observed for Ag and La0.6Sr0.4Co0.2Fe0.8O3-? electrocatalysts, respectively, when a voltage of 0.8 V is applied. However, Pt electrocatalyst shows a negligible ammonia formation rate lower than 1 10-12 mol cm-2 s-1. This is ascribed to the high activity of Pt for the hydrogen evolution reaction rather than the ammonia formation reaction. The conversion efficiency of all electrocatalysts is below 1%, primarily due to the limited nitrogen disassociation activity of the electrocatalysts.

  5. Structure and properties of antimony-doped lanthanum molybdate La{sub 2}Mo{sub 2}O{sub 9}

    SciTech Connect

    Alekseeva, O. A., E-mail: olalex@ns.crys.ras.ru; Verin, I. A.; Sorokina, N. I. [Russian Academy of Sciences, Shubnikov Institute of Crystallography (Russian Federation); Kharitonova, E. P.; Voronkova, V. I. [Moscow State University (Russian Federation)

    2011-05-15

    Polycrystalline samples of the composition La{sub 2}Mo{sub 2-x}Sb{sub x}O{sub 9-y}, where 0 {<=} x {<=} 0.05, were prepared by solid-phase synthesis. Single crystals of La{sub 2}Mo{sub 1.96}Sb{sub 0.04}O{sub 8.17} were obtained by spontaneous crystallization from flux. The structure of the metastable {beta}{sub ms} phase of this compound was determined at room temperature by X-ray diffraction. It was found that the La, Mo, and O1 atoms are displaced from the threefold axis on which they are located in the high-temperature {beta} phase. It was shown that molybdenum atoms in the crystal structure are partially replaced by antimony atoms, which are located on the threefold axis. In antimony-doped crystals, lanthanum atoms partially return to the site on the threefold axis and the coordination environment of molybdenum cations becomes more ordered, thus facilitating the stabilization of the cubic phase at room temperature. Calorimetric measurements (DSC) showed that the introduction of Sb as the dopant into the La{sub 2}Mo{sub 2}O{sub 9} structure leads to a decrease in the temperature of the {alpha} {yields} {beta} phase transition from 570 to 520 Degree-Sign C and to the partial suppression of this transition. The temperature behavior of the conductivity confirms the DSC data. Thus, doping with Sb contributes to the stabilization of the cubic phase at room temperature.

  6. Structural and magnetic properties of yttrium and lanthanum-doped Ni-Co and Ni-Co-Zn spinel ferrites

    NASA Astrophysics Data System (ADS)

    Stergiou, Charalampos; Litsardakis, George

    2014-11-01

    Rare earth doping of Co-rich spinel ferrites is investigated through the preparation of two groups of polycrystalline Ni-Co and Ni-Co-Zn ferrites, where Fe is partly substituted by Y and La. The characterization of the sintered ferrites by means of X-ray powder diffraction and Rietveld profile analysis, indicates the subtle expansion of the spinel unit cell and the cation redistribution in the doped ferrites in order to accommodate the incorporation of Y and La in the lattice. The impurity traces, detected only in the Ni-Co-Zn group, is ascribed to the Zn population in the tetrahedral A-sites impeding the cation transfer. Moreover, the examined microstructure of the doped Ni-Co samples comprises enlarged and more homogeneous grains, whereas grain growth is moderated in the doped Ni-Co-Zn ferrites. The discussed characteristics of the crystal and magnetic structure along with the morphological aspects define the impact of Y and La doping on the static magnetic properties of Ni-Co and Ni-Co-Zn ferrites, saturation magnetization MS and coercivity HC, which were extracted from the respective hysteresis loops.

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

    DOEpatents

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

    1992-07-21

    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.

  8. Modified giant dielectric properties of samarium doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    SciTech Connect

    Thongbai, Prasit, E-mail: pthongbai@kku.ac.th [Integrated Nanotechnology Research Center (INRC), and Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand)] [Integrated Nanotechnology Research Center (INRC), and Department of Physics, Faculty of Science, Khon Kaen University, Khon Kaen 40002 (Thailand); Putasaeng, Bundit; Yamwong, Teerapon [National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani, 12120 (Thailand)] [National Metal and Materials Technology Center (MTEC), Thailand Science Park, Pathumthani, 12120 (Thailand); Maensiri, Santi [School of Physics, Institute of Science, Suranaree University, Nakhon Ratchasima 30000 (Thailand)] [School of Physics, Institute of Science, Suranaree University, Nakhon Ratchasima 30000 (Thailand)

    2012-09-15

    Highlights: ? Grain size of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics was greatly decreased by doping with Sm{sup 3+}. ? ?? and tan ? decreased with increasing the concentration of Sm{sup 3+} doping. ? Ca{sub 0.925}Sm{sub 0.05}Cu{sub 3}Ti{sub 4}O{sub 12} exhibited ?? ? 10,863 and low tan ? ? 0.043 at 20 C and 1 kHz. -- Abstract: Effects of Sm{sup 3+} substitution on the microstructure and dielectric properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics were investigated. The grain size of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics was greatly decreased by doping with Sm{sup 3+}, resulting from the ability of Sm{sup 3+} to inhibit the grain growth rate. This result can cause a decrease in the dielectric constant (??) and loss tangent (tan ?) of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics. Interestingly, high dielectric permittivity (?? ? 10,863) and low loss tangent (tan ? ? 0.043 at 20 C and 1 kHz) were observed in the Ca{sub 0.925}Sm{sub 0.05}Cu{sub 3}Ti{sub 4}O{sub 12} ceramic. Nonlinear electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics were modified by doping with Sm{sup 3+}. The dielectric relaxation behavior of Sm-doped CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics can be well ascribed based on the internal barrier layer capacitor model of Schottky barriers at the grain boundaries.

  9. Lanthanum carbonate.

    PubMed

    Freemont, A J

    2006-12-01

    Controlling hyperphosphatemia in patients with chronic renal failure on renal dialysis is a major problem. None of the available calcium- or aluminum-based phosphate binders match the requirements for an ideal agent, each having its own limitations. The introduction of sevelamer hydrochloride represented a step change in management. Lanthanum carbonate is an alternative nonaluminium, noncalcium phosphate binder. Taken with food, it is well tolerated. It is poorly absorbed and does not require functioning kidneys to be removed from the body. There is no evidence from current studies that it accumulates to biologically significant levels in tissues, but despite the large numbers of patients included in clinical trials, experience with long-term dosing is limited and, as with every new drug used in this type of clinical setting, patients should be carefully monitored as experience with the drug increases. Lanthanum carbonate binds phosphate effectively across the physiological pH range of the upper gastrointestinal tract, and has no detrimental effect on calcium, vitamin D or parathyroid hormone metabolism. From the extensive trial data it seems that lanthanum carbonate is an effective and practical phosphate binder. Lanthanum carbonate and sevelamer are two new oral phosphate binding agents that with others currently in preclinical trials, such as stabilized polynuclear iron idroxide, could well represent a significant breakthrough in the management of hyperphosphatemia in patients with chronic renal failure in whom dietary phosphate restriction and cheaper oral phosphate binding agents prove unsatisfactory. Comparative trials and enhanced clinical experience are needed before the exact place of these competing and complementary therapies can be properly identified in patient management. PMID:17285149

  10. Synthesis of lanthanum oxide doped photocatalytic nano titanium oxide through aqueous solgel method for titania multifunctional ultrafiltration membrane

    Microsoft Academic Search

    K. A. Manjumol; V. S. Smitha; P. Shajesh; K. V. Baiju; K. G. K. Warrier

    2010-01-01

    An all aqueous sol gel route has been demonstrated for the synthesis of titania multifunctional ultrafiltration membrane on\\u000a porous alumina substrate. Doping with lanthana was used to increase the thermal stability of anatase phase. This resulted\\u000a in a nanoporous membrane with considerable percentage of anatase phase even after consolidation at 800C. The highly homogeneous\\u000a membranes with a thickness of ~45?m

  11. 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)

    Lu, Feng

    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.

  12. Microstructure, magnetoresistance, and magnetic properties of pulsed-laser-deposited external, internal, and mixed-doped lanthanum manganite films

    Microsoft Academic Search

    Srinivas V. Pietambaram; D. Kumar; Rajiv K. Singh; C. B. Lee; Vidya S. Kaushik

    1999-01-01

    In this article we report our studies on the microstructure, magnetoresistance (MR) behavior, and magnetic properties of the La1?x?yCaxMnO3 system in thin-film form. By varying the values of x and y in La1?x?yCaxMnO3, we have synthesized an external- (x=0.3,y=0), an internal- (x=0,y=0.3), and a mixed-doped (x=0.2,y=0.1) system with the same Mn3+\\/Mn4+ ratio. Thin films of these materials have been grown

  13. Microstructure, magnetoresistance, and magnetic properties of pulsed-laser-deposited external, internal, and mixed-doped lanthanum manganite films

    Microsoft Academic Search

    Srinivas V. Pietambaram; D. Kumar; Rajiv K. Singh; C. B. Lee; Vidya S. Kaushik

    1999-01-01

    In this article we report our studies on the microstructure, magnetoresistance (MR) behavior, and magnetic properties of the La1-x-yCaxMnO3 system in thin-film form. By varying the values of x and y in La1-x-yCaxMnO3, we have synthesized an external- (x=0.3, y=0), an internal- (x=0, y=0.3), and a mixed-doped (x=0.2, y=0.1) system with the same Mn3+\\/Mn4+ ratio. Thin films of these materials

  14. Dielectric behavior of samarium-doped BaZr{sub 0.2}Ti{sub 0.8}O{sub 3} ceramics

    SciTech Connect

    Li, Yuanliang, E-mail: lylll_2007@126.com [Analysis and Testing Center, Hebei United University, Tangshan 063009 (China); Wang, Ranran [English Department, Tianjin Maritime Vocational Institute, Tianjin 300457 (China); Ma, Xuegang [Analysis and Testing Center, Hebei United University, Tangshan 063009 (China); Li, Zhongqiu [Chemical College, Shijiazhuang University, Shijiazhuang 050035 (China); Sang, Rongli [Analysis and Testing Center, Hebei United University, Tangshan 063009 (China); Qu, Yuanfang [Key Laboratory for Advanced Ceramics and Machining Technology, Ministry of Education, Tianjin University, Tianjin 300072 (China)

    2014-01-01

    Graphical abstract: - Highlights: We investigate dielectric properties and phase transition of Sm{sup 3+}-doped BaZr{sub 0.2}Ti{sub 0.8}O{sub 3} ceramics. The additive amount of Sm{sub 2}O{sub 3} can greatly affect the dielectric properties. The materials undergo a diffuse type ferroelectric phase transition. There is an alternation of substitution preference of Sm{sup 3+} ion for the host cations in perovskite lattice. - Abstract: The dielectric properties and phase transition of Sm{sup 3+}-doped BaZr{sub 0.2}Ti{sub 0.8}O{sub 3} (BZT20) ceramics were investigated. Room temperature X-ray diffraction study suggested that the compositions had single-phase cubic symmetry. Microstructure studies showed that the grain size decreased and that the Sm{sub 2}O{sub 3} amount markedly affected the dielectric properties of BZT20. A dielectric constant of 5700 at 0.2 mol% Sm{sub 2}O{sub 3} and a dissipation factor of only 0.0011 at 2 mol% Sm{sub 2}O{sub 3} were observed, indicating that BZT20 had significant potential applications. Moreover, the dielectric constant, dissipation factor, phase-transition temperature, and maximum dielectric constant increased with increased Sm{sub 2}O{sub 3} amount at ?0.2 mol% Sm{sub 2}O{sub 3} but decreased with increased Sm{sub 2}O{sub 3} amount at >0.2 mol% Sm{sub 2}O{sub 3}.

  15. Field effect and magnetically induced capacitive tuning in hole doped lanthanum(1-x) strontium(x) manganese oxide

    NASA Astrophysics Data System (ADS)

    Marton, Zsolt

    Electrostatic modulation of interface conduction between semiconductors and insulating oxides is the foundation of semiconductor technology. This field effect concept can be applied on complex oxides, such as high temperature superconductors and colossal magnetoresistive manganites, in order to create new electronic and magnetic phases. Competition and coexistence of multiple nanoscale phases make them exciting to study around phase transitions. This study on hole doped La1-xSrxMnO3 systems has a two-fold purpose. One is the demonstration of the field effect on La1-xSr xMnO3 (x = 0.125, 0.2, 0.3, 0.5) thin films. It is an important step towards electrostatic control of material properties, however, a challenging task because of their charge carrier densities of 0.01-1 hole/unit cell, a few orders of magnitude larger than in doped semiconductors. Control by linear dielectrics needs huge, constantly applied bias. Energy efficient tuning with low voltages requires highly polar ferroelectric. Pb(Zr0.2Ti 0.8)O3 was chosen, whose remanence provides 0.5 charge carrier/unit cell on the manganite/ferroelectric interface. La1-xSrxMnO 3/Pb(Zr0.2Ti0.8)O3 heterostructures were synthesized by pulsed laser epitaxy and remarkable conduction modifications were observed in the La1-xSrxMnO3. This can be a strong foundation of a new tool to research electronic oxides. The second purpose of this work is to utilize the phase separation in manganites. There has been extensive research on multiferroic materials, in which dielectric and magnetic responses are controlled by magnetic and electric field, respectively. In order to demonstrate magnetically tuned capacitance, insulating La7/8Sr1/8MnO3 was studied. Drastic capacitance change in magnetic field was shown through a phase transitions and explained in the framework of electronic phase separation. It makes this material eligible for high frequency magnetoelectric applications. Modulating charge carriers, mobility and magnetism in magnetic oxides, superconductors and superlattices has a great impact on the emerging field of oxide electronics. These compounds overcome the scaling limitations of conventional semiconductors; using low operation voltage oxide ferroelectrics lowers energy consumption. This thesis shows that changing fundamental physical properties of complex oxides on the atomic scale is possible by ferroelectric field effect. This technique is proposed as a tool to study thin films, artificially stacked structures and to induce and optimize novel phases and phenomena.

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

    SciTech Connect

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

    2011-12-31

    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.

  17. Crystal structure and ionic conductivity of Mg-doped apatite-type lanthanum silicates La10Si6-xMgxO27-x (x = 0-0.4)

    NASA Astrophysics Data System (ADS)

    Yin, Guang-Chao; Yin, Hong; Zhong, Lin-Hong; Sun, Mei-Ling; Zhang, Jun-Kai; Xie, Xiao-Jun; Cong, Ri-Dong; Wang, Xin; Gao, Wei; Cui, Qi-Liang

    2014-04-01

    Lanthanum silicates La10Si6-xMgxO27-x (x = 0-0.4) were prepared by solid state synthesis to investigate the effect of Mg doping on crystal structure and ionic conductivity. Rietveld analysis of the powder XRD patterns reveals that Mg substitution on Si site results in significant enlargement of channel triangles, favoring oxide-ion conduction. Furthermore, an increase of Mg concentration significantly influences the linear density of interstitial oxygen, which plays an important role in ionic conductivity. The Arrhenius plots of La10Si6-xMgxO27-x (x = 0-0.4) suggest that Mg-doped samples present higher conductivity and lower activation energy than non-doped La10Si6O27, and La10Si5.8Mg0.2O26.8 exhibits the highest conductivity with a value of 3.010-2 S cm-1 at 700 C. Such conductive behavior agrees well with the refined results. The corresponding mechanism has been discussed in this paper.

  18. Oxygen Reduction Activity of Lanthanum Strontium Nickel Ferrite

    Microsoft Academic Search

    Gregory W. Coffey; John S. Hardy; Larry R. Pederson; Peter C. Rieke; Edwin C. Thomsen

    2003-01-01

    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

  19. Thermovoltaic effect in polycrystalline samarium sulfide

    NASA Astrophysics Data System (ADS)

    Kaminski?, V. V.; Didik, V. A.; Kazanin, M. M.; Romanova, M. V.; Solov'ev, S. M.

    2009-11-01

    A thermovoltaic effect has been observed for the first time in a polycrystalline sample of samarium sulfide (SmS) with artificially created concentration gradient of excess (overstoichiometric) samarium ions, in which an electric voltage of 12-22.5 mV was generated in a temperature interval of 370-485 K. It is shown that the specific voltage generation in SmS due to the thermovoltaic effect can be observed in a temperature range of 100-1800 K.

  20. Reaction, transformation and delamination of samarium zirconate thermal barrier coatings

    E-print Network

    Wadley, Haydn

    Reaction, transformation and delamination of samarium zirconate thermal barrier coatings Hengbei online 24 March 2011 Keywords: Samarium zirconate Interface reaction Bilayers Delamination The rare earth zirconates have attracted interest for thermal barrier coatings (TBCs) because they have very low intrinsic

  1. Removal of the samarium isobaric interference from promethium mass analysis

    SciTech Connect

    Shaw, R.W.; Young, J.P.; Smith, D.H.

    1988-02-01

    Resonance ionization mass spectroscopy (RIMS) is used to eliminate isobaric interference when determining the isotopic abundances of an element. In this application, RIMS is applied to the determination of promethium with the removal of samarium interference. In particular, promethium-147 is separated form samarium-147 and samarium-152.

  2. Removal of the samarium isobaric interference from promethium mass analysis

    Microsoft Academic Search

    Robert W. Shaw; J. P. Young; D. H. Smith

    1988-01-01

    Resonance ionization mass spectroscopy (RIMS) is used to eliminate isobaric interference when determining the isotopic abundances of an element. In this application, RIMS is applied to the determination of promethium with the removal of samarium interference. In particular, promethium-147 is separated form samarium-147 and samarium-152.

  3. Improved Sinterability and Performance of Lanthanum Ferrite SOFC Cathodes

    Microsoft Academic Search

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

    2003-01-01

    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.

  4. Lanthanum-Induced Gastrointestinal Histiocytosis

    PubMed Central

    Araya, Hiwot; Longacre, Teri A.; Pasricha, Pankaj J.

    2015-01-01

    A patient with end-stage renal disease (ESRD) on hemodialysis presented with fever, anorexia, and nausea shortly after starting oral lanthanum carbonate for phosphate control. Gastric and duodenal biopsies demonstrated diffuse histiocytosis with intracellular aggregates of basophilic foreign material. Transmission electron microscopy, an underutilized diagnostic test, revealed the nature of the aggregates as heavy metal particles, consistent with lanthanum. Symptoms and histiocytosis improved after discontinuation of lanthanum. Lanthanum may be an underdiagnosed cause of gastrointestinal histiocytosis.

  5. Lanthanum-Induced Gastrointestinal Histiocytosis.

    PubMed

    Rothenberg, Michael E; Araya, Hiwot; Longacre, Teri A; Pasricha, Pankaj J

    2015-04-01

    A patient with end-stage renal disease (ESRD) on hemodialysis presented with fever, anorexia, and nausea shortly after starting oral lanthanum carbonate for phosphate control. Gastric and duodenal biopsies demonstrated diffuse histiocytosis with intracellular aggregates of basophilic foreign material. Transmission electron microscopy, an underutilized diagnostic test, revealed the nature of the aggregates as heavy metal particles, consistent with lanthanum. Symptoms and histiocytosis improved after discontinuation of lanthanum. Lanthanum may be an underdiagnosed cause of gastrointestinal histiocytosis. PMID:26157959

  6. Synthesis of Samarium Cobalt Nanoblades

    SciTech Connect

    Darren M. Steele

    2010-08-25

    As new portable particle acceleration technologies become feasible the need for small high performance permanent magnets becomes critical. With particle accelerating cavities of a few microns, the photonic crystal fiber (PCF) candidate demands magnets of comparable size. To address this need, samarium cobalt (SmCo) nanoblades were attempted to be synthesized using the polyol process. Since it is preferable to have blades of 1-2 {micro}m in length, key parameters affecting size and morphology including method of stirring, reaction temperature, reaction time and addition of hydroxide were examined. Nanoparticles consisting of 70-200 nm spherical clusters with a 3-5 nm polyvinylpyrrolidone (PVP) coating were synthesized at 285 C and found to be ferromagnetic. Nanoblades of 25nm in length were observed at the surface of the nanoclusters and appeared to suggest agglomeration was occurring even with PVP employed. Morphology and size were characterized using a transmission electron microscope (TEM). Powder X-Ray Diffraction (XRD) analysis was conducted to determine composition but no supportive evidence for any particular SmCo phase has yet been observed.

  7. Synthesis and luminescent properties of Ln 3+ (Eu 3+, Sm 3+, Dy 3+)-doped lanthanum aluminum germanate LaAlGe 2O 7 phosphors

    Microsoft Academic Search

    Yu-Chun Li; Yen-Hwei Chang; Yu-Feng Lin; Yee-Shin Chang; Yi-Jing Lin

    2007-01-01

    The novel phosphor of LaAlGe2O7 activated with the trivalent rare-earth Ln3+ (Ln=Eu, Sm, Dy) ions were synthesized by solid-state method, and their characterization and luminescent properties were investigated. The absorption, emission and excitation spectra, and decay curves were employed to study the luminescence properties. The calcined powders of the Eu3+, Sm3+ and Dy3+ ions doped in the LaAlGe2O7 emit bright

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

    Microsoft Academic Search

    E. L. BROSHA; R. MUKUNDAN

    2000-01-01

    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 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

  9. Oxygen Reduction Activity of Lanthanum Strontium Nickel Ferrite

    SciTech Connect

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

    2003-06-01

    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.

  10. Thermal, electrical, and electrochemical properties of Lanthanum-doped Ba0.5Sr0.5 Co0.8Fe0.2O3 ?

    NASA Astrophysics Data System (ADS)

    Li, Shuyan; L, Zhe; Huang, Xiqiang; Wei, Bo; Su, Wenhui

    2007-09-01

    Crystal structure, thermogravimetry (TG), thermal expansion coefficient (TEC), electrical conductivity and AC impedance of (Ba0.5Sr0.5)1 xLaxCo0.8Fe0.2O3 ? (BSLCF; 0.05?x?0.20) were studied in relation to their potential use as intermediate temperature solid oxide fuel cell (IT-SOFC) cathode. A single cubic pervoskite was observed by X-ray diffraction (XRD). The TEC of BSLCF was increasing slightly with the increasing content of La, and all the compounds showed abnormal expansion at high temperature. Proved by the TG result, it was associated with the loss of lattice oxygen. The electrical conductivity, which is the main defect of Ba0.5Sr0.5 Co0.8Fe0.2O3 ? (BSCF), was improved by La doping, e.g., the compound of x=0.20 demonstrated a conductivity of ?=376 S cm-1 at 392 C. The increase of electrical conductivity resulted from the increased concentration of charge carrier induced by La doping. In addition, the AC impedance revealed the better electrochemical performance of BSLCF. For example, at 500 C, the sample with composition x=0.15 yielded the resistance values of 2.12 ? cm2, which was only 46% of BSCF.

  11. Effect of trace lanthanum ion on dissolution and crystal growth of calcium carbonate

    NASA Astrophysics Data System (ADS)

    Kamiya, Natsumi; Kagi, Hiroyuki; Tsunomori, Fumiaki; Tsuno, Hiroshi; Notsu, Kenji

    2004-07-01

    Impurity effects of trace lanthanum ion (La 3+) on the dissolution and growth of calcium carbonate were studied with in situ observation techniques. Dissolution kinetics of two polymorphs of calcium carbonate, calcite and vaterite, were investigated by monitoring the pH in the solution with laser-induced fluorescence spectroscopy using a pH-sensitive reagent, seminaphthorhodafluors. No effect on dissolution of vaterite was observed with the spectroscopic observations, whereas calcite dissolution was significantly inhibited by lanthanum ion with concentrations higher than 1 ?M. Crystal growth and dissolution processes of calcite under the lanthanum-doped condition were observed by means of atomic force microscopy. Step propagations during crystal growth and dissolution of calcite were inhibited by trace lanthanum ion (5 ?M). An insoluble thin layer of lanthanum carbonate deposited on the step site of the calcite surface could be a possible cause of the inhibitions observed both for dissolution and growth.

  12. [Radiographic disappearance of lanthanum].

    PubMed

    Pastori, Giordano

    2015-01-01

    In 2006, Cerny and Kunzendorf in the New England Journal of Medicine Images in clinical medicine, showed the radiographic appearance of lanthanum for the first time. After many years we noticed the inverse phenomenon. In a peritoneal dialysis patient treated with lanthanum carbonate, we had two radiography of the abdomen for monitoring the peritoneal catheter. In the first radiography contrast material was seen in colon. In the most recent radiography contrast material disappeared. The patient was always taking the same dose of lanthanum carbonate (1000 mg bid), although at the time of the first radiography he took the chewable tablets, for the last radiography he took the new powder formulation. We found a report in literature highlighting this phenomenon meanwhile indicating a greater chelating effect for the powder. Our hypothesis is that despite the same lanthanum dose, powder provides a greater surface area of binding and a more dispersed bowel distribution to explain a masked radio-opacity. Considering the wide availability of the powder, this must be taken into account especially in evaluating therapeutic compliance. PMID:25774580

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

    SciTech Connect

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

    2000-10-01

    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.

  14. Structural investigation of La{sub 9.33}Si{sub 6}O{sub 26}- and La{sub 9}AESi{sub 6}O{sub 26+{delta}}-doped apatites-type lanthanum silicate (AE=Ba, Sr and Ca) by neutron powder diffraction

    SciTech Connect

    Lambert, S. [CEA Le Ripault, BP 16 37260 MONTS (France)]. E-mail: sebastien.lambert@cea.fr; Vincent, A. [CEA Le Ripault, BP 16 37260 MONTS (France); Bruneton, E. [CEA Le Ripault, BP 16 37260 MONTS (France); Beaudet-Savignat, S. [CEA Le Ripault, BP 16 37260 MONTS (France); Guillet, F. [CEA Le Ripault, BP 16 37260 MONTS (France); Minot, B. [CEA Le Ripault, BP 16 37260 MONTS (France); Bouree, F. [LLB CEA Saclay, 91191 GIF sur YVETTE (France)

    2006-08-15

    Crystalline structures of La{sub 9.33}Si{sub 6}O{sub 26} and La{sub 9}AESi{sub 6}O{sub 26+{delta}} (AE=Ba, Sr and Ca) doped apatites-type lanthanum silicates were investigated by X-ray and neutron powder diffraction at room temperature. The results obtained after different models testing show that the apatite structure is best described using the P6{sub 3} space group. The loss of the mirror symmetry perpendicular to the ionic conduction channel direction results from heterogeneous La{sup 3+}/AE{sup 2+} distribution of the sites so-called ''4f''. The Rietveld refinements do not show splitting of the conduction oxygen (0,0,14) site but rather a very large spread of the nuclear density associated to this site. This effect is more pronounced for the La{sub 9}AESi{sub 6}O{sub 26+{delta}}-doped compounds. Large anisotropic thermal displacement parameters are also observed for the oxygens associated to the isolated [SiO{sub 4}], suggesting a rotation of this tetrahedron around the Si site. Lastly, vacancies were also systematically observed in the lanthanum nine-coordinated sites.

  15. Energy Transfer in Rare Earth Ion Clusters and Fluorescence from Rare Earth Doped LANTHANUM(1.85)STRONTIUM(0.15)COPPER -OXYGEN(4) Superconductors.

    NASA Astrophysics Data System (ADS)

    Tissue, Brian Max

    1988-12-01

    Laser spectroscopy of rare earth ions in solids was used to study mechanisms of non-resonant energy transfer within rare earth clusters, and to detect insulating, impurity phases in rare earth doped La_{1.85 }Sr_{0.15}CuO _4 superconductors. The mechanisms of phonon-assisted, non-resonant energy transfer were studied in well-defined dimer sites in Er^{3+ }:SrF_2 and Pr ^{3+}:CaF_2. Application of a magnetic field to Er^{3+} :SrF_2 greatly increased the energy transfer rate. The magnetic field dependence in Er^{3+}:SrF _2 indicates that the mechanism of non-resonant energy transfer is a two-phonon, resonant process (Orbach process). Application of a magnetic field to Pr ^{3+}:CaF_2 had no effect on the energy transfer rate because no significant Zeeman splittings occurred. The temperature dependence of the energy transfer rate in Pr^{3+ }:CaF_2 showed the mechanism to be a one-phonon-assisted process at low temperatures and predominantly an Orbach process above 10 K. In the second part of this thesis, laser spectroscopy of a Eu ^{3+} probe ion is developed to detect impurity phases in La_{1.85 }Sr_{0.15}CuO _4 superconductors. Two impurity phases were found in polycrystalline La_ {1.85}Sr_{0.15} CuO_4: unreacted La _2O_3 starting material, and a La-silicate phase, which formed from contamination during sintering. The spectroscopic technique was found to be more than 100 times more sensitive than powder x -ray diffraction to detect minor impurity phases. In preparing the superconductors, several studies were made on the effect of Pr^{3+}, Eu ^{3+}, Bi^{3+ }, and fluorine dopants on the superconducting properties of La_{1.85}Sr _{0.15}CuO_4 and La_2Cuo_4 . Pr^{3+}, Eu ^{3+}, Bi^ {3+}, and F_2 doping all decreased the superconductivity in La_ {1.85}Sr^{0.15} CuO_4. Treating semi-conducting La_2CuO_4 in F_2 gas converted it to a superconductor with an onset T_{rm c} of 30-35 K.

  16. Tunable band gap of iron-doped lanthanum-modified bismuth titanate synthesized by using the thermal decomposition of a secondary phase

    NASA Astrophysics Data System (ADS)

    Han, Jun Young; Bark, Chung Wung

    2015-05-01

    The photoelectric properties of complex oxides have prompted interest in materials with a tunable band gap because of the absorption. The substitution of iron atoms in La-modified bismuth titanate (BLT) can lead to dramatic improvements in the band gap; however, the substitution of iron atoms while maintaining the original bismuth layer structure without forming a BiFeO3 secondary phase is quite challenging. Therefore, a series of Fe-doped BLT (Fe-BLT) samples were synthesized using a solid reaction at various calcination temperatures (300 900C) to remove the secondary phase. The structural and the optical properties were analyzed by using X-ray diffraction and ultraviolet-visible absorption spectroscopy. This paper reports a new route by using high-temperature calcination, to synthesize the Aurivillius phase with a reduced optical band gap due to the thermal decomposition of BiFeO3 during high-temperature calcination. This simple route to reduce the second phase can be adapted to other complex oxides for use in emerging oxide optoelectronic devices.

  17. Synthesis and Magnetic Properties of Novel Lanthanide SERIES(2-X) Metal(x) Copper OXYGEN(4+Y) Compositions (lanthanide Series = Lanthanum, Praseodymium, Neodymium, Samarium, Europium, Gadolinium; Metal = Calcium, Strontium, Barium; 0 <= X <= 0.2; -0.5 <= Y <= 0.5)

    NASA Astrophysics Data System (ADS)

    Cho, Jin Hyung

    1992-01-01

    Ln_2CuO_4 (Ln = La, Pr, Nd, Sm, Eu, Gd) undergo structural transitions to oxygen-reduced structures Ln_2CuO_{4-d} with Ln = La, d = 1/3 and Ln = Pr, Nd, Sm, Eu, Gd, d = 1/2. The Nd_2CuO_4-type (T^'-phase) La _2CuO_{4+d} is observed after reoxygenation of oxygen-reduced La_2CuO _{3.67} structure below 500 ^circC. The magnetic properties of T/O (K_2NiF_4-type structure) -phase La_2CuO_4 systems show quite different behaviors compared with those of conventional solid state reacted La_2CuO_4 systems. The implications of these nonsuperconducting behaviors within the superconducting carrier concentrations are discussed from the structural point of view. La_{2-x}M_{x }CuO_{4+d} (M = Ca, Sr; x = 0.05, 0.15), synthesized by the low temperature route, also contain excess oxygen and show different physical properties. ^{139 }La NQR measurements of nonsuperconducting La_{1.85}Sr_{0.15 }CuO_{4.04} show metallic properties. The tolerance factor, which is based on ionic radii, is quite successful to describe structural properties of K_2NiF_4 related cuprate compounds. With anisotropic thermal motions of apical oxygens in La_2CuO_4, we discuss the crucial role of out-of-plane oxygens for stabilization of cuprate structures. The magnetic phase diagram and phase separation of La_{2-x}Sr_{x}CuO _{4+delta} system (0.000 <= x<= 0.030, 0.0<=delta) are reported. From the decrease of T_ {c} by doping level, we infer the localization and pair-breaking mechanism induced by doped holes. Phase separation is realized within the appearance of three-dimensional antiferromagnetic order. We also observe scaling properties of susceptibilities versus renormalized temperatures and infer the finite size effects by doped holes from the scaling. ^{139}La NQR spin-lattice relaxation rates vs temperature are presented for La_{2-x}Sr_{x }CuO_4 with x = 0.02 to 0.08. The spin -lattice relaxation rate below ~2 T_{N}(x) shows a power -law critical behavior while above ~2 T_{N}(x) it follows an exponential law with a small x-dependent spin-stiffness constant, where T_{N} is the magnetic ordering temperature. It is argued that the spin-lattice relaxation rate arises from fluctuations of the staggered magnetization in locally ordered mesoscopic domains. We infer that the magnetically ordered state is not a conventional spin glass.

  18. Effects of samarium dopant on photocatalytic activity of TiO 2 nanocrystallite for methylene blue degradation

    Microsoft Academic Search

    Qi Xiao; Zhichun Si; Jiang Zhang; Chong Xiao; Zhiming Yu; Guanzhou Qiu

    2007-01-01

    Sm3+-doped TiO2 nanocrystalline was synthesized by a solgel auto-combustion method and characterized by X-ray diffraction, Brunauer-Emmett-Teller\\u000a method (BET), UVvis diffuse reflectance spectroscopy (DRS), and also photoluminescence (PL) emission spectroscopy. The photocatalytic\\u000a activity of Sm3+TiO2 catalyst was evaluated by measuring degradation rates of methylene blue (MB) under either UV or visible light. The results\\u000a showed that doping with the samarium ions

  19. Tripyrrolidinophosphoric acid triamide as an activator in samarium diiodide reductions.

    PubMed

    McDonald, Chriss E; Ramsey, Jeremy D; Sampsell, David G; Butler, Julie A; Cecchini, Michael R

    2010-11-19

    The electrochemical and spectrophotometric characterization of the complex formed from samarium diiodide and 4 equiv of tripyrrolidinophosphoric acid triamide (TPPA) is presented. Kinetic studies indicate that the SmI(2)/TPPA complex possesses reactivity greater than the complex formed between samarium diiodide and 4 equiv of HMPA. Examples of the use of SmI(2)/TPPA in synthesis are presented. PMID:20979412

  20. Vapor deposited samarium zirconate thermal barrier coatings Hengbei Zhao a,

    E-print Network

    Wadley, Haydn

    Vapor deposited samarium zirconate thermal barrier coatings Hengbei Zhao a, , Carlos G. Levi b form 24 March 2009 Available online 1 April 2009 Keywords: Samarium zirconate Directed-vapor deposition Thermal barrier coatings The rare earth zirconates (M2Zr2O7, M=LaGd) have a low intrinsic thermal

  1. Electrical properties of lanthanum chromite based ceramics in hydrogen and oxidizing atmospheres at high temperatures

    NASA Astrophysics Data System (ADS)

    Schmidt, V. H.

    1981-06-01

    Several results regarding the effect of hydrogen on lanthanum chromite were determined. Thermally-activated diffusion of hydrogen through La(Mg)CrO3 was found with a high activation energy. It was found that its electrical conductivity drops drastically, especially at low temperature, after exposure to hydrogen at high temperature. Also, the curvature of most of the conductivity plots, as well as the inability to observe the Hall effect, lends support to the proposal by Karim and Aldred that the small-polaron model which predicts thermally activated mobility is applicable to doped lanthanum chromite. From differential thermal analysis, an apparent absorption of hydrogen near 3000 C was noticed. Upon cooling the lanthanum chromite in hydrogen and subsequently reheating it in air, desorption occurred near 1700 C. The immediate purpose of this study was to determine whether hydrogen has a deleterious effect on lanthanum chromite in solid oxide fuel cells.

  2. Samarium for osteoblastic bone metastases and osteosarcoma.

    PubMed

    Anderson, Pete

    2006-08-01

    Samarium-153 lexidronam (153Sm-EDTMP) is FDA approved for painful osteoblastic bone metastases that image on bone scan. 153Sm-EDTMP decay has a therapeutic beta-emission and a gamma-photon for bone scan imaging. Monitoring of osteosarcoma radiation treatment effectiveness was performed with bone, CT, MRI and PET/CT fusion imaging. Bone scan and PET/CT improved in 5 out of 9 and 16 out of 18 osteosarcoma sites, respectively. 153Sm-EDTMP targets multiple sites of disease, with a single administration. Side effects of 153Sm-EDTMP (0.5-2.5 mCi/kg) have been minimal and include transient thrombocytopenia and neutropenia. 153Sm-EDTMP can be combined with radiation therapy, bisphosphonates and/or chemotherapy to synergistically improve palliation. This article reviews the rationale, indications and monitoring of standard-dose samarium and investigational high-dose 153Sm-EDTMP treatment of cancer involving bone. PMID:16859431

  3. Samarium(III) catalyzed one-pot construction of coumarins

    Microsoft Academic Search

    Sushilkumar S. Bahekar; Devanand B. Shinde

    2004-01-01

    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.

  4. Samarium-neodymium direct dating of fluorite mineralization

    Microsoft Academic Search

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

    1991-01-01

    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 (CaF) 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

  5. 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

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

    1995-01-01

    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

  6. Ames Lab 101: Lanthanum Decanting

    SciTech Connect

    Riedemann, Trevor

    2010-01-01

    Ames Laboratory scientist Trevor Riedemann explains the process that allows Ames Laboratory to produce some of the purest lanthanum in the world. This and other high-purity rare-earth elements are used to create alloys used in various research projects and play a crucial role in the Planck satellite mission.

  7. Ultrasonic Attenuation in Lanthanum Monochalcogenides

    Microsoft Academic Search

    Raja Ram Yadav; Devraj Singh

    2001-01-01

    Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation are studied in Lanthanum Monochalcogenides in direction at different higher temperatures. For evaluation of ultrasonic absorption coefficients the second and third order elastic constants (SOEC) and (TOEC) are also calculated. Shear wave attenuation shows maximum along propagation direction with polarized along and the attenuation increases at higher temperatures. Thermo-elastic loss is

  8. MAGNETISM AND ELECTRON TRANSPORT IN MAGNETORESISTIVE LANTHANUM CALCIUM

    E-print Network

    MAGNETISM AND ELECTRON TRANSPORT IN MAGNETORESISTIVE LANTHANUM CALCIUM MANGANITE A DISSERTATION with the large negative magnetoresistance found in lanthanum calcium manganite. Such large magnetoresistances 4, the intrinsic magnetic and electron transport properties of lanthanum calcium manganite

  9. SOLITONS AND OPTICAL FIBERS: Self-Q-switched ytterbium-doped cladding-pumped fibre laser

    NASA Astrophysics Data System (ADS)

    Grukh, Dmitrii A.; Kurkov, Andrei S.; Razdobreev, I. M.; Fotiadi, A. A.

    2002-11-01

    A self-Q-switched ytterbium-doped double-clad fibre laser is described. A samarium-doped fibre is used as a filter for protecting a pump source. A fibre coupler is employed to obtain a nonlinear feedback. The mechanism of pulse formation in the laser is considered, and the dependence of its output pulse on the coupler parameters is studied.

  10. Samarium-neodymium direct dating of fluorite mineralization

    SciTech Connect

    Chesley, J.T.; Halliday, A.N. (Univ. of Michigan, Ann Arbor (United States)); Scrivener, R.C. (British Geological Survey, Exeter (England))

    1991-05-17

    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 (CaF{sub 2}) 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 tin deposits of southwest England demonstrates its use as a precise chronometer of mineralization. The concentrations of light rare earth elements (LREEs) in the fluorites are highly variable and suggest the coeval precipitation of an LREE-rich phase as the most likely cause of the extreme variation in samarium/neodymium ratios.

  11. Samarium-145 and its use as a radiation source

    DOEpatents

    Fairchild, Ralph G. (Setauket, NY); Laster, Brenda H. (Plainview, NY); Packer, Samuel (Great Neck, NY)

    1989-01-01

    The present invention covers a new radiation source, samarium-145, with radiation energies slightly above those of I-125 and a half-life of 340 days. The samarium-145 source is produced by neutron irradiation of SM-144. This new source is useful as the implanted radiation source in photon activation therapy of malignant tumors to activate the stable I-127 contained in the IdUrd accumulated in the tumor, causing radiation sensitization and Auger cascades that irreperably damage the tumor cells. This new source is also useful as a brachytherapy source.

  12. Basis for developing samarium AMS for fuel cycle analysis

    NASA Astrophysics Data System (ADS)

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

    2010-04-01

    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.

  13. Rapid Synthesis of Nonstoichiometric Lanthanum Sulfide

    NASA Technical Reports Server (NTRS)

    Matsuda, S.; Shapiro, E.; Danielson, L.; Hardister, H.

    1987-01-01

    New process relatively fast and simple. Improved method of synthesizing nonstoichiometric lanthanum sulfide faster and simpler. Product purer because some of prior sources of contamination eliminated.

  14. Precise Microwave Characterisation of YBa 2 Cu 3 O 7?? Films on Sapphire and Lanthanum Aluminate Substrates

    Microsoft Academic Search

    Mohan V. Jacob; Janina Mazierska

    2003-01-01

    We have precisely measured the surface resistance (RS) of high quality YBCO thin films, deposited on Lanthanum Aluminate and Silver doped YBCO thin films on Cesium buffered Sapphire substrates using the Hakki-Coleman dielectric resonator at frequency of 10 GHz as a function of temperature from 25 K to 85 K. We have also studied the microwave power dependence of YBCO

  15. Thermoelectric Properties of Lanthanum Sulfide

    NASA Technical Reports Server (NTRS)

    Wood, C.; Lockwood, R.; Parker, J. B.; Zoltan, A.; Zoltan, L. D.; Danielson, L.; Raag, V.

    1987-01-01

    Report describes measurement of Seebeck coefficient, electrical resistivity, thermal conductivity, and Hall effect in gamma-phase lanthanum sulfide with composition of La3-x S4. Results of study, part of search for high-temperature thermoelectric energy-conversion materials, indicate this sulfide behaves like extrinsic semiconductor over temperature range of 300 to 1,400 K, with degenerate carrier concentration controlled by stoichiometric ratio of La to S.

  16. Radiation Effects in Lanthanum Pyrozirconate

    SciTech Connect

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

    2006-09-01

    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.

  17. Computation of Nonlinear Impedance Spectra in Samaria Doped Ceria

    Microsoft Academic Search

    Francesco Ciucci

    2009-01-01

    Samarium Doped Ceria (SDC) electrodes are currently of great interest for solid oxide fuel cells (SOFC) applications. For example, ceria-containing anodes can be operated directly on hydrocarbons without coking, and in addition can be used at lower temperatures than Ni\\/YSZ. In order to design, optimize, and characterize electrodes, it is very useful to have models to aid in interpreting experimental

  18. A novel design of anode-supported solid oxide fuel cells with Y 2O 3-doped Bi 2O 3, LaGaO 3 and La-doped CeO 2 trilayer electrolyte

    Microsoft Academic Search

    Weimin Guo; Jiang Liu

    2010-01-01

    Anode-supported solid oxide fuel cells (SOFCs) with a trilayered yttria-doped bismuth oxide (YDB), strontium- and magnesium-doped lanthanum gallate (LSGM) and lanthanum-doped ceria (LDC) composite electrolyte film are developed. The cell with a YDB (18?m)\\/LSGM (19?m)\\/LDC (13?m) composite electrolyte film (designated as cell-A) shows the open-circuit voltages (OCVs) slightly higher than that of a cell with an LSGM (31?m)\\/LDC (17?m) electrolyte

  19. La doping effect on TZM alloy oxidation behavior , Kuai-She Wang a,

    E-print Network

    Volinsky, Alex A.

    coating a b s t r a c t Powder metallurgy methods were utilized to prepare lanthanum-doped (La, stearic acid ethanol solution containing lanthanum ni- trate, was used along with TiH2 and ZrH2 powders, 900 C, 1200 C heat preservation 2 h respectively, finally sintering on 1900 C, heat preservation 4

  20. Heating-induced endothermal effect in semiconducting samarium sulfide

    NASA Astrophysics Data System (ADS)

    Egorov, V. M.; Kaminski?, V. V.

    2009-08-01

    The effect of heat absorption is revealed in the temperature range where the thermovoltaic effect occurs in single-crystal samarium sulfide (SmS). It is shown that the heat absorption is caused by the collective injection of electrons from donor levels into the conduction band.

  1. Spray pyrolytic deposition and characterization of lanthanum selenide (La 2Se 3) thin films

    Microsoft Academic Search

    G. D. Bagde; S. D. Sartale; C. D. Lokhande

    2003-01-01

    The versatile spray pyrolysis technique was employed to prepare thin films of lanthanum selenide (La2Se3) on glass and fluorine doped tin oxide (FTO) coated glass substrates under optimized conditions. The deposition temperature was 250C. The X-ray studies reveal that the films are polycrystalline with single La2Se3 phase. The estimated optical band gap was found to be 2.6eV. The dielectric properties

  2. Synthesis and characterization of lanthanum carbide nanotubes.

    PubMed

    Awasthi, Kalpana; Singh, A K; Srivastava, O N

    2002-02-01

    Lanthanum carbide nanotubes have been synthesized by d.c. arc evaporation (approximately 20-30 V, approximately 200 Amp) of lanthanum metal (90 wt.%)-loaded graphite rod in a helium atmosphere (665 mbar). To explore the possibility of formation of lanthanum carbide nanotubes, the experiments were carried out with lanthanum metal in different concentrations (i.e., 30, 50, 70, and 90 wt.%) in the graphite rod. The as-synthesized samples were characterized by transmission electron microscopy and X-ray diffractometry. Lanthanum carbide nanotubes (LCNTs) with a diameter of approximately 65 to 95 nm and a length of approximately 0.2 to 1.5 microns were obtained in this study. PMID:12908323

  3. The features of structural transformations in lanthanum manganites La{sub 1?x}A{sub x}MnO{sub 3+?} (A = Ca, Sr, Ba)

    SciTech Connect

    Sedykh, Vera D., E-mail: sedykh@issp.ac.ru [Institute of Solid State Physics, Russian Academy of Sciences, Chernogolovka (Russian Federation)

    2014-10-27

    In this work, the effect of the ionic radius and concentration of a doping element on the features of the structural transformations in polycrystalline lanthanum manganites, La{sub 1?x}A{sub x}MnO{sub 3+?} (A = Ca, Sr, Ba), has been studied by Mssbauer spectroscopy and X-ray diffraction analysis. For Mssbauer investigations, a small amount of {sup 57}Fe (2 at%) Mssbauer isotope was introduced into the samples. It follows from the analysis of the obtained data that both common features of the structural transformations and differences between them exist in lanthanum manganites depending on ionic radius and concentration of a doping element.

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

    NASA Astrophysics Data System (ADS)

    Yan, Bing; Chen, Xi; Wu, Jianhua

    2007-08-01

    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(CH 3COO) 2 (Zn(AC) 2), NaOH, PEG as precursors at room temperature. The characteristic luminescence spectra for f-f transitions of Tb 3+, Eu 3+, Dy 3+ were observed. It is worthy to point out that ZnO is the excellent host for lanthanum ions by the assembly of PEG matrices.

  5. Ultrasonic Attenuation in Lanthanum Monochalcogenides

    NASA Astrophysics Data System (ADS)

    Yadav, Raja; Singh, Devraj

    2001-06-01

    Ultrasonic attenuation due to phonon-phonon interaction and thermoelastic relaxation are studied in Lanthanum Monochalcogenides in <110> direction at different higher temperatures. For evaluation of ultrasonic absorption coefficients the second and third order elastic constants (SOEC) and (TOEC) are also calculated. Shear wave attenuation shows maximum along <110> propagation direction with polarized along <110> and the attenuation increases at higher temperatures. Thermo-elastic loss is very small compared to phonon-viscosity loss. Behavior of temperature dependence of the absorption is the same as in case of pure metals and dielectric crystals.

  6. Improved Sinterability and Performance of Lanthanum Ferrite SOFC Cathodes

    SciTech Connect

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

    2003-10-01

    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.

  7. Self-activity in lanthanum halides

    Microsoft Academic Search

    W. J. Kernan

    2006-01-01

    Scintillators fabricated from lanthanum halides, specifically cerium-activated lanthanum bromide (LaBr3 [Ce]) and lanthanum chloride (LaCl3 [Ce]), have been shown to exhibit energy resolution far superior to that for thallium-activated sodium iodide. The high resolution, high Z, and high density (LaBr3 5.29 g\\/cm3 and LaCl3 3.79 g\\/cm3) of these materials hold out the prospect of use for building superior room-temperature, hand-held

  8. [Study on time-resolved fluorimetry of samarium].

    PubMed

    Pan, L; Wang, S; Dong, X

    1997-02-01

    In this paper, a simple and highly sensitive laser fluorimetric system is described, and the value of time discrimination for suppressing unwanted signals and decreasing the minimum detectable concentration is demonstrated. It is confirmed that time discrimination is very useful for ultratrale determination of fluorescent complex. This technique is successful with the combined use of a pulsed laser and a pulse-gate signal detection system for samarium complex. The linear range and the detectin limit of the method are 0. 01-10microg/ml and 3.3ng/ml, respectively. The RSD for Sm3+ (0. 5microg/ml) ( n =12) is 3.7%. The method was used to detemine samarium in rare earth mixtures. The recovery was in the range of 90.0-110.0%, and the mean recovery was 101.4% ( n = 6 ) PMID:15810428

  9. Basis for developing samarium AMS for fuel cycle analysis

    Microsoft Academic Search

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

    2010-01-01

    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

  10. Colossal magnetoresistance properties of samarium based manganese perovskites

    Microsoft Academic Search

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

    1996-01-01

    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

  11. Stabilized lanthanum sulphur compounds. [thermoelectric materials

    NASA Technical Reports Server (NTRS)

    Reynolds, G. H.; Elsner, N. B.; Shearer, C. H. (inventors)

    1983-01-01

    Lanthanum sulfide is maintained in the stable cubic phase form over a temperature range of from 500 C to 1500 C by adding to it small amounts of calcium, barium, or strontium. This compound is an excellent thermoelectric material.

  12. Field free, directly heated lanthanum boride cathode

    DOEpatents

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

    1991-01-01

    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.

  13. Field free, directly heated lanthanum boride cathode

    DOEpatents

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

    1987-02-02

    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.

  14. Compact lanthanum hexaboride hollow cathode.

    PubMed

    Goebel, Dan M; Watkins, Ronald M

    2010-08-01

    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 LaB(6) 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. PMID:20815605

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

    PubMed

    Liao, Ting; Sasaki, Taizo; Sun, Ziqi

    2013-10-28

    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

  16. Spectral down-conversion in Sm-doped borate glasses for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Dyrba, Marcel; Miclea, Paul T.; Schweizer, Stefan

    2010-05-01

    Borate glasses and borate glass ceramics are good candidates as a matrix material for fluorescent ions like samarium. The chosen network modifier influences the fluorescence efficiency of the incorporated rare earth ion. Sm3+-doped lithium, sodium, barium and lead borate glasses were examined with respect to their fluorescence properties and potential use as a down-converting top layer of a solar cell.

  17. An experimental analysis of a doped lithium fluoride direct absorption solar receiver

    NASA Technical Reports Server (NTRS)

    Kesseli, James; Pollak, Tom; Lacy, Dovie

    1988-01-01

    An experimental analysis of two key elements of a direct absorption solar receiver for use with Brayton solar dynamic systems was conducted. Experimental data are presented on LiF crystals doped with dysprosium, samarium, and cobalt fluorides. In addition, a simulation of the cavity/window environment was performed and a posttest inspection was conducted to evaluate chemical reactivity, transmissivity, and condensation rate.

  18. Ionization of Samarium by Chemical Releases in the Upper Atmosphere

    NASA Astrophysics Data System (ADS)

    Siefring, C. L.; Bernhardt, P. A.; Holmes, J. M.; Pedersen, T. R.; Caton, R.; Miller, D.; Groves, K. M.

    2014-12-01

    The release of Samarium vapor into the upper atmosphere was studied using during the Air Force Research Laboratory sponsored Metal Oxide Space Cloud (MOSC) rocket launches in May 2009. The Naval Research Laboratory supported these experiments with 3-D photochemical modeling of the artificial plasma cloud including (1) reactions with atomic oxygen, (2) photo excitation, (3) photoionization, (4) dissociative recombination, and (5) ion and neutral diffusion. NRL provided the experimental diagnostic instrument on the rocket which was a dual frequency radio beacon on the rocket to measure changes in total electron content. The AFRL provided ground based diagnostics of incoherent scatter radar and optical spectroscopy and imagery. The NRL Chemical Release Model (CRM) has over 600 excited states of atomic Samarium neutrals, atomic ions, along with Samarium Oxide Ions and electrons. Diffusive transport of neutrals in cylindrical geometry and ions along magnetic field lines is computed along with the reactive flow to predict the concentrations of Sm, Sm-Ion, Sm0, and SmO Ion. Comparison of the CRM with observations demonstrates that Sm release into the upper atmosphere initially produces enhanced electron densities and SmO-Ions. The diatomic ions recombine with electrons to yield neutral Sm and O. Only the photo ionization of Sm yields a stable atomic ion that does not substantially recombine. The MOSC releases in sunlight yielded long duration ion clouds that can be replicated with the CRM. The CRM predicts that Sm releases in darkness would not produce long duration plasma clouds because of the lack of photo excitation and photoionization.

  19. A ceria layer as diffusion barrier between LAMOX and lanthanum strontium cobalt ferrite along with the impedance analysis

    Microsoft Academic Search

    Hun-Chieh Chang; Dah-Shyang Tsai; Wen-Hung Chung; Ying-Sheng Huang; Minh-Vien Le

    2009-01-01

    A thin interlayer of samarium doped ceria (SDC) is applied as diffusion barrier between La1?xSrxCoyFe1?yO3x=0.10.4, y=0.20.8 (LSCF) cathode and La1.8Dy0.2Mo1.6W0.4O9 (LDMW82) electrolyte to obstruct MoSr diffusion and solid state reaction in the intermediate temperature range of SOFC. We demonstrate the effectiveness of the diffusion barrier through contrasting the clearly defined interfaces of LSCF\\/SDC\\/LDMW82 against a rugged growing product layer of

  20. Samarium Diiodide-Mediated Reactions in Total Synthesis

    PubMed Central

    Nicolaou, K. C.; Ellery, Shelby P.; Chen, Jason S.

    2009-01-01

    Introduced by Henri Kagan more than three decades ago, samarium diiodide (SmI2) has found increasing applications in chemical synthesis. This single-electron reducing agent has been particularly useful in CC bond formations, including those found in total synthesis endeavors. This Review highlights selected applications of SmI2 in total synthesis, with special emphasis on novel transformations and mechanistic considerations. The examples discussed are both illustrative of the power of this reagent in complex molecule construction and inspirational for the design of synthetic strategies toward such targets, both natural and designed. PMID:19714695

  1. Influence of samarium doping on electronic and magneto-transport properties of La{sub 0.9?x}Sm{sub x}Sr{sub 0.1}MnO{sub 3} (0.1?x?0.5) nanoparticles

    SciTech Connect

    Das, Proloy T., E-mail: dasproloy@phy.iitkgp.ernet.in; Nath, Tapan Kumar [Department of Physics and Meteorology, IIT Kharagpur, Kharagpur-721302, W.B. (India); Gupta, Kajal; Jana, Paresh Chandra [Department of Physics and Techno Physics, Vidyasagar University, Midnapore-721102, W.B. (India)

    2014-04-24

    We report detailed field dependent electronic- (?-T) and magneto- transport (MR-H) studies of La{sub 1?x}Sm{sub x}Sr{sub 0.1}MnO{sub 3} (0.1?x?0.5) nanoparticles. Doping induced disorder at La site is observed in field dependent ?-T measurements of the sample. At low doping side, nice metal to insulator transition (MIT) peak appears in ?-T data whereas with increasing of Sm{sup +3} contents, metallic behavior is suppressed under the insulating background although a weak signature of MIT is found. Anomalous resistive nature of the samples with increasing of x can be explained in such a way that doping at nonmagnetic La site with magnetic Sm+3 ion induces an extra magnetic coupling in the system which changes the long range ferromagnetic ordering to spin glass/cluster glass state in antiferromagnetic background. The field dependent magneto resistance (MR) mechanism at different temperatures is investigated using spin polarized tunneling model of conduction electrons between two adjacent grains at the grain boundaries. For the sample of x=0.5, maximum 83 % change in MR is found at 8 T near MIT which leads the colossal magneto resistance effect.

  2. Luminescence properties of Sm 3+-doped polycrystalline ZrO 2

    Microsoft Academic Search

    S. Lange; I. Sildos; M. Hartmanova; J. Aarik; V. Kiisk

    2008-01-01

    We obtained samarium-doped zirconia using two different routes. In one, atomic layer deposited thin crystalline films were doped by using ion implantation; this sample was mainly monoclinic. The other method, the skull-melting technique, yielded polycrystalline bulk zirconia containing both monoclinic and tetragonal phases of ZrO2. Thorough photoluminescence (PL) measurements of Sm emission in these materials were performed using pulsed laser

  3. Effect of yttrium and lanthanum on the tensile creep behavior of aluminum oxide

    SciTech Connect

    Cho, J.; Harmer, M.P.; Chan, H.M.; Rickman, J.M.; Thompson, A.M. [Lehigh Univ., Bethlehem, PA (United States). Dept. of Materials Science and Engineering

    1997-04-01

    The tensile creep behavior of two rare-earth dopant systems, lanthanum- and yttrium-doped alumina, are compared and contrasted in order to better understand the role of oversized, isovalent cation dopants in determining creep behavior. It was found that, despite some microstructural differences, these systems displayed qualitatively a similar improvement in creep resistance, supporting the hypothesis that creep is strongly influenced by segregation. Differences in primary creep behavior and activation energy for steady-state creep were, however, observed for these systems. Given these results, it is expected that creep behavior can be further optimized by adjusting the dopant level and by controlling the microstructure.

  4. Aqueous solgel synthesis of lanthanum phosphate nano rods starting from lanthanum chloride precursor

    Microsoft Academic Search

    Sasidharan Sankar; Krishna Gopakumar Warrier

    2011-01-01

    Aqueous solgel technique is reported for synthesizing nanosize, rod shaped lanthanum phosphate particles starting from lanthanum\\u000a chloride, which is suitable for variety of applications such as machinable ceramics, thermal barrier coatings and luminescent\\u000a materials. The phosphate particles are having rod like morphology having an overall size in the range 25100nm and with an\\u000a average aspect ratio 4. The morphology is

  5. Investigation into Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation Detection

    SciTech Connect

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

    2011-07-06

    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 [1]. 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 [2]. 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.

  6. Effect of samarium nanoparticles on the electrical transport properties of polyaniline

    NASA Astrophysics Data System (ADS)

    Gupta, K.; Mukherjee, P. S.; Meikap, A. K.; Jana, P. C.

    2014-06-01

    A comprehensive study of the effect of samarium nanoparticles on electrical transport properties of polyaniline has been reported. Samples are prepared by chemical oxidative polymerization of aniline in the presence of samarium nanoparticles and characterized by XRD, FESEM, EDS, HRTEM and UV-Vis spectrometer. When the samarium content in polyaniline matrix increases, energy band gap decreases and conductivity increases by four orders of magnitude. A transformation of negative to positive magnetoconductivity has been observed by incorporating samarium nanoparticles in polyaniline matrix. Two types of activation behavior have been observed from the dielectric relaxation behavior. AC conductivity strongly depends on magnetic field. Although, at present, no theoretical model is found in literature to explain directly the behavior of ac conductivity in the presence of magnetic field, it may be due to the change of grain and interfacial boundary resistances by magnetic field.

  7. On-line ultrasonic characterisation of barium doped lanthanum perovskites

    NASA Astrophysics Data System (ADS)

    Thamilmaran, P.; Arunachalam, M.; Sankarrajan, S.; Sakthipandi, K.

    2015-06-01

    Perovskite manganite samples La1-xBaxMnO3 with the composition of x=0.30, 0.33 and 0.36 were prepared by employing solid state reaction technique. The X-ray diffraction (XRD) patterns confirmed the rhombhedral structure with R3c space group of the samples. The obtained energy dispersive analysis X-rays (EDX) spectra of the samples have confirmed the elemental composition of the samples. The scanning electron microscope (SEM) images of the samples were used to find out the size of the particles. In-situ ultrasonic measurements were carried out on the samples by through transmission method. The temperature dependence of the ultrasonic parameters revealed interesting features of the samples. The observed ultrasonic velocities and attenuation both in longitudinal and shear mode are related to the paramagnetic (PM) to ferromagnetic (FM) phase transition in the prepared samples. The results confirmed that an increase in the barium content in the sample leads to an increase in the phase transition temperature TC.

  8. Peculiar histiocytic lesions with massive lanthanum deposition in dialysis patients treated with lanthanum carbonate.

    PubMed

    Haratake, Joji; Yasunaga, Chikao; Ootani, Akifumi; Shimajiri, Shohei; Matsuyama, Atsuji; Hisaoka, Masanori

    2015-06-01

    Pathologic lesions caused by lanthanum carbonate (LC), a recently developed phosphate-binding agent, have not been recorded. A peculiar gastroduodenal histiocytic lesion associated with a mucosal lanthanum overload was reported. Our routine gastrointestinal biopsy series included 6 cases with heavy lanthanum burden in the gastroduodenal mucosa. In addition to routine histopathologic examinations, a series of immunohistochemical analysis and electron microscopic examinations associated with x-ray diffraction and elemental analysis were performed. Six cases, 3 of male and 3 of female individuals with ages from 59 to 69 years, were all patients of end-stage renal diseases managed under dialysis and treated with LC for >21 months. Endoscopic examinations demonstrated gastric erosions in 3, gastric polyps in 2, and duodenal ulcer in 1. In the mucosal layer, there were numerous non-Langerhans cell histiocytes, stained with CD68 but not S100 protein, engulfing a large amount of mineral-like materials. An electron microscopic and elemental analysis revealed a similar distribution of lanthanum and phosphorus in the histiocytes. Long-standing LC administration can cause massive mucosal accumulation of lanthanum in the tissue histiocytes associated with several forms of gastroduodenal lesions. A long-standing outcome is not clear at present; hence, careful follow-up studies of these patients may be needed. PMID:25602800

  9. Adsorption of lanthanum to goethite in the presence of gluconate

    SciTech Connect

    Hull, Laurence C.; Sarah Pepper; Sue Clark

    2005-05-01

    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.

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

    SciTech Connect

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

    1995-09-01

    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.

  11. Microanalysis of a grain boundary's blocking effect in lanthanum silicate electrolyte for intermediate-temperature solid oxide fuel cells.

    PubMed

    Yan, Pengfei; Mineshige, Atsushi; Mori, Toshiyuki; Wu, Yuanyuan; Auchterlonie, Graeme John; Zou, Jin; Drennan, John

    2013-06-12

    In order to study the grain boundary's (GB's) blocking effect in lanthanum silicate electrolyte, high density Al-doped apatite-type lanthanum silicate was synthesized and characterized by impedance spectroscopy, scanning electron microscopy, X-ray diffraction, and transmission electron microscopy. Microstructural characterization indicated that the GB's blocking effect was an intrinsic effect. Further microanalysis shows that the GB region is rich in La and poor in Si in comparing with the grain interior (GI). Our discussion suggested that the chemical variation from GI to GB, on the one hand, could degrade the GB region's conductivity; on the other hand, it introduced a strong space-charge effect at GBs. The latter was believed to play a dominant role in the GB's blocking effect. PMID:23697778

  12. Reaction of lanthanum and cerium hexaborides with refractory metals

    Microsoft Academic Search

    V. P. Bondarenko; Vo V. Morozov; L. V. Chernyak

    1971-01-01

    The least work function and the greatest stability of thermionic properties are exhibited by lanthanum and cerium hexaborides [3], while tantalum, tungsten, and rhenium are the most frequently used substrate materials, and it was for this reason that it was decided to study the reaction of lanthanum and cerium hexaborides with tantalum, tungsten, and rhenium. In addition, to obtain a

  13. THE INFLUENCE OF COMPOSITIONAL VARIABLES ON THE THERMODYNAMIC PROPERTIES OF LANTHANUM STRONTIUM FERRITE MANGANITES AND LANTHANUM STRONTIUM MANGANITES

    Microsoft Academic Search

    S. Tanasescu; N. D. Totir; D. I. Marchidan; A. Turcanu

    1997-01-01

    In order to obtain a better understanding of the stability limits of perovskite phases used in new SOFC (solid oxide fuel cell) cathodes materials, a study of the thermodynamic properties of some perovskite-type oxides based on lanthanum strontium ferrite manganite and lanthanum strontium manganite was initiated. For the determination of thermodynamic quantities, a solid state electrochemical technique has been employed.

  14. Lanthanum complexes of spheroidal carbon shells

    SciTech Connect

    Heath, J.R.; O'Brien, S.C.; Zhang, Q.L.; Liu; Curl, R.F.

    1985-01-01

    Laser vaporization of graphite in a high-pressure supersonic nozzle produced a remarkable stable C60 molecule in high yield with striking and exciting new properties. Specifically it was found that the stability of the new species arises from its unique ability to close into a spheroidal, aromatic molecule in the form of a truncated icosahedron. This should be an exceptionally strong binding site for a wide range of atoms. Evidence is presented for clusters of carbon atoms which form very stable complexes with lanthanum atoms, particularly C60 La. Such aromatic egg-shell complexes of metal atoms may be stable enough to survive in normal condensed-phase chemical environments.

  15. Intermediate temperature fuel cell with a doped ceriacarbonate composite electrolyte

    Microsoft Academic Search

    Chun Xia; Yi Li; Ye Tian; Qinghua Liu; Zhiming Wang; Lijun Jia; Yicheng Zhao; Yongdan Li

    2010-01-01

    The performance of a composite electrolyte composed of a samarium doped ceria (SDC) and a binary eutectic carbonate melt phase has been examined. This material shows higher ionic conductivity than pure SDC in intermediate temperature region. SDC with different morphologies is obtained by co-precipitation, solgel and glycine-nitrate combustion preparation techniques. A tri-layer single cell is prepared with a cost-effective co-pressing

  16. Nonlinear Optical Properties Of Lanthanum Gallogermanate Glasses

    NASA Astrophysics Data System (ADS)

    Harikuttan, C. Unnithan; Dhanya, I.; Predeep, P.; Jayakumar, S.

    2008-04-01

    The oxide glasses are of important class of materials, especially because of their high transparency in mid IR region. Lanthanum Gallogermanate glass is having greater interest for IR transmission applications due to their long IR cut off wave length in comparison with phosphate, borate or silicate glasses. Various optoelectronic parameters such as Nonlinear Refractive Index (N?), Polarisibity (P). Bandgap Energy(Eg), Susceptibility (?0)are determined for series I glass systems consist of x La2O3-GeO2-0.25 Ga2O3 with x = (0.2,0.25,0.33 & 0.5) and for series II glass systems with 0.25 La2O3-GeO2-x Ga2O3 with x = (0.2,0.25 & 0.5) using the available data. The values obtained are compared with pure 2 glass system. It is observed that with the addition of La2O3 in series I, enhance the non linearity in the glass system while with the addition of glass modifier Ga2O3 in Series II, rcduce the non linearity factor. With proper addition of dopants such as La2O3 or the conditional glass former like Ga2O3, in Lanthanum Gallogermate glassy network, the non linearity factor can be maximized, which will be useful in producing second harmonic generation leading to different optoelectronic applications such as optical modulation, optical rectification and frequency doubling.

  17. ppt level detection of samarium(III) with a coated graphite sensor based on an antibiotic.

    PubMed

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

    2004-07-01

    N-[2-[4-[[[(Cyclohexylamino)carbonyl]amino]sulfonyl]phenyl]ethyl]-5-methyl pyrazine carboxamide (glipizid) was explored as an electro-active material for preparing a polymeric membrane-based sensor selective to samarium ions. The membrane incorporated 30% poly(vinyl chloride) (PVC), 53% benzyl acetate (BA), 11% glipizid and 6% sodium tetraphenyl borate. When coated on the surface of a graphite electrode, it exhibits Nernstian responses in the concentration range of 1.0 x 10(-5) to 1.0 x 10(-10) M, with a detection limit of 8.0 x 10(-11)M samarium. The electrode shows high selectivity towards samarium over several cations (alkali, alkaline earth, transition and heavy metal ions), and specially lanthanide ions. The proposed sensor has a very short response time (< 15 s), and can be used in a wide pH range for at least ten weeks. It was used as an indicator electrode in potentiometric titration of Sm(III) ions with an EDTA solution, and for determination of samarium in binary and ternary mixtures. PMID:15293392

  18. Reversible C-C coupling in phenanthroline complexes of divalent samarium and thulium.

    PubMed

    Nocton, Grgory; Ricard, Louis

    2015-02-28

    The reaction of a series of organolanthanide fragments of samarium and thulium with phenanthroline is reported. All adducts couple in the 4-position of the phenanthroline ligand to yield the 4-4' dimers when they crystallize. The analysis of the solution structure revealed a thermally reversible C-C coupling in all cases. PMID:25634655

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

    Microsoft Academic Search

    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

    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

  20. Lanthanum Halide Nanoparticle Scintillators for Nuclear Radiation Detection

    SciTech Connect

    Guss, P. P., Guise, R., Yuan, D., Mukhopadhyay, S., O'Brien, R., Lowe, D.

    2013-02-01

    Nanoparticles with sizes <10 nm were fabricated and characterized for their nanocomposite radiation detector properties. This work investigated the properties of several nanostructured radiation scintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum tribromide, lanthanum trifluoride, or cerium tribromide. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation.

  1. Lanthanum sulfides as high temperature thermoelectric materials

    NASA Technical Reports Server (NTRS)

    Danielson, L. R.; Matsuda, S.; Raag, V.

    1984-01-01

    Thermoelectric property measurements have been made for the nonstoichiometric lanthanum sulfides, LaS(R) with R in the range 1.33-1.50. The Seebeck coefficients and electrical resistivities increase with temperature from 200 to 1100 C. Power factors (defined as Seebeck coefficient squared divided by electrical resistivity) generally increase both as the temperature is increased and as the compound composition is varied from LaS(1.48) to LaS(1.35). The power factor values combined with estimates of thermal conductivities for LaS(1.38) and LaS(1.4) yield figures of merit greater than 0.0005 at 1000 C.

  2. Sintering aid for lanthanum chromite refractories

    DOEpatents

    Flandermeyer, Brian K. (Bolingbrook, IL); Poeppel, Roger B. (Glen Ellyn, IL); Dusek, Joseph T. (Downers Grove, IL); Anderson, Harlan U. (Rolla, MO)

    1988-01-01

    An electronically conductive interconnect layer for use in a fuel cell or other electrolytic device is formed with sintering additives to permit densification in a monolithic structure with the electrode materials. Additions including an oxide of boron and a eutectic forming composition of Group 2A metal fluorides with Group 3B metal fluorides and Group 2A metal oxides with Group 6B metal oxides lower the required firing temperature of lanthanum chromite to permit densification to in excess of 94% of theoretical density without degradation of electrode material lamina. The monolithic structure is formed by tape casting thin layers of electrode, interconnect and electrolyte materials and sintering the green lamina together under common densification conditions.

  3. Influence of the degree of crystal perfection and deviation from the stoichiometric composition on the diffusion processes in samarium sulfide

    NASA Astrophysics Data System (ADS)

    Kaminski?, V. V.; Golubkov, A. V.; Didik, V. A.; Romanova, M. V.; Skoryatina, E. A.; Usacheva, V. P.; Shalaev, B. N.; Sharenkova, N. V.

    2009-10-01

    The processes of diffusion of samarium and europium in nonstoichiometric samarium sulfide (SmS) at temperatures in the range 950-1600C have been investigated by the radioactive isotope method and the method of weight loss upon evaporation of excess samarium. It has been found that there is a correlation between the diffusion coefficient D and the size of coherent X-ray scattering regions in SmS samples, as well as between the diffusion coefficient and the degree of deviation from the stoichiometric composition: the diffusion coefficient of impurities decreases as the size of coherent X-ray scattering regions increases and the stoichiometric composition is approached. The calculation of the diffusion coefficient of electrons in samarium sulfide at T = 77-300 K has demonstrated that the value of D increases with increasing temperature and increasing size of coherent scattering regions.

  4. Neurotoxicological consequence of long-term exposure to lanthanum.

    PubMed

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

    2006-08-20

    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 daily intake of lanthanides. However, the effects of lanthanides on human body, especially on the central nervous system, are still unclear. The aim of this study was to determine whether long-term lanthanum exposure results in persistent alternations in nervous system function. Wistar rats were exposed to lanthanum chloride (LaCl(3)) through oral administration at 0, 0.1, 2 and 40mg/kg concentration from 4 weeks through 6 months of age. Morris water maze test showed that lanthanum exposure at 40mg/kg could significantly impair the behavioral performance. To fully investigate the neurotoxicological consequence of lanthanum exposure, brain elemental distributions and neurochemicals were also investigated. The distributions of brain elements such as Ca, Fe and Zn were significantly altered after lanthanum exposure. Moreover, 40mg/kg LaCl(3) significantly inhibited the activity of Ca(2+)-ATPase; the function of the central cholinergic system was also noticeably disturbed and the contents of some monoamines neurotransmitters were significantly decreased. These findings indicate that chronic exposure to lanthanum could possibly impair the learning ability and this deficit may be possibly attributed to the disturbance of the homeostasis of trace elements, enzymes and neurotransmitter systems in brain. Therefore, the application of lanthanide, especially in pharmacology, should be cautious. PMID:16542800

  5. EQUILIBRIUM OF THE SYSTEM LANTHANUM NITRATE-PRASEODYMIUM NITRATE-NITRIC ACID-WATER-TRIBUTYL PHOSPHATE

    Microsoft Academic Search

    B. M. Sharp; M. Smutz

    1960-01-01

    A study of the extraction characteristics of the three systems lanthanum nitrate--nitric acid--water--tributyl phosphate, praseodymium nitrate--nitric acid--water--tributyl phosphate, and lanthanum nitrate--praseodymium nitrate nitric acid -water--tributyl phosphate was conducted. The separation factors between praseodymium and lanthanum for the system lanthanum nitrate--praseodymium nitrate-nitric acid--water--tributyl phosphate were shown to be a function of the total nitrate concentration of an equilibrium phase and ;

  6. Medium Resolution Spectra of Solar Illuminated Sounding Rocket Samarium Vapor Releases

    NASA Astrophysics Data System (ADS)

    Holmes, J. M.; Pedersen, T. R.; Miller, D.; Caton, R.; Bernhardt, P. A.

    2014-12-01

    Samarium spectra in the visible wavelengths (400-900 nm) are presented from the Metal Oxide Space Clouds (MOSC) sounding rocket launches of 2014 May 01 and 09. The two releases occurred in twilight at the ground, but with distinctly different solar elevation angles. Resonance-fluorescence spectral lines are identified throughout this wavelength range, and are attributed to Sm, Sm+, SmO and SmO+. Even given the wide spectral range of the instrument, the spectral resolution throughout the range was 1.5 nm or better. The time variation of spectral line intensity from various neutral and ionized atomic and molecular products are compared with a time dependent model of the samarium release, yielding estimates of photoionization rates, autoionization rates (reaction with O to form SmO+), and relative populations of energy levels giving rise to the spectra.

  7. 40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ...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...

  8. 40 CFR 721.10370 - Phosphonic acid, p-octyl-, lanthanum (3+) salt (2:1).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ...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...

  9. Cytogenetic and developmental toxicity of cerium and lanthanum to sea urchin embryos

    E-print Network

    Paris-Sud XI, Universit de

    Cytogenetic and developmental toxicity of cerium and lanthanum to sea urchin embryos Rahime Oral1 was to evaluate the toxicity of two rare earth elements (REE), cerium and lanthanum on sea urchin embryos further studies of a more extended REE series. Key words: rare earth elements; cerium; lanthanum; sea

  10. Atomic Layer Deposition of Lanthanum-Based Ternary Oxides Hongtao Wang,a

    E-print Network

    . Lanthanum yttrium oxide thin films were also deposited by ALD under the similar condition, in order to show obtained films with EOT values 1 nm and very low leakage. Polycrystalline lanthanum yttrium oxide thinAtomic Layer Deposition of Lanthanum-Based Ternary Oxides Hongtao Wang,a Jun-Jieh Wang,b Roy Gordon

  11. Topological surface state in the Kondo insulator samarium hexaboride.

    PubMed

    Kim, D J; Xia, J; Fisk, Z

    2014-05-01

    Topological invariants of electron wavefunctions in condensed matter reveal many intriguing phenomena. A notable example is provided by topological insulators, which are characterized by an insulating bulk coexisting with a metallic boundary state. Although there has been intense interest in Bi-based topological insulators, their behaviour is complicated by the presence of a considerable residual bulk conductivity. Theories predict that the Kondo insulator system SmB6, which is known to undergo a transition from a Kondo lattice metal to a small-gap insulator state with decreasing temperature, could be a topological insulator. Although the insulating bulk and metallic surface separation has been demonstrated in recent transport measurements, these have not demonstrated the topologically protected nature of the metallic surface state. Here we report thickness-dependent transport measurements on doped SmB6, and show that magnetic and non-magnetic doping results in contrasting behaviour that supports the conclusion that SmB6 shows virtually no residual bulk conductivity. PMID:24658115

  12. The effects of samarium-cobalt magnets and pulsed electromagnetic fields on tooth movement.

    PubMed

    Darendeliler, M A; Sinclair, P M; Kusy, R P

    1995-06-01

    The purpose of this study was to determine whether the application of either samarium cobalt magnets or pulsed electromagnetic fields could increase the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the effect of a magnetic field on bony physiology and metabolism and to monitor for possible systemic side effects. Fifteen grams of laterally directed orthodontic force were applied to move the maxillary central incisors of a sample of 18 young male Hartley guinea pigs divided into three groups: group 1, an orthodontic coil spring was used to move the incisors; group 2, a pair of samarium-cobalt magnets provided the tooth moving force; and group 3, a coil spring was used in combination with a pulsed electromagnetic field. The results showed that both the static magnetic field produced by the samarium-cobalt magnets and the pulsed electromagnetic field used in combination with the coil spring were successful in increasing the rate of tooth movement over that produced by the coil springs alone. The mechanism producing this effect appears to have involved a reduction in the "lag" phase often seen in orthodontic tooth movement. Both magnetically stimulated groups also showed increases in both the organization and amount of new bone deposited in the area of tension between the orthodontically moved maxillary incisors. PMID:7771362

  13. Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation and Detection

    SciTech Connect

    Paul Guss, Sanjoy Mukhopadhyay, Ron Guise, Ding Yuan

    2010-06-09

    Scintillator materials are used to detect, and in some cases identify, gamma rays. Higher performance scintillators are expensive, hard to manufacture, fragile, and sometimes require liquid nitrogen or cooling engines. But whereas lower-quality scintillators are cheap, easy to manufacture, and more rugged, their performance is lower. At issue: can the desirable qualities of high-and low-performance scintillators be combined to achieve better performance at lower cost? Preliminary experiments show that a LaF{sub 3}:Ce oleic acid-based nanocomposite exhibits a photopeak when exposed to {sup 137}Cs source gamma-radiation. The chemical synthesis of the cerium-doped lanthanum halide nanoparticles are scalable and large quantities of material can be produced at a time, unlike typical crystal growth processes such as the Bridgeman process. Using a polymer composite (Figure 1), produced by LANL, initial measurements of the unloaded and 8% LaF{sub 3}:Ce-loaded sample have been made using {sup 137}Cs sources. Figure 2 shows an energy spectrum acquired for CeF{sub 3}. The lighter plot is the measured polymer-only spectrum and the black plot is the spectrum from the nanocomposite scintillator. As the development of this material continues, the energy resolution is expected to improve and the photopeak-to-Compton ratio will become greater at higher loadings. These measurements show the expected Compton edge in the polymer-only sample, and the Compton edge and photo-peak expected in the nanophosphor composites that LANL has produced. Using a porous VYCORR with CdSe/ZnS core shell quantum dots, Letant has demonstrated that he has obtained signatures of the 241Am photopeak with energy resolution as good at NaI (Figure 3). We begin with the fact that CeBr{sub 3} crystals do not have a self-activity component as strong as the lanthanum halides. The radioactive 0.090% {sup 138}La component of lanthanum leads to significant self-activity, which will be a problem for very large detector volumes. Yet a significant strength of the nanostructure detector concept is the ability to create extremely large detector volumes by mixing nanoparticles into a transparent matrix. This would argue for use of nanoparticles other than lanthanum halides. Nanocomposites are easy to prepare; it is much less costly to use nanocomposites than to grow large whole crystals of these materials. The material can be fabricated at an industrial scale, further reducing cost. This material potentially offers the performance of $300/cc material (e.g., lanthanum bromide) at a cost of $1/cc. Because the material acts as a plastic, it is rugged and flexible, and can be made in large sheets, increasing the sensitivity of a detector using it. It would operate at ambient temperatures. Very large volumes of detector may be produced at greatly reduced cost, enhancing the non-proliferation posture of the nation for the same dollar value.

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

    SciTech Connect

    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

    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.

  15. Synthesis of La and Nb doped PZT powder by the gel-combustion method

    Microsoft Academic Search

    M. Cernea; G. Montanari; C. Galassi; A. L. Costa

    2006-01-01

    Lanthanum and niobium doped PZT with composition (Pb0.93La0.07)[(Zr0.60Ti0.40)]0.9825Nb0.0175O3 (PZTLN) was prepared by the gel-combustion method. A precursor sol was obtained from lead nitrate, zirconyl nitrate, lanthanum oxide, peroxo-citrato-niobium and a peroxo-citrate complex of titanium isopropoxide as starting precursors. Various molar ratios of citrate\\/nitrate (CA\\/NO3- = 1.3, 0.36 and 0.09) were used to prepare very fine powders of PZTLN. The gels

  16. Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

    NASA Astrophysics Data System (ADS)

    Chi, Su (Ike); Farias, Stephen; Cammarata, Robert

    2013-03-01

    Tellurium alloys are characterized by their high performance thermoelectric properties and recent research has shown nanostructured tellurium alloys display even greater performance than bulk equivalents. Increased thermoelectric efficiency of nanostructured materials have led to significant interests in developing thin film and nanowire structures. Here, we report on the first successful electrodeposition of lanthanum telluride thin films and nanowires. The electrodeposition of lanthanum telluride thin films is performed in ionic liquids at room temperature. The synthesis of nanowires involves electrodepositing lanthanum telluride arrays into anodic aluminum oxide (AAO) nanoporous membranes. These novel procedures can serve as an alternative means of simple, inexpensive and laboratory-environment friendly methods to synthesize nanostructured thermoelectric materials. The thermoelectric properties of thin films and nanowires will be presented to compare to current state-of-the-art thermoelectric materials. The morphologies and chemical compositions of the deposited films and nanowires are characterized using SEM and EDAX analysis.

  17. 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

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

    1983-01-01

    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

  18. The influence of compositional variables on the thermodynamic properties of lanthanum strontium ferrite manganites and lanthanum strontium manganites

    SciTech Connect

    Tanasescu, S.; Totir, N.D.; Marchidan, D.I.; Turcanu, A. [Inst. of Physical Chemistry, Bucharest (Romania)] [Inst. of Physical Chemistry, Bucharest (Romania)

    1997-07-01

    In order to obtain a better understanding of the stability limits of perovskite phases used in new SOFC (solid oxide fuel cell) cathodes materials, a study of the thermodynamic properties of some perovskite-type oxides based on lanthanum strontium ferrite manganite and lanthanum strontium manganite was initiated. For the determination of thermodynamic quantities, a solid state electrochemical technique has been employed. The relative partial molar free energies, enthalpies, and entropies of oxygen dissolution in the perovskite phase, as well as the partial pressures of oxygen, have been obtained in the temperature range of 1,073--1,273 K. The results evidence the influence of different compositional variables on the thermodynamic properties.

  19. Synthesis of nickel nanoparticles supported on hollow samaria-doped ceria particles via the solution-spray plasma technique: Anode catalysts for SOFCs

    Microsoft Academic Search

    Ryuta Nishida; Katsuyoshi Kakinuma; Hanako Nishino; Takeo Kamino; Hisao Yamashita; Masahiro Watanabe; Hiroyuki Uchida

    2009-01-01

    Aiming at SOFC anode applications, we have synthesized nanometer-sized nickel catalysts supported on hollow spherical particles of samaria-doped ceria (Ni\\/SDC) by spraying a mixed solution of nickel, samarium, and cerium nitrates into an atmospheric pressure plasma. The as-prepared particles consisted of SDC (average diameter dSDC=ca. 0.8m) and uniformly dispersed nanometer-sized NiO particles. When reduced in H2 at 800C or 1000C,

  20. Lanthanum and silver nitrate mixed titrants laid to rest

    Microsoft Academic Search

    W SELIG

    1985-01-01

    A pyrolytic graphite sensor conditioned in neutral permanganate and previously reported has been used in a study of the titration of all four halogens in a single titration with a mixed titrant of lanthanum (II) and silver nitrates. This sensor was found to be able to differentiate F⁻ and total X⁻ but could not differentiate between the individual X⁻ components.

  1. Ion-assisted deposition of lanthanum fluoride thin films

    Microsoft Academic Search

    James D. Targove; John P. Lehan; Linda J. Lingg; H. Angus Macleod; J. A. Leavitt; McIntyre L. C. Jr

    1987-01-01

    Ion-assisted deposition has been used to deposit lanthanum fluoride thin films with near-unity film packing densities and no significant increase in absorption. Rutherford backscattering analysis has determined the effect of ion bombardment on the film stoichiometries including the degree of fluorine deficiency. Oxygen atoms or compounds appear to occupy most of the available anion vacancies if sufficient oxygen is available

  2. Thermophysical Properties of Sulfides of Lanthanum, Praseodymium, Gadolinium, and Dysprosium

    Microsoft Academic Search

    G. G. Gadzhiev; Sh. M. Ismailov; M. M. Khamidov; Kh. Kh. Abdullaev; V. V. Sokolov

    2000-01-01

    The temperature dependence of the thermal conductivity, electrical conductivity, thermoelectromotive force, and thermal expansion coefficient for sulfides of lanthanum, gadolinium, praseodymium and dysprosium of the composition Ln3 xVxS4 is investigated in the temperature range from 300 to 1200 K. It is shown that the transfer phenomena and thermoelectrical properties of the investigated compositions depend on the concentration of current

  3. Ab initio energetics of lanthanum substitution in ferroelectric bismuth titanate

    NASA Astrophysics Data System (ADS)

    Shah, S. H.; Bristowe, P. D.

    2011-04-01

    Using first principles calculations and atomistic thermodynamics the bulk and defect properties of orthorhombic bismuth titanate (Bi4Ti3O12) and bismuth lanthanum titanate (Bi3.25La0.75Ti3O12) have been investigated. Heats of formation, valid chemical conditions for synthesis, lanthanum substitution energies and oxygen and bismuth vacancy formation energies have been computed. The study improves our understanding of how native point defects and substitutional impurities influence the ferroelectric properties of these layered perovskite materials. It is found that lanthanum incorporation could occur on either of the two distinct bismuth sites in the structure and that the effect of substitution is to increase the formation energy of nearby native oxygen vacancies. The results provide direct atomistic evidence over a range of chemical conditions supporting the suggestion that lanthanum incorporation reduces the oxygen vacancy concentration. Oxygen vacancies contribute to ferroelectric fatigue by interacting strongly with domain walls, and therefore a decrease in their concentration is beneficial. The conditions that favor the greatest reduction in oxygen vacancy concentration are described.

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

    SciTech Connect

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

    1988-01-01

    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.

  5. Structural Characterization of Methanol Substituted Lanthanum Halides.

    PubMed

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

    2010-05-10

    The first study into the alcohol solvation of lanthanum halide [LaX(3)] derivatives as a means to lower the processing temperature for the production of the LaBr(3) scintillators was undertaken using methanol (MeOH). Initially the de-hydration of {[La(micro-Br)(H(2)O)(7)](Br)(2)}(2) (1) was investigated through the simple room temperature dissolution of 1 in MeOH. The mixed solvate monomeric [La(H(2)O)(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 CaH(2), 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 {[LaBr(2.75)*5.25(MeOH)](+0.25) [LaBr(3.25)*4.75(MeOH)](-0.25)} (4). The fully substituted species was ultimately isolated through the dissolution of dried LaBr(3) in MeOH forming the 8-coordinated [LaBr(3)(MeOH)(5)] (5) complex. It was determined that the concentration of the crystallization solution directed the structure isolated (4 concentrated; 5 dilute) The other LaX(3) derivatives were isolated as [(MeOH)(4)(Cl)(2)La(micro-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 ((139)La) 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. PMID:20514349

  6. Oxygen ion conductivity of the ceria-samarium oxide system with fluorite structure

    Microsoft Academic Search

    Hidenori Yahiro; Yukari Eguchi; Koichi Eguchi; Hiromichi Arai

    1988-01-01

    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

  7. Chelating ligand-mediated hydrothermal synthesis of samarium orthovanadate with decavanadate as vanadium source.

    PubMed

    Li, Quanguo; Zuo, Wenli; Li, Feng

    2013-01-01

    A new ethylenediaminetetraacetic acid- (EDTA-) mediated hydrothermal route to prepare chrysanthemum-shaped samarium orthovanadate (SmVO?) nanocrystals with decavanadate (K?V??O??9H?O) 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 SmVO? 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

  8. Preparation and crystal structure of new samarium complexes with glutamic acid

    NASA Astrophysics Data System (ADS)

    Torres, Julia; Kremer, Carlos; Pardo, Helena; Suescun, Leopoldo; Mombr, Alvaro; Castiglioni, Jorge; Domnguez, Sixto; Mederos, Alfredo; Kremer, Eduardo

    2003-11-01

    Samarium complexes with glutamic acid containing cationic [Sm 2(Glu) 2(H 2O) 8] 4+ units have been prepared and characterized by using elemental analysis, infrared absorption spectra and thermal analysis. In addition, the crystal and molecular structure of [Sm 2(Glu) 2(H 2O) 8](ClO 4) 43H 2O was determined by X-ray diffraction. The presence of glutamic acid in the Sm coordination sphere allows the formation of a singular extended 2D arrangement. Sm atoms are nine coordinated, in a monocapped square antiprism geometry. They are connected by means of different ?-COO - bridges, involving ?- and ?-carboxylate groups of the amino acid.

  9. Nano- and microsized Eu(3+) and Tb(3+)-doped lanthanide hydroxycarbonates and oxycarbonates. The influence of glucose and fructose as stabilizing ligands.

    PubMed

    Kaczmarek, Anna M; Miermans, Linde; Van Deun, Rik

    2013-04-01

    Europium and terbium-doped lanthanum hydroxycarbonate and lanthanum oxycarbonate nanoparticles were fabricated under two different reaction conditions using lanthanide acetate and urea as the starting materials. The photoluminescence properties of these hydroxycarbonate and oxycarbonate particles, and of their colloidal suspensions in water, were studied. The Eu(3+) (5)D(0)?(7)F(J) and Tb(3+) (5)D(4)?(7)F(J) emission spectra and the luminescence lifetimes in the two carbonate matrices were measured. Terbium-doped cerium oxycarbonate particles were synthesized, and the energy transfer process from Ce(3+) to Tb(3+) was investigated. The synthesis of lanthanum and cerium oxycarbonates was also carried out in the presence of stabilizing ligands: glucose and fructose. The influence of these ligands on the structure and luminescence was explored. PMID:23361038

  10. Extensive lanthanum deposition in the gastric mucosa: the first histopathological report.

    PubMed

    Makino, Mutsuki; Kawaguchi, Kenji; Shimojo, Hisashi; Nakamura, Hironori; Nagasawa, Masaki; Kodama, Ryo

    2015-01-01

    Lanthanum carbonate is one of the new phosphate binders used for the treatment of hyperphosphatemia in patients with chronic kidney disease. It is poorly absorbed from the gastrointestinal tract, forms insoluble complexes within the lumen, and prevents the absorption of dietary phosphate. A 63-year-old female with a 7-year history of peritoneal dialysis, who was treated with lanthanum carbonate for four years, underwent endoscopic submucosal dissection for intramucosal gastric cancer. Resected specimens showed massive accumulation of macrophages containing fine, granular, brown material in the lamina propria. This was confirmed as lanthanum deposition by scanning electron microscopy with energy dispersive x-ray spectroscopy. Although lanthanum may be poorly absorbed, increased tissue accumulation of lanthanum, particularly in the liver and bone, has been reported in animals with chronic kidney disease. This report indicates enhanced gastrointestinal absorption of lanthanum in some patients or conditions, although its clinical significance awaits further studies. PMID:25413959

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

    SciTech Connect

    Kang, Youjun; Liu, Chunmeng; Kuang, Xiaojun [KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)] [KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Mi, Jinxiao [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China)] [Department of Materials Science and Engineering, Xiamen University, Xiamen 361005 (China); Liang, Hongbin, E-mail: cesbin@mail.sysu.edu.cn [KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)] [KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Su, Qiang [KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)] [KLGHEI of Environment and Energy Chemistry, MOE Laboratory of Bioinorganic and Synthetic Chemistry, State Key Laboratory of Optoelectronic Materials and Technologies, School of Chemistry and Chemical Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2012-10-15

    The lithium-containing lanthanum-oxycarbonate-like borate, Li{sub 0.6}La{sub 2}O{sub 2.25}(BO{sub 3}){sub 0.7}, has been synthesized by solid-state reactions and was found to be isostructural with the type II lanthanum-oxycarbonate La{sub 2}O{sub 2}(CO{sub 3}). The new compound, lithium-containing lanthanum-oxycarbonate-like borate Li{sub 0.6}La{sub 2}O{sub 2.25}(BO{sub 3}){sub 0.7} has been synthesized and its structure characterized by the Rietveld method using powder X-ray diffraction data. It crystallizes in space group P6{sub 3}/mmc with lattice parameters of a=b=4.03396(3) A, c=16.5863(2) A, V=233.746(4) A{sup 3}. The mechanism of the lithium incorporation in the borate is that four Li{sup +} cations replace one (B{sub 2}O){sup 4+} group, i.e. Li{sub 0.6}La{sub 2}O{sub 2.25}(BO{sub 3}){sub 0.7} can be described as Li{sub 2x}La{sub 2}O{sub 1.5+2.5x}(BO{sub 3}){sub 1-x}, x=0.3 and the lithium incorporation stabilized the type II borate. The luminescent properties of Li{sub 0.6}La{sub 2}O{sub 2.25}(BO{sub 3}){sub 0.7} doped with Eu{sup 3+} were studied, indicating a potential application in white light emitting diodes (WLEDs). - Graphical abstract: The similar compounds of the new compound Li{sub 0.6}La{sub 2}O{sub 2.25}(BO{sub 3}){sub 0.7}. Projections along the b-axes of crystal structures for (a) La{sub 2}O{sub 2}CO{sub 3}-II, (b) A-type La{sub 2}O{sub 3}, (c) Li{sub 0.52}La{sub 2}O{sub 2.52}(CO{sub 3}){sub 0.74}. Highlights: Black-Right-Pointing-Pointer The new compound Li{sub 0.6}La{sub 2}O{sub 2.25}(BO{sub 3}){sub 0.7} has been synthesized. Black-Right-Pointing-Pointer Its structure is characterized by the Rietveld method using powder X-ray diffraction data. Black-Right-Pointing-Pointer This compound crystallizes in space group P6{sub 3}/mmc. Black-Right-Pointing-Pointer The mechanism of lithium incorporation in borate is that two Li{sup +} cations replace one (BO{sub 0.5}){sup 2+} group. Black-Right-Pointing-Pointer The Eu{sup 3+} doped samples have potential application in WLEDs.

  12. A rapid separation method for determination of promethium-147 and samarium-151 in environmental samples with high performance liquid chromatography

    Microsoft Academic Search

    M. Yoshida; S. Sumiya; H. Watanabe; K. Tobita

    1995-01-01

    A rapid separation method was developed for determination of low level promethium-147 and samarium-151. The rapid method, applied to environmental samples, provided speed and efficiency for the respective separation of Pm and Sm from other lanthanides with the simplified technique of high performance liquid chromatography (HPLC) system. The separation time of Pm and Sm in HPLC separation was shortened by

  13. Trace Element Partitioning Determined by Beta Track Mapping: An Experimental Study Using Carbon and Samarium as Examples

    Microsoft Academic Search

    Bjrn O. Mysen; Martin G. Seitz

    1975-01-01

    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

  14. Trace element partitioning determined by beta track mapping: An experimental study using carbon and samarium as examples

    Microsoft Academic Search

    Bjrn O. Mysen; Martin G. Seitz

    1975-01-01

    A technique for experimental determination of concentrations and distribution of trace elements is described. The technique employs nuclear emulsions to register beta particles from spontaneous decay of 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

  15. Nanoscale assembly of lanthanum silica with dense and porous interfacial structures

    PubMed Central

    Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R.; Smart, Simon; Diniz da Costa, Joo C.

    2015-01-01

    This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate. PMID:25644988

  16. Nanoscale assembly of lanthanum silica with dense and porous interfacial structures.

    PubMed

    Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R; Smart, Simon; Diniz da Costa, Joo C

    2015-01-01

    This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate. PMID:25644988

  17. Nanoscale assembly of lanthanum silica with dense and porous interfacial structures

    NASA Astrophysics Data System (ADS)

    Ballinger, Benjamin; Motuzas, Julius; Miller, Christopher R.; Smart, Simon; Diniz da Costa, Joo C.

    2015-02-01

    This work reports on the nanoscale assembly of hybrid lanthanum oxide and silica structures, which form patterns of interfacial dense and porous networks. It was found that increasing the molar ratio of lanthanum nitrate to tetraethyl orthosilicate (TEOS) in an acid catalysed sol-gel process alters the expected microporous metal oxide silica structure to a predominantly mesoporous structure above a critical lanthanum concentration. This change manifests itself by the formation of a lanthanum silicate phase, which results from the reaction of lanthanum oxide nanoparticles with the silica matrix. This process converts the microporous silica into the denser silicate phase. Above a lanthanum to silica ratio of 0.15, the combination of growth and microporous silica consumption results in the formation of nanoscale hybrid lanthanum oxides, with the inter-nano-domain spacing forming mesoporous volume. As the size of these nano-domains increases with concentration, so does the mesoporous volume. The absence of lanthanum hydroxide (La(OH)3) suggests the formation of La2O3 surrounded by lanthanum silicate.

  18. A comparison of the effect of rare earth vs Si site doping on the conductivities of apatite-type rare earth silicates

    Microsoft Academic Search

    J. E. H. Sansom; E. Kendrick; J. R. Tolchard; M. S. Islam; P. R. Slater

    2006-01-01

    Apatite-type lanthanum silicate (La9.33Si6O26) has been attracting significant recent interest due to its high oxide ion conductivity. In this paper, synthesis and conductivity\\u000a data for a range of doped samples (Mg, Ca, Sr, Ba, B, Ga and Zn) are reported, in particular, to compare the effect of rare\\u000a earth vs Si site doping. The results show that Ga, B and

  19. Reactivity between La(Sr)FeO 3 cathode, doped CeO 2 interlayer and yttria-stabilized zirconia electrolyte for solid oxide fuel cell applications

    Microsoft Academic Search

    Ana Martnez-Amesti; Aitor Larraaga; Lide M. Rodrguez-Martnez; Andrs T. Aguayo; Jose L. Pizarro; Maria L. N; Ander Laresgoiti; Maria I. Arriortua

    2008-01-01

    Detailed X-ray diffraction (XRD) analysis of two different Sr-doped LaFeO3 cathodes, YSZ electrolyte and two Sm\\/Gd-doped CeO2 interlayer and their mixtures were used to evaluate the formation of undesired secondary reaction compounds. The analysis of room temperature X-ray diffraction data of the mixtures indicates the crystallization of strontium and\\/or lanthanum zirconates between the cathode and the electrolyte materials and no

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

    SciTech Connect

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

    1987-07-01

    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.

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

    SciTech Connect

    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

    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.

  2. Enhanced field emission from lanthanum hexaboride coated multiwalled carbon nanotubes: Correlation with physical properties

    NASA Astrophysics Data System (ADS)

    Patra, Rajkumar; Ghosh, S.; Sheremet, E.; Jha, Menaka; Rodriguez, R. D.; Lehmann, D.; Ganguli, A. K.; Schmidt, H.; Schulze, S.; Hietschold, M.; Zahn, D. R. T.; Schmidt, O. G.

    2014-10-01

    Detailed results from field emission studies of lanthanum hexaboride (LaB6) coated multiwalled carbon nanotube (MWCNT) films, pristine LaB6 films, and pristine MWCNT films are reported. The films have been synthesized by a combination of chemical and physical deposition processes. An impressive increase in field enhancement factor and temporal stability as well as a reduction in turn-on field and threshold field are observed in LaB6-coated MWCNTs compared to pristine MWCNT and pristine LaB6 films. Surface morphology of the films has been examined by scanning electron microscopy. Introduction of LaB6 nanoparticles on the outer walls of CNTs LaB6-coated MWCNTs films is confirmed by transmission electron microscopy. The presence of LaB6 was confirmed by X-ray photoelectron spectroscopy results and further validated by the Raman spectra. Raman spectroscopy also shows 67% increase in defect concentration in MWCNTs upon coating with LaB6 and an upshift in the 2D band that could be attributed to p-type doping. Ultraviolet photoelectron spectroscopy studies reveal a reduction in the work function of LaB6-coated MWCNT with respect to its pristine counterpart. The enhanced field emission properties in LaB6-coated MWCNT films are correlated with a change in microstructure and work function.

  3. Visible emission in Sm3+ and Tb3+ doped phosphate glass excited by UV radiation

    NASA Astrophysics Data System (ADS)

    Zmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Czajkowski, Karol; Ragin, Tomasz

    2013-10-01

    In the article analysis of UV absorption and visible fluorescence of Sm3+ and Tb3+ ions doped phosphate glass with molar composition: 65P2O5 + 8Al2O3 + 10BaO + 17(Na2O + MgO + ZnO) have been investigated. As a result of optical pumping fabricated glass with radiation from a deuterium lamp four luminescence bands were observed near to the wavelength of 600 nm for Sm3+ ions and 550 nm for Tb3+ ions. It was found that larger energy gap between laser and ground levels leads to the strongest emission in the visible range in terbium doped glasses than in glasses doped with samarium ions. Both fabricated glasses are characterized by the ability to selectively detect the radiation in the UV range.

  4. Microwave absorption in single crystals of lanthanum aluminate

    Microsoft Academic Search

    Claudio Zuccaro; Michael Winter; Norbert Klein; Knut Urban

    1997-01-01

    A very sensitive dielectric resonator technique is employed to measure loss tangent tan ? and relative permittivity &egr;r of lanthanum aluminate (LaAlO3) single crystals at 4300 K and 412 GHz. A variety of single crystals grown by different techniques and purchased from different suppliers are considered. For T>150 K the loss tangent tan ? is almost sample independent with linear

  5. Origin of strong acidity in lanthanum-exchanged zeolites

    E-print Network

    Carvajal Freese, Ralf R.

    1989-01-01

    compositions for the hydrocarbon process include Czo-C4o molecules comprised of single and fused aromatic rings, naphthene rings, and paraffins (3). These molecules are converted mainly by acid-catalyzed reactions, such as isomerization, polymerization...ORIGIN OF STRONG ACIDITY IN LANTHANUM- EXCHANGED ZEOLITES A Thesis by RALF R. CARVAJAL FREESE Submitted to the Office of Graduate Studies of Texas A&M University in the partial fulfillment of the requirements for the degree of MASTER...

  6. Titanialanthanum phosphate photoactive and hydrophobic new generation catalyst

    Microsoft Academic Search

    Chembolli K. Jyothi; Kanakkanmavudi B. Jaimy; Swapankumar Ghosh; Sasidharan Sankar; V. S. Smitha; K. G. K. Warrier

    2011-01-01

    Titanialanthanum phosphate nanocomposites with multifunctional properties have been synthesized by aqueous solgel method. The precursor sols with varying TiO2:LaPO4 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

  7. EFFECT OF LANTHANUM ON RICE PRODUCTION, NUTRIENT UPTAKE, AND DISTRIBUTION

    Microsoft Academic Search

    Z. B. Xie; J. G. Zhu; H. Y. Chu; Y. L. Zhang; Q. Zeng; H. L. Ma; Z. H. Cao

    2002-01-01

    Split root solution culture experiments were conducted to study the effects of the rare earth element lanthanum (La) on rice (Oryza sativa) growth, nutrient uptake and distribution. Results showed that low concentrations of La could promote rice growth including yield (0.05 mg L to 1.5 mg L), dry root weight (0.05 mg L to 0.75 mg L) and grain numbers

  8. Lanthanum halide nanoparticle scintillators for nuclear radiation detection

    SciTech Connect

    Guss, Paul; Guise, Ronald [Remote Sensing Laboratory, P.O. Box 98521, M/S RSL-48, Las Vegas, Nevada 89193 (United States); Yuan Ding [National Security Technologies, LLC, Los Alamos Operations, P.O. Box 809, M/S LAO/C320, Los Alamos, New Mexico 87544 (United States); Mukhopadhyay, Sanjoy [Remote Sensing Laboratory-Andrews, Building 1783, Arnold Avenue Andrews AFB, Maryland 20762 (United States); O'Brien, Robert; Lowe, Daniel [University of Nevada, Las Vegas, 4505 S. Maryland Parkway, Las Vegas, Nevada 89154 (United States); Kang Zhitao; Menkara, Hisham [Georgia Tech Research Institute, 925 Dalney St., Atlanta, Georgia 30332 (United States); Nagarkar, Vivek V. [RMD, Inc., 44 Hunt Street, Watertown, Massachusetts 02472 (United States)

    2013-02-14

    Nanoparticles with sizes <10 nm were fabricated and characterized for their nanocomposite radiation detector properties. This work investigated the properties of several nanostructured radiation scintillators, in order to determine the viability of using scintillators employing nanostructured lanthanum trifluoride. Preliminary results of this investigation are consistent with the idea that these materials have an intrinsic response to nuclear radiation that may be correlated to the energy of the incident radiation.

  9. Effect of Ba doping on performance of LST as anode in solid oxide fuel cells

    Microsoft Academic Search

    Adrien Vincent; Jing-Li Luo; Karl T. Chuang; Alan R. Sanger

    2010-01-01

    The level of barium doping in lanthanum strontium titanate (La0.4Sr0.6?xBaxTiO3, 0?x?0.2; LST, x=0; LSBT, x>0), prepared by solid state synthesis, affects its performance as anode in solid oxide fuel cells (SOFCs). Cell structures of LST and all LSBT were similar. The oxidation state of Ti in all compounds was reduced by a comparable amount when LST or LSBT was heated

  10. Intramolecular nucleophilic acyl substitution reactions mediated by samarium(II) iodide: A convergent approach to the preparation of enantiomerically enriched 4-hydroxy ketones from 3-iodopropyl carboxylates

    SciTech Connect

    Molander, G.A.; Shakya, S.R. [Univ. of Colorado, Boulder, CO (United States)

    1994-06-17

    A combination of samarium(II) iodide and iron(III) catalyst have been investigated with respect to the ability to stereochemically convert carboxylates to ketones. Racemization of centers {alpha} to the carbonyl were observed.

  11. Raman studies of lanthanum cuprate superconductors

    SciTech Connect

    Weber, W.H.; Peters, C.R.; Logothetis, E.M.

    1989-03-01

    Raman-scattering studies of the high-T/sub c/ superconductor La/sub 2-//sub x/(Sr, Ba)/sub x/CuO/sub 4/ are briefly reviewed. A detailed analysis of the phonon-mode symmetries is given along with a discussion of the effects expected from the orthorhombic-to-tetragonal phase transition, which is known to occur in these materials. Survey spectra are given for powders, ceramics, and single crystals, and an oxide of Cu is identified as the primary impurity phase. Extensive spectra are given from oriented single crystals of La/sub 2/CuO/sub 4/ and La/sub 1.85/Sr/sub 0.15/CuO/sub 4/, and several mode assignments are made. Spectra for the high-temperature tetragonal phase and the low-temperature orthorhombic phase are given for each material. The soft phonon associated with the phase transition is seen in La/sub 2/CuO/sub 4/ as is a broad peak arising from two-magnon scattering. Neither of these features is seen in the Sr-doped sample.

  12. Novel NiBa 1+ x Zr 0.3Ce 0.5Y 0.2O 3? ? hydrogen electrodes as effective reduction barriers for reversible solid oxide cells based on doped ceria electrolyte thin film

    Microsoft Academic Search

    Yuanyuan Rao; Zhiquan Wang; Wei Zhong; Ranran Peng; Yalin Lu

    Samarium-doped ceria (SDC) is evaluated as electrolyte materials for intermediate temperature reversible solid oxide cells (RSOCs). The bulk resistances of cells with SDC thin-film electrolytes are 0.16 and 0.23?cm2 when operating in solid oxide electrolysis cell (SOEC) mode and in solid oxide fuel cell (SOFC) mode, respectively. This result suggests that the electrolyte is reduced to a greater extent in

  13. Lanthanum hexaaluminate novel thermal barrier coatings for gas turbine applications materials and process development

    Microsoft Academic Search

    R. Gadow; M. Lischka

    2002-01-01

    Lanthanum hexaaluminate (LHA) with a magnetoplumbite structure is a promising competitor to yttria partially stabilized zirconia (Y-PSZ) as a thermal barrier coating (TBC), since most zirconia coatings age significantly, including undesired densification at temperatures exceeding 1100 C. The microstructure of calcined lanthanum hexaaluminate powders and thermally sprayed coatings show a platelet structure. The magnetoplumbite structure is characterized by the highly

  14. Electric-fieldtemperature phase diagram of the relaxor ferroelectric lanthanum-modified lead zirconate titanate

    E-print Network

    Bobnar, Vid

    ferroelectrics. S0163-1829 99 00233-7 I. INTRODUCTION Lanthanum-modified lead zirconate titanate ceramics Pb1 x than EC 5 kV/cm a long-range ferroelectric order is established in 9/65/35 PLZT ceramics. In particularElectric-fieldtemperature phase diagram of the relaxor ferroelectric lanthanum-modified lead

  15. 23 to 300{degrees}C demagnetization resistance of samarium-cobalt permanent magnets

    SciTech Connect

    Niedra, J.M.; Overton, E.

    1991-10-01

    The influence of temperature on the knee point and squareness of the M-H demagnetization characteristic of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperatures in demagnetization-resistant permanent magnet devices. Composite plots of the knee field and the demagnetizing field required to produce a given magnetic induction swing below remanence were obtained for several commercial Sm{sub 2}Co{sub 17}-type magnet samples in the temperature range of 23 to 300{degrees}C. The knee point was used to define the limits of operation safe against irreversible demagnetization, and the resulting plots are interpreted to show the temperature-induction swing limits of safe magnet operation. The observed second quadrant M-H characteristic squareness is shown, by two measures, to increase gradually with temperature and to peak in the interval 200 to 300{degrees}C.

  16. The 23 to 300 C demagnetization resistance of samarium-cobalt permanent magnets

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.; Overton, Eric

    1991-01-01

    The influence of temperature on knee point and squareness of the M-H demagnetization characteristic of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperature in demagnetization resistent permanent magnet devices. Composite plots of the knee field and the demagnetizing field required to produce a given magnetic induction swing below remanence were obtained for several commercial Sm2Co17 type magnet samples in the temperature range of 23 to 300 C. Using the knee point to define the limits of operation safe against irreversible demagnetization, such plots are shown to provide an effective overview of the useable regions in the space of temperature-induction swing parameters. The observed second quadrant M-H characteristic squareness is shown, by two measures, to increase gradually with temperature, reaching a peak in the interval 200 to 300 C.

  17. Chelating Ligand-Mediated Hydrothermal Synthesis of Samarium Orthovanadate with Decavanadate as Vanadium Source

    PubMed Central

    Zuo, Wenli

    2013-01-01

    A new ethylenediaminetetraacetic acid- (EDTA-) mediated hydrothermal route to prepare chrysanthemum-shaped samarium orthovanadate (SmVO4) nanocrystals with decavanadate (K6V10O289H2O) 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

  18. 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

    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

    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.

  19. Synthesis, structural and optical properties of Sm{sup 3+} and Nd{sup 3+} doped cadmium sulfide nanocrystals

    SciTech Connect

    L, Saravanan, E-mail: ljsaravanan@yahoo.co.in [Centre for Nanoscience and Technology, Anna University, Chennai 600025 (India); Tunghai Green Energy Development and Management Institute, Tunghai University, Taichung 40704, Taiwan (China); R, Jayavel [Centre for Nanoscience and Technology, Anna University, Chennai 600025 (India); A, Pandurangan [Institute for Catalysis and Petroleum Technology, Anna University, Chennai 600025 (India); Jih-Hsin, Liu; Hsin-Yuan, Miao [Tunghai Green Energy Development and Management Institute, Tunghai University, Taichung 40704, Taiwan (China)

    2014-04-01

    Graphical abstract: Samarium (Sm{sup 3+}) and neodymium (Nd{sup 3+}) doped cadmium sulfide nanocrystals have been prepared via precipitation method. The structural and the luminescent properties of the as-synthesised nanocrystals have been discussed. - Highlights: Cubic phase lanthanide ion doped cadmium sulfide nanocrystals were prepared by co-precipitation method. HRTEM displays randomly aggregated nanoparticles with well-defined lattice fringes. Energy gap and optical properties were affected by the different doping ions. Effect of Sm and Nd ion doping on photo-emission of CdS nanocrystals was clarified. - Abstract: Cubic phase samarium (Sm{sup 3+}) and neodymium (Nd{sup 3+}) doped cadmium sulfide nanocrystals were synthesized through the chemical co-precipitation method. The crystallite size computed with high intense (1 1 1) peak using Scherrer formula was ?3 nm. Morphology was examined with scanning electron microscopy (SEM). The transmission electron microscopy (TEM) images further established the formation of nanoclusters and EDAX spectra confirms the presence of cadmium, sulphide and rare earth elements in the sample. SAED pattern shows the crystallinity of the synthesized sample. Blue shift in the bandgap energy in the reflectance UV spectra, illustrates size quantization effect and dopant ion incorporation into the host lattice. The effect of doping concentrations of Sm{sup 3+} and Nd{sup 3+} on the luminescence spectra of CdS was studied. The emission spectra revealed that the intensity increased considerably in the presence of dopant ions. The variation in the optical properties and the enhancement in the luminescence were discussed for different doping levels.

  20. High-temperature studies of the magnetic susceptibility of samarium and the Al{sub 2}Sm compound

    SciTech Connect

    Uporova, N. S., E-mail: fominans@rambler.ru [Ural State Pedagogical University (Russian Federation); Uporov, S. A. [Russian Academy of Sciences, Institute of Metallurgy, Ural Branch (Russian Federation); Sidorov, V. E. [Ural State Pedagogical University (Russian Federation)

    2012-02-15

    The magnetic susceptibility of metallic samarium and the Al{sub 2}Sm intermetallic compound has been experimentally studied by the Faraday method in the temperature range of 300-1800 K. It has been shown that the temperature dependences of the magnetic susceptibility of Sm and Al{sub 2}Sm in a crystalline state can be described in the framework of Van Vleck paramagnetism theory taking into account variable valence and the contribution from the conduction electrons. Using this theoretical interpretation of the data, the effective valence of samarium in the metallic state and in the Al{sub 2}Sm intermetallic compound has been estimated as a function of the temperature.

  1. Studies on effective atomic numbers, electron densities from mass attenuation coefficients near the K edge in some samarium compounds.

    PubMed

    Akman, F; Durak, R; Turhan, M F; Kaal, M R

    2015-07-01

    The effective atomic numbers and electron densities of some samarium compounds were determined using the experimental total mass attenuation coefficient values near the K edge in the X-ray energy range from 36.847 up to 57.142keV. The measurements, in the region from 36.847 to 57.142keV, were done in a transmission geometry utilizing the K?2, K?1, K?1 and K?2 X-rays from different secondary source targets excited by the 59.54keV gamma-photons from an Am-241 annular source. This paper presents the first measurement of the effective atomic numbers and electron densities for some samarium compounds near the K edge. The results of the study showed that the measured values were in good agreement with the theoretically calculated ones. PMID:25880612

  2. Phase transformation, thermal expansion and electrical conductivity of lanthanum chromite

    SciTech Connect

    Gupta, Sapna; Mahapatra, Manoj K.; Singh, Prabhakar, E-mail: singh@engr.uconn.edu

    2013-09-01

    Graphical abstract: - Highlights: Orthorhombic and rhombohedral phases co-exist at ?260 C and cubic above 1000 C. Polymorphic changes with temperature in air and Ar3%H{sub 2} are observed. Lattice volume change in Ar3%H{sub 2} atmosphere corresponds to Cr{sup 4+} ? Cr{sup 3+} transition. Change in valence state of Cr{sup 4+} to Cr{sup 3+} results in lower electrical conductivity. Experimental evidence is provided for poor densification of LaCrO{sub 3} in air. - Abstract: This paper addresses discrepancies pertaining to structural, thermal and electrical properties of lanthanum chromite. Experimental evidence is provided to support the hypothesis for poor densification in air as well as reduction in electrical conductivity in reducing atmosphere. Sintering condition for the synthesis of LaCrO{sub 3} was optimized to 1450 C and 10 h. Thermo-analytical (differential scanning calorimetry DSC) and high temperature X-ray diffraction (HT-XRD) studies show that orthorhombic lanthanum chromite transforms into rhombohedral structure at ?260 C and cubic structure above 1000 C. Co-existence of the structural phases and the variation in each polymorph with temperature in both air and 3%H{sub 2}Ar atmosphere is reported. Presence and absence of Cr-rich phase at inter-particle neck are observed in oxidizing and reducing atmospheres respectively. The linear thermal expansion co-efficient was calculated to be 10.8 0.2 10{sup ?6} C{sup ?1} in the temperature range of RT1400 C. Electrical conductivity of lanthanum chromite was found to be 0.11 S/cm in air. A decrease in electrical conductivity (0.02 S/cm at 800 C) of LaCrO{sub 3}, as observed in reducing atmosphere (3%H{sub 2}Ar), corresponds to lattice volume change as indicated by peak shift in HT-XRD results.

  3. Synthesis, structure and luminescence properties of samarium (III) and dysprosium (III) complexes with a new tridentate organic ligand

    Microsoft Academic Search

    Bao-Li An; Meng-Lian Gong; Ming-Xing Li; Ji-Ming Zhang

    2004-01-01

    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

  4. TEM-characterization of magnetic samarium- and cobalt-rich-nanocrystals formed in hexagonal SiC

    Microsoft Academic Search

    Johannes Biskupek; Ute Kaiser; Hannes Lichte; Andreas Lenk; Thomas Gemming; Gunnar Pasold; Wolfgang Witthuhn

    2005-01-01

    Using analytical transmission electron microscopy techniques, nanocrystals embedded in 4HSiC are studied which formed after high dose samarium (Sm), cobalt (Co), and Sm-and-Co-ion implantations and annealing. SmSi2, Sm5C2, Co2Si and SmCo-rich nanocrystals have been identified in terms of their crystallography, shape, strain, size, and orientation relationship to the matrix. It is shown, moreover, that cluster creations of foreign atoms (nanocrystals)

  5. MOCVD of very thin films of lead lanthanum titanate

    Microsoft Academic Search

    D. B. Beach; C. E. Vallet

    1995-01-01

    Films of lead lanthanum titanate were deposited using metal-organic chemical vapor deposition (MOCVD) at temperatures between 500 and 550°C in a hot-wall reactor. The precursors used were Pb(THD), La(THD), and Ti(THD)(I-OPr) where THD = 2,2,6,6-tetramethyl-3,5-heptanedionate, OCH, and I-OPr = isopropoxide, OCH. The three precursors were delivered to the reactor using a single solution containing all three precursors dissolved in tetraglyme

  6. Strontium-doped samarium manganite as cathode materials for oxygen reduction reaction in solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Li, W.; Xiong, C. Y.; Jia, L. C.; Pu, J.; Chi, B.; Chen, X.; Schwank, J. W.; Li, J.

    2015-06-01

    SmxSr1-xMnO3 with x = 0.3, 0.5 and 0.8, denoted as SSM37, SSM55 and SSM82, respectively, have been prepared via a sol-gel route as materials for cathodes in solid oxide fuel cells. Their activities in the oxygen reduction reaction (ORR) have been evaluated in comparison with the state-of-the-art cathode material La0.8Sr0.2MnO3 (LSM82) by electrochemical impedance spectroscopy (EIS), X-ray photoelectron spectroscopy (XPS) and thermogravimetry (TG). Among all the prepared cathodes, the SSM55 exhibits the lowest values, while the LSM82 exhibits the highest polarization resistance, at open circuit voltage (OCV) and temperatures from 650 to 800 C. This result indicates that the prepared SmxSr1-xMnO3 is a promising replacement for LSM82 as cathode material for SOFCs, and the SSM55 represents the optimal concentration in SmxSr1-xMnO3 series. The remarkably high ORR activity of the SSM55 is ascribed to its high surface Mn4+/Mn3+ and Oad/Olattice ratios and fast surface oxygen exchange kinetics.

  7. PERMEABILITY OF SERTOLI CELL TIGHT JUNCTIONS TO LANTHANUM AFTER LIGATION OF DUCTUS DEFERENS AND DUCTULI EFFERENTES

    PubMed Central

    Neaves, William B.

    1973-01-01

    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. PMID:4761331

  8. Novel borothermal route for the synthesis of lanthanum cerium hexaborides and their field emission properties

    SciTech Connect

    Menaka [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)] [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India); Patra, Rajkumar; Ghosh, Santanu [Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)] [Department of Physics, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India); Ganguli, Ashok K., E-mail: ashok@chemistry.iitd.ac.in [Department of Chemistry, Indian Institute of Technology, Hauz Khas, New Delhi-110016 (India)

    2012-10-15

    The present study describes the development of a simple approach to stabilize polycrystalline lanthanum cerium hexaborides without using any flux and at ambient pressure. The nanostructured lanthanum-cerium borides were synthesized using hydroxide precursors. These precursors (La{sub 1-x}Ce{sub x}(OH){sub 3}, x=0.1, 0.2, 0.3 and 0.5) were synthesized via hydrothermal route in the presence of Tergitol (surfactant, nonylphenol ethoxylate) as a capping agent. The precursors on heating with boron at 1300 Degree-Sign C lead to the formation of nanostructures (cubes, rods and pyramids) of lanthanum cerium hexaboride. We have investigated the field emission behaviour of the hexaboride films fabricated by spin coating. It was observed that the pyramidal shaped nanostructures of La{sub 0.5}Ce{sub 0.5}B{sub 6} shows excellent field emission characteristics with high field enhancement factor of 4502. - Graphical abstract: Nanostructured lanthanum cerium hexaboride with efficient field emission have fabricated by low temperature hydroxide precursor mediated route. Highlights: Black-Right-Pointing-Pointer New methodology to prepare lanthanum cerium hexaboride at 1300 Degree-Sign C via borothermal route. Black-Right-Pointing-Pointer Nanostructured lanthanum cerium hexaboride film by spin coating process. Black-Right-Pointing-Pointer Nanopyramids based lanthanum cerium hexaboride shows excellent field emission.

  9. Structural studies of apatite-type oxide ion conductors doped with cobalt.

    PubMed

    Tolchard, Julian R; Sansom, Jonathan E H; Islam, M Saiful; Slater, Peter R

    2005-04-01

    A series of Co doped lanthanum silicate apatite-type phases, La9.83Si4.5Co1.5O26, La9.66Si5CoO26, La10Si5CoO26.5 and La8BaCoSi6O26, have been synthesised, and neutron diffraction, EXAFS and XANES used to investigate their structures in detail. All compositions were shown to possess the hexagonal apatite structure, and the results confirmed that cobalt can be doped onto both the La and Si sites within the structure depending on the starting composition. The Co doping is shown to cause considerable local distortions within the apatite structure. In the case of Si site doping two compositions showed anisotropic peak broadening, which has been attributed to incommensurate ordering of oxygen within the apatite channels. PMID:15782264

  10. Effects of lanthanum at snake twitch and tonic muscle fibre endplates.

    PubMed Central

    Coniglio, L M; Hendricks, G M; Parsons, R L

    1993-01-01

    1. The effects of 1 mM lanthanum on miniature endplate current (MEPC) frequency, amplitude, and decay time course were studied in voltage-clamped twitch and tonic muscle fibres in the garter snake, Thamnophis. 2. Lanthanum produced a marked increase in MEPC frequency in both fibre types. The maximum frequency in lanthanum was greater at twitch endplates than at tonic endplates although the increase in frequency relative to control levels was as great in tonic fibres as in twitch fibres. 3. In twitch fibres continually exposure to lanthanum, the frequency of MEPCs reached a peak value and then declined progressively until, after approximately 6 h, no MEPCs were recorded. In contrast, at tonic endplates exposed to 1 mM lanthanum, MEPC frequency remained elevated above control levels for periods greater than 20 h. 4. Lanthanum decreased the mean amplitude of MEPCs, skewed the amplitude distribution and increased MEPC duration at both twitch and tonic fibre endplates. 5. Ultrastructural analysis showed that after a 15 min exposure to 1 mM lanthanum, approximately half of the boutons innervating a twitch fibre contained fewer synaptic vesicles than boutons at control endplates, whereas nerve terminals innervating tonic fibre endplates were similar in appearance to those in control preparations. At endplates on both fibres, the postsynaptic membrane was more electron dense than that of control preparations. 6. Following a 6 h exposure to lanthanum, all nerve terminals innervating twitch endplates contained only a few synaptic vesicles and numerous intracellular deposits of electron dense material. The nerve terminals innervating tonic endplates still contained many synaptic vesicles, but the number appeared to be less than that of tonic terminals in untreated preparations. 7. The results demonstrate that lanthanum stimulates spontaneous quantal transmitter release from nerve terminals innervating either twitch or tonic fibres. However, the terminals innervating twitch fibres become depleted of synaptic vesicles, whereas this does not occur as readily in nerve terminals innervating tonic fibres. Images Fig. 5 Fig. 6 PMID:8410700

  11. Lead lanthanum zirconate titanate ceramic thin films for energy storage.

    PubMed

    Tong, Sheng; Ma, Beihai; Narayanan, Manoj; Liu, Shanshan; Koritala, Rachel; Balachandran, Uthamalingam; Shi, Donglu

    2013-02-01

    An acetic-acid-based sol-gel method was used to deposit lead lanthanum zirconate titanate (PLZT, 8/52/48) thin films on either platinized silicon (Pt/Si) or nickel buffered by a lanthanum nickel oxide buffer layer (LNO/Ni). X-ray diffraction and scanning electron microscopy of the samples revealed that dense polycrystalline PLZT thin films formed without apparent defects or secondary phases. The dielectric breakdown strength was greater in PLZT thin films deposited on LNO/Ni compared with those on Pt/Si, leading to better energy storage. Finally, optimized dielectric properties were determined for a 3-?m-thick PLZT/LNO/Ni capacitor for energy storage purposes: DC dielectric breakdown strength of ?1.6 MV/cm (480 V), energy density of ?22 J/cc, energy storage efficiency of ?77%, and permittivity of ?1100. These values are very stable from room temperature to 150 C, indicating that cost-effective, volumetrically efficient capacitors can be fabricated for high-power energy storage. PMID:23373765

  12. Interfacial behavior of Cyanex 302 and kinetics of lanthanum extraction.

    PubMed

    Wu, Dongbei; Xiong, Ying; Li, Deqian; Meng, Shulan

    2005-10-01

    In this paper, interfacial tension of Cyanex 302 is measured by a Sigma-701 tensiometer and the adsorption parameters are calculated according to the Gibbs and Szyszkowski adsorption isotherms. The interfacial adsorbed behavior of Cyanex 302 is investigated. The results demonstrate that the dimer is the predominant species in the bulk organic phase; however, the monomer is adsorbed at the interface and more interfacially active. The effects of aqueous pH, ion strength, and temperature on the interfacial activity of Cyanex 302 in heptane are discussed and explained in detail. The lower interfacial activity of Cyanex 302 in aromatic hydrocarbon than in aliphatic hydrocarbon has also been determined. The values of interfacial excess at the saturated interface increase in the order n-heptane>cyclohexane>toluene>benzene, which is consistent with the order of extractability of lanthanum by Cyanex 302 in these diluents. The interfacial activity data are used to discuss the kinetic mechanism of lanthanum(III) extraction. It is shown that an interfacial mechanism is very probable, and the extraction limiting step is the reaction between the Cyanex 302 molecules in the organic phase sublayer and the adsorbed intermediate complex. PMID:15925375

  13. Yttrium and lanthanum hydride films with switchable optical properties

    NASA Astrophysics Data System (ADS)

    Huiberts, J. N.; Griessen, R.; Rector, J. H.; Wijngaarden, R. J.; Dekker, J. P.; de Groot, D. G.; Koeman, N. J.

    1996-03-01

    IN many substances, changes in chemical composition, pressure or temperature can induce metal-to-insulator transitions1. Although dramatic changes in optical and electrical properties accompany such transitions, their interpretation is often complicated by attendant changes in crystallographic structure2. Yttrium, lanthanum and the trivalent rare-earth elements form hydrides that also exhibit metal-insulator transitions3-5, but the extreme reactivity and fragility of these materials hinder experimental studies5,6. To overcome these difficulties, we have coated thin films of yttrium and lanthanum with a layer of palladium through which hydrogen can diffuse. Real-time transitions from metallic (YH2 or LaH2) to semiconducting (YH3 or LaH3) behaviour occur in these films during continuous absorption of hydrogen, accompanied by pronounced changes in their optical properties. Although the timescale on which this transition occurs is at present rather slow (a few seconds), there appears to be considerable scope for improvement through the choice of rare-earth element and by adopting electrochemical means for driving the transition. In view of the spectacular changes in optical properties-yttrium hydride, for example, changes from a shiny mirror to a yellow, transparent window-metal hydrides might find important technological applications.

  14. Cellulose-lanthanum hydroxide nanocomposite as a selective marker for detection of toxic copper

    PubMed Central

    2014-01-01

    In this current report, a simple, reliable, and rapid method based on modifying the cellulose surface by doping it with different percentages of lanthanum hydroxide (i.e., 1% La(OH)3-cellulose (LC), 5% La(OH)3-cellulose (LC2), and 10% La(OH)3-cellulose (LC3)) was proposed as a selective marker for detection of copper (Cu(II)) in aqueous medium. Surface properties of the newly modified cellulose phases were confirmed by Fourier transform infrared spectroscopy, field emission scanning electron microscope, energy dispersive X-ray spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopic analysis. The effect of pH on the adsorption of modified cellulose phases for Cu(II) was evaluated, and LC3 was found to be the most selective for Cu(II) at pH6.0. Other parameters, influencing the maximum uptake of Cu(II) on LC3, were also investigated for a deeper mechanistic understanding of the adsorption phenomena. Results showed that the adsorption capacity for Cu(II) was improved by 211% on the LC3 phase as compared to diethylaminoethyl cellulose phase after only 2h contact time. Adsorption isotherm data established that the adsorption process nature was monolayer with a homogeneous adsorbent surface. Results displayed that the adsorption of Cu(II) onto the LC3 phase obeyed a pseudo-second-order kinetic model. Selectivity studies toward eight metal ions, i.e., Cd(II), Co(II), Cr(III), Cr(VI), Cu(II), Fe(III), Ni(II), and Zn(II), were further performed at the optimized pH value. Based on the selectivity study, it was found that Cu(II) is highly selective toward the LC3 phase. Moreover, the efficiency of the proposed method was supported by implementing it to real environmental water samples with adequate results. PMID:25258599

  15. Hydrothermal Synthesis, Characterization, and Tribological Behavior of Oleic Acid-Capped Lanthanum Borate with Different Morphologies

    Microsoft Academic Search

    Zhengfeng Jia; Yanqiu Xia

    2011-01-01

    In this paper, nano\\/microstructure lanthanum borates were synthesized by hydrothermal route. Furthermore, oleic acid-capped\\u000a nano\\/microstructure lanthanum borates (OANLBs) were also prepared. The nano\\/microstructure of lanthanum borate is characterized\\u000a by means of Fourier transform-infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), and transmission\\u000a electron microscopy (TEM). At the same time, the friction and wear properties of OANLBs as additives in poly-alpha-olefin

  16. Alleviate Effects of Lanthanum on Stress Induced by cadmium on Carassius auratus

    Microsoft Academic Search

    Wei Zhenlin; Liu Xiaolin

    2009-01-01

    Impact on liver tissue of Carassius auratus by 0.5 mg\\/L-1 cadmium with additional 0.25, 0.5 and 1.0 mg\\/L-1 lanthanum was measured by ROS content, MDA content and Fourier Transform infrared spectrum analysis. The results showed 0.5 and 1.0 mg\\/L-1 lanthanum could alleviate cadmium stress by eliminate excessive ROS and MDA within 1-3 days, and 1.0 mg\\/L-1 lanthanum could decrease these

  17. Radio-opaque fecal impaction and pseudo-occlusion in a dialyzed patient taking lanthanum carbonate.

    PubMed

    Muller, Clotilde; Muller, Sandrine; Sissoko, Aicha; Klein, Alexandre; Faller, Bernadette; Chantrel, Francois

    2012-10-01

    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

  18. Lanthanum-hexaboride carbon composition for use in corrosive hydrogen-fluorine environments

    DOEpatents

    Holcombe, C.E. Jr.; Kovach, L.; Taylor, A.J.

    1980-01-22

    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.

  19. UV light sensing properties of Sm doped vertically aligned ZnO nanorod arrays

    NASA Astrophysics Data System (ADS)

    Kumar, D. Ranjith; Ranjith, K. S.; Rajendrakumar, R. T.

    2015-06-01

    Samarium doped ZnO nanorods were grown on silicon substrate by using vapor phase transport method (VPT) with the growth temperature of 950C. The synthesized nanorods were characterized by XRD, field emission scanning electron microscopy, Raman spectra, and photocurrent measurements. The XRD result revealed that Sm was successfully doped into lattice plane of hexagonal ZnO nanorods. The FESEM result confirms the pure ZnO has nanorod like morphology with an average diameter and length of 130nm and 10m respectively. The above observation is supported by the Micro-Raman spectroscopy result. The photocurrent in the visible region has been significantly enhanced due to deposition of Sm on the surface of the ZnO nanorods. Sm acts as a visible sensitizer because of its lower band gap compared to ZnO.

  20. Study of samarium modified lead zirconate titanate and nickel zinc ferrite composite system

    NASA Astrophysics Data System (ADS)

    Rani, Rekha; Juneja, J. K.; Singh, Sangeeta; Raina, K. K.; Prakash, Chandra

    2015-03-01

    In the present work, composites of samarium substituted lead zirconate titanate and nickel zinc ferrite with compositional formula 0.95Pb1-3x/2 SmxZr0.65Ti0.35O3-0.05Ni0.8Zn0.2Fe2O4 (x=0, 0.01, 0.02 and 0.03) were prepared by the conventional solid state route. X-ray diffraction analysis was carried out to confirm the coexistence of individual phases. Microstructural study was done by using scanning electron microscope. Dielectric constant and loss were studied as a function of temperature and frequency. To study ferroelectric and magnetic properties of the composite samples, corresponding P-E and M-H hysteresis loops were recorded. Change in magnetic properties of electrically poled composite sample (x=0.02) was studied to confirm the magnetoelectric (ME) coupling. ME coefficient (dE/dH) of the samples (x=0 and 0.02) was measured as a function of DC magnetic field.

  1. Polarization-based isotope-selective two-color photoionization of atomic samarium using broadband lasers

    NASA Astrophysics Data System (ADS)

    Seema, A. U.; Rath, Asawari D.; Mandal, P. K.; Dev, Vas

    2015-03-01

    An isotope separation method based on polarization selection rules is applied to atomic samarium by using two-color resonance ionization spectroscopy with broadband lasers. In this method, odd isotopes with nonzero nuclear spin are selectively excited, while even isotopes with zero nuclear spin are prohibited from excitation using two parallel linearly polarized lasers. We have identified a two-color excitation scheme 0 cm-1 ( J = 0) ? 15650.5 cm-1 ( J = 1) ? 33116.8 cm-1 ( J = 1) ? Sm+ for selective excitation of the odd isotopes of Sm I. Using this scheme, selective excitation of odd isotopes of Sm I (147Sm and 149Sm) with an isotopic selectivity better than 40 has been demonstrated. In addition, the effect of different polarization states of the excitation lasers and relative polarization angle between them on the selectivity of odd isotopes has also been studied. The dependence of the even mass isotope signal on the relative polarization angle followed sin2 ?, which is in excellent agreement with theoretical predictions.

  2. Development and evaluation of copper-67 and samarium-153 labeled conjugates for tumor radioimmunotherapy

    SciTech Connect

    Srivastava, S.C.; Mausner, L.F.; Mease, R.C.; Meinken, G.E.; Joshi, V.; Kolsky, K.; Sweet, M.; Steplewski, Z.

    1995-02-01

    The potential of utilizing receptor-specific agents such as monoclonal antibodies (MAb), and MAb-derived smaller molecules, as carriers of radionuclides for the selective destruction of tumors has stimulated much research activity. The success of such applications depends on many factors, especially the tumor binding properties of the antibody reagent, the efficiency of labeling and in-vivo stability of the radioconjugate and, on the careful choice of the radionuclide best suited to treat the tumor under consideration. The radiolabeled antibody technique for radioimmunotherapy (RIT), however, has experienced many limitations, and its success has not matched the expectations that were raised more than a decade ago. The problems that have been identified include: (i) degradation of antibody immunoreactivity resulting from chemical manipulations required for labeling; (ii) lack of suitable radioisotopes and methods for stable attachment of the radiolabel; (iii) in-vivo instability of the radioimmunoconjugates; (iv) excessive accumulation of activity in non-target locations; and (v) lack of radioimmunoconjugate accessibility to cells internal to a tumor mass. A careful choice of the radionuclide(s) best suited to treat the tumor under consideration is one of the most important requirements for successful radioimmunotherapy. This study evaluates copper 67 and samarium 153 for tumor radioimmunotherapy.

  3. Lunar prospector measurements of the distribution of incompatible elements gadolinium, samarium and thorium

    SciTech Connect

    Elphic, R.C.; Lawrence, D.J.; Feldman, W.C.; Barraclough, B.L. [Los Alamos National Lab., NM (United States); Maurice, S. [Observatoire Midi-Pyrenees, Toulouse (France); Binder, A.B. [Lunar Research Inst., Gilroy, CA (United States); Lucey, P.G. [Univ. of Hawaii, Manoa, HI (United States). Hawaii Inst. of Geophysics and Planetology

    1999-04-01

    Lunar Prospector neutron spectrometer (NS) and gamma ray spectrometer (GRS) observations have been used to map out the distribution of incompatible elements on the lunar surface. Specifically, the GRS data provide maps of the distribution of thorium and potassium while the NS data provide information on the distribution of iron and titanium, and the rare earth elements gadolinium and samarium. Using results of analysis of Celementine spectral reflectance (CSR) data, the Fe- and Ti-contributions to the NS data can be removed, leaving primarily rare earth element contributions from Gd and Sm. The Th and K maps correlate with the inferred Gd and Sm maps (r {approximately} 0.93), but there are regions of significant disagreement. One of these is in the KREEP-rich circum-Imbrium ring. No clear explanation has emerged for this disagreement, though Th, K, Gd and Sm have differing degrees of incompatibility. These results clearly are important to discussions of the geochemistry of the Procellarum-Imbrium Th-rich Terrane and the South-Pole-Aitken Terrane.

  4. Uranyl Sensitization of Samarium(III) Luminescence in a Two-Dimensional Coordination Polymer

    SciTech Connect

    Knope, Karah E. [George Washington Univ., Washington, DC (United States); de Lill, Daniel T. [Univ. of Nevada, Reno, NV (United States); Rowland, Clare E. [George Washington Univ., Washington, DC (United States); Cantos, Paula M. [George Washington Univ., Washington, DC (United States); de Bettencourt-Dias, Ana [Univ. of Nevada, Reno, NV (United States); Cahill, Christopher L. [George Washington Univ., Washington, DC (United States)

    2012-01-02

    Heterometallic carboxyphosphonates UO?2+/Ln3+ have been prepared from the hydrothermal reaction of uranyl nitrate, lanthanide nitrate (Ln = Sm, Tb, Er, Yb), and phosphonoacetic acid (H?PPA). Compound 1, (UO?)?(PPA)(HPPA)?Sm(H?O)2H?O (1) adopts a two-dimensional structure in which the UO?2+ metal ions bind exclusively to the phosphonate moiety, whereas the Ln3+ ions are coordinated by both phosphonate and carboxylate functionalities. Luminescence studies of 1 show very bright visible and near-IR samarium(III)-centered emission upon direct excitation of the uranyl moiety. The Sm3+ emissive state exhibits a double-exponential decay with lifetimes of 67.2 6.5 and 9.0 1.3 ?s as measured at 594 nm, after excitation at both 365 and 420 nm. No emission is observed in the region typical of the uranyl cation, indicating that all energy is either transferred to the Sm3+ center or lost to nonradiative processes. Herein we report the synthesis, crystal structure, and luminescent behavior of 1, as well as those of the isostructural terbium, erbium, and ytterbium analogues.

  5. The action of lanthanum ions and formaldehyde on the proton-pumping function of bacteriorhodopsin.

    PubMed

    Drachev, A L; Drachev, L A; Kaulen, A D; Khitrina, L V

    1984-01-16

    The photochemical cycle and the proton-pumping function of bacteriorhodopsin modified with lanthanum and formaldehyde has been studied. In both preparations, the M412 leads to BR570 transition time has been found to increase considerably. The deceleration of the photochemical cycle has been shown to be accompanied by inhibition of the millisecond phase of the photoelectrical response of bacteriorhodopsin membranes associated with phospholipid-impregnated collodion film. Photoelectrogenic activity measured with permeable ion probe in proteoliposomes was also inhibited. Effects of lanthanum were reversed by EDTA. Formation of M412 was slightly accelerated and the microsecond electrogenic phase was not affected by lanthanum and by formaldehyde. It is concluded that lanthanum, but not formaldehyde, can be used as a specific reversible inhibitor of the second half of the bacteriorhodopsin photocycle and of the associated H+ uptake on the cytoplasmic side of the halobacterial membrane. Possible mechanisms of these effects are discussed. PMID:6321172

  6. Self-Correction of Lanthanum-Cerium Halide Gamma Spectra (pre-print)

    SciTech Connect

    Ding Yuan, Paul Guss, and Sanjoy Mukhopadhyay

    2009-04-01

    Lanthanum-cerium halide detectors generally exhibit superior energy resolutions for gamma radiation detection compared with conventional sodium iodide detectors. However, they are also subject to self-activities due to lanthanum-138 decay and contamination due to beta decay in the low-energy region and alpha decay in the high-energy region. The detectors self-activity and crystal contamination jointly contribute a significant amount of uncertainties to the gamma spectral measurement and affect the precision of the nuclide identification process. This paper demonstrates a self-correction procedure for self-activity and contamination reduction from spectra collected by lanthanum-cerium halide detectors. It can be implemented as an automatic self-correction module for the future gamma radiation detector made of lanthanum-cerium halide crystals.

  7. Lanthanum Molybdate Nanoparticles from the Bradley Reaction: Factors Influencing Their Composition, Structure, and Functional Characteristics as Potential Matrixes for Luminescent Phosphors

    PubMed Central

    2014-01-01

    Interaction of lanthanum isopropoxide with molybdenum(VI) alkoxides in La/Mo ratios varying from 3:1 to 1:1 in acetophenon or allyl alcohol as solvents offers nanosized poorly crystalline products of complex composition, where the precipitation of Mo-rich ones is followed by the formation of La-rich ones with conservation of the reaction stoichiometry in total. Thermal treatment of the precipitates at temperatures over 700 C leads to the formation of stoichiometric phases of the ?- and ?-La2Mo2O9 compositions. Introduction of smaller Re3+ cations such as Sm3+ by doping favors stabilization of the La2xRExMo2O9 phase with improved crystallinity even after lower-temperature thermal treatment. The doping is successful only when the Re3+ (Sm3+, Eu3+, and Tb3+) is introduced as an alkoxide: application of Re3+(acac)3 as Re3+ sources leads to materials free from Re3+. The produced samples were characterized by XPD, TGA, SEM, and TEM studies as well as the luminescent properties for the Sm3+-doped phases. PMID:24392745

  8. Luminescence study on Eu or Tb doped lanthanum-gadolinium pyrosilicate crystal

    NASA Astrophysics Data System (ADS)

    Kurosawa, Shunsuke; Shishido, Toetsu; Sugawara, Takamasa; Nomura, Akiko; Yubuta, Kunio; Pejchal, Jan; Murakami, Rikito; Yokota, Yuui; Shoji, Yasuhiro; Ohashi, Yuji; Kamada, Kei; Yoshikawa, Akira

    2015-03-01

    (Eu0.01, Gd0.90, La0.09)2Si2O7 (Eu:La-GPS) and (Tb0.01, Gd0.90, La0.09)2Si2O7 (Tb:La-GPS) crystals were grown by the floating zone method, and their optical and scintillation properties were investigated. Gd3+-to-Tb3+ or -Eu3+ energy transfer processes were found, and photo-luminescence and radio-luminescence emission spectra showed 5D0-7Fi (i = 1-4) Eu3+ transitions in Eu:La-GPS, and 5D3-7Fi (i = 3-6) and 5D4-7Fi (i = 3-6) transitions in Tb:La-GPS. Using these scintillators, alpha-ray imaging was possible with a CMOS camera. These materials can be used for X-ray detection as well.

  9. Ce doped lanthanum tri-bromide SPET scanner for molecular imaging

    NASA Astrophysics Data System (ADS)

    Pani, R.; Pellegrini, R.; Cinti, M. N.; Bennati, P.; Betti, M.; Vittorini, F.; Mattioli, M.; Trotta, G.; Orsolini Cencelli, V.; Scaf, R.; Navarria, F.; Bollini, D.; Baldazzi, G.; Moschini, G.; de Notaristefani, F.

    2007-02-01

    The availability of LaBr 3:Ce crystals from St. Gobain has started various investigations in the field of medical imaging, in particular in PET, SPECT and Compton camera systems. At present LaBr 3:Ce crystals are available in a continuous shape covering up to 1010 cm 2 with a thickness of 1 cm, in contrast, serious concerns are arising in pixellated manufacturing. With the aim of verifying the potentials introduced by LaBr 3:Ce for SPET imaging, two small ? cameras based on Anger camera principle have been assembled and imaging performances were compared. Two crystals of LaBr 3:Ce and NaI(Tl) with the same detection area (55 cm 2) and thickness of 5 and 1.5 mm, respectively were been integrally assembled with a H8500 Hamamatsu flat panel PMT. Through the thicker crystal, the LaBr 3:Ce camera showed superior imaging and detection performances at 140 keV compared with the NaI(Tl) one, with 0.9 mm FWHM intrinsic spatial resolution, 8% FWHM energy resolution and 80% intrinsic detection efficiency.

  10. Fabrication and spectral properties of Nd 3+-doped yttrium lanthanum oxide transparent ceramics

    NASA Astrophysics Data System (ADS)

    Hu, Xiaoman; Yang, Qiuhong; Dou, Chuanguo; Xu, Jun; Zhou, Hongxu

    2008-06-01

    Transparent 1 at% Nd3+:Y1.9La0.1O3 ceramics were fabricated with nanopowders prepared by carbonate coprecipitation method. The powder compacts were sintered in H2 atmosphere at 1550 C for 30 h. The Nd3+:Y1.9La0.1O3 ceramics display uniform grains of about 50 ?m and high transparency. The highest transmittance of the ceramics reaches 67%. The strongest absorption peak is in the wavelength of 820 nm with absorption cross section of 2.48 10-20 cm2. The absorption is still high at LD wavelength 806 nm with absorption cross section of 1.78 10-20 cm2 and broad full width at half maximum (FWHM) of about 6.3 nm. The strongest emission peak was centered at 1078 nm with large stimulated emission cross section of 9.63 10-20 cm2 and broad FWHM of about 7.8 nm. The broad absorption and emission bandwidth of Nd3+:Y1.9La0.1O3 transparent ceramics are favorable to achieve the miniaturized LD pumping apparatus and ultrashort modelocked pulse laser output, respectively.

  11. Thermodynamics, defect structure, and charge transfer in doped lanthanum cobaltites: an overview

    Microsoft Academic Search

    A. N. Petrov; V. A. Cherepanov; A. Yu. Zuev

    2006-01-01

    This work, based on the experimental and theoretical research performed by the authors during last three decades, presents\\u000a an overview of phase and defect thermodynamics, electronic transport properties, and the stability of cobaltite-based mixed\\u000a conductors that are promising for electrode and membrane applications. Attention is centered on (1) the phase equilibria in\\u000a LaMeCoTO (where Me=Ca, Sr, Ba and T=Mn, Fe,

  12. Synthesis and Physicochemical Properties of Yttrium Oxide Doped with Neodymium and Lanthanum

    NASA Astrophysics Data System (ADS)

    Kruk, A.; Mrzek, M.; Domaga?a, J.; Brylewski, T.; Gawlik, W.

    2014-09-01

    Transparent La0.1Nd0.1Y1.8O3 ceramics were prepared by use of the ethylenediaminetetraacetic acid gel process followed by sintering by hot isostatic pressing. The structure and morphology of the powders and bulk samples and the optical properties of bulk samples were investigated by use of x-ray diffraction (XRD), scanning electron microscopy, visible and near-infrared reflectance spectroscopy, and study of magneto-optic (Faraday) effects. The powders consisted of many agglomerates of fine, oval particles. XRD studies of the powder and bulk sample confirmed their single-phase composition, and spectrophotometric and magneto-optical studies in the range 500-1000 nm revealed their potential for application as an optical materials.

  13. Investigation of the spectroscopic properties of Yb 3+-doped yttrium lanthanum oxide transparent ceramic

    Microsoft Academic Search

    Q. H. Yang; J. Ding; H. W. Zhang; J. Xu

    2007-01-01

    Spectroscopic properties of (Y0.9?xLa0.1Ybx)2O3 transparent ceramic were studied. Two main absorption peaks of the specimen are centered at 940 and 970nm, which are suitable for InGaAs laser diode pumping. The main emission peaks were located at 1032 and 1075nm with larger emission cross-section and longer fluorescence lifetime than those of Yb:Y2O3. These properties of (Y0.9?xLa0.1Ybx)2O3 transparent ceramic are favorable to

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

    Microsoft Academic Search

    Peng-nian Huang; A. Petric

    1996-01-01

    The solid solution range of the La(Sr)Ga(Mg)O 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

  15. Single-Longitudinal-Mode Lanthanum-Codoped Bismuth-Based Erbium Doped Fiber Ring Laser

    E-print Network

    Wai, Ping-kong Alexander

    a tunable fiber Bragg grating (FBG) Fabry Perot etalon 4 , and introducing a saturable absorber with a tunable FBG5 . When employing an FBG, the mode competition and mode hopping instabilities could not be avoided because of the broad bandwidth of the FBG. In this paper, we propose and experimentally

  16. Optical and transport properties of lanthanum-doped stannate BaSnO3

    Microsoft Academic Search

    B. Hadjarab; A. Bouguelia; M. Trari

    2007-01-01

    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-delta which is a mixed phase for x > 0.02, behaviour readily understood in terms of the lone pair cation Sn2+. The magnetic

  17. Crystal growth and characterization of rare-earth-doped gallates of alkaline earth and lanthanum

    NASA Astrophysics Data System (ADS)

    Ryba-Romanowski, Witold; Golab, Stanislaw; Berkowski, Marek

    1991-08-01

    We present the results of investigation of crystal growth optical and mechanical properties of optically uniaxial and piezoelectric crystals Owing to several advantages the crystals are well suited for practical application as laser active materials or high temperature piezoelectric sensors. I . I NT R 0 D U C T I 0 N During past few years a considerable progress has been made in the growing technique of single crystals of compounds with a general chemical formula ABC3O7 where A:Ba B:La Sm and C : Al Several compounds belonging to that large family were first obtained in the polycrystalline form y sintering the stoichiometric mixture of oxides at high temperature. 1 Preliminary x-ray investigation indicated that the crystals were of tetragonal symmetry space group P421m - D32d. Since all these compounds have identical structure and nearly the same unit cell parameters can expect that they will form solid solutions with a nonlimited or limited mutual solubility. In this paper we summarize the available information concernig the crystal growth and properties of two representatives of these compounds.

  18. Oxygen exchange and diffusion coefficients of strontium-doped lanthanum ferrites by electrical conductivity relaxation

    Microsoft Academic Search

    J. E. ten Elshof; M. H. R. Lankhorst; H. J. M. Bouwmeester

    1997-01-01

    Perovskite-type solid oxide solutions La{sub 1-x}SrFeO{sub 3-δ} are candidate materials for use as high temperature electrodes and oxygen separation membranes. Electrical conductivity relaxation experiments were performed on thin specimens of La{sub 1-x}SrFeO{sub 3-δ} (x = 0.1, 0.4) at oxygen partial pressures p{sub O} = 10⁻⁵ to 1 bar in the temperature range 923 to 1,223 K. The transient response of

  19. Synthesis and physicochemical characterization of nanocrystalline cobalt doped lanthanum strontium ferrite

    Microsoft Academic Search

    Chaubey Nityanand; Wani Bina Nalin; Bharadwaj Shyamala Rajkumar; Chattopadhyaya Mahesh Chandra

    2011-01-01

    Nanosized crystallites of La0.6Sr0.4Fe0.8Co0.2O3?? (LSCF), a promising cathode material for Intermediate Temperature-Solid Oxide Fuel Cells (IT-SOFCs) has been synthesized by alternative methods like ceramic route, polymerisable complex process and gel-combustion method and calcined at different temperatures. X-ray diffraction studies were used for the determination of phase purity, crystal structure and average crystallite size of the samples. Microstructure of LSCF samples

  20. Cerium and lanthanum promote floral initiation and reproductive growth of Arabidopsis thaliana

    Microsoft Academic Search

    Ya-Wen He; Chiang-Shiong Loh

    2000-01-01

    The effects of cerium and lanthanum on the vegetative growth, floral initiation and reproductive growth of Arabidopsis thaliana were studied. Addition of cerium nitrate (0.510 ?M) or lanthanum nitrate (0.550 ?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

  1. Dielectric, electromechanical, optical, and mechanical properties of lanthanum-modified lead titanate ceramics

    Microsoft Academic Search

    T. Yamamoto; HIDEJI IGARASHI; KIYOSHI OKAZAKI

    1983-01-01

    Dielectric, electromechanical, optical, and mechanical properties of hot-pressed lanthanum-modified PbTiO ceramics were measured as a function of crystal tetragonality, c\\/a, in a range of tetragonal-to-cubic phases. The results obtained in this study are summarized as follows: The c\\/a changes linearly as a function of lanthanum content. Similarly, Curie point changed linearly and remanent polarization, coercive field, and coupling factors decreased

  2. B-site substituted lanthanum strontium ferrites as electrode materials for electrochemical applications

    Microsoft Academic Search

    Ulrich F. Vogt; Josef Sfeir; Joerg Richter; Christian Soltmann; Peter Holtappels

    2008-01-01

    For electrochemical systems such as solid oxide fuel cells (SOFCs) or solid oxide electrolyzer cells (SOECs), perovskites are widely used as cathode material for the reduction of molecular oxygen. At present, strontium-substituted lanthanum manganite, La 1-x Sr x MnO 3-? (LSM), is used as standard SOFC cathode material for operation at high temperatures, whereas strontium-substituted lanthanum ferrite (LSF) is alternatively

  3. Effect of lanthanum on ion absorption in cucumber seedling leaves.

    PubMed

    Zeng, F L; Shi, P; Zhang, M F; Deng, R W

    2000-01-01

    Scanning electron microscope and energy-dispersive X-ray analysis were used to study the tissular distributions of elements Na, Mg, Cl, K, Ca, Mn, and Fe in leaves of cucumber seedlings in the absence or presence of La3+. The results showed that the atomic percentages of Na, Mg, Cl, K, and Ca were basically reduced and those of Mn and Fe were increased in the presence of La3+; in addition, at 0.02 mM La3+, the reduced or increased degrees were higher than those at 2.0 mM La3+. The effects of La3+ on ion absorption were similar to those of Ca2+, suggesting that the rare earth element lanthanum affects the plant physiological mechanism by regulating the Ca2+ level in plant cell. PMID:11314984

  4. Synthesis and characterization of strontium-lanthanum apatites

    SciTech Connect

    Boughzala, K. [U.R. Materiaux Inorganiques, Departement de Chimie, Faculte des Sciences, 5000 Monastir (Tunisia); Salem, E. Ben [U.R. Materiaux Inorganiques, Departement de Chimie, Faculte des Sciences, 5000 Monastir (Tunisia); Chrifa, A. Ben [Laboratoire de Thermodynamique Appliquee, Departement de Chimie, Faculte des Sciences de Tunis, Campus Universitaire, 1060 Tunis (Tunisia); Gaudin, E. [Institut de Chimie de la Matiere Condensee, Universite de Bordeaux, CNRS (UPR9048) 87 Avenue du Dr Schweitzer, 33608 Pessac Cedex (France); Bouzouita, K. [U.R. Materiaux Inorganiques, Departement de Chimie, Faculte des Sciences, 5000 Monastir (Tunisia)]. E-mail: khaled.bouzouita@ipeim.rnu.tn

    2007-07-03

    Two series of strontium-lanthanum apatites, Sr{sub 10-x}La {sub x}(PO{sub 4}){sub 6-x}(SiO{sub 4}) {sub x}F{sub 2} and Sr{sub 10-x}La {sub x}(PO{sub 4}){sub 6-x}(SiO{sub 4}) {sub x}O with 0 {<=} x {<=} 6, were synthesized by solid state reaction in the temperature range of 1200-1400 deg. C. The obtained materials were characterized by powder X-ray diffraction, infrared absorption spectroscopy and solid {sup 31}P Nuclear Magnetic Resonance. Pure solid solutions were obtained within a limited range of unsubstituted phosphate and silicate apatites. A variation of the lattice parameters was observed, with an increase of a and a decrease of c parameters, related to the radius of the corresponding substituted ions.

  5. Fabrication of calcium lanthanum sulfide ceramic by carbonate coprecipitating method

    SciTech Connect

    Tsai, M.S.; Hon, M.H. (National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering)

    1995-03-01

    Translucent CLS (calcium lanthanum sulfide) pellets were formed by the carbonate coprecipitation method, CS[sub 2] sulfurization, and hot press sintering. For a La/Ca = 2.5 pellet with 1.3 mm in thickness, the transmittance at 13 [mu]m is about 25% after sintering at 1,150 C for 30 minutes and resulfurizing at 950 C for 1 hour. For a La/Ca = 15 pellet with 0.9 mm in thickness the IR transmittance is about 51% at 13 [mu]m after sintering at 1,050 C for 2 hours and resulfurizing at 950 C for 1 hour. Beta-La[sub 2]S[sub 3] is present as a second phase after sintering at 1,150 C for 30 minutes. After resulfurization, the second phase disappears for the La/Ca = 2.5 pellet, but still exists in the La/Ca = 15 pellet.

  6. The management of hyperphosphatemia by lanthanum carbonate in chronic kidney disease patients

    PubMed Central

    Shigematsu, Takashi; Nakashima, Yuri; Ohya, Masaki; Tatsuta, Koichi; Koreeda, Daisuke; Yoshimoto, Wataru; Yamanaka, Shintaro; Sakaguchi, Toshifumi; Hanba, Yoshiyuki; Mima, Toru; Negi, Shigeo

    2012-01-01

    Hyperphosphatemia has been shown to be involved not only in the onset and progression of secondary hyperparathyroidism but also in vascular calcification. In addition, it influences the clinical course of patients with chronic kidney disease. Phosphate (Pi) binder is required in the management of hyperparaphosphatemia, because dietary Pi restriction and Pi removal by hemodialysis alone are insufficient. Lanthanum carbonate, a powerful Pi binder, has a similar effect to aluminum hydroxide in reducing serum Pi levels. As it is excreted via the liver, lanthanum carbonate has an advantage in patients with renal failure. The effect of lanthanum carbonate on serum Pi levels is almost two times higher than that of calcium (Ca) carbonate, which is commonly used. Lanthanum carbonate and Ca carbonate have an additive effect. Worldwide, there is 6 years worth of clinical treatment data on lanthanum carbonate; however, we have 3 years of clinical use in Japanese patients with hyperphosphatemia. No serious side effects have been reported. However, the most important concern is bone toxicity, which has been observed with use of aluminum hydroxide. For this study, clinical research involved analysis of bone biopsies. Although osteomalacia is the most noticeable side effect, this was not observed. Both the high- and the low-turnover bone disease concentrated into a normal bone turnover state. However, as the authors have less than 10 years clinical experience with lanthanum carbonate, patients should be monitored carefully. In addition, it is necessary to demonstrate whether potent treatment effects on hyperphosphatemia improve the long-term outcome. PMID:22723728

  7. Tribological behaviors of lanthanum-based phosphonate 3-aminopropyltriethoxysilane self-assembled films

    NASA Astrophysics Data System (ADS)

    Gu, Qinlin; Cheng, Xianhua

    2007-06-01

    Lanthanum-based thin films deposited on the phosphonate 3-aminopropyltriethoxysilane (APTES) self-assembled monolayer (SAM) were prepared on the hydroxylated glass substrate by a self-assembling process from specially formulated solution. Chemical compositions of the films and chemical state of the elements were detected by X-ray photoelectron spectrometry (XPS). The thickness of the films was determined with an ellipsometer, while the morphologies of the original and worn surfaces of the samples were analyzed by means of atomic force microscopy (AFM) and scanning electron microscopy (SEM), respectively. The tribological properties of the films sliding against GCr15 steel ball were evaluated on a UMT-2MT reciprocating friction and wear tester. As the results, the target film was obtained and reaction may have taken place between the film and the glass substrate. The tribological results show that lanthanum-based thin films are superior in reducing friction and resisting wear compared with APTES-SAM and phosphorylated APTES-SAM. SEM observation of the morphologies of worn surfaces indicates that the wear of APTES-SAM and the phosphorylated APTES-SAM is characteristic of brittle fracture and severe abrasion. Differently, slight abrasion and micro-crack dominate the wear of lanthanum-based thin films. The superior friction reduction and wear resistance of lanthanum-based thin films are attributed to the enhanced load-carrying capacity of the inorganic lanthanum particles in the lanthanum-based thin films as well as good adhesion of the films to the substrate.

  8. Gas permeability of lanthanum oxycarbide targets for the SPES project

    NASA Astrophysics Data System (ADS)

    Biasetto, L.; Innocentini, M. D. M.; Chacon, W. S.; Corradetti, S.; Carturan, S.; Colombo, P.; Andrighetto, A.

    2013-09-01

    The creation of a porous matrix made of interconnected and permeable paths is a key step for the processing of optimized metal carbide targets in the SPES (Selective Production of Exotic Species) project. Unlike close or non-connected open pores, permeable pores link more efficiently the interior and the surface of target disks, and therefore facilitate the effusion and convection transport mechanisms for a faster extraction of exotic nuclei with short decay times. This work describes the analysis of the interconnected porosity of lanthanum oxycarbide targets through the evaluation of permeability coefficients obtained in argon flow experiments at room and high temperature. Samples were produced by the sacrificial template method using phenolic resin (PR) as source of carbon for the carbothermal reaction of lanthanum oxide, and different amounts of polymethilmetacrylate (PMMA) microbeads as template for the production of porosity. Results showed that conventional targets prepared without sacrificial templates displayed relatively high total porosity (45.6%), but very low permeability coefficients (k1 = 4.21 10-17 m2 and k2 = 1.90 10-15 m), comparable to other dense ceramic materials. The linear increase in total porosity from 64.8% to 88.9% achieved by the gradual increase of PMMA from 30% to 80 wt.% resulted in a remarkable increase of five orders of magnitude for k1 (2.36 10-12 m2) and eight orders for k2 (7.48 10-7 m2). The addition of sacrificial fillers was found to be much more efficient to create interconnected and permeable paths in the structure than the carbothermal reduction itself. Preliminary tests with argon flow up to 450 C revealed that the porous matrix also became more permeable with the increase in the gas temperature due to thermal expansion effects, but the extent of this gain depended on the initial porosity level of the sample.

  9. Synthesis and spectroscopy studies of fullerenes and discovery of macroscopic quantities of doped fullerenes

    SciTech Connect

    Chai, Yan.

    1992-01-01

    Synthesis techniques of carbon arc and laser vaporization in the furnace for production of fullerenes have been developed. The optimum conditions for the high yields of fullerenes were tested and studied. A fullerene growth model was proposed to explain the formation of the fullerenes and the extraordinary high yield of C[sub 60]. The results of a test of this growth model was in agreement with the implications of the model. The electronic spectra of neutral C[sub 60] and C[sub 70] in the regions from 375 to 415 nm and 595 to 640 nm have been studied in a supersonically cooled molecular beam by resonant two-photon ionization spectroscopy method. Sharp spectal features were observed in both regions for C[sub 60] and in only the longer wavelength region for C[sub 70]. Neither molecule has the spectra that correspond to the diffuse interstellar bands. The first method to produce macroscopic quantities of internal metal-doped fullerenes was developed successfully and improved. Lanthanum-doped fullerenes were produced by laser vaporization of a lanthanum oxide/graphite composite rod in a flow of argon at 1200[degrees]C. Many properties of these endohedral complexes were investigated in detail. Similar results were obtained with yttrium-doped fullerenes, and double-doped endohedral fullerene complexes were first observed as a stable species in both sublimed film and toluene solution. Macroscopic quantities of other interesting metal-doped or B-doped fullerenes have been obtained and studied. Purification of these metal-doped fullerenes is in the process.

  10. Analysis of the regenerative H 2S poisoning mechanism in Ce 0.8Sm 0.2O 2-coated Ni\\/YSZ anodes for intermediate temperature solid oxide fuel cells

    Microsoft Academic Search

    Jeong Woo Yun; Sung Pil Yoon; Hee Su Kim; Suk Woo Nam

    2011-01-01

    Ceria is used as a sulfur sorbent due to its high affinity for sulfide at high temperatures. In addition, the ionic conductivity of ceria can be dramatically increased by doping with rare metals, including lanthanum, samarium, and gadolinium. Therefore, to enhance sulfur tolerance and improve anode performance, we modified an Ni-based anode with a thin layer coating of Sm0.2Ce0.8O2?? (SDC)

  11. Torque magnetometry study of Fe and Ni doped SmB6

    NASA Astrophysics Data System (ADS)

    Tinsman, Colin; Li, Gang; Lawson, Benjamin; Yu, Fan; Asaba, Tomoya; Wang, Xiangfeng; Paglione, Johnpierre; Li, Lu

    2015-03-01

    There has been renewed interest in the past few years regarding Samarium Hexaboride, a promising candidate to be a topological Kondo insulator. Work on this material represents an extension of the categorization of materials by the topology of their electronic band structure into systems with strong correlation effects. It is known that by introducing magnetic impurities, such as Iron, Nickel, and Europium, the magnetic ground state of SmB6 could be greatly altered. In this study we will present our torque magnetometry data of Fe and Ni doped SmB6, down to 20 mK, and up to 45 Tesla. It is found that the overall symmetry of the angular dependence of torque with respect to magnetic field changed for both Fe-doped SmB6 and Ni-doped SmB6. For pure SmB6, the angular dependence is proportional to sin (2 ?) , as expected for a paramagnetic material. By contrast, for Fe-doped SmB6 and Ni-doped SmB6, the torque vs. tilt angle profile becomes sin (4 ?) . Furthermore, for FexSmB6 the field dependence of torque shows a sharp bend feature around 9 Tesla, which softens with elevating temperature, and could be related to magnetic moment re-alignment.

  12. The extraction of thulium, dysprosium and samarium by di(n-octyl)arsinc acid (HDOAA) in chloroform

    E-print Network

    El Seoud, Monica Irma

    1974-01-01

    in the organic phase after equilibration was obtained by base titration of a 2 ml aliquot of the organic phase diluted with 50 ml 955 ethanol. Preparation of the chloride-free Thulium(III) extraction systems: For some experiments the chloride ion was removed...THE EXTRACTION OF THULIUM, DYSPROSIUM AND SAMARIUM BY DI (n-OCTYL)ARSINIC ACID (HDOAA) IN CHLOROFORM A Thesis by MONICA I. EL SEOUD Submitted to the Graduate College of Texas ARM University in partial fulfillment of the requirements...

  13. Toxicity of Two Different Sized Lanthanum Oxides in Cultured Cells and Sprague-Dawley Rats

    PubMed Central

    2015-01-01

    In recent years, the use of both nano- and micro-sized lanthanum has been increasing in the production of optical glasses, batteries, alloys, etc. However, a hazard assessment has not been performed to determine the degree of toxicity of lanthanum. Therefore, the purpose of this study was to identify the toxicity of both nano- and micro-sized lanthanum oxide in cultured cells and rats. After identifying the size and the morphology of lanthanum oxides, the toxicity of two different sized lanthanum oxides was compared in cultured RAW264.7 cells and A549 cells. The toxicity of the lanthanum oxides was also analyzed using rats. The half maximal inhibitory concentrations of micro-La2O3 in the RAW264.7 cells, with and without sonication, were 17.3 and 12.7 times higher than those of nano-La2O3, respectively. Similar to the RAW264.7 cells, the toxicity of nano-La2O3 was stronger than that of micro-La2O3 in the A549 cells. We found that nano-La2O3 was absorbed in the lungs more and was eliminated more slowly than micro-La2O3. At a dosage that did not affect the body weight, numbers of leukocytes, and concentrations of lactate dehydrogenase and albumin in the bronchoalveolar lavage (BAL) fluids, the weight of the lungs increased. Inflammatory effects on BAL decreased over time, but lung weight increased and the proteinosis of the lung became severe over time. The effects of particle size on the toxicity of lanthanum oxides in rats were less than in the cultured cells. In conclusion, smaller lanthanum oxides were more toxic in the cultured cells, and sonication decreased their size and increased their toxicity. The smaller-sized lanthanum was absorbed more into the lungs and caused more toxicity in the lungs. The histopathological symptoms caused by lanthanum oxide in the lungs did not go away and continued to worsen until 13 weeks after the initial exposure. PMID:26191385

  14. Modification of chitosan by using samarium for potential use in drug delivery system.

    PubMed

    Kusrini, Eny; Arbianti, Rita; Sofyan, Nofrijon; Abdullah, Mohd Aidil A; Andriani, Fika

    2014-01-01

    In the presence of hydroxyl and amine groups, chitosan is highly reactive; therefore, it could be used as a carrier in drug delivery. For this study, chitosan-Sm complexes with different concentrations of samarium from 2.5 to 25 wt.% have been successfully synthesized by the impregnation method. Chitosan combined with Sm3+ ions produced a drug carrier material with fluorescence properties; thus, it could also be used as an indicator of drug release with ibuprofen (IBU) as a model drug. We evaluated the spectroscopic and interaction properties of chitosan and Sm3+ ions, the interaction of chitosan-Sm matrices with IBU as a model drug, and the effect of Sm3+ ions addition on the chitosan ability to adsorb the drug. The result showed that the hypersensitive fluorescence intensity of chitosan-Sm (2.5 wt.%) is higher than the others, even though the adsorption efficiency of chitosan-Sm 2.5wt.% is lower (29.75%) than that of chitosan-Sm 25 wt.% (33.04%). Chitosan-Sm 25 wt.% showed the highest efficiency of adsorption of ibuprofen (33.04%). In the release process of ibuprofen from the chitosan-Sm-IBU matrix, the intensity of orange fluorescent properties in the hypersensitive peak of 4G5/2?6H7/2 transition at 590 nm was observed. Fluorescent intensity increased with the cumulative amount of IBU released; therefore, the release of IBU from the Sm-modified chitosan complex can be monitored by the changes in fluorescent intensity. PMID:24177873

  15. Effects of low-dose capecitabine on Samarium-153-EDTMP therapy for painful bone metastases

    PubMed Central

    Barai, Sukanta; Gambhir, Sanjay; Rastogi, Neeraj; Mandani, Anil; Siddegowda, Murthy

    2015-01-01

    Introduction: Samarium-153 (Sm-153)-EDTMP is routinely used for pain palliation in skeletal metastasis, however most patients report partial response. Many strategies have been contemplated to make radiation therapy for pain more effective, one of them being the use of radiosensitizers. Capecitabine is a chemotherapeutic drug and is routinely combined with external beam radiation to make the target more radio-sensitive. Aim of the study was to evaluate whether combining capecitabine in radiosensitizing dose with Sm-153-EDTMP produces superior analgesia compared to Sm alone. Materials and Methods: Forty-four patients with skeletal metastases from various primaries were randomized into two groups: The study group received 1 mCi/kg Sm-153-EDTMP plus capecitabine (1,650 mg/m2) orally for 8 days (equivalent to four t of 153Sm-EDTMP) and the control arm received 1 mCi/kg Sm-153-EDTMP plus placebo for the 8 days. After treatment, the patients were followed up for 12 weeks to evaluate the degree and duration of pain palliation and hematologic toxicity. Results: All 44 patients reported different degrees of pain relief with none reporting complete pain relief for the entire duration of 12 weeks posttherapy observation period. However the level of pain relief obtained in study arm was significantly better than the control arm with mean posttherapy pain score being 1.29 1.05 and 3.59 2.77 respectively with P of 0.001. Transient and mild hematologic toxicity, as determined by World Health Organization criteria, was apparent in both arms without significant differences. Conclusion: The addition of a low-dose of capecitabine significantly enhances the analgesic effect of Sm-153 without any additional side effects. PMID:25829727

  16. Transport properties near the metal to insulator transition in samarium substituted (Bi,Pb)-2212 system

    SciTech Connect

    Shabna, R.; Sarun, P. M.; Vinu, S.; Syamaprasad, U. [National Institute for Interdisciplinary Science and Technology, CSIR, Trivandrum 695019 (India)

    2009-06-01

    The electrical transport properties of insulating and superconducting samples of Bi{sub 1.7}Pb{sub 0.4}Sr{sub 2-x}Sm{sub x}Ca{sub 1.1}Cu{sub 2.1}O{sub 8+d}elta system is studied across the metal to insulator transition (MIT) region by varying the x values from 0.5 to 1.0 in steps of 0.1. X-ray diffraction analysis, scanning electron microscopy, energy dispersive x-ray analysis (EDAX), and electrical resistivity measurements have been employed for the characterization of all samples. The x-ray and EDAX analyses indicate that samarium (Sm) atoms are incorporated into the crystalline structure of Bi{sub 1.7}Pb{sub 0.4}Sr{sub 2}Ca{sub 1}Cu{sub 2}O{sub 8+d}elta[(Bi,Pb)-2212]. Samples with x<=0.6 undergo superconducting transitions while those with 0.7<=x<=1.0 exhibit semiconducting behavior. The MIT is observed at 0.6

  17. Physical and optical properties of Li2O-MgO-B2O3 doped with Sm3+

    NASA Astrophysics Data System (ADS)

    Reduan, S. A.; Hashim, S.; Ibrahim, Z.; Alajerami, Y. S. M.; Mhareb, M. H. A.; Maqableh, M.; Dawaud, R. S. E. S.; Tamchek, N.

    2014-02-01

    Samarium oxide doped lithium magnesium borate glass has been prepared using conventional melting method. The density and molar volume have been calculated and analyzed while their optical properties were studied by measuring the optical absorption and luminescence spectra at room temperature. From the XRD results, since the patterns do not exhibit any diffraction line thus it confirms their amorphous nature. It was found that the density of the glass samples increased and the molar volume decreased with respect to Sm3+ ions content. Meanwhile, the absorption spectra of this study showed four absorption bands with most outstanding peak at 1230 nm (6H5/2-6F7/2). Three emitted spectra transition were observed in this study which are 4G5/2-6H5/2 (blue), 4G5/2-6H9/2 (green), and 4G5/2-6H11/2(yellowish green). A great enhancement in the PL peaks at green region are observed particularly with the 0.5 mol% concentration, which may attribute to the energy transfer from Mg2+ to the trivalent ions of samarium oxide. Beyond the optimum concentration an opposite effect was remarked. This dwindling is attributed to the concentration quenching phenomenon. The current results agreed with other systematic studies that Sm3+ doped with lithium magnesium borate glasses are attractive solid-state laser materials for generation of various visible lights.

  18. Preparation and electrochemical characterization of Sr and Mn-doped LaGaO 3 as anode materials for LSGM-based SOFCs

    Microsoft Academic Search

    Qingxi Fu; Xingyan Xu; Dingkun Peng; Xingqin Liu; Guangyao Meng

    2003-01-01

    Sr- and Mn-doped lanthanum gallate powders (LSGMn, La0.9Sr0.1Ga1 - xMnxO3 - d, x = 0.20, 0.35, 0.43) were prepared by glycine-nitrate combustion synthesis. X-ray diffraction patterns indicate the perovskite structure was formed without any second phase after calcining the powders at 1000C for 4 h. Compacts of powders synthesized under stoichiometric combustion were sintered to densities over 95% of theoretical

  19. Complexation of uranium(VI) and samarium(III) with oxydiacetic acid: temperature effect and coordination modes.

    PubMed

    Rao, Linfeng; Garnov, Alexander Yu; Jiang, Jun; Di Bernardo, Plinio; Zanonato, PierLuigi; Bismondo, Arturo

    2003-06-01

    The complexation of uranium(VI) and samarium(III) with oxydiacetate (ODA) in 1.05 mol kg(-1) NaClO(4) is studied at variable temperatures (25-70 degrees C). Three U(VI)/ODA complexes (UO(2)L, UO(2)L(2)(2-), and UO(2)HL(2)(-)) and three Sm(III)/ODA complexes (SmL(j)((3-2)(j)+) with j = 1, 2, 3) are identified in this temperature range. The formation constants and the molar enthalpies of complexation are determined by potentiometry and calorimetry. The complexation of uranium(VI) and samarium(III) with oxydiacetate becomes more endothermic at higher temperatures. However, the complexes become stronger due to increasingly more positive entropy of complexation at higher temperatures that exceeds the increase in the enthalpy of complexation. The values of the heat capacity of complexation (Delta C(p) degrees in J K(-1) mol(-1)) are 95 +/- 6, 297 +/- 14, and 162 +/- 19 for UO(2)L, UO(2)L(2)(2-), and UO(2)HL(2)(-), and 142 +/- 6, 198 +/- 14, and 157 +/- 19 for SmL(+), SmL(2)(-), and SmL(3)(3-), respectively. The thermodynamic parameters, in conjunction with the structural information from spectroscopy, help to identify the coordination modes in the uranium oxydiacetate complexes. The effect of temperature on the thermodynamics of the complexation is discussed in terms of the electrostatic model and the change in the solvent structure. PMID:12767209

  20. Preparation and Quality Control of the [153Sm]-Samarium Maltolate Complex as a Lanthanide Mobilization Product in Rats

    PubMed Central

    Naseri, Zohreh; Hakimi, Amir; Jalilian, Amir R.; Nemati Kharat, Ali; Bahrami-Samani, Ali; Ghannadi-Maragheh, Mohammad

    2011-01-01

    Development of lanthanide detoxification agents and protocols is of great importance in management of overdoses. Due to safety of maltol as a detoxifying agent in metal overloads, it can be used as a lanthanide detoxifying agent. In order to demonstrate the biodistribution of final complex, [153Sm]-samarium maltolate was prepared using Sm-153 chloride (radiochemical purity >99.9%; ITLC and specific activity). The stability of the labeled compound was determined in the final solution up to 24h as well as the partition coefficient. Biodistribution studies of Sm-153 chloride, [153Sm]-samarium maltolate were carried out in wild-type rats comparing the critical organ uptakes. Comparative study for Sm3+ cation and the labeled compound was conducted up to 48 h, demonstrating a more rapid wash out for the labeled compound. The effective and biological half lives of 2.3 h and 2.46h were calculated for the complex. The data suggest the detoxification property of maltol formulation for lanthanide overdoses. PMID:21773065

  1. Gamma spectrometry and chemical characterization of ceramic seeds with samarium-153 and holmium-166 for brachytherapy proposal.

    PubMed

    Valente, Eduardo S; Campos, Tarcsio P R

    2010-12-01

    Ceramic seeds were synthesized by the sol-gel technique with Si:Sm:Ca and Si:Ho:Ca. One set of seeds was irradiated in the TRIGA type nuclear reactor IPR-R1 and submitted to instrumental neutron activation analysis (INAA), K(0) method, to determine mass percentage concentration of natural samarium and holmium in the seed as well as to determine all existing radionuclides and their activities. Attention was paid to discrimination of Si-31, Ca-40, Ca-45, Ca-47, Ca-49, Sm-145, Sm-155, Sm-153 and Ho-166. A second sample was submitted to atomic emission spectrometry (ICP-AES) also to determine samarium and holmium concentrations in weight. A third sample was submitted to X-ray fluorescence spectrometry to qualitatively determine chemical composition. The measured activity was due to Sm-153 and Ho-166 with a well-characterized gamma spectrum. The X-ray fluorescence spectrum demonstrated that there is no discrepancy in seed composition. The maximum ranges in the water of beta particles from Sm-153 and Ho-166 decay were evaluated, as well as the dose rate and total dose delivered within the volume delimited by the range of the beta particles. The results are relevant for investigation of the viability of producing Sm-153 and Ho-166 radioactive seeds for use in brachytherapy. PMID:20685128

  2. ON THE SEPARATION OF RARE EARTH ELEMENTS. VI. FURTHER STUDY OF RARE EARTH ELEMENT SEPARATION BY COMPLEX ELUTION. METHOD OF RAPID LANTHANUM SEPARATION

    Microsoft Academic Search

    Massonne

    1958-01-01

    Lanthanum was separated from a mixture of rare earth elements by ion ; exchange. All the nare earths, with the exception of lanthanum, were eluted from ; the resin with a 4% solution of beta -oxyethyliminodiacetic acid at pH 5 and a ; temperature of 70 icient laborato C. The lanthanum was then eluted with a 4% ; nitryltriacetic acid

  3. Comparison of Effects of Overload on Parameters and Performance of Samarium-Cobalt and Strontium-Ferrite Radially Oriented Permanent Magnet Brushless DC Motors

    Microsoft Academic Search

    N. A. Demerdash; T. A. Nyamusa

    1985-01-01

    Effects of high momentary overloads on the samarium-cobalt and strontium-ferrite permanent magnets and the magnetic field in electronically commutated brushless dc machines, as well as their impact on the associated machine parameters were studied. The effect of overload on the machine parameters, and subsequently on the machine system performance was also investigated. This was accomplished through the combined use of

  4. Synthesis of l -chiro- inositol and (?)-conduritol F from d-sorbitol by a highly stereoselective intramolecular pinacol coupling promoted by samarium diiodide

    Microsoft Academic Search

    Jose Luis Chiara; Nuria Valle

    1995-01-01

    A synthesis of l-chiro-inositol and (?)-conduritol F starting from readily available d-sorbitol is described. The route involves as a key step an efficient one-pot sequence consisting of the Swern oxidation of a 1,6-diol followed by a highly stereoselective intramolecular pinacol coupling of the resultant dialdehyde, promoted by samarium diiodide.

  5. Effect of the temperature of calcination on the catalytic performance of manganese- and samarium-manganese-based oxides in the complete oxidation of acetone

    Microsoft Academic Search

    A. Gil; L. M. Ganda; S. A. Korili

    2004-01-01

    The effect of the calcination temperature on manganese-based catalysts used in the complete oxidation of acetone has been studied. The catalysts, containing manganese and samarium and being in bulk oxide form, were prepared in the laboratory and calcined at 673, 823, 1073 and 1273K. The calcination temperature controls and modifies the type of single manganese oxide present, the development of

  6. Titania-lanthanum phosphate photoactive and hydrophobic new generation catalyst

    SciTech Connect

    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

    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.

  7. Myelinated nerve fibres and the fate of lanthanum tracer: an in vivo study.

    PubMed

    Mackenzie, M L; Shorer, Z; Ghabriel, M N; Allt, G

    1984-01-01

    The permeability of the marginal tight junctional system of myelin was tested in the rat employing the electron-dense tracer lanthanum nitrate. Lanthanum was either included in the fixative used for vascular perfusion (at a concentration of 20 mM) or was microinjected in vivo into the sural or tibial nerve (5, 10 and 20 mM). After 5-60 minutes, the microinjected nerves were fixed either by immersion or vascular perfusion. Lanthanum tracer was present in the intraperiod line gap of myelin, irrespective of the mode of application of the tracer, the method of fixation or the time of exposure to lanthanum. However, the tracer was present more extensively when included in the fixative compared with in vivo microinjection. Internodally, lanthanum was usually restricted to the inner, or more commonly, the outer lamellae of larger fibres, while all lamellae were usually penetrated by tracer in smaller fibres. Paranodally, compact myelin was more extensively penetrated. The periaxonal space (between axon and Schwann cell) was readily accessible to tracer. It is concluded that the marginal tight junctional system of myelin is apparently of the 'leaky' type and is permeable to ions. The findings have implications for the electrophysiology and pathophysiology of the myelinated nerve fibre. PMID:6368509

  8. Influence of lanthanum oxide as quality promoter on cathodes for MCFC

    NASA Astrophysics Data System (ADS)

    Escudero, M. J.; Nvoa, X. R.; Rodrigo, T.; Daza, L.

    A novel material based on lithium nickel mixed oxides modified by lanthanum impregnation was investigated as an alternative cathode for molten carbonate fuel cells (MCFCs). The electrochemical behaviour of the new cathode material was evaluated in an eutectic mixture of lithium and potassium (Li:K, 62:38) at 650 C by electrochemical impedance spectroscopy (EIS) as a function of lanthanum content, immersion time and gas composition. The impedance spectra inform on electrode structural changes during the first 100 h. The loss of lithium and the low dissolution of nickel and lanthanum are responsible of these changes. Later on, the structure reaches a stable state. The lanthanum-impregnated cathodes show higher catalytic activity for oxygen reduction and lower dissolution of nickel oxide than the lanthanum-free sample. The cathode material having 0.3 wt.% of La 2O 3 shows the best behaviour. The loss of lithium was confirmed by X-ray diffraction (XRD) and inductive coupled plasma-atomic emission spectroscopy (ICP-AES).

  9. Lanthanum carbonate stimulates bone formation in a rat model of renal insufficiency with low bone turnover.

    PubMed

    Fumoto, Toshio; Ito, Masako; Ikeda, Kyoji

    2014-09-01

    Control of phosphate is important in the management of chronic kidney disease with mineral and bone disorder (CKD-MBD), for which lanthanum carbonate, a non-calcium phosphate-binding agent, has recently been introduced; however, it remains to be determined whether it has any beneficial or deleterious effect on bone remodeling. In the present study, the effects of lanthanum carbonate were examined in an animal model that mimics low turnover bone disease in CKD, i.e., thyroparathyroidectomized (TPTX) and 5/6 nephrectomized (NX) rats undergoing a constant infusion of parathyroid hormone (PTH) and thyroxine injections (TPTX-PTH-5/6NX). Bone histomorphometry at the second lumbar vertebra and tibial metaphysis revealed that both bone formation and resorption were markedly suppressed in the TPTX-PTH-5/6NX model compared with the sham-operated control group, and treatment with lanthanum carbonate was associated with the stimulation of bone formation but not an acceleration of bone resorption. Lanthanum treatment caused a robust stimulation of bone formation with an activation of osteoblasts on the endosteal surface of femoral diaphysis, leading to an increase in cortical bone volume. Thus, lanthanum carbonate has the potential to stimulate bone formation in cases of CKD-MBD with suppressed bone turnover. PMID:24126694

  10. Dietary administration in rodent studies distorts the tissue deposition profile of lanthanum carbonate; brain deposition is a contamination artefact?

    PubMed

    Damment, Stephen J P; Cox, Alan G; Secker, Roger

    2009-08-10

    Lanthanum carbonate is a non-calcium phosphate binder used to control hyperphosphataemia in patients with chronic kidney disease who are undergoing dialysis. Ultrastructurally, lanthanum ions are too large to traverse the tight junctions in the blood-brain barrier, yet tissue distribution studies using dietary administration have reported low concentrations in rodent brain, raising concern about accumulation. To investigate this, tissue lanthanum concentrations were measured in rats given the same lanthanum carbonate dose via powdered diet or oral gavage (838 and 863 mg/kg/day). Additional rats were dosed intravenously with lanthanum chloride (0.03 mg/kg/day), a route enabling much higher plasma lanthanum concentrations. After 28 days, median lanthanum concentrations in liver, bone, kidney and heart showed a direct relationship with those in plasma (highest after intravenous and lowest after dietary dosing). In contrast, brain concentrations were dramatically higher after dietary administration (< or =500 ng/g), compared to the other routes (LLOQ of 11 ng/g). An identical skewed pattern was noted for skin, a tissue readily contaminated in powdered diet studies. These data indicate that brain deposition is a contamination artefact caused by transfer of lanthanum from cranial skin to brain as animals are manipulated during autopsy. Dietary administration should be avoided in distribution studies of trace elements due to the high contamination risk. PMID:19464128

  11. Arbuscular mycorrhizal fungi mediated uptake of nutrient elements by Chinese milk vetch ( Astragalus sinicus L.) grown in lanthanum spiked soil

    Microsoft Academic Search

    Xiu-Hua Chen; Bin Zhao

    2009-01-01

    A greenhouse experiment was conducted to study the effect of mycorrhizal colonization by Gigaspora margarita, Glomus intraradices, and Acaulospora laevis on nutrient uptake of K, Ca, Mg, Cu, Zn, Fe, and Mn by Astragalus sinicus L. in soils spiked with lanthanum at five rates (0, 1, 5, 10, and 20mg kg?1). Lanthanum application significantly decreased the concentrations of K, Ca,

  12. 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

    Boyle, Timothy J.; Ottley, Leigh Anna M.; Yang, Pin; Chen, Ching-Fong; Sanchez, Margaret R.; Bell, Nelson Simmons

    2008-10-01

    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.

  13. Comparison of effects of overload on parameters and performance of samarium-cobalt and strontium-ferrite radially oriented permanent magnet brushless DC motors

    SciTech Connect

    Demerdash, N.A.; Nehl, T.W.; Nyamusa, T.A.

    1985-08-01

    Effects of high momentary overloads on the samarium-cobalt and strontium-ferrite permanent magnets and the magnetic field in electronically commutated brushless dc machines, as well as their impact on the associated machine parameters were studied. The effect of overload on the machine parameters, and subsequently on the machine system performance was also investigated. This was accomplished through the combined use of finite element analysis of the magnetic field in such machines, perturbation of the magnetic energies to determine machine inductances, and dynamic simulation of the performance of brushless dc machines, when energized from voltage source inverters. These effects were investigated through application of the above methods to two equivalent 15 hp brushless dc motors, one of which was built with samarium-cobalt magnets, while the other was built with strontium- ferrite magnets. For momentary overloads as high as 4.5 p.u. magnet flux reductions of 29% and 42% of the no load flux were obtained in the samarium-cobalt and strontiumferrite machines, respectively. Corresponding reductions in the line to line armature inductances of 52% and 46% of the no load values were reported for the samarium-cobalt and strontium-ferrite cases, respectively. The overload affected the profiles and magnitudes of armature induced back emfs. Subsequently, the effects of overload on machine parameters were found to have significant impact on the performance of the machine systems, where findings indicate that the samarium-cobalt unit is more suited for higher overload duties than the strontium-ferrite machine.

  14. Proton-Proton Correlation in Central Collisions of Lanthanum + Lanthanum at 1.2 Gev/a

    NASA Astrophysics Data System (ADS)

    Chang, James W.

    1992-01-01

    Central collisions between 1.2 GeV/A lanthanum projectiles and lanthanum nuclei are analysed for HBT-based proton-proton (pp) correlation. The La + La collision system is unique in that it has both the largest beam and beam + target size in any of the pp correlation analyses performed. The data is obtained from LBL's BEVALAC experiment E684HX. The time-of-flight system also with the Heavy Ion Spectrometer System (HISS) allows identification of protons at average mass resolution of 40.6 MeV (5%). The systematic background is removed from the correlation by the event-mixing method. The correlation from data is compared to the calculated correlation which uses a Gaussian source distribution and pp wavefunction resulting from Fermi statistics, S-wave Reid soft-core nuclear potential, and full Coulomb potential. The RMS radius of the La + La system is found to be 4.90 +/- 0.22 fm when systematic corrections are applied. When this radius (r_sp{RMS}{p }) is compared to the radius obtained using pion-pion correlation on the same data (r_sp {RMS}{pi} = 7.31 +/- 0.29 fm), it is found that the r _sp{RMS}{p}/r_sp{RMS }{pi} ratio is 0.67. Survey of other proton and pion correlation results from same systems reveal that r_sp{RMS} {p} < r_sp{RMS}{pi } in general, with the ratio r_sp {RMS}{p}/r_sp{RMS} {pi} decreasing with increase in colliding system size. Survey of pp correlation results from other experiments are considered to test the bore -cut and billiard-ball models. It is found that when the system is large (A_{total} > 118), the bore-cut model underestimates the size, and the billiard-ball model overestimates the size. The billiard -ball model looks attractive due to the smoothness of the transition between correct size estimation and overestimation. A conjecture is made that if this model is true, then the over-estimation of size may be a signature of nucleon density increase at large colliding systems. Compromise scenarios between the bore-cut and billiard-ball models are introduced to compensate for their inadequacies. This thesis demonstrates that when the colliding system is large, the measured size must be accompanied by a model-dependent interpretation.

  15. Study of prolonged administration of lanthanum carbonate in dialysis patients.

    PubMed

    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

    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

  16. Deposition and investigation of lanthanum-cerium hexaboride thin films

    SciTech Connect

    Kuzanyan, A.S. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia)]. E-mail: akuzan@ipr.sci.am; Harutyunyan, S.R. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia); Vardanyan, V.O. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia); Badalyan, G.R. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia); Petrosyan, V.A. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia); Kuzanyan, V.S. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia); Petrosyan, S.I. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia); Karapetyan, V.E. [Institute for Physical Research NAS, Ashtarak, 378410 (Armenia); Wood, K.S. [NRL, Washington, DC 20375 (United States); Wu, H.-D. [SFA/NRL, Washington, DC 20375 (United States); Gulian, A.M. [Physics Art Frontiers/NRL, Washington, DC 20375 (United States)

    2006-09-15

    Thin films of lanthanum-cerium hexaboride, the promising thermoelectric material for low-temperature applications, are deposited on various substrates by the electron-beam evaporation, pulsed laser deposition and magnetron sputtering. The influence of the deposition conditions on the films X-ray characteristics, composition, microstructure and physical properties, such as the resistivity and Seebeck coefficient, is studied. The preferred (100) orientation of all films is obtained from XRD traces. In the range of 780-800 deg. C deposition temperature the highest intensity of diffractions peaks and the highest degree of the preferred orientation are observed. The temperature dependence of the resistivity and the Seebeck coefficient of films are investigated in the temperature range of 4-300 K. The features appropriate to Kondo effect in the dependences {rho}(T) and S(T) are detected at temperatures below 20 K. Interplay between the value of the Seebeck coefficient, metallic parameters and Kondo scattering of investigated films is discussed. - Graphical abstract: Kondo scattering in (La,Ce)B{sub 6} films: temperature dependence of the resistivity of (La,Ce)B{sub 6} films on various substrates and the ceramics La{sub 0.99}Ce{sub 0.01}B{sub 6}.

  17. Observation of the highly excited states of Lanthanum

    SciTech Connect

    Xue, P.; Xu, X. Y.; Huang, W.; Xu, C. B.; Zhao, R. C.; Xie, X. P. [Department of Modern Applied Physics, Tsinghua University, Beijing 100084 (China)

    1997-01-15

    The highly excited states of Lanthanum are studied by means of laser resonance ionization time-of-flight spectrometer. Based on the two-step laser resonance excitation with intermediate state 5d{sup 2}({sup 3}F)6p {sup 2}D{sub 5/2}{sup 0}, three new Rydberg state (RS) series (5d{sup 2}(a{sup 3}F{sub 2})ns, 5d{sup 2}(a{sup 3}F{sub 3})nd and 5d{sup 2}(a{sup 1}D{sub 2})ns) and a number of autoionizing states (AIS) are obtained. Theoretical calculation leads the quantum defects of ns and nd series to the value {delta}s=4.35 and {delta}{sub d}=2.80 respectively, which are very close to the experimental results. The Rydberg state series 5d{sup 2}(a{sup 3}F{sub 2})ns gives the first ionization limit to be 44979.8{+-}0.3 cm{sup -1}, which is an order more accurate than ever.

  18. The Bayo Canyon/radioactive lanthanum (RaLa) program

    SciTech Connect

    Dummer, J.E.; Taschner, J.C.; Courtright, C.C.

    1996-04-01

    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.

  19. The role of chemical interactions between thorium, cerium, and lanthanum in lymphocyte toxicity.

    PubMed

    Oliveira, Monica S; Duarte, Isabelle M; Paiva, Amanda V; Yunes, Samira N; Almeida, Carlos E; Mattos, Rita C; Sarcinelli, Paula N

    2014-01-01

    Thorium, cerium, and lanthanum are metals present in several types of minerals, the most common of which is monazite. Cerium and lanthanum are elements in the lanthanides series. Thorium, an actinide metal, is a hazardous element due to its radioactive characteristics. There is a lack of information describing the possible chemical interactions among these elements and the effects they may have on humans. Toxicological analyses were performed using cell viability, cell death, and DNA damage assays. Chemical interactions were evaluated based on the Loewe additivity model. The results indicate that thorium and cerium individually have no toxic effects on lymphocytes. However, thorium associated with lanthanum increases the toxicity of this element, thereby reducing the viability of lymphocytes at low concentrations of metals in the mixture. PMID:23930795

  20. Novel borothermal route for the synthesis of lanthanum cerium hexaborides and their field emission properties

    NASA Astrophysics Data System (ADS)

    Menaka; Patra, Rajkumar; Ghosh, Santanu; Ganguli, Ashok K.

    2012-10-01

    The present study describes the development of a simple approach to stabilize polycrystalline lanthanum cerium hexaborides without using any flux and at ambient pressure. The nanostructured lanthanum-cerium borides were synthesized using hydroxide precursors. These precursors (La1-xCex(OH)3, x=0.1, 0.2, 0.3 and 0.5) were synthesized via hydrothermal route in the presence of Tergitol (surfactant, nonylphenol ethoxylate) as a capping agent. The precursors on heating with boron at 1300 C lead to the formation of nanostructures (cubes, rods and pyramids) of lanthanum cerium hexaboride. We have investigated the field emission behaviour of the hexaboride films fabricated by spin coating. It was observed that the pyramidal shaped nanostructures of La0.5Ce0.5B6 shows excellent field emission characteristics with high field enhancement factor of 4502.

  1. [Ultrastructural study of the intercellular junction and lanthanum penetration in the mouse blastocyst].

    PubMed

    Uehara, S; Oikawa, N; Chida, S; Yohkaichiya, T; Tsuiki, A; Hoshiai, H; Yajima, A

    1986-12-01

    Cell junctions in mouse blastocyst were ultrastructurally investigated with or without lanthanum tracer. Tight junctions, gap junctions and desmosomes were observed in the trophectoderm. The tight junction was located near the zona pellucida in all trophoblast interspaces, whereas the gap junction and the desmosome, which were infrequently observed, were localized far from the zona pellucida. However, the desmosomes in the trophectoderm of the expanded blastocyst after culture increased in number and came to be located near the zona pellucida. The trophoblast layer excluded lanthanum whose invasion was interrupted by the tight junction. There were a few intermediate junctions in the interspace between the trophoblast and the inner cell mass cell as well as between the inner cell mass cells. These findings indicate that a substances whose molecular weight exceeds that of lanthanum (138.9) may not flow into the blastocyst through the intercellular space. Moreover, it is speculated that the intercellular connection is strengthened during the expansion of the blastocyst. PMID:3805829

  2. Nanocomposite Lanthanum Zirconate Thermal Barrier Coating Deposited by Suspension Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Wang, Chaohui; Wang, You; Wang, Liang; Hao, Guangzhao; Sun, Xiaoguang; Shan, Fan; Zou, Zhiwei

    2014-10-01

    This work seeks to develop an innovative nanocomposite thermal barrier coating (TBC) exhibiting low thermal conductivity and high durability compared with that of current TBCs. To achieve this objective, nanosized lanthanum zirconate particles were selected for the topcoat of the TBC system, and a new processsuspension plasma spraywas employed to produce desirable microstructural features: the nanocomposite lanthanum zirconate TBC contains ultrafine splats and high volume porosity, for lower thermal conductivity, and better durability. The parameters of plasma spray experiment included two main variables: (i) spray distance varying from 40 to 80 mm and (ii) the concentration of suspension 20, 25, and 30 wt.%, respectively. The microstructure of obtained coatings was characterized with scanning electron microscope and x-ray diffraction. The porosity of coatings is in the range of 6-10%, and the single phase in the as-sprayed coatings was pyrochlore lanthanum zirconate.

  3. Effects of Lanthanum and Ethylenediaminetetraacetate on Leaf Movements of Mimosa1

    PubMed Central

    Campbell, Neil A.; Thomson, William W.

    1977-01-01

    Lanthanum and ethylenediaminetetraacetate (EDTA) profoundly affect the rapid leaf movements of Mimosa pudica L. Lanthanum, which mimics calcium but does not penetrate the plasmalemma, inhibits the closing response but does not affect reopening. A low concentration of EDTA retards the reopening process while a higher EDTA concentration prevents the closing movement. There is evidence that the EDTA effects result from chelation of calcium ions rather than chelation of other cations. These results are discussed with regard to the role of calcium in leaf movements. Images PMID:16660153

  4. LaZnB(5)O(10), the first lanthanum zinc borate.

    PubMed

    Jiao, Zhi-Wei; Wang, Ru-Ji; Wang, Xiao-Qing; Shen, De-Zhong; Shen, Guang-Qiu

    2009-01-01

    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

  5. LaZnB5O10, the first lanthanum zinc borate

    PubMed Central

    Jiao, Zhi-Wei; Wang, Ru-Ji; Wang, Xiao-Qing; Shen, De-Zhong; Shen, Guang-Qiu

    2010-01-01

    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. PMID:21579905

  6. Selective isotope determination of lanthanum by diode-laser-initiated resonance-ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Young, J. P.; Shaw, R. W.

    1995-08-01

    A diode-laser step has been incorporated into a resonance-ionization mass spectrometry optical excitation process to enhance the isotopic selectivity of the technique. Lanthanum isotope ratio enhancements as high as 103 were achieved by use of a single-frequency cw diode laser tuned to excite the first step of a three-step excitation-ionization optical process; the subsequent steps were excited by use of a pulsed dye laser. Applying the same optical technique, we measured atomic hyperfine constants for the high-lying even-parity 4D5/2 state of lanthanum at 30354 cm-1 . The general utility of this spectral approach is discussed.

  7. Synthesis, characterization, and cytotoxic activity of new lanthanum(III) complexes of bis-coumarins.

    PubMed

    Kostova, Irena; Momekov, Georgi; Tzanova, Tzvetomira; Karaivanova, Margarita

    2006-01-01

    Complexes of lanthanum(III) with bis-coumarins: 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one) (H(2)L1) and bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane (H(2)L2) 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-, (1)H-, and (13)C-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 nu(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 H(2)L1 and H(2)L2 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 H(2)L1 at 100 or 200 microM led to a DNA-laddering. The findings suggest that the observed cytotoxicity of the lanthanum complex of H(2)L1 on BV-173 is at least partly mediated through induction of programmed cell death. PMID:17497005

  8. Hartree-Fock-Bogoliubov Calculations in Coordinate Space: Neutron-Rich Sulfur, Zirconium, Cerium, and Samarium Isotopes

    E-print Network

    V. E. Oberacker; A. S. Umar; E. Teran; A. Blazkiewicz

    2003-09-29

    Using the Hartree-Fock-Bogoliubov (HFB) mean field theory in coordinate space, we investigate ground state properties of the sulfur isotopes from the line of stability up to the two-neutron dripline ($^{34-52}S$). In particular, we calculate two-neutron separation energies, quadrupole moments, and rms-radii for protons and neutrons. Evidence for shape coexistence is found in the very neutron-rich sulfur isotopes. We compare our calculations with results from relativistic mean field theory and with available experimental data. We also study the properties of neutron-rich zirconium ($^{102,104}Zr$), cerium ($^{152}Ce$), and samarium ($^{158,160}Sm$) isotopes which exhibit very large prolate quadrupole deformations.

  9. Photoneutron cross sections for samarium isotopes: Toward a unified understanding of (? ,n ) and (n ,? ) reactions in the rare earth region

    NASA Astrophysics Data System (ADS)

    Filipescu, D. M.; Gheorghe, I.; Utsunomiya, H.; Goriely, S.; Renstrm, T.; Nyhus, H.-T.; Tesileanu, O.; Glodariu, T.; Shima, T.; Takahisa, K.; Miyamoto, S.; Lui, Y.-W.; Hilaire, S.; Pru, S.; Martini, M.; Koning, A. J.

    2014-12-01

    Photoneutron cross sections were measured for the seven stable samarium isotopes 144 ,147 ,148 ,149 ,150 ,152 ,154Sm near the neutron threshold with quasi-monochromatic laser-Compton scattering ? rays . Our photoneutron cross sections are found to be low by 20%-37% relative to existing data. The photoneutron data are analyzed with the talys reaction code by considering the Skyrme Hartree-Fock-Bogoliubov (HFB) plus quasiparticle random phase approximation (QRPA) model and the axially symmetric deformed Gogny HFB plus QRPA model of the E 1 ? -ray strength. Using the ? -ray strength function constrained by the present photoneutron data, we made a thorough analysis of the reverse (n ,? ) cross sections including the radioactive nucleus 151Sm with a half-life of 90 yr. The radiative neutron capture cross section for 153Sm with the half-life of 1.928 d is deduced with the ? -ray strength function method.

  10. Irradiation-induced reduction and luminescence properties of Sm 2+ doped in BaBPO 5

    NASA Astrophysics Data System (ADS)

    Huang, Yanlin; Jang, Kiwan; Zhao, Wanxue; Cho, Eunjin; Lee, Ho Sueb; Wang, Xigang; Qin, Dake; Zhang, Ying; Jiang, Chanfang; Seo, Hyo Jin

    2007-12-01

    Usually, Sm 2+ ions could be reduced by heating the materials in reducing atmospheres. Exposure to ionizing radiations is also known to cause Sm 3+?Sm 2+ conversion. In this work, BaBPO 5 doped with the samarium ion was prepared by high temperature solid-state reaction. Sm 2+ ions were obtained by two different reduction methods, i.e., heating in H 2 reduced atmosphere and X-ray irradiation. The measurements of X-ray diffraction (XRD), and scanning electron microscope (SEM) were investigated. It is found that the conversion of Sm 3+?Sm 2+ is very efficient in BaBPO 5 hosts after X-ray irradiation. Sm 2+ ions under these two reduction methods exhibit different characteristics that were studied by measurements of luminescence and decay. The results showed that the luminescence properties of Sm 2+ ions in BaBPO 5 were highly dependent on the sample preparation conditions.

  11. Cyan-white-red luminescence from europium doped Al2O3-La2O3-SiO2 glasses.

    PubMed

    Yang, Hucheng; Lakshminarayana, G; Zhou, Shifeng; Teng, Yu; Qiu, Jianrong

    2008-04-28

    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

  12. Spacecraft charging control by thermal, field emission with lanthanum-hexaboride emitters

    NASA Technical Reports Server (NTRS)

    Morris, J. F.

    1978-01-01

    Thermal, field emitters of lanthanum (or perhaps cerium) hexaboride (LaB6) with temperature variability up to about 1500K are suggested for spacecraft charging control. Such emitters operate at much lower voltages with considerably more control and add plasma-diagnostic versatility. These gains should outweigh the additional complexity of providing heat for the LaB6 thermal, field emitter.

  13. Measurement of lanthanum and technetium in uranium fuels by inductively coupled plasma atomic emission spectroscopy

    Microsoft Academic Search

    K. Carney; P. Crane; D. Cummings; J. Krsul; R. McKnight

    1999-01-01

    An important parameter in characterizing an irradiated nuclear fuel is determining the amount of uranium fissioned. By determining the amount of uranium fissioned in the fuel a burnup performance parameter can be calculated, and the amount of fission products left in the fuel can be predicted. The quantity of uranium fissioned can be calculated from the amount of lanthanum and

  14. Recovery of Zinc, Cadmium, and Lanthanum by Biopolymer Gel Particles of Alginic Acid

    Microsoft Academic Search

    Yasuhiro Konishi; Satoru Asai; Yuji Midoh; Muneharu Oku

    1993-01-01

    Biopolymer gel particles of alginic acid were found to be a useful material for recovering zinc, cadmium, and lanthanum from aqueous solutions. The metals sorbed by the gel particles could be completely eluted by using dilute HCl solution of 0.1 kmol\\/m. The distribution ratios of the individual metals between the gel and liquid phases were measured by using a batch

  15. Lanthanum trichloride: An efficient catalyst for the silylation of hydroxyl groups by activating hexamethyldisilazane (HMDS)

    Microsoft Academic Search

    Akkirala Venkat Narsaiah

    2007-01-01

    A variety of hydroxy functional groups was protected as their corresponding trimethylsilyl ethers using HMDS in the presence of lanthanum trichloride. The catalyst LaCl3 activates the HMDS and accelerates the reaction under mild reaction conditions at room temperature to afford the corresponding silylated products in excellent yields.

  16. Comparative evaluation of the in vitro efficacy of lanthanum carbonate chewable tablets.

    PubMed

    Yang, Yongsheng; Bykadi, Srikant; Carlin, Alan S; Shah, Rakhi B; Yu, Lawrence X; Khan, Mansoor A

    2013-04-01

    The aims of this study were to systematically evaluate the effects of pH levels, phosphate concentrations, and tablet integrity on the phosphate binding profiles of lanthanum carbonate chewable tablets, and to compare the in vitro phosphate binding efficacy of one reference and two test products of lanthanum carbonate chewable tablets. Langmuir equation was utilized to calculate the binding constants k1 and k2 . The phosphate binding to the tablets of lanthanum carbonate product was pH dependent, with a faster binding rate at low pH. The crushed tablets bind phosphate more rapid. Compared with the whole tablets, the kinetic binding profiles from the crushed tablets were less variable under all conditions for both test and reference products. The phosphate level has a significant impact on the phosphate binding for both whole and crushed tablets under all pH conditions, with more binding at higher phosphate concentration. The phosphate binding profiles displayed significant difference among the products. For a crushed tablet, the phosphate binding to lanthanum reached equilibrium within 8 h under all conditions. The 90% confidence interval for the k2 ratio (test/reference) was well within the 80%-125% under all pH conditions. However, the k1 ratio varies from 54% to 144%. 2013 Wiley Periodicals, Inc. and the American Pharmacists Association J Pharm Sci 102:1370-1381, 2013. PMID:23334989

  17. Crack tip 90 domain switching in tetragonal lanthanum-modified lead zirconate titanate under an

    E-print Network

    Zhu, Ting

    ) Lanthanum-modified lead zirconate titanate ferroelectric ceramics (Pb0.96La0.04)(Zr0.40Ti0.60)0.99O3 were. I. INTRODUCTION Perovskite-type ferroelectric ceramics have been used as sensors, actuators conditions. However, ferroelectric ceramics are brittle and they may degrade under com- bined electrical

  18. Fluoride removal in water by a hybrid adsorbent lanthanum-carbon.

    PubMed

    Vences-Alvarez, Esmeralda; Velazquez-Jimenez, Litza Halla; Chazaro-Ruiz, Luis Felipe; Diaz-Flores, Paola E; Rangel-Mendez, Jose Rene

    2015-10-01

    Various health problems associated with drinking water containing high fluoride levels, have motivated researchers to develop more efficient adsorbents to remove fluoride from water for beneficial concentrations to human health. The objective of this research was to anchor lanthanum oxyhydroxides on a commercial granular activated carbon (GAC) to remove fluoride from water considering the effect of the solution pH, and the presence of co-existing anions and organic matter. The activated carbon was modified with lanthanum oxyhydroxides by impregnation. SEM and XRD were performed in order to determine the crystal structure and morphology of the La(III) particles anchored on the GAC surface. FT-IR and pKa's distribution were determined in order to elucidate both the possible mechanism of the lanthanum anchorage on the activated carbon surface and the fluoride adsorption mechanism on the modified material. The results showed that lanthanum ions prefer binding to carboxyl and phenolic groups on the activated carbon surface. Potentiometric titrations revealed that the modified carbon (GAC-La) possesses positive charge at a pH lower than 9. The adsorption capacity of the modified GAC increased five times in contrast to an unmodified GAC adsorption capacity at an initial F(-) concentration of 20mgL(-1). Moreover, the presence of co-existing anions had no effect on the fluoride adsorption capacity at concentrations below 30mgL(-1), that indicated high F(-) affinity by the modified adsorbent material (GAG-La). PMID:26070190

  19. Thermal and Mechanical Properties of Polyethylene Terephthalate\\/Polycarbonate Nanocomposites Modified by Lanthanum Acetyl Acetonate Hydrate

    Microsoft Academic Search

    Yousef Ahmad Mubarak

    2011-01-01

    In attempts to improve the thermal and mechanical properties of polyethylene terephthalate\\/polycarbonate (PET\\/PC) blends nanofil 9 was used. Blending was carried out in a Brabender plasticorder, the chopped composites were then extruded using a single screw extruder to prepare samples for the thermal and mechanical testing. Lanthanum acetyl acetonate hydrate was used as a catalyst for potential transesterification reactions that

  20. Nitric Oxide Alleviates Oxidative Stress Caused by Lanthanum in Rice Leaves

    Microsoft Academic Search

    Xiao Qiang; Ru Qiaomei; Wu Feihua; Huang Xuan; Pei Zhenming; Zheng Hailei

    2007-01-01

    The effect of NO on lanthanum-induced antioxidant activities in rice was evaluated. The results showed that the uptake and translocation of La from root to shoot were obviously inhibited by 10 ?mol L?1 sodium nitroprusside (SNP), a donor of NO, in the seedlings grown in Mura B nutrient solution with 100 ?mol L?1 La. Although the content of

  1. Effects of Lanthanum on the Change of Calcium Level in the Root Cells of Rice

    Microsoft Academic Search

    Dongwu Liu; Xue Wang; Xiaohui Chen; Yousheng Lin; Zhiwei Chen; Hongzhi Xu

    2012-01-01

    Rare earth elements (REEs) have been widely used in agriculture for the growth of crops in China since the 1980s. As a secondary messenger, calcium ion (Ca) participates in physiological and biochemical reactions in plants via cellular or intercellular signal transduction networks. The aim of this study was to investigate the effects of trivalent lanthanum (La) on the change of

  2. Effect of Lanthanum on Nodule Count and Nodularity of Ductile Iron

    Microsoft Academic Search

    M. Ashraf Sheikh; Javed Iqbal

    2007-01-01

    The present study aims at finding out the effect of the addition of a single rare earth element, that is, lanthanum on the nodularity and nodule count of ductile iron under controlled conditions. For this purpose, four melts with different compositions were made, using a 28 kg inductotherm medium frequency induction furnace. The temperature was carefully maintained between 1400 and

  3. Morphological and Humidity Sensing Investigations on Niobium, Neodymium, and Lanthanum Oxides

    Microsoft Academic Search

    Bal Chandra Yadav; Monika Singh

    2010-01-01

    This paper reports a comparative study of moisture sensing properties of niobium penta oxide, neodymium oxide, and lanthanum oxides. Pellets of these materials were made by using hydraulic pressing machine (M.B. Instruments, New Delhi, India) at a pressure of 616 MPa. These pellets were used as sensing elements and thermally annealed at temperatures 200C and 400C successively. After each step

  4. History of Doping and Doping Control

    Microsoft Academic Search

    Rudhard Klaus Mller

    \\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

  5. REFOS study: efficacy and safety of lanthanum carbonate in clinical practice in Spain.

    PubMed

    Torregrosa, Jos-Vicente; Gonzlez-Parra, Emilio; Gonzlez, M Teresa; Cannata-Anda, Jorge

    2014-05-21

    Lanthanum carbonate is a powerful phosphate binder that has shown efficacy and safety in clinical trials for hyperphosphataemia management, although there are few data in regular clinical practice. The study's objective was to evaluate, in regular clinical practice, its efficacy and safety in patients on dialysis. We retrospectively collected data from 15 months of monitoring, corresponding to 3 months prior to the start of treatment with lanthanum carbonate until 12 months after the start. Results included values of serum calcium, phosphorus, alkaline phosphatase, iPTH, hepatic enzymes and haemogram, as well as the daily-prescribed dose of lanthanum carbonate, the concomitant medication, treatment compliance and adverse events. 647 patients were included of which 522 completed the study. Abandonment, for the most part, was due to gastrointestinal disorders (26%) and hypophosphatemia (19%). Serum phosphorus decreased from 6.41.7 mg/dl (start) to 4.91.4 mg/dl (12 months) (P<.001). At the end of the monitoring period, 47% were within the desired phosphorus range (3.5-5mg/dl). There were no significant variations in the remaining parameters. Initial dose of lanthanum carbonate: 1900 mg/day; and end dose: 2300 mg/day. The variables independently associated with phosphataemia were baseline serum phosphorus and treatment compliance. In relation to safety, we observed 238 slight or moderate adverse effects in 117 patients, with 88% linked to gastrointestinal abnormalities. In conclusion, lanthanum carbonate reduces the serum phosphorus values in patients on dialysis with a good safety profile and acceptable adherence to that profile, with gastrointestinal disorders being the most frequent adverse effect. PMID:24849057

  6. Lanthanum acetate inhibits vascular calcification induced by vitamin D3 plus nicotine in rats.

    PubMed

    Zhou, Ye-Bo; Jin, Shao-Ju; Cai, Yan; Teng, Xu; Chen, Li; Tang, Chao-Shu; Qi, Yong-Fen

    2009-08-01

    Lanthanum, a rare earth element, has been used to decrease serum phosphorus level in patients with chronic renal disease and hyperphosphatemia. We aimed to observe the effect and mechanism of two doses of lanthanum acetate (375 and 750 mg/kg/day) on vascular calcification induced by vitamin D3 plus nicotine treatment in rats for 4 weeks. As compared with control rats, rats with calcification showed widespread calcified nodules and irregular elastic fibers in calcified aorta on von Kossa calcium staining and increased aortic calcium and phosphorus contents, alkaline phosphatase (ALP) activity and bone-related protein expressions for osteopontin (OPN) and type III sodium dependent phosphate cotransporter Pit-1 (Pit-1). After treatment with either dose of lanthanum acetate, the calcified nodules and degree of irregular elastic fibers decreased in aortas. Lanthanum acetate at 750 mg/kg/day was more effective than 375 mg/kg/day in lessening vascular calcification by significantly reducing plasma phosphorus level, calcium x phosphorus product and ALP activity, by 30.3%, 28.6%, and 68.6%, respectively; reducing aortic phosphorus and calcium contents and ALP activity, by 48%, 53.1%, and 63.5% (all P < 0.01), respectively; reducing aortic mRNA level of OPN and Pit-1, by 55.8% (P < 0.01) and 38.8% (P < 0.05) and protein level of OPN and Pit-1, by 37.2% and 27.2% (both P < 0.01), respectively; and increasing carboxylated matrix Gla-protein (MGP) protein expression by 33.7% (P < 0.05), as compared with rats treated with vitamin D3 and nicotine alone. Lanthanum acetate could effectively inhibit the pathogenesis of vascular calcification. PMID:19546357

  7. Lanthanum carbonate as a first-line phosphate binder: the "cons".

    PubMed

    Dreke, Tilman B

    2007-01-01

    Controlling serum phosphorus levels in patients with renal failure is critical. The use of oral phosphate-binding agents is universal for patients with end-stage kidney disease to reduce phosphate absorption. The therapeutic goal is to reduce serum phosphorus levels without disturbing calcium homeostasis or promoting accumulation of potentially toxic elements from the medication. Aluminum hydroxide effectively reduces serum phosphorus, but has largely been abandoned as a first-line phosphate binder because of hazards associated with metal absorption and tissue accumulation. Traditional calcium-based phosphate binders tend to promote hypercalcemia and calcium overloading, and are linked to accelerated cardiovascular calcification. Interest in aluminum-free, calcium-free phosphate-binding agents continues to grow. Sevelamer hydrochloride, a metal-free, calcium-free hydrogel, is not absorbed, has been proven safe and efficacious in controlling serum phosphorus, and is associated with attenuated progression of cardiovascular calcification. Lanthanum carbonate is a newer aluminum-free, calcium-free phosphate-binding agent. Lanthanum is a rare-earth trace metal with industrial and agricultural applications. As a therapeutic, this metal-based binder appears effective in reducing serum phosphorus, yet concerns remain about lanthanum accumulation in tissues during long-term oral administration. Similar to the metal aluminum, lanthanum is absorbed in the intestine and accumulates in body tissues, especially in the liver, bone, muscle, kidney, and brain. Moreover, the rate of intestinal absorption of lanthanum is enhanced in chronic renal failure. Our experience with aluminum hydroxide suggests caution regarding the long-term use of another metal-based agent that displays enhanced absorption in the uremic state and progressive tissue accumulation. PMID:17635823

  8. Interaction of oxygen with samarium on Al{sub 2}O{sub 3} thin film grown on Ni{sub 3}Al(111)

    SciTech Connect

    Cheng, Dingling; Xu, Qian, E-mail: qianxu@ustc.edu.cn, E-mail: jfzhu@ustc.edu.cn; Han, Yong; Ye, Yifan; Pan, Haibin; Zhu, Junfa, E-mail: qianxu@ustc.edu.cn, E-mail: jfzhu@ustc.edu.cn [National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei 230029 (China)] [National Synchrotron Radiation Laboratory and Collaborative Innovation Center of Suzhou Nano Science and Technology, University of Science and Technology of China, Hefei 230029 (China)

    2014-03-07

    The interaction between oxygen and samarium (Sm) on the well-ordered thin Al{sub 2}O{sub 3} film grown on Ni{sub 3}Al(111) has been investigated by X-ray photoelectron spectroscopy and synchrotron radiation photoemission spectroscopy. At Sm coverage higher than one monolayer, exposure of oxygen to the Sm films at room temperature leads to the formation of both samarium peroxide (O{sub 2}{sup 2?}) states and regular samarium oxide (O{sup 2?}) states. By contrast, when exposing O{sub 2} to Sm film less than one monolayer on Al{sub 2}O{sub 3}, no O{sub 2}{sup 2?} can be observed. Upon heating to higher temperatures, these metastable O{sub 2}{sup 2?} states dissociate, supplying active O atoms which can diffuse through the Al{sub 2}O{sub 3} thin film to further oxidize the underlying Ni{sub 3}Al(111) substrate, leading to the significant increase of the Al{sub 2}O{sub 3} thin film thickness. Therefore, it can be concluded that Sm, presumably in its peroxide form, acts as a catalyst for the further oxidation of the Ni{sub 3}Al substrate by supplying the active oxygen species at elevated temperatures.

  9. Optical studies of Sm? ions doped zinc alumino bismuth borate glasses.

    PubMed

    Swapna, K; Mahamuda, Sk; Srinivasa Rao, A; Shakya, S; Sasikala, T; Haranath, D; Vijaya Prakash, G

    2014-05-01

    Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm(3+)) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm(3+) ions were estimated from absorption spectral information using Judd-Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410 nm laser excitation demonstrates very distinct and intense orange-red emission for all the doped glasses. The suitable concentration of Sm(3+) ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the (4)G5/2 level of Sm(3+) ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1 mol% of Sm(3+) ions doped ZnAlBiB glasses are most suitable for the development of visible orange-red lasers. PMID:24530709

  10. Optical studies of Sm3+ ions doped Zinc Alumino Bismuth Borate glasses

    NASA Astrophysics Data System (ADS)

    Swapna, K.; Mahamuda, Sk.; Srinivasa Rao, A.; Shakya, S.; Sasikala, T.; Haranath, D.; Vijaya Prakash, G.

    Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm3+) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm3+ ions were estimated from absorption spectral information using Judd-Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410 nm laser excitation demonstrates very distinct and intense orange-red emission for all the doped glasses. The suitable concentration of Sm3+ ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the 4G5/2 level of Sm3+ ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1 mol% of Sm3+ ions doped ZnAlBiB glasses are most suitable for the development of visible orange-red lasers.

  11. Structural phase transitions and superconductivity in lanthanum copper oxides

    SciTech Connect

    Crawford, M.K.; Harlow, R.L.; McCarron, E.M. [DuPont, Wilmington, DE (United States)] [and others

    1996-12-31

    Despite the enormous effort expended over the past ten years to determine the mechanism underlying high temperature superconductivity in cuprates there is still no consensus on the physical origin of this fascinating phenomenon. This is a consequence of a number of factors, among which are the intrinsic difficulties in understanding the strong electron correlations in the copper oxides, determining the roles played by antiferromagnetic interactions and low dimensionality, analyzing the complex phonon dispersion relationships, and characterizing the phase diagrams which are functions of the physical parameters of temperature and pressure, as well as the chemical parameters of stoichiometry and hole concentration. In addition to all of these intrinsic difficulties, extrinsic materials issues such as sample quality and homogeneity present additional complications. Within the field of high temperature superconductivity there exists a subfield centered around the material originally reported to exhibit high temperature superconductivity by Bednorz and Mueller, Ba doped La{sub 2}CuO{sub 4}. This is structurally the simplest cuprate superconductor. The authors report on studies of phase differences observed between such base superconductors doped with Ba or Sr. What these studies have revealed is a fascinating interplay of structural, magnetic and superconducting properties which is unique in the field of high temperature superconductivity and is summarized in this paper.

  12. TlBaCaCuO-(2212) thin films on lanthanum aluminate and sapphire substrates for microwave filters

    Microsoft Academic Search

    H. Schneidewind; M. Manzel; G. Bruchlos; K. Kirsch

    2001-01-01

    High-quality Tl2Ba2CaCu2O8 films for microwave filter application are prepared on both sides of 2 inch lanthanum aluminate substrates as well as on double-sided CeO2 coated r-cut sapphire substrates. The films have thicknesses as high as 1 m in the case of lanthanum aluminate substrates. On CeO2 buffered sapphire substrates it is possible to prepare crack-free superconducting films as thick as

  13. Facile preparation of apatite-type lanthanum silicate by a new water-based solgel process

    SciTech Connect

    Yamagata, Chieko, E-mail: yamagata@ipen.br [Nuclear and Energy Research Institute Instituto de Pesquisas Energticas e Nucleares CCTM (Centro de Cincia e Tecnologia de Materiais), So Paulo (Brazil); Elias, Daniel R.; Paiva, Mayara R.S.; Misso, Agatha M.; Castanho, Sonia R.H. Mello [Nuclear and Energy Research Institute Instituto de Pesquisas Energticas e Nucleares CCTM (Centro de Cincia e Tecnologia de Materiais), So Paulo (Brazil)

    2013-06-01

    Highlights: ? We use a Na{sub 2}SiO{sub 3} waste solution as source of Si. ? We present a simple, rapid and low temperature method of lanthanum silicate apatite preparation. ? TEOS, a high cost reagent, was successfully substituted by a cheap price Na{sub 2}SiO{sub 3}, to obtain pure La{sub 9.56}(SiO{sub 4})6O{sub 2.33} lanthanum silicate apatite. - Abstract: In recent years, apatite-type lanthanum silicates ([Ln{sub 10?x}(XO{sub 4})6O{sub 31.5x}] (X = Si or Ge)) have been studied for use in SOFC (solid oxide fuel cells), at low temperature (600800 C), due to its ionic conductivity which is higher than that of YSZ (Yttrium Stabilized Zirconia) electrolyte. For this reason they are very promising materials as solid electrolyte for SOFCs. Synthesis of functional nanoparticles is a challenge in the nanotechnology. In this work, apatite-type lanthanum silicate nanoparticles were synthesized by a water-based solgel process, i.e., solgel technique followed by chemical precipitation of lanthanum hydroxide on the gel of the silica. Na{sub 2}SiO{sub 3} waste solution was used as silica source. Spherical aerogel silica was prepared by acid catalyzed reaction, followed by precipitation of lanthanum hydroxide to obtain the precursor of apatite-type lanthanum silicate. Powders of apatite-type lanthanum silicate achieved from the precursor were characterized by thermal analysis, X-ray diffraction (XRD), scanning electron microscopy (SEM) and specific surface area measurements (BET). The apatite phase was formed at 900 C.

  14. Luminescence properties of Pr-doped (La,Gd)2Si2O7 grown by the floating zone method

    NASA Astrophysics Data System (ADS)

    Murakami, Rikito; Kurosawa, Shunsuke; Shishido, Toetsu; Sugawara, Takamasa; Nomura, Akiko; Yubuta, Kunio; Suzuki, Akira; Shoji, Yasuhiro; Ohashi, Yuji; Pejchal, Jan; Kamada, Kei; Yokota, Yuui; Yoshikawa, Akira

    2015-05-01

    Scintillation properties of a Pr-doped gadolinium lanthanum pyrosilicate (Pr:La-GPS) crystal grown by the floating zone (FZ) method were investigated, because the Pr3+ 5d4f transition is expected to show a shorter decay time than the Ce3+ 5d4f transition. In both ?-ray radioluminescence and photoluminescence spectra, the emission peak related to the Pr3+ 5d4f transition was observed at around 350 nm. The photoluminescence decay time of Pr:La-GPS was found to be as short as ?23 ns, whereas Ce:La-GPS had a decay time of ?31 ns.

  15. Cytotoxic activity of new lanthanum (III) complexes of bis-coumarins.

    PubMed

    Kostova, Irena; Momekov, Georgi; Zaharieva, Maya; Karaivanova, Margarita

    2005-06-01

    Complexes of lanthanum (III) with bis-coumarins: bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-2-yl-methane; bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-3-yl-methane and bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-4-yl-methane 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 ca. 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-, (1)H- 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 nu(C=O) red shift observed, participation of the carbonyl groups in the coordination to the metal ion was also suggested. Cytotoxic screening by MTT assay was carried out. In the present study, we performed comparative evaluation of the cytotoxic effects of the three newly synthesized lanthanum complexes against the acute myeloid leukemia derived HL-60 and the chronic myeloid leukemia (CML)-derived BV-173. In addition the cytotoxic effects of La (III) complex with bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-2-yl-methane were evaluated on the SKW-3 cells. In order to elucidate some of the mechanistic aspects of the observed cytotoxic effects we evaluated the ability of this complex to trigger programmed cell death (apoptosis by means of agarose gel electrophoretic analysis of DNA), isolated from the cytosolic fraction of treated SKW-3 cells. In addition, microscopic morphological evaluation of the treated cells was carried out in order to establish morphological features indicative for programmed cell death. PMID:15922838

  16. Nonaqueous synthesis of metal oxide nanoparticles: Short review and doped titanium dioxide as case study for the preparation of transition metal-doped oxide nanoparticles

    SciTech Connect

    Djerdj, Igor [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zuerich (Switzerland)], E-mail: igor.djerdj@mat.ethz.ch; Arcon, Denis [Institute Jozef Stefan, Jamova 39, 1000 Ljubljana (Slovenia); Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana (Slovenia); Jaglicic, Zvonko [Institute of Mathematics, Physics and Mechanics, Jadranska 19, 1000 Ljubljana (Slovenia); Faculty of Civil and Geodetic Engineering, University of Ljubljana, Jamova 2, 1000 Ljubljana (Slovenia); Niederberger, Markus [ETH Zuerich, Department of Materials, Wolfgang-Pauli-Strasse 10, 8093 Zuerich (Switzerland)], E-mail: markus.niederberger@mat.ethz.ch

    2008-07-15

    The liquid-phase synthesis of metal oxide nanoparticles in organic solvents under exclusion of water is nowadays a well-established alternative to aqueous sol-gel chemistry. In this article, we highlight some of the advantages of these routes based on selected examples. The first part reviews some recent developments in the synthesis of ternary metal oxide nanoparticles by surfactant-free nonaqueous sol-gel routes, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the presentation of structural peculiarities of manganese oxide nanoparticles with an ordered Mn vacancy superstructure. These examples show that nonaqueous systems, on the one hand, allow the preparation of compositionally complex oxides, and, on the other hand, make use of the organic components (initially present or formed in situ) in the reaction mixture to tailor the morphology. Furthermore, obviously even the crystal structure can differ from the corresponding bulk material like in the case of MnO nanoparticles. In the second part of the paper we present original results regarding the synthesis of dilute magnetic semiconductor TiO{sub 2} nanoparticles doped with cobalt and iron. The structural characterization as well as the magnetic properties with special attention to the doping efficiency is discussed. - Graphical abstract: In the first part of this article, nonaqueous sol-gel routes to ternary metal oxide nanoparticles are briefly reviewed, followed by the discussion of the morphology-controlled synthesis of lanthanum hydroxide nanoparticles, and the appearance of an unprecedented superstructure in MnO nanoparticles. In the second part, doping experiments of TiO{sub 2} with Fe and Co are presented, along with their characterization including magnetic measurements.

  17. Doped Colloidal Artificial Ice

    E-print Network

    A. Libal; C. J. Olson Reichhardt; C. Reichhardt

    2015-07-02

    We examine square and kagome artificial spin ice for colloids confined in arrays of double-well traps. Unlike magnetic artificial spin ices, colloidal and vortex artificial spin ice realizations allow creation of doping sites through double occupation of individual traps. We find that doping square and kagome ice geometries produces opposite effects. For square ice, doping creates local excitations in the ground state configuration that produce a local melting effect as the temperature is raised. In contrast, the kagome ice ground state can absorb the doping charge without generating non-ground-state excitations, while at elevated temperatures the hopping of individual colloids is suppressed near the doping sites. These results indicate that in the square ice, doping adds degeneracy to the ordered ground state and creates local weak spots, while in the kagome ice, which has a highly degenerate ground state, doping locally decreases the degeneracy and creates local hard regions.

  18. Measurement of lanthanum and technetium in uranium fuels by inductively coupled plasma atomic emission spectroscopy.

    SciTech Connect

    Carney, K.; Crane, P.; Cummings, D.; Krsul, J.; McKnight, R.

    1999-06-10

    An important parameter in characterizing an irradiated nuclear fuel is determining the amount of uranium fissioned. By determining the amount of uranium fissioned in the fuel a burnup performance parameter can be calculated, and the amount of fission products left in the fuel can be predicted. The quantity of uranium fissioned can be calculated from the amount of lanthanum and technetium present in the fuel. Lanthanum and technetium were measured in irradiated fuel samples using an Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP-AES) instrument and separation equipment located in a shielded glove-box. A discussion of the method, interferences, detection limits, quality control and a comparison to other work will be presented.

  19. Sorption of tartrate ions to lanthanum (III)-modified calcium fluor- and hydroxyapatite.

    PubMed

    Aissa, Abdallah; Debbabi, Mongi; Gruselle, Michel; Thouvenot, Ren; Flambard, Alexandrine; Gredin, Patrick; Beaunier, Patricia; Tnsuaadu, Kaia

    2009-02-01

    The present article details the formation of lanthanum-modified apatites and the binding process of tartrate ions with these obtained apatites. Chemical analyses, FT-IR and (31)P NMR spectroscopies, XRD powder, TGA, and TEM analyses were employed for studying the reaction between Ca(10)(PO(4))(6)(OH)(2) (HAp) or Ca(10)(PO(4))(6)(F)(2) (FAp) and LaCl(3). The reaction was found to take place mainly through partial dissolution of the apatite followed by precipitation of a new phase containing lanthanum phosphate. When La(3+) was introduced in the presence of L(+)-tartaric acid (TAH(2)), no fundamental changes were observed in the HAp or FAp structures. However, there did occur a formation of a new phase of Ca or/and La tartrate salt. PMID:18996541

  20. Highly stable, mesoporous mixed lanthanum-cerium oxides with tailored structure and reducibility

    SciTech Connect

    Liang, Shuang; Broitman, Esteban; Wang, Yanan; Cao, Anmin; Veser, Goetz

    2011-05-01

    Pure and mixed lanthanum and cerium oxides were synthesized via a reverse microemulsion-templated route. This approach yields highly homogeneous and phase-stable mixed oxides with high surface areas across the entire range of La:Ce ratios from pure lanthana to pure ceria. Surprisingly, all mixed oxides show the fluorite crystal structure of ceria, even for lanthanum contents as high as 90%. Varying the La:Ce ratio not only allows tailoring of the oxide morphology (lattice parameter, pore structure, particle size, and surface area), but also results in a fine-tuning of the reducibility of the oxide which can be explained by the creation of oxygen vacancies in the ceria lattice upon La addition. Such finely controlled syntheses, which enable the formation of stable, homogeneous mixed oxides across the entire composition range, open the path towards functional tailoring of oxide materials, such as rational catalyst design via fine-tuning of redox activity.

  1. Near fifty percent sodium substituted lanthanum manganitesA potential magnetic refrigerant for room temperature applications

    SciTech Connect

    Sethulakshmi, N.; Anantharaman, M. R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Al-Omari, I. A. [Department of Physics, Sultan Qaboos University, PC 123 Muscat, Sultanate of Oman (Oman); Suresh, K. G. [Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076 (India)

    2014-03-03

    Nearly half of lanthanum sites in lanthanum manganites were substituted with monovalent ion-sodium and the compound possessed distorted orthorhombic structure. Ferromagnetic ordering at 300?K and the magnetic isotherms at different temperature ranges were analyzed for estimating magnetic entropy variation. Magnetic entropy change of 1.5?Jkg{sup ?1}K{sup ?1} was observed near 300?K. An appreciable magnetocaloric effect was also observed for a wide range of temperatures near 300?K for small magnetic field variation. Heat capacity was measured for temperatures lower than 300?K and the adiabatic temperature change increases with increase in temperature with a maximum of 0.62?K at 280?K.

  2. Fluorescence properties and electron paramagnetic resonance studies of {gamma}-irradiated Sm{sup 3+}-doped oxyfluoroborate glasses

    SciTech Connect

    Babu, B. Hari; Ravi Kanth Kumar, V. V. [Department of Physics, Pondicherry University, Kalapet, Puducherry-605 014 (India)

    2012-11-01

    The permanent photoinduced valence manipulation of samarium doped oxyfluoroborate glasses as a function of {gamma}-ray irradiation has been investigated using a steady-state fluorescence and electron paramagnetic resonance techniques. An increase in SrF{sub 2} 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 Sm{sup 3+} to Sm{sup 2+} ion. The energy transfer mechanism of induced permanent photoreduction of Sm{sup 3+} to Sm{sup 2+} 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 SrF{sub 2} content in the glass and also with the irradiation dose.

  3. Fluorescent Complexes of Nucleic Acids\\/8Hydroxyquinoline\\/Lanthanum(III) and the Fluorometry of Nucleic Acids

    Microsoft Academic Search

    Cheng Zhi Huang; Ke An Li; Shen Yang Tong

    1996-01-01

    The ternary fluorescent complexes of nucleic acids\\/8-hydroxyquinoline\\/ lanthanum (III) were studied. Nucleic acids in the study involve natured and thermally denatured calf thymus DNA, fish sperm DNA and yeast RNA. In the range of pH 8.08.4 (controlled by NH3-NH4Cl buffer) ternary fluorescent complexes are formed which emit at 485.0 nm for calf thymus DNA and at 480.0 nm for yeast

  4. Chemicospectral determination of yttrium, lanthanum, and cerium by three-phase iodide extraction system

    Microsoft Academic Search

    I. S. Kalmykova; V. F. Mezentseva; E. V. Ponosova

    1974-01-01

    The extraction of rare-earth elements into chloroform with DAM in the usual two-phase system was investigated earlier [3]. Subsequent investigations showed that yttrium, lanthanum, and cerium are capable of being extracted by a mixture of chloroform and benzene, and a third phase, with a volume not greater than 1.5 ml, is formed in this case as with other elements. To

  5. Thermopower of lanthanum monochalcogenides subjected to uniform compression up to 22 GPa

    NASA Astrophysics Data System (ADS)

    Stepanov, N. N.; Morozova, N. V.; Kar'kin, A. E.; Korobeinikov, I. V.; Golubkov, A. V.; Kaminskii, V. V.

    2015-03-01

    It is shown that lanthanum monochalcogenides (LaS, LaSe, LaTe), in which metal ions are trivalent at least up to 22 GPa, may be used as reference materials in finding the stability domains of a variable-valence state in rare-earth elements in different compounds studied under pressure. The thermopower of these materials throughout the pressure interval studied varies between 1 and 4 ?V/K.

  6. Lanthanum Chromite Based Catalysts for Oxidation of Methane Directly on SOFC Anodes

    Microsoft Academic Search

    Joseph Sfeir; Philippe A Buffat; Pedro Mckli; Nicolas Xanthopoulos; Ruben Vasquez; Hans Joerg Mathieu; Jan Van herle; K Ravindranathan Thampi

    2001-01-01

    Catalytic properties of substituted lanthanum chromites were investigated for their use as anode materials for direct methane oxidation in solid oxide fuel cell (SOFC) anode materials. Different reaction mixtures were chosen to simulate the various SOFC operating conditions: partial oxidation, CO2 reforming by recycling, and H2O reforming. All experiments were performed in methane-rich atmospheres. Alkaline earth elements such as Ca,

  7. Chromium and copper substituted lanthanum nano-ferrites: Their synthesis, characterization and application studies

    NASA Astrophysics Data System (ADS)

    Jauhar, Sheenu; Singhal, Sonal

    2014-10-01

    Nano-crystalline lanthanum ferrites substituted by chromium and copper having formula LaMxFe1-xO3 (M = Cr, Cu; 0.0 ? x ? 0.5) were synthesized using sol-gel auto-combustion method. The formation of ferrite particles was confirmed using Fourier Transform Infra-Red (FT-IR) spectra and powder X-ray Diffraction (XRD) techniques. The entire ferrite compositions were found to be pure phased with same symmetry as LaFeO3. The average crystallite size was calculated to be ?60 nm. The ferrite compositions were observed to behave as semi-conductors, as their resistivity decreased with increasing temperature. These ferrite compositions were employed as catalysts in the decomposition of hydrogen peroxide solution (0.17 M). Pure LaFeO3 was found to have a very low catalytic activity towards the decomposition of hydrogen peroxide solution, while presence of copper in the lanthanum ferrite lattice was found to significantly enhance its catalytic activity. The rate constant in case of reactions catalysed by LaCu0.5Fe0.5O3 was nearly 25 times larger than that obtained from reactions catalysed by pure LaFeO3. However, chromium substitution was not found to influence the catalytic activity of lanthanum ferrites as chromium substituted lanthanum ferrites exhibited very low catalytic activity. This was explained on the basis of relative stability of oxidation states of the substituent ions and the presence of defects in the crystal lattice.

  8. Lanthanum phosphate-bonded composite nickel electrodes for alkaline water electrolysis

    Microsoft Academic Search

    H. Dumont; P. W. Wrona; J. M. Lalancette; H. Mnard; L. Brossard

    1992-01-01

    Nickel-powder electrodes bonded with a polymer of lanthanum phosphate were prepared and tested for their performance in water electrolysis of KOH aqueous solutions. Disintegration of the phosphate-bonded electrodes made with spiky filamentary nickel particles is strongly reduced at open circuit potential with LaPO4 rather than AlPO4 as the binding material, but the electrocatalytic performance toward hydrogen evolution is practically the

  9. Photoinduced non-linear optical effects in lanthanum calcium borate single crystals

    Microsoft Academic Search

    Ali H. Reshak; S. Auluck; I. V. Kityk; A. Majchrowski; D. Kasprowicz; M. Drozdowski; J. Kisielewski; T. Lukasiewicz; E. Michalski

    2006-01-01

    We have revealed that lanthanum calcium borate (La2CaB10O19) crystals show two-photon absorption (TPA) favored by UV laser field. UV-induced TPA measurements were performed under illumination\\u000a of a Xe-F laser (? = 217nm) as a photoinducing (pumping) beam. This pumping laser beam created a thin surface layer (about\\u000a 85 nm) that was a source of the observed photoinduced TPA. Use of

  10. Growth and optical properties of a new nonlinear optical lanthanum calcium borate crystal

    Microsoft Academic Search

    X. W. Xu; T. C. Chong; G. Y. Zhang; S. D. Cheng; M. H. Li; C. C. Phua

    2002-01-01

    The monoclinic lanthanum calcium borate La2CaB10O19 (LCB) crystal was grown from its stoichiometric melt by the top-seeded pulling method. The unpolarized transmission spectrum of a 1-mm-thick (001)-cut LCB crystal was measured in the wavelength range of 1903100nm. The crystal exhibited a high transmittance (>80%) and a short absorption edge (<190nm). The phase-matched second-harmonic generation (SHG) properties within the (010) plane

  11. Electrical properties of alloys of lanthanum hexaboride with transition metals. I

    Microsoft Academic Search

    V. P. Bondarenko; B. A. Kovenskaya; V. V. Morozov

    1970-01-01

    1.A study has been made of the effect of hafnium, tantalum, tungsten, and rhenium admixtures on the resistivity and thermal emf of lanthanum hexaboride.2.The addition of 0.5% hafnium or tungsten causes a sharp (up to 2025%) decrease in the resistivity and thermal emf, due to a redistribution of the electron density and to a change in the mobility during the

  12. Photostrictive effect in lanthanum-modified lead zirconate titanate ceramics near the morphotropic phase boundary

    Microsoft Academic Search

    Patcharin Poosanaas; Kenji Uchino

    1999-01-01

    Photostrictive effect in lanthanum-modified lead zirconate titanate (PLZT) ceramics, one of the promising candidates for photostrictive materials, has been investigated with different contents of La and the ratio of Zr\\/Ti near the morphotropic phase boundary compositions. The maximum photocurrent and photovoltage were obtained at different compositions of PLZT ceramics: maximum photocurrent at 4\\/48\\/52, maximum photovoltage at 5\\/54\\/46. New figures of

  13. Design of a lanthanum bromide detector for time-of-flight PET

    Microsoft Academic Search

    A. Kuhn; S. Surti; J. S. Karp; P. S. Raby; K. S. Shah; A. E. Perkins; G. Muehllehner

    2004-01-01

    Recent improvements in the growth and packaging of lanthanum bromide (LaBr3), in addition to its superb intrinsic properties of high light output, excellent energy resolution, and fast decay time, make it a viable detection material for a positron emission tomography (PET) scanner based on time-of-flight (TOF). We have utilized theoretical simulations and experimental measurements to investigate the design and performance

  14. Room temperature synthesis of high temperature stable lanthanum phosphateyttria nano composite

    SciTech Connect

    Sankar, Sasidharan; Raj, Athira N.; Jyothi, C.K. [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India)] [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India); Warrier, K.G.K., E-mail: wwarrierkgk@yahoo.co.in [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India)] [Material Sciences and Technology Division, National Institute for Interdisciplinary Science and Technology, Council of Scientific and Industrial Research, Thiruvananthapuram 695019 (India); Padmanabhan, P.V.A. [Bhabha Atomic Research Centre, Mumbai 400085 (India)] [Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2012-07-15

    Graphical abstract: A facile aqueous solgel route involving precipitationpeptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Highlights: ? A novel lanthanum phosphateY{sub 2}O{sub 3} nano composite is synthesized for the first time using a modified facile sol gel process. ? The composite becomes crystalline at 600 C and X-ray diffraction pattern is indexed for monoclinic LaPO{sub 4} and cubic yttria. ? The composite synthesized was tested up to 1300 C and no reaction between the phases of the constituents is observed with the morphologies of the phases being retained. -- Abstract: A facile aqueous solgel route involving precipitationpeptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Lanthanum phosphate (80 wt%)yttria (20 wt%) nano composite (LaPO{sub 4}20%Y{sub 2}O{sub 3}), has an average particle size of ?70 nm after heat treatment of precursor at 600 C. TGDTA analysis reveals that stable phase of the composite is formed on heating the precursor at 600 C. The TEM images of the composite show rod shape morphology of LaPO{sub 4} in which yttria is acquiring near spherical shape. Phase identification of the composite as well as the phase stability up to 1300 C was carried out using X-ray diffraction technique. With the phases being stable at higher temperatures, the composite synthesized should be a potential material for high temperature applications like thermal barrier coatings and metal melting applications.

  15. Lanthanum silicate coated magnetic microspheres as a promising affinity material for phosphopeptide enrichment and identification.

    PubMed

    Cheng, Gong; Liu, Yan-Lin; Zhang, Ji-Lin; Sun, De-Hui; Ni, Jia-Zuan

    2012-08-01

    Novel Fe(3)O(4)@La(x)Si(y)O(5) affinity microspheres consisting of a superparamagnetic Fe(3)O(4) core and an amorphous lanthanum silicate shell have been synthesized. The core-shell-structured Fe(3)O(4)@La(x)Si(y)O(5) microspheres, with a mean size of ca. 480 nm, had rough lanthanum silicate surfaces and displayed relatively strong magnetism (47.2 emu g(-1)). This novel affinity material can be used for selective capture, rapid magnetic separation, and part dephosphorylation (which plays an important role in identifying phosphopeptides in MS) of the phosphopeptides in a peptide mixture. Its ability to selectively trap and magnetically isolate as well as label the phosphopeptides was evaluated using a standard phosphorylated protein (?-casein) and a real sample (human serum). Phosphopeptides and their corresponding label ions were detected for concentrations of ?-casein as low as 1 10(-9) M and in mixtures of ?-casein and BSA with molar ratios as low as 1:50. In addition, this affinity material, with its labeling properties, is superior to commercial TiO(2) beads in terms of interference from non-phosphopeptide molecules. These results reveal that the lanthanum silicate coated magnetic microspheres represent a promising affinity material for the rapid purification and recognition of phosphopeptides. PMID:22722743

  16. Impact of lanthanum carbonate on cortical bone in dialysis patients with adynamic bone disease.

    PubMed

    Yajima, Aiji; Inaba, Masaaki; Tominaga, Yoshihiro; Tanaka, Motoko; Otsubo, Shigeru; Nitta, Kosaku; Ito, Akemi; Satoh, Shigeru

    2013-04-01

    Among the most serious problems in patients with chronic kidney disease (CKD) is fragility of cortical bone caused by cortical thinning and increased cortical porosity; the cortical fragility is sometimes irreversible, with fractures generally initiating from cortical bone. Therefore, development of treatments for problems of cortical bone is urgently desired. Cortical bone has the three surfaces, including the periosteal surface, intracortical spaces and endocortical surface. Bone turnover at the endocortical surface and intracortical resorption spaces are increased as compared with that at cancellous surface. Bone growth sometimes depends on apposition at the periosteal surface. We treated hyperphosphatemia in two hemodialysis patients with adynamic bone disease with 750-1500?mg/day of lanthanum carbonate, which is a non-calcium containing phosphate binder; the treatment resulted in a decrease of the serum phosphorus levels (P levels), without significant change of the serum intact parathyroid hormone levels. We now report that treatment of these patients with lanthanum carbonate increased mineralization of the periosteal surface, increased bone mass within the intracortical resorption spaces and increased mineralization of the minimodeling surface at the endocortical surface. In addition, woven bone volume in cortical bone was decreased and mineralization of bone units, namely, osteons, was increased. Although these findings were not observed across all surfaces of the cortical bone in the patients, it is expected that lanthanum carbonate would increase the cortical stability in CKD patients, with consequent reduction in the fracture rate in these patients. PMID:23586512

  17. Efficacy of continuous oral administration of lanthanum carbonate over 24 months.

    PubMed

    Ishizu, Takashi; Hong, Zhang; Matsunaga, Tsuneaki; Kaneko, Yoko; Taru, Yoshinori

    2013-04-01

    To examine the efficacy of long-term administration of lanthanum carbonate, changes in serum Ca, phosphate, whole parathyroid hormone (wPTH), and ALP were examined in 40 patients who were able to tolerate dosage of lanthanum carbonate over a continuous period of 24 months. Concurrently, concomitant administration of other phosphate binders, cinacalcet, vitamin D, etc., was also examined. After 24 months, serum phosphorus levels (P levels) had decreased to within management target of guidelines, from 6.16??1.44?mg/dL to 5.58??1.15?mg/dL, and this effect was maintained for 2 years. There were no changes in Ca level. wPTH did not change significantly but tended to increase at 12 months. The dose of concomitantly administered calcium carbonate and sevelamer hydrochloride was reduced. The P-lowering function of lanthanum carbonate still held steady at 24 months following the start of dosage. Because of the rising trend seen in wPTH, dose of cinacalcet and/or vitamin D need to be modulated. Reducing the number of concomitantly administered phosphate binder tablets was desirable from the standpoint of patient adherence. PMID:23586509

  18. Multicenter study of long-term (two-year) efficacy of lanthanum carbonate.

    PubMed

    Ando, Ryoichi; Kimura, Hitoshi; Sato, Hidehiko; Iwamoto, Shunsuke; Yoshizaki, Yuki; Chida, Yoshiko; Ishida, Yuji; Takayama, Masanobu; Yamada, Kouei; Tachibana, Ken; Ohtsuka, Masakazu; Kikuchi, Kan; Inoue, Atsushi

    2013-04-01

    Long-term efficacy of lanthanum carbonate on hyperphosphatemia was examined in multicenter dialysis patients. Outcome and efficacy after 2 years was investigated in 101 patients who had undergone lanthanum carbonate administration. Thirty-three cases dropped out by the 2-year point; patients undergoing at least 2 years of administration totaled 68. Reasons for dropping out were as follows: improvement of hyperphosphatemia, nine cases; changing hospitals, seven cases; medical complications, five cases; digestive symptoms, four cases; poor compliance, four cases; parathyroidectomy, two cases; death, two cases. The mean dosage was increased from initial daily dosage of 744?mg to 1266?mg after 1 year, and to 1246?mg after 2 years. Serum phosphate concentration decreased significantly from the initial 6.15?mg to 5.57?mg/dL after 1 year, and to 5.45?mg/dL after 2 years. Although a lowering trend was observed in corrected calcium levels, the difference was not significant. Parathyroid hormone was unchanged. Achievement rate of Japanese Society for Dialysis Therapy (JSDT) management target values for both phosphorus and calcium improved from 32.7% to 50.0% after 1 year, and to 56.5% after 2 years. Lanthanum carbonate is useful as a therapeutic tool for hyperphosphatemia over long durations. PMID:23586506

  19. Deposition of Sm 2O 3 doped CeO 2 thin films from Ce(DPM) 4 and Sm(DPM) 3 (DPM=2,2,6,6-tetramethyl-3,5-heptanedionato) by aerosol-assisted metalorganic chemical vapor deposition

    Microsoft Academic Search

    Yinzhu Jiang; Haizheng Song; Qianli Ma; Guangyao Meng

    2006-01-01

    Samarium-doped ceria (SDC) thin films were prepared from Sm(DPM)3 (DPM=2,2,6,6-tetramethyl-3,5-heptanedionato) and Ce(DPM)4 using the aerosol-assisted metalorganic chemical vapor deposition method. ?-Al2O3 and NiO-YSZ (YSZ=Y2O3-stabilized ZrO2) disks were chosen as substrates in order to investigate the difference in the growth process on the two substrates. Single cubic structure could be obtained on either ?-Al2O3 or NiO-YSZ substrates at deposition temperatures above

  20. The distribution of the lanthanum anomaly in the Dutch branches of the Rhine River

    NASA Astrophysics Data System (ADS)

    Verheul, M.; Klaver, G.; Bakker, I.; Petelet-Giraud, E.

    2011-12-01

    The elements lanthanum to lutetium, usually referred as the REE, are increasingly used in numerous high technology products and processes. Such products are Gadolinium chelates, used as contrasting agents in medical imaging, and produce positive anthropogenic Gd-anomalies in rare earth shale normalized (Reenasc) patterns in rivers, surface and ground waters and shallow seas. Because of the increased use of the REE, the monitoring program of the Rhine-Meuse branches and surface water influenced by them in the Netherlands was extended from 2008 with the REE. In this monitoring program both the total and dissolved (< 0.45 ?m) fraction are analyzed. At the monitoring station Lobith, where the River Rhine enters the Netherlands, the REEnasc-patterns show beside the well-known Gd-anomaly a distinct La-anomaly. This positive La-anomaly in the Rhine River is recently also reported by Kulaksiz and Bau (2011, sampling was done in 2009) and first occur in the Rhine River north of the city of Worms, 400km upstream of the Dutch-German border. Kulaksiz and Bau could show that this anomaly is of anthropogenic origin and can be traced back to the effluent from a production plant for fluid catalytic cracking catalysts at Rhine river-km 447.4. The amount of anthropogenic lanthanum in the total fraction in Lobith station is an order of magnitude larger than in the dissolved fraction indicating that the suspended matter in the Rhine River is the major carrier of the anthropogenic lanthanum. All REEnasc- patterns of the branches of the Rhine River show in addition to the Gd-anomaly a positive La-anomaly, while in the Meuse River only a Gd-anomaly is observed. In the influenced surface waters of the Rhine and Meuse Rivers always a Gd-anomaly occurs but in those influenced by the Rhine tributaries also the La-anomaly occurs. In the poster the load of lanthanum over the years 2008, 2009 and 2010 in the dissolved and total fraction at Lobith and the distribution of the La anomaly over the branches of the Rhine River in the Netherlands (4 monitoring stations) and influenced surface water (5 monitoring stations) will be shown. The Meuse monitoring stations will be given for comparison. Kulaksiz, S., Bau, M., 2011. Rare earth elements in the Rhine River, Germany: First case of anthropogenic lanthanum as a dissolved microcontaminant in the hydrosphere. Environment International, 37: 973-879.

  1. Nitrogen-doped perovskite-type La2Ti2O7 decorated on graphene composites exhibiting efficient photocatalytic activity toward bisphenol A in water.

    PubMed

    Hua, Zulin; Zhang, Xiaoyuan; Bai, Xue; Lv, Lingling; Ye, Zhengfang; Huang, Xin

    2015-07-15

    Nitrogen-doped lanthanum titanate decorated on graphene sheets (GR/N-doped La2Ti2O7) used as photocatalyst was prepared by a two-step process. To synthesize GR/N-doped La2Ti2O7, La2Ti2O7 was initially developed under heat treatment in NH3 and subsequently decorated on GR by hydrothermal processing. The resulting GR/N-doped La2Ti2O7 was characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, Raman spectroscopy, and X-ray photoelectron spectroscopy. Characterization results indicated that N-doped La2Ti2O7 was approximately 6-8nm thick with single-crystalline perovskite structure and chemically attached onto GR nanosheets by the formation of TiN bond, TiC bond, and oxynitrides. The application of GR/N-doped La2Ti2O7 composites to bisphenol A decomposition exhibits high photocatalytic efficiency under irradiation compared with pure La2Ti2O7 materials. This finding was due to the synergistic effect of great adsorption, enhanced light absorption, efficient charge separation and transfer processes in the presence of GR, and reduced band gap energy because of N doping. This study provides new insights into the fabrication and practical application of high-performance photocatalysts in wastewater treatment. PMID:25801131

  2. Effectiveness of radiation synovectomy with Yttrium-90 and Samarium-153 particulate hydroxyapatite in rheumatoid arthritis patients with knee synovitis: a controlled, randomized, double-blinded trial.

    PubMed

    Dos Santos, Marla Francisca; Furtado, Rita Nely Vilar; Konai, Monique Sayuri; Castiglioni, Mario Luiz Vieira; Marchetti, Renata Rosa; Silva, Constancia Pagano Gonalves; Natour, Jamil

    2011-01-01

    The aim of the present study was to investigate the long-term effectiveness of and tolerance to Yttrium-90 and Samarium-153-particulate hydroxyapatite radiation synovectomy in patients with rheumatoid arthritis (RA) and chronic knee synovitis. Eight-four patients (90 knees) with chronic knee synovitis and RA (according to the American College of Rheumatology criteria) participated in a controlled, double-blinded trial. Patients were randomized to receive an intra-articular injection with either 5mCi Yttrium-90 plus 40mg of triamcinolone hexacetonide (Y/TH Group), 15mCi Samarium-153 hydroxyapatite plus 40mg of triamcinolone hexacetonide (Sm/TH Group), or 40mg triamcinolone hexacetonide alone (Control Group). Blinded examination at baseline, 1, 4, 12, 32, and 48weeks post-intervention included a visual analog scale for joint pain and swelling, morning stiffness, range of motion, knee circumference, Likert scale, percentage of improvement, Stanford Health Assessment Questionnaire, Lequesne index, use of non-steroidal anti-inflammatory drugs and corticosteroids, events and adverse effects, calls to the physician, and hospital visits. There were three withdrawals prior to the injections. Regarding the pain, there was a significantly better response in the Y/TH Group versus the Sm/TH Group at T1 (p?=?0.025) and versus TH alone at T48 (p?=?0.026). The Sm/TH group had more adverse effects (p?=?0.042), but these were mild and transitory. For the pain parameter alone, Yttrium-90 radiosynovectomy associated to TH proved superior to Samarium-153 hydroxyapatite radiosynovectomy associated to TH at T1 and to synovectomy with TH at T48. No other statistically significant inter-group differences were detected. PMID:21120562

  3. Phase constitution in Sr and Mg doped LaGaO{sub 3} system

    SciTech Connect

    Zheng Feng; Bordia, Rajendra K.; Pederson, Larry R

    2004-01-03

    Sr and Mg doped lanthanum gallate perovskites (La{sub 1-x}Sr{sub x}Ga{sub 1-y}Mg{sub y}O{sub 3-{delta}}, shortened as LSGM-XY where X and Y are the doping levels in mole percentage (mol%) at the La- or A-site and the Ga- or B-site, respectively) are promising electrolyte materials for intermediate temperature solid oxide fuel cells (SOFCs). In this study, we have investigated the primary perovskites as well as the secondary phases formed in terms of doping content changes and A/B ratio variations in these materials. Fifteen powder compositions (three doping levels, X=Y=0, 0.1, and 0.2 mol; and five A/B ratios 0.95, 0.98, 1.00, 1.02, and 1.05) were synthesized by the glycine-nitrate combustion process (GNP). These powders were equilibrated by calcining at 1500 deg. C for 9 h prior to crystalline phase characterization by X-ray powder diffraction (XRD). From the results of this study and the available phase diagrams in the literature on constituent binary oxide systems, we propose a crystalline phase diagram of the La{sub 2}O{sub 3}-SrO-Ga{sub 2}O{sub 3}-MgO quaternary system at elevated temperature (1500 deg. C)

  4. Phase Constitution in Sr and Mg doped LaGaO3 System

    SciTech Connect

    Zheng, F; Bordia, Rajendra K.; Pederson, Larry R.

    2004-01-03

    Sr and Mg doped lanthanum gallate perovskites (La1-xSrxGa1-yMgyO3-delta, shortened as LSGM-XY where X and Y are the doping levels in mole percentage (mol%) at the La- or A-site and the Ga- or B-site, respectively) are promising electrolyte materials for intermediate temperature solid oxide fuel cells (SOFCs). In this study, we have investigated the primary perovskites as well as the secondary phases formed in terms of doping content changes and A/B ratio variations in these materials. Fifteen powder compositions (three doping levels, X = Y = 0, 0.1, and 0.2 mol; and five A/B ratios 0.95, 0.98, 1.00, 1.02, and 1.05) were synthesized by the glycine-nitrate combustion process (GNP). These powders were equilibrated by calcining at 1500 degreesC for 9 h prior to crystalline phase characterization by X-ray powder diffraction (XRD). From the results of this study and the available phase diagrams in the literature on constituent binary oxide systems, we propose a crystalline phase diagram of the La2O3-SrO-Ga2O3-MgO quaternary system at elevated temperature (1500 degreesC). (C) 2003 Elsevier Ltd. All rights reserved

  5. Dimeric samarium(III) alkoxides bearing N 2O 2 tetradentate Schiff bases and their utility for the catalytic epoxidation of trans-chalcone

    Microsoft Academic Search

    Steven A. Schuetz; Elizabeth A. Bowman; Carter M. Silvernail; Victor W. Day; John A. Belot

    2005-01-01

    Two anhydrous, dimeric samarium(III) complexes bearing a bulky ?-alkoxide (diphenylmethoxide) ligand and different saturated tetradentate Schiff bases {bis-5,5?-(1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato and bis-5,5?-(2,2-dimethyl-1,3-propanediyldiimino)-2,2-dimethyl-4-hexene-3-onato} were synthesized and fully characterized. The complexes differ only in alkyl substitution at the three-carbon amino linker between the ketoiminato halves, with one having a CH2 group and the other a C(CH3)2 substituent along the free-ligand idealized mirror plane. Both

  6. First-principles study of codoping in lanthanum bromide

    NASA Astrophysics Data System (ADS)

    Erhart, Paul; Sadigh, Babak; Schleife, Andr; berg, Daniel

    2015-04-01

    Codoping of Ce-doped LaBr3 with Ba, Ca, or Sr improves the energy resolution that can be achieved by radiation detectors based on these materials. Here, we present a mechanism that rationalizes this enhancement on the basis of first-principles electronic structure calculations and point defect thermodynamics. It is shown that incorporation of Sr creates neutral VBr-SrLa complexes that can temporarily trap electrons. As a result, Auger quenching of free carriers is reduced, allowing for a more linear, albeit slower, scintillation light yield response. Experimental Stokes shifts can be related to different CeLa-SrLa-VBr triple complex configurations. Codoping with other alkaline as well as alkaline-earth metals is considered as well. Alkaline elements are found to have extremely small solubilities on the order of 0.1 ppm and below at 1000 K. Among the alkaline-earth metals the lighter dopant atoms prefer interstitial-like positions and create strong scattering centers, which has a detrimental impact on carrier mobilities. Only the heavier alkaline-earth elements (Ca, Sr, Ba) combine matching ionic radii with sufficiently high solubilities. This provides a rationale for the experimental finding that improved scintillator performance is exclusively achieved using Sr, Ca, or Ba. The present mechanism demonstrates that codoping of wide-gap materials can provide an efficient means for managing charge carrier populations under out-of-equilibrium conditions. In the present case dopants are introduced that manipulate not only the concentrations but also the electronic properties of intrinsic defects without introducing additional gap levels. This leads to the availability of shallow electron traps that can temporarily localize charge carriers, effectively deactivating carrier-carrier recombination channels. The principles of this mechanism are therefore not specific to the material considered here but can be adapted for controlling charge carrier populations and recombination in other wide-gap materials.

  7. J. Phys. C: Solid State Phys., Vol. 8, 1975.Printed in Great Britain. @ 1975 The metal-insulator transition in lanthanum strontium vanadate

    E-print Network

    Chen, Reuven

    -insulator transition in lanthanum strontium vanadate M Sayer, R Chent, R Fletcher and A Mansinght Department of Physics cluster formation is of importance. 1. Introduction Lanthanum strontium vanadate La,-xSr,V03 (0 I x .4) is a perovskite whose electrical properties change from those of a semiconductor to a metal as the strontium

  8. Mesoporous mn- and la-doped cerium oxide/cobalt oxide mixed metal catalysts for methane oxidation.

    PubMed

    Vickers, Susan M; Gholami, Rahman; Smith, Kevin J; MacLachlan, Mark J

    2015-06-01

    New precious-metal-free mesoporous materials were investigated as catalysts for the complete oxidation of methane to carbon dioxide. Mesoporous cobalt oxide was first synthesized using KIT-6 mesoporous silica as a hard template. After removal of the silica, the cobalt oxide was itself used as a hard template to construct cerium oxide/cobalt oxide composite materials. Furthermore, cerium oxide/cobalt oxide composite materials doped with manganese and lanthanum were also prepared. All of the new composite materials retained the hierarchical long-range order of the original KIT-6 template. Temperature-programmed oxidation measurements showed that these cerium oxide/cobalt oxide and doped cerium oxide/cobalt oxide materials are effective catalysts for the total oxidation of methane, with a light-off temperature (T50%) of ?400 C observed for all of the nanostructured materials. PMID:26000732

  9. Effects of Samarium Doping on Optical Properties of Zn 0.9 (Co 1-xSm x) 0.1O Diluted Magnetic Semiconductor

    Microsoft Academic Search

    Zhang Zhicheng; Zheng Yongping; Lai Fachun; Lai Heng; Huang Zhinan; Huang Zhigao

    2006-01-01

    Transparent ZnO and Zn0.9(Co1-xSmx)0.1O (x = 0.0, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.0) films were prepared by sol-gel method. For the prepared Zn0.9(Co1-xSmx)0.1O systems, the influences of dopant concentration of Sm on the structural and optical properties were investigated. Three additional absorption peaks around 570, 620, and 660 nm wavelengths were observed in low Sm content

  10. Visible light emission and energy transfer processes in Sm-doped nitride films

    SciTech Connect

    Zanatta, A. R. [Instituto de Fisica de Sao Carlos - USP, Sao Carlos 13560-250 - SP (Brazil)

    2012-06-15

    Even though the great interest in studying the near-infrared light emission due to Er{sup 3+} ions for telecommunication purposes, efficient visible radiation can be achieved from many different rare-earth (RE) ions. In fact, visible and/or near-infrared light emission takes place in RE-doped wide bandgap semiconductors following either photon or electron excitation, suggesting their technological potential in devices such as light-emitting diodes (LED's) and flat-panel displays, for example. Taking into consideration these aspects, the present contribution reports on the investigation of AlN, BeN, GeN, and SiN thin films doped with samarium. The samples were prepared by sputtering and as a result of the deposition method and conditions they present an amorphous structure and Sm concentrations in the low 0.5 at. %. After deposition, the samples were submitted to thermal annealing treatments and investigated by different spectroscopic techniques. A detailed examination of the experimental data allowed to identify optical transitions due to Sm{sup 3+} and Sm{sup 2+} ions as well as differences in their mechanisms of photon excitation and recombination. Moreover, it is shown that the Sm-related spectral features and emission intensity are susceptible, respectively, to the atomic environment the Sm{sup 3+}/Sm{sup 2+} ions experience and to the presence of non-radiative recombination centers.

  11. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    NASA Astrophysics Data System (ADS)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 C-150 C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  12. Phase I Trial of Vertebral Intracavitary Cement and Samarium (VICS): Novel Technique for Treatment of Painful Vertebral Metastasis

    SciTech Connect

    Ashamalla, Hani, E-mail: haa9002@nyp.or [Department of Radiation Oncology, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Cardoso, Erico [Department of Surgery, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Macedon, Mark; Guirguis, Adel [Department of Radiation Oncology, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Weng Lijun [Department of Nuclear Medicine, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Ali, Shamsah [Department of Surgery, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States); Mokhtar, Bahaa; Ashamalla, Michael; Panigrahi, Nokul [Department of Radiation Oncology, New York Methodist Hospital, Weill Medical College, Cornell University, Brooklyn, NY (United States)

    2009-11-01

    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 ({sup 153}Sm-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 {sup 153}Sm with kyphoplasty. Methods and Materials: A total of 33 procedures were performed in 26 patients. Of these 26 patients, 7 underwent procedures performed at two vertebral levels. The mean age of the cohort was 64 years (range, 33-86). The kyphoplasty procedure was performed using a known protocol; 1-4 mCi of {sup 153}Sm was admixed with the bone cement and administered under tight radiation safety measures. Serial nuclear body scans were obtained. Pain assessment was evaluated using a visual analog pain score. Results: All patients tolerated the procedure well. No procedure-related morbidities were noted. No significant change had occurred in the blood counts at 1 month after the procedure. One case was not technically satisfactory. Nuclear scans revealed clear radiotracer uptake in the other 32 vertebrae injected. Except for the first patient, no radiation leakage was encountered. The mean pain score using the visual analog scale improved from 8.6 before to 2.8 after the procedure (p < .0001). Follow-up bone scans demonstrated a 43% decrease in the tracer uptake. Conclusion: The results of our study have shown that the combination of intravertebral administration of {sup 153}Sm and kyphoplasty is well tolerated with adequate pain control. No hematologic adverse effects were found. A reduction of the bone scan tracer uptake was observed in the injected vertebrae. Longer follow-up is needed to study the antineoplastic effect of the procedure.

  13. Radioactive synovectomy with (90) yttrium and (153) samarium hydroxyapatite in haemophilic joints: preliminary study on radiation safety.

    PubMed

    Thomas, S; Mendes, J D; Souza, S A; Lorenzato, C S; Assi, P E; Pacheco, L R L; Gabriel, M B; Bordim, A; Gutfilen, B; da Fonseca, L M B

    2013-07-01

    Most countries still do not achieve 1 IU of factor VIII/capita sufficient for survival. Although primary prophylaxis prevents synovitis, is not universally used. Chronic synovitis is treated with arthroscopy at expense of considerable amount of coagulation factors, and specialized surgeons. Radioactive synovectomy (RS) is a minimally invasive and cost effective alternative to arthroscopy, often considered first the option for persistent synovitis. Even without established causation with cancer, RS is avoided by some, due to this concern. We aim contributing to the understanding of RS safety regarding malignancy, presenting a large number of treated patients, and a single case of cancer. Three centres in Brazil applied RS with (90) Yttrium Citrate, (90) Yttrium hydroxyapatite or (153) Samarium hydroxyapatite in haemophilic joints and performed a survey addressing cancer in these patients. Four hundred and eighty eight patients (ages 3-51) received 1-3 RS (total 842) and follow-up was 6 months to 9 years. One patient aged 14 years presented Ewing sarcoma, 11 months after RS. The tumour was treated successfully with surgery and chemotherapy. Causality of cancer by RS is improbable in this case. Accordingly, latency here is far below minimum 5-10 years for radio-induction of solid tumours. Moreover, ES is not a typically radio-induced tumour, even at high doses. In agreement with others, though recognizing limitations, this study suggests RS is safe regarding cancer induction. Synovitis is a known burden for patients. The decision of making reasonable usage of RS should be outweighed with the risks of leaving synovitis untreated. PMID:23534894

  14. Influence of La doping on structural and dielectric properties of SrBi{sub 2}Nb{sub 2}O{sub 9} ceramics

    SciTech Connect

    Verma, Maya; Sreenivas, K.; Gupta, Vinay [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)

    2009-01-15

    Lanthanum doped SrBi{sub 2}Nb{sub 2}O{sub 9} ceramics with the chemical formula SrBi{sub 2-x}La{sub x}Nb{sub 2}O{sub 9} (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 La{sup 3+} dopant, having no lone pair electrons. Shifting of Raman phonon modes indicates the reduced rattling space of NbO{sub 6} octahedra with increase in La doping concentration. Further, the softening of lowest frequency phonon mode with increasing x in SBLN shows the transition from ferroelectric to paraelectric at room temperature. The dielectric properties for all the compositions are studied as a function of temperature (25 to 500 deg. C) over the frequency range of 10 kHz-1 MHz. With increase in lanthanum doping concentration the phase transition becomes diffused and transition temperature gets shifted toward lower temperature. A phase transition from normal ferroelectric to paraelectric has been observed via relaxor-type ferroelectrics with increase in x. The frequency dependence of transition temperature was studied in terms of Vogel-Fulcher relation for SBLN (x=0.4)

  15. Barium carbonate nanoparticle to enhance oxygen reduction activity of strontium doped lanthanum ferrite for solid oxide fuel cell

    NASA Astrophysics Data System (ADS)

    Hong, Tao; Chen, Fanglin; Xia, Changrong

    2015-03-01

    BaCO3 nanoparticles are demonstrated as outstanding catalysts for high-temperature oxygen reduction reaction (ORR) on the La0.8Sr0.2FeO3-? (LSF) cathode for solid oxide fuel cells (SOFCs) based on ytrria-stabilized zirconia (YSZ) electrolytes. Thermal gravitational and X-ray diffraction measurements show that BaCO3 is stable and chemically compatible with LSF under the fabrication and operation conditions of intermediate-temperature SOFCs. The BaCO3 nanoparticles can greatly reduce the interfacial polarization resistance; from 2.96 to 0.84 ? cm2 at 700 C when 12.9wt% BaCO3 is infiltrated to the porous LSF electrode on the YSZ electrolyte. Electrochemical impedance spectroscopy shows that there is about one order of magnitude decrease in the low-frequency resistance, indicating that BaCO3 nanoparticles can greatly enhance the surface steps for ORR. Electrical conductivity relaxation investigation indicates about one order of magnitude increase in the chemical oxygen surface exchange coefficient when BaCO3 is applied, directly demonstrating significant increase in the kinetics for ORR. In addition, LSF cathodes with infiltrated BaCO3 nanoparticles have shown excellent stability and substantially enhanced cell performance as demonstrated with single cells, suggesting BaCO3 nanoparticles are very effective in enhancing ORR on LSF.

  16. Doped lanthanum ferrite cathode development for use in single-step co-fired solid oxide fuel cells

    Microsoft Academic Search

    Peter Andrew Zink

    2010-01-01

    A major obstacle to the commercialization of solid oxide fuel cells (SOFCs) is the high operating temperature range (800 to 1000C). Lowering the operating temperature to approximately 600C allows for cost reduction through the use of inexpensive stack housing and sealing materials, but conventional SOFC cathode materials have high charge transfer resistance at those temperatures which results in poor performance.

  17. Synthesis of La{sup 3+} doped nanocrystalline ceria powder by urea-formaldehyde gel combustion route

    SciTech Connect

    Biswas, M. [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India)] [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India); Bandyopadhyay, S., E-mail: sbando@cgcri.res.in [Central Glass and Ceramic Research Institute, Kolkata 700 032 (India)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Nano LC synthesized by gel combustion, using urea-formaldehyde fuel for first time. Black-Right-Pointing-Pointer Largely single crystals were produced in average range of 20-30 nm. Black-Right-Pointing-Pointer La{sup 3+} doping increases cell dimension linearly. Black-Right-Pointing-Pointer La{sup 3+} doping introduces ionic point defects but does not change electronic band gap. Black-Right-Pointing-Pointer Presence of Ce{sup 3+} indicates that this synthesis route produces reactive powders. -- Abstract: Nanocrystalline ceria powders doped with various concentrations of lanthanum oxide have been prepared following gel combustion route using for the first time urea-formaldehyde as fuel. The synthesized products were characterized by XRD, FESEM, TEM, PL and UV-vis spectroscopy. Peak positions of XRD were refined and the lattice parameters were obtained by applying Cohen's method. Unit cell parameter increases with concentration of La{sup 3+} ion and the variation is consistently linear. XRD calculations showed the dependence of crystallite size on dopant concentrations at lower level. TEM observation revealed unagglomerated particles to be single crystals in the average range of 20-30 nm. Band gap of the La{sup 3+} doped ceria materials does not change with doping. Spectroscopic experiments proved the existence of Ce{sup 3+} in the formed powder.

  18. Aero dopes and varnishes

    NASA Technical Reports Server (NTRS)

    Britton, H T S

    1927-01-01

    Before proceeding to discuss the preparation of dope solutions, it will be necessary to consider some of the essential properties which should be possessed of a dope film, deposited in and on the surface of an aero fabric. The first is that it should tighten the material and second it should withstand weathering.

  19. Study of transition metal oxide doped LaGaO 3 as electrode materials for LSGM-based solid oxide fuel cells

    Microsoft Academic Search

    Fanglin Chen; Meilin Liu

    1998-01-01

    Transition metal oxide doped lanthanum gallates, La0.9Sr0.1Ga0.8M0.2O3 (where M=Co, Mn, Cr, Fe, or V), are studied as mixed ionic-electronic conductors (MIECs) for electrode applications. The\\u000a electrochemical properties of these materials in air and in H2 are characterized using impedance spectroscopy, open cell voltage measurement, and gas permeation measurement. Three single\\u000a cells based on La0.9Sr0.1Ga0.8 Mg0.2O3 (LSGM) electrolyte (1.13 to 1.65?mm

  20. Optoenergy storage and random walks assisted broadband amplification in Er3+-doped (Pb,La)(Zr,Ti)O3 disordered ceramics.

    PubMed

    Xu, Long; Zhao, Hua; Xu, Caixia; Zhang, Siqi; Zou, Yingyin K; Zhang, Jingwen

    2014-02-01

    A broadband optical amplification was observed and investigated in Er3+-doped electrostrictive ceramics of lanthanum-modified lead zirconate titanate under a corona atmosphere. The ceramic structure change caused by UV light, electric field, and random walks originated from the diffusive process in intrinsically disordered materials may all contribute to the optical amplification and the associated energy storage. Discussion based on optical energy storage and diffusive equations was given to explain the findings. Those experiments performed made it possible to study random walks and optical amplification in transparent ceramics materials. PMID:24514195

  1. Electroinduced structural change- and random walks-based impact on the light emission in Er3+/Yb3+ doped (Pb,La)(Zr,Ti)O3 ceramics

    NASA Astrophysics Data System (ADS)

    Xu, L.; Zhang, J.; Zhang, S.; Xu, C.; Zou, Y. K.; Zhao, H.

    2013-06-01

    Remarkable enhancement/reduction of light emission and competition among different wavebands with rare earth doped lanthanum lead zirconate titanate ceramics were observed in a corona atmosphere caused by an externally applied electric field. Quantum-mechanical analyses, based on variation of structural symmetry of the unit cell and hence the crystal field due to electrostriction, were given to elucidate the effect. Apart from the symmetry of crystal field, the obvious contribution from the optoenergy storage and weak localization of light involved were discussed. These results are promising in designing and implementation of lasers and sensors.

  2. Comparison between features and performance characteristics of fifteen hp samarium cobalt and ferrite based brushless dc motors operated by same power conditioner

    SciTech Connect

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

    1983-01-01

    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 Co/sub 5/) is used as permanent magnet material, while in the other the magnets were made of strontium ferrite number 8. The two machines were built to operate from the same power conditioner, which consisted of a transistor chopper in series with a three phase full wave inverter/converter bridge, which consists of six transistor-diode switches. Both of the two motors achieved a continuous 2 hour rating of more than 15 hp with a peak one minute rating of 35 hp. System efficiency (combined motor and conditioner) under rated conditions of 90% was achieved for both machines. Details of these and other performance characteristics and design parameters are presented and analyzed to assess the impact of the choice of magnet material on design and performance for this, as well as other applications.

  3. Production of high-purity gadolinium-153. 2. Removal of samarium, terbium, and microamounts of europium from gadolinium by extraction chromatography

    SciTech Connect

    Mel`nik, M.I.; Karelin, E.A.; Filimonov, V.T. [Research Inst. of Atomic Reactors, Dimitrovgrad (Russian Federation)

    1995-03-01

    Extraction and extraction-chromatographic behavior of Sm, Eu, Gd, and Tb in the system di-2-ethylhexyl hydrogen phosphate (DEHP)-decane-nitric acid has been studied at various concentrations of nitric acid and lanthanide in aqueous phase. The optimal range of nitric acid concentrations for extraction-chromatographic separation of samarium, europium, gadolinium, and terbium has been determined. The influence of gadolinium concentration on distribution of europium and terbium has been examined. At gadolinium content in solution below 50% of the dynamic exchange capacity of the column, the gadolinium distribution coefficient slightly decreases with increasing gadolinium concentration in the initial solution, the distribution factors of the impurity lanthanides remaining virtually unchanged. With further increase in gadolinium content in the initial solution, the gadolinium distribution factor drastically decreases, and {open_quotes}tails{close_quotes} are formed at the expense of increasing fraction of the extracted complex form GdA{sub 3}. These data allowed a conclusion that composition of extracted complexes is different for Sm, Eu, Gd, and Tb. Conditions proposed for extraction-chromatographic purification of gadolinium in the system DEHP-decane-nitric acid provide for removal of impurity lanthanides (samarium, terbium, and microamounts of europium) with the purification factors greater than 100 (Sm, Tb) and about 2 (Eu) at the column charge of up to 50%.

  4. Preliminary Investigation of Lanthanum-Cerium Bromide Self-Activity Removal

    SciTech Connect

    Yuan, D., Guss, P.

    2011-09-01

    It has been reported that detectors made of lanthanum-cerium halides (LaBr3:Ce and CeBr3) have superior energy resolution for gamma-radiation detection compared to what is offered by conventional sodium iodide (NaI:T1) detectors16. Although superior energy resolution may be observed, one major barrier that has hindered the rapid adaptation of lanthanum halides is their self-activity, due primarily to the presence of isotope 138La, and the ? contamination, due to the trace amount of actinides68. It has also been observed that the lanthanum-cerium halides contain a substantial amount of self-activity caused by the radioactive isotope 138La. Additionally, LaBr3:Ce spectra are also affected by ? contaminations in the low-energy region. To use either LaBr3:Ce or CeBr3 for high-sensitivity gamma detection, it may be necessary to have the self-activity as well as ? and ? contaminations removed or reduced. This paper describes a novel algorithmic approach for self-activity and contamination reduction for LaBr3:Ce and CeBr3 detectors using a third reference NaI:T1 detector. We present a computational procedure for separating self-activity from the gamma spectra obtained by LaBr3:Ce detectors. With the self-activity spectra precalculated, it is possible to perform real-time self-activity removal. This procedure can be implemented as an automatic self-activity subtraction module for gamma-radiation detectors made of LaBr3:Ce and/or CeBr3 crystals. With this approach, it is possible to develop a new generation of LaBr3:Ce detectors capable of producing spectra as clean as those obtained by conventional NaI:T1 detectors, but with much improved energy resolutions.

  5. Temperature Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    2003-01-01

    Lanthanum titanate (La2Ti2O7) a layered distorted perovskite (1) with space group Pna2(sub 1) has been shown to have potential as a high temperature piezoelectric (2). However this highly refractory oxide compound must be consolidated at relatively high temperatures approximately 1400 C. Commercial La2Ti207 powders were mechanically alloyed with additions of Y2O3 to lower the consolidation temperature by 300 C and to provide post processing mechanical stability. Temperature dependent electrical, elastic and anelastic behavior were selected as nondestructive means of evaluating the effects of yttria on the properties of this ferroceramic material.

  6. Superconducting Hg-Ba-Ca-Cu-O thin films on lanthanum aluminate and sapphire substrates

    Microsoft Academic Search

    Thomas Stelzner; Henrik Schneidewind; Gisela Bruchlos

    2003-01-01

    Epitaxial c-axis-oriented HgBa2CaCu2O6+? (Hg-1212) thin films have been prepared on lanthanum aluminate as well as on CeO2 buffered r-plane sapphire substrates using a Tl-Hg cation-exchange process. Films on LaAlO3 exhibited superconducting transition temperatures (Tc) up to 122 K and critical current densities in the range of 2.2-3.1 MA\\/cm2 at 77 K and under self-field. For the microwave surface resistance (Rs)

  7. Determination of lanthanum by graphite furnace atomic absorption spectrometry with a tantalum platform

    NASA Astrophysics Data System (ADS)

    Skroce, A.; McCormick, M.; Meehan, B.; Dolic, V.; Peverill, K.

    1993-11-01

    A simple and sensitive method has been developed for the determination of lanthanum by graphite furnace atomic absorption spectroscopy (GFAAS). The element was determined under stabilized temperature platform furnace (STPF) conditions with atomization from a tantalum platform. Under optimized furnace conditions, the use of the tantalum surface provided better analytical sensitivity than atomization from graphite. The characteristic mass and detection limit of the methods were 220 pg and 40 ?g/l, respectively. At higher concentrations, the precision was about 4% RSD. The tube life was greater than 250 firings. Nitric and sulphuric acids decreased tube life.

  8. Lanthanum-induced neurotoxicity: solving the riddle of its involvement in cognitive impairment?

    PubMed

    Zarros, Apostolos; Byrne, Ashleigh-Maria; Boomkamp, Stephanie D; Tsakiris, Stylianos; Baillie, George S

    2013-11-01

    The conclusion of a series of recent reports highlights the significant neurotoxic effects that rare earth elements, such as lanthanum (La), can have during neurodevelopment. These findings are, herein, combined and presented using a simplified schematic overview that provides a putative solution to the riddle of La-induced cognitive impairment. Our commentary also highlights potential targets for further investigations into the mechanisms which underpin La-induced neurotoxicity, with a focus on the crucial role of the hippocampus. Within this context, a central role for the cyclic-adenosine monophosphate signalling pathway is proposed. PMID:23934103

  9. Temperature-Dependent Electrical and Micromechanical Properties of Lanthanum Titanate with Additions of Yttria

    NASA Technical Reports Server (NTRS)

    Goldsby, Jon C.

    2010-01-01

    Temperature-dependent elastic properties were determined by establishing continuous flexural vibrations in the material at its lowest resonance frequency of 31tHz. The imaginary part of the complex impedance plotted as a function of frequency and temperature reveals a thermally activated peak, which decreases in magnitude as the temperature increases. Additions of yttria do not degrade the electromechanical in particularly the elastic and anelastic properties of lanthanum titanate. Y2O3/La2Ti2O7 exhibits extremely low internal friction and hence may be more mechanical fatigue-resistant at low strains.

  10. Fabrication of Lanthanum Telluride 14-1-11 Zintl High-Temperature Thermoelectric Couple

    NASA Technical Reports Server (NTRS)

    Ravi, Vilupanur A.; Li, Billy Chun-Yip; Fleurial, Pierre; Star, Kurt

    2010-01-01

    The development of more efficient thermoelectric couple technology capable of operating with high-grade heat sources up to 1,275 K is key to improving the performance of radioisotope thermoelectric generators. Lanthanum telluride La3-xTe4 and 14-1-11 Zintls (Yb14MnSb11) have been identified as very promising materials. The fabrication of advanced high-temperature thermoelectric couples requires the joining of several dissimilar materials, typically including a number of diffusion bonding and brazing steps, to achieve a device capable of operating at elevated temperatures across a large temperature differential (up to 900 K). A thermoelectric couple typically comprises a heat collector/ exchanger, metallic interconnects on both hot and cold sides, n-type and ptype conductivity thermoelectric elements, and cold-side hardware to connect to the cold-side heat rejection and provide electrical connections. Differences in the physical, mechanical, and chemical properties of the materials that make up the thermoelectric couple, especially differences in the coefficients of thermal expansion (CTE), result in undesirable interfacial stresses that can lead to mechanical failure of the device. The problem is further complicated by the fact that the thermoelectric materials under consideration have large CTE values, are brittle, and cracks can propagate through them with minimal resistance. The inherent challenge of bonding brittle, high-thermal-expansion thermoelectric materials to a hot shoe material that is thick enough to carry the requisite electrical current was overcome. A critical advantage over prior art is that this device was constructed using all diffusion bonds and a minimum number of assembly steps. The fabrication process and the materials used are described in the following steps: (1) Applying a thin refractory metal foil to both sides of lanthanum telluride. To fabricate the n-type leg of the advanced thermoelectric couple, the pre-synthesized lanthanum telluride coupon was diffusion bonded to the metal foil using a thin adhesion layer. (2) Repeating a similar process for the 14-1-11 Zintl p-type leg of the advanced thermoelectric couple. (3) Bonding thick CTE-matched metal plates on the metallized lanthanum telluride and Yb14MnSb11 to form the hot and cold sides of the thermoelectric couple. The calculated conversion efficiency of such an advanced couple would be about 10.5 percent, about 35 percent better than heritage radioisotope thermoelectric technology that relies on Si-Ge alloys. In addition, unlike Si-Ge alloys, these materials can be combined with many other thermoelectric materials optimized for operation at lower temperatures to achieve conversion efficiency in excess of 15 percent (a factor of 2 increase over heritage technology).

  11. Characterization of catalytic lanthanum oxide for double bond isomerization of n-butenes

    E-print Network

    Fox, Janan Sherlene

    1978-01-01

    of the rare earth oxides should have favorable cata- lytic propert1es for oxidat1on reactions. 8oreskov and co-workers have also investigated homomolecular and isotopic exchange of oxygen on cerium diox1de (25) and lanthanum oxide (26). The observed... activation energies for cerium dioxide were approximately the same for both the homomolecular and the isotopic exchange, viz. , 28 and 29 kcal/mol, respectively; the reaction order with respect to oxygen was 0. 84. The rate-limiting step of the reac...

  12. A-site deficiency, phase purity and crystal structure in lanthanum strontium ferrite powders

    Microsoft Academic Search

    T. Striker; J. A. Ruud; Y. Gao; W. J. Heward; C. Steinbruchel

    2007-01-01

    Lanthanum strontium ferrite (LSF) powders of average composition of (La1?x? Srx?) y?FeO3+?, were fabricated over a range of average strontium composition between 0.2?x??0.5 and average A-site occupancy between 0.8?y??1.0. Samples that were originally determined to be perovskite phase pure using X-ray diffraction with CuK? radiation were found to have significant amounts of non-perovskite phases when evaluated using high-energy synchrotron radiation.

  13. Synthesis of La and Nb doped PZT powder by the gel-combustion method

    NASA Astrophysics Data System (ADS)

    Cernea, M.; Montanari, G.; Galassi, C.; Costa, A. L.

    2006-03-01

    Lanthanum and niobium doped PZT with composition (Pb0.93La0.07)[(Zr0.60Ti0.40)]0.9825Nb0.0175O3 (PZTLN) was prepared by the gel-combustion method. A precursor sol was obtained from lead nitrate, zirconyl nitrate, lanthanum oxide, peroxo-citrato-niobium and a peroxo-citrate complex of titanium isopropoxide as starting precursors. Various molar ratios of citrate/nitrate (CA/NO3- = 1.3, 0.36 and 0.09) were used to prepare very fine powders of PZTLN. The gels resulting from these sols were transformed into powders by an auto-combustion process at <=400 C. The powders consisted of rhombohedral PZT (PbZr0.60Ti0.40O3), pyrochlore (Pb2Ti2O6) and lead carbonate (Pb2OCO3) phases. The pure rhombohedral phase is found in PZTLN pellets sintered at 1100 C for all citrate/nitrate ratios. Titanium and niobium precursors were modified with peroxo radicals. During the gel-combustion reaction, the temperature of the gel increases, leading to lead evaporation. The loss of lead as well as the particle size increases as the CA/NO3- ratio decreases. The smallest grained powder (about 50 nm) was obtained with the ratio CA/NO3- equal to 0.09.

  14. Isoelectronic co-doping

    DOEpatents

    Mascarenhas, Angelo

    2004-11-09

    Isoelectronic co-doping of semiconductor compounds and alloys with deep acceptors and deep donors is used to decrease bandgap, to increase concentration of the dopant constituents in the resulting alloys, and to increase carrier mobilities lifetimes. Group III-V compounds and alloys, such as GaAs and GaP, are isoelectronically co-doped with, for example, N and Bi, to customize solar cells, thermal voltaic cells, light emitting diodes, photodetectors, and lasers on GaP, InP, GaAs, Ge, and Si substrates. Isoelectronically co-doped Group II-VI compounds and alloys are also included.

  15. Preconcentration of some metal ions with lanthanum-8-hydroxyquinoline co-precipitation system.

    PubMed

    Feist, Barbara; Mikula, Barbara

    2014-03-15

    A method of separation and preconcentration of cadmium, copper, nickel, lead and zinc at trace level using 8-hydroxyquinoline as a chelating agent and lanthanum(III) as a carrier element is proposed. The heavy metals were determined after preconcentration by inductively coupled plasma optical emission spectrometry (ICP-OES). The results were compared with those obtained using flame atomic absorption spectrometry (F-AAS). The influence of several parameters such as pH, amount of lanthanum(III) as a carrier element, amount of 8-hydroxyquinoline, duration of co-precipitation was examined. Moreover, effects of inorganic matrix on recovery of the determined elements were studied. The detection limits (DL) for ICP-OES were 0.31, 2.9, 1.4, 3.2 and 1.2 ?g L(-1) for Cd, Cu, Ni, Pb and Zn, respectively, whereas for F-AAS DL were 0.63, 1.1, 3.2, 2.7 and 0.74 ?g L(-1). The recovery of the method for the determined elements was better than 94% with relative standard deviation between 0.63% and 2.9%. The preconcentration factor was 60. The proposed method was successfully applied for determination of Cd, Cu, Ni, Pb, and Zn in plant materials. Accuracy of the proposed method was verified using certified reference material (NCS ZC85006 Tomato). PMID:24206710

  16. Biodiesel production by free fatty acid esterification using Lanthanum (La3+) and HZSM-5 based catalysts.

    PubMed

    Vieira, Sara S; Magriotis, Zuy M; Santos, Nadiene A V; Saczk, Adelir A; Hori, Carla E; Arroyo, Pedro A

    2013-04-01

    In this work the use of the heterogeneous catalysts pure (LO) and sulfated (SLO) lanthanum oxide, pure HZSM-5 and SLO/HZSM-5 (HZSM-5 impregnated with sulfated lanthanum oxide (SO4(2-)/La2O3)) was evaluated. The structural characterization of the materials (BET) showed that the sulfation process led to a reduction of the SLO and SLO/HZSM-5 surface area values. FTIR showed bands characteristic of the materials and, FTIR-pyridine indicated the presence of strong Brnsted sites on the sulfated material. In the catalytic tests the temperature was the parameter that most influenced the reactions. The best reaction conditions were: 10% catalyst, 100C temperature and 1:5 m(OA)/m(meOH) for LO, SLO, SLO/HZSM-5 and 10% catalyst, 100C temperature and 1:20 m(OA)/m(meOH) for HZSM-5. Under these conditions the conversions were: 67% and 96%, for LO and SLO, respectively and 80% and 100%, for HZSM-5 and SLO/HZSM-5, respectively. All catalysts deactivated after the first use, but the deactivation of SLO/HZSM-5 was smaller. PMID:23428822

  17. Three-year follow-up of lanthanum carbonate therapy in hemodialysis patients.

    PubMed

    Takeuchi, Kazuhisa; Matsuda, Etsuko; Sekino, Makoto; Hasegawa, Yukiko; Kamo, Yoshie; Kikuchi, Natsue; Sekino, Hiroshi

    2013-04-01

    For 3 years following the start of lanthanum carbonate therapy, effects on other pharmaceutical treatment with sevelamer hydrochloride (SH), calcium carbonate (CC), and vitamin D, and those on clinical condition were examined. Dialysis patients with hyperphosphatemia (89 cases; average age 55.2 years; dialysis history of 10 years; 50 male and 39 female), who agreed to start lanthanum carbonate (LC) administration, were observed for a mean period of 32.6??6.2 months. Mean daily dosages of CC and SH before starting LC were 2.68?g and 0.73?g; mean daily dosage amounts of LC, CC, and SH at the time of final evaluation were 0.87?g, 2.30?g, and 0.99?g, respectively. After the application of LC, serum phosphate as well as serum calcium controls were significantly improved, and the amounts of active vitamin D agents applied was significantly increased. In conclusion, LC is useful in managing serum phosphorus levels (P levels), and little incidence of hypercalcemia suggests favorable concomitant use with active vitamin D agents in LC therapy. PMID:23586508

  18. Syntheses, Characterization, Thermal, and Antimicrobial Studies of Lanthanum(III) Tolyl/Benzyldithiocarbonates

    PubMed Central

    Andotra, Savit; Kalgotra, Nidhi; Pandey, Sushil K.

    2014-01-01

    Lanthanum(III) tris(O-tolyl/benzyldithiocarbonates), [La(ROCS2)] (R = o-, m-, p-CH3C6H4 and C6H5CH2), were isolated as yellow solid by the reaction of LaCl37H2O with sodium salt of tolyl/benzyldithiocarbonates, ROCS2Na (R = o-, m-, p-CH3C6H4 and C6H5CH2), in methanol under anhydrous conditions in 1?:?3 molar ratio. These complexes have formed adducts with nitrogen and phosphorus donor molecules by straightforward reaction of these complexes with donor ligands, which have the composition of the type [La(ROCS2)3nL] (where n = 2, L = NC5H5 or P(C6H5)3 and n = 1, L = N2C12H8 or N2C10H8). Elemental analyses, mass, IR, TGA, and heteronuclear NMR (1H, 13C and 31P) spectroscopic studies indicated bidentate mode of bonding by dithiocarbonate ligands leading to hexacoordinated and octacoordinated geometry around the lanthanum atom. Antimicrobial (antifungal and antibacterial) activity of the free ligands and some of the complexes have also been investigated which exhibited significantly more activity for the complexes than the free ligands. PMID:24817836

  19. Solution processed lanthanum aluminate gate dielectrics for use in metal oxide-based thin film transistors

    NASA Astrophysics Data System (ADS)

    Esro, M.; Mazzocco, R.; Vourlias, G.; Kolosov, O.; Krier, A.; Milne, W. I.; Adamopoulos, G.

    2015-05-01

    We report on ZnO-based thin-film transistors (TFTs) employing lanthanum aluminate gate dielectrics (LaxAl1-xOy) grown by spray pyrolysis in ambient atmosphere at 440 C. The structural, electronic, optical, morphological, and electrical properties of the LaxAl1-xOy films and devices as a function of the lanthanum to aluminium atomic ratio were investigated using a wide range of characterization techniques such as UV-visible absorption spectroscopy, impedance spectroscopy, spectroscopic ellipsometry, atomic force microscopy, x-ray diffraction, and field-effect measurements. As-deposited LaAlOy dielectrics exhibit a wide band gap (6.18 eV), high dielectric constant (k 16), low roughness (1.9 nm), and very low leakage currents (<3 nA/cm2). TFTs employing solution processed LaAlOy gate dielectrics and ZnO semiconducting channels exhibit excellent electron transport characteristics with hysteresis-free operation, low operation voltages (10 V), high on/off current modulation ratio of >106, subthreshold swing of 650 mV dec-1, and electron mobility of 12 cm2 V-1 s-1.

  20. Lanthanum chloride impairs spatial learning and memory and downregulates NF-?B signalling pathway in rats.

    PubMed

    Zheng, Linlin; Yang, Jinghua; Liu, Qiufang; Yu, Fei; Wu, Shengwen; Jin, Cuihong; Lu, Xiaobo; Zhang, Lifeng; Du, Yanqiu; Xi, Qi; Cai, Yuan

    2013-12-01

    Exposure to rare earth elements (REEs) is known to impair intelligence in children and cause neurobehavioral abnormalities in animals. However, the mechanisms underlying these phenomena are not clear. Lanthanum is often used to study the effects of REEs. The aim of this study was to investigate the influence of lanthanum chloride (LaCl3) on spatial learning and memory and a possible underlying mechanism involving nuclear factor-kappa B (NF-?B) signalling pathway expression in the hippocampus. The rats were exposed to 0, 0.25, 0.50 or 1.00 % LaCl3 in drinking water during pregnancy and lactation (i.e. while feeding their offspring). After weaning, young rats continued to receive 0, 0.25, 0.50 and 1.00 % LaCl3 in the drinking water for 1 month. LaCl3 exposure impaired the spatial learning and memory of young rats and significantly decreased the expression of phosphorylated I?B kinase complex, phosphorylated I?B?, NF-?B, c-fos, c-jun and brain-derived neurotrophic factor in the hippocampus. These results indicate that LaCl3 exposure impairs spatial learning and memory in rats by inhibiting NF-?B signalling pathway. PMID:23670203

  1. Lanthanum chloride promotes mitochondrial apoptotic pathway in primary cultured rat astrocytes.

    PubMed

    Yang, Jinghua; Liu, Qiufang; Qi, Ming; Lu, Shuai; Wu, Shengwen; Xi, Qi; Cai, Yuan

    2013-09-01

    Population surveys and animal experiments have shown that rare earth elements (REEs) cause neurological defects. However, the detailed mechanisms underlying these effects are still unclear. Given that lanthanum is commonly used for investigating into REEs-induced neurological defects, this study chose lanthanum chloride (LaCl3 ) to show that LaCl3 promotes mitochondrial apoptotic pathway in primary cultured rat astrocytes by regulating expression of Bcl-2 family proteins. The main findings of this study are (1) LaCl3 treatment (0.25, 0.5, and 1.0 mM for 12-48 h) induced the astrocytes damages with a concentration-dependent manner, which were confirmed with methyl thiazolyl tetrazolium and lactate dehydrogenase release assays, and morphological examination. (2) A 24 h treatment of LaCl3 concentration-dependently decreased mitochondrial membrane potential, increased cytochrome c release from mitochondria into cytosol, elevated caspase 9 and 3 expression, and promoted astrocyte apoptosis. (3) LaCl3 treatment increased the ratio of pro-apoptotic Bax and antiapoptotic Bcl-2 proteins, which in turn broke the balance among pro-apoptotic and antiapoptotic Bcl-2 family proteins, leading to astrocyte apoptosis. Our results indicate that LaCl3 alters Bcl-2 family protein expressions, which in turn promote mitochondrial apoptotic pathway, and thus astrocytic damage. PMID:21793157

  2. Lanthanum chloride impairs spatial memory through ERK/MSK1 signaling pathway of hippocampus in rats.

    PubMed

    Liu, Huiying; Yang, Jinghua; Liu, Qiufang; Jin, Cuihong; Wu, Shengwen; Lu, Xiaobo; Zheng, Linlin; Xi, Qi; Cai, Yuan

    2014-12-01

    Rare earth elements (REEs) are used in many fields for their diverse physical and chemical properties. Surveys have shown that REEs can impair learning and memory in children and cause neurobehavioral defects in animals. However, the mechanism underlying these impairments has not yet been completely elucidated. Lanthanum (La) is often selected to study the effects of REEs. The aim of this study was to investigate the spatial memory impairments induced by lanthanum chloride (LaCl3) and the probable underlying mechanism. Wistar rats were exposed to LaCl3 in drinking water at 0% (control, 0mM), 0.25% (18mM), 0.50% (36mM), and 1.00% (72mM) from birth to 2months after weaning. LaCl3 considerably impaired the spatial learning and memory of rats in the Morris water maze test, damaged the synaptic ultrastructure and downregulated the expression of p-MEK1/2, p-ERK1/2, p-MSK1, p-CREB, c-FOS and BDNF in the hippocampus. These results indicate that LaCl3 exposure impairs the spatial learning and memory of rats, which may be attributed to disruption of the synaptic ultrastructure and inhibition of the ERK/MSK1 signaling pathway in the hippocampus. PMID:25316495

  3. Lanthanum hexaaluminatea new material for atmospheric plasma spraying of advanced thermal barrier coatings

    NASA Astrophysics Data System (ADS)

    Friedrich, C.; Gadow, R.; Schirmer, T.

    2001-12-01

    One of the main application fields of the thermal spraying process is thermal barrier coatings (TBCs). Today, partially stabilized zirconia (YSZ or MSZ) is mainly used as a TBC material. At temperatures above 1000 C, zirconia layers age distinctively, including phenomena shrinkage and microcrack formation. Therefore, there is a considerable interest in TBCs for higher temperature applications. In this paper, lanthanum hexaaluminate, a newly developed TBC material with long-term stability up to 1400 C, is presented. It ages significantly more slowly at these high temperatures than commercial zirconia-based TBCs. Its composition favors the formation of platelets, which prevent a densification of the coating by postsintering. It consists of La2O3, Al2O3, and MgO. Its crystal structure corresponds to a magnetoplumbite phase. Lanthanum hexaaluminate powders were produced using two different fabrication routes, one based on salts and the other one based on oxides. To optimize the granulate, various raw materials and additives were tested. The slurry was spray dried in a laboratory spray drier and calcined at 1650 C. Using these two powders, coatings were produced by atmospheric plasma spraying (APS). The residual stresses of the coatings were measured by the hole drilling method, and the deposition process was optimized with respect to the residual stresses in the TBC. The coatings were extensively analyzed regarding phase composition, thermal expansion, and long-term stability, as well as microstructural properties.

  4. Structural, microstructural and vibrational characterization of apatite-type lanthanum silicates prepared by mechanical milling

    SciTech Connect

    Rodriguez-Reyna, E. [Cinvestav-Saltillo, Apartado Postal 663, 25000-Saltillo, Coahuila (Mexico); Fuentes, A.F. [Cinvestav-Saltillo, Apartado Postal 663, 25000-Saltillo, Coahuila (Mexico)]. E-mail: antonio.fernandez@cinvestav.edu.mx; Maczka, M. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2 (Poland); Hanuza, J. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw 2 (Poland); Department of Bioorganic Chemistry, Faculty of Engineering and Economics, University of Economics, Wroclaw (Poland); Boulahya, K. [Departamento de Quimica Inorganica, Facultad de Ciencias Quimicas, Universidad Complutense, 28040-Madrid (Spain); Amador, U. [Departamento de Ciencias Quimicas, Facultad de Farmacia, Universidad San Pablo CEU, 28668-Boadilla del Monte, Madrid (Spain)

    2006-02-15

    Apatite-type lanthanum silicates have been successfully prepared at room temperature by dry milling hexagonal A-La{sub 2}O{sub 3} and either amorphous or low cristobalite SiO{sub 2}. Milling a stochiometric mixture of these chemicals in a planetary ball mill with a moderate rotating disc speed (350 rpm), allows the formation of the target phase after only 3 h although longer milling times are needed to eliminate all SiO{sub 2} and La{sub 2}O{sub 3} traces. Thus, the mechanically activated chemical reaction proceeds faster when using amorphous silica instead of low cristobalite as silicon source and pure phases are obtained after only 9 and 18 h, respectively. As obtained powder phases are not amorphous and show an XRD pattern as well as IR and Raman bands characteristic of the lanthanum silicate. The domain size of the as-prepared phases varies gradually with the temperature of post-milling thermal treatment with activation energies of about 26(8) and 52(10) kJ mol{sup -1} K{sup -1} for the apatites obtained from amorphous silica and low-cristobalite, respectively. These values suggest crystallite growth to be favored when using amorphous silica as reactant.

  5. Progress in rare-earth-doped mid-infrared fiber lasers.

    PubMed

    Seddon, Angela B; Tang, Zhuoqi; Furniss, David; Sujecki, Slawomir; Benson, Trevor M

    2010-12-01

    The progress, and current challenges, in fabricating rare-earth-doped chalcogenide-glass fibers for developing mid-infrared (IR) fiber lasers are reviewed. For the first time a coherent explanation is forwarded for the failure to date to develop a gallium-lanthanum-sulfide glass mid-IR fiber laser. For the more covalent chalcogenide glasses, the importance of optimizing the glass host and glass processing routes in order to minimize non-radiative decay and to avoid rare earth ion clustering and glass devitrification is discussed. For the first time a new idea is explored to explain an additional method of non-radiative depopulation of the excited state in the mid-IR that has not been properly recognized before: that of impurity multiphonon relaxation. Practical characterization of candidate selenide glasses is presented. Potential applications of mid-infrared fiber lasers are suggested. PMID:21165021

  6. Ionic liquid-mediated synthesis of meso-scale porous lanthanum-transition-metal perovskites with high CO oxidation performance.

    PubMed

    Lu, Hanfeng; Zhang, Pengfei; Qiao, Zhen-An; Zhang, Jinshui; Zhu, Huiyuan; Chen, Jihua; Chen, Yinfei; Dai, Sheng

    2015-04-01

    Lanthanum-transition-metal perovskites with robust meso-scale porous frameworks (meso-LaMO3) are synthesized through the use of ionic liquids. The resultant samples demonstrate a rather high activity for CO oxidation, by taking advantage of unique nanostructure-derived benefits. This synthesis strategy opens up a new opportunity for preparing functional mesoporous complex oxides of various compositions. PMID:25727232

  7. Lanthanum-exchanged zeolites as active and selective catalysts for the generation of singlet oxygen from hydrogen peroxide.

    PubMed

    Wahlen, Joos; De Vos, Dirk; De Hertogh, Sigrid; Nardello, Veronique; Aubry, Jean-Marie; Alsters, Paul; Jacobs, Pierre

    2005-02-21

    Lanthanum(III)-exchanged zeolites Beta and USY are active and selective catalysts for the generation of singlet oxygen from H2O2 showing superior activity and oxidant efficiency compared to unsupported La-catalysts, e.g. La(OH)3. PMID:15700084

  8. Rare earth elements and plant growth: I. Effects of lanthanum and cerium on root elongation of corn and mungbean

    Microsoft Academic Search

    E. Diatloff; F. W. Smith; C. J. Asher

    1995-01-01

    Root elongation of corn (Zea mays cv. Hycorn 82) and mungbean (Vigna radiata cv. Berken) seedlings was measured in dilute complete nutrient solutions to which varying amounts of lanthanum (La) or cerium (Ce) had been added. The nutrient solutions were aged for 9 d prior to conducting the root elongation experiments and solution samples ultra?filtered to 0.025 ?m before chemical

  9. Rare earth elements in the Rhine River, Germany: First case of anthropogenic lanthanum as a dissolved microcontaminant in the hydrosphere

    Microsoft Academic Search

    Serkan Kulaks?z; Michael Bau

    2011-01-01

    The distribution of dissolved rare earth elements (REE) in the Rhine River, Germany, shows the anthropogenic gadolinium (Gd) microcontamination that is commonly observed in rivers in densely populated countries with a highly evolved health care system. However, the Rhine River also carries anomalously high concentrations of lanthanum (La), which produce very large positive La anomalies in normalized REE distribution patterns.

  10. Penetration of lanthanum through the main pancreatic duct epithelium in cats following exposure to infected human bile

    Microsoft Academic Search

    Thomas Arendt

    1991-01-01

    The main pancreatic duct epithelium acts as a barrier to the diffusion of molecules from the duct lumen into pancreatic acinar and interstitial tissue. We studied sequential ultrastructural characteristics of the loss of epithelial barrier function in the cat using lanthanum, an electron-opaque tracer, following perfusion of the duct from the tail to the duodenum with infected human bile. Tight

  11. Preparation, characterization, and circularly polarized luminescence of lanthanum and europium 1,1?-binaphthyl-2,2?-diyl phosphate complexes

    PubMed Central

    Pedziwiatr, Marta; Kosareff, Nicole M.; Muller, Gilles; Koposov, Alexey Y.; Nemykin, Victor N.; Riehl, James P.; Legendziewicz, Janina

    2009-01-01

    Solvated tris-complexes of (R)- and (S)-1,1?-binaphthyl-2,2?-dyil phosphate with lanthanum(III) and europium(III) centers were prepared and characterized by spectroscopic methods and elemental analysis. Circularly polarized luminescence (CPL) spectra for the optically active isomers of the europium complexes are also reported. PMID:19777143

  12. Results for aliovalent doping of CeBr3 with Ca2+

    NASA Astrophysics Data System (ADS)

    Guss, Paul; Foster, Michael E.; Wong, Bryan M.; Patrick Doty, F.; Shah, Kanai; Squillante, Michael R.; Shirwadkar, Urmila; Hawrami, Rastgo; Tower, Joshua; Yuan, Ding

    2014-01-01

    Despite the outstanding scintillation performance characteristics of cerium tribromide (CeBr3) and cerium-activated lanthanum tribromide, their commercial availability and application are limited due to the difficulties of growing large, crack-free single crystals from these fragile materials. This investigation employed aliovalent doping to increase crystal strength while maintaining the optical properties of the crystal. One divalent dopant (Ca2+) was used as a dopant to strengthen CeBr3 without negatively impacting scintillation performance. Ingots containing nominal concentrations of 1.9% of the Ca2+ dopant were grown, i.e., 1.9% of the CeBr3 molecules were replaced by CaBr2 molecules, to match our target replacement of 1 out of 54 cerium atoms be replaced by a calcium atom. Precisely the mixture was composed of 2.26 g of CaBr2 added to 222.14 g of CeBr3. Preliminary scintillation measurements are presented for this aliovalently doped scintillator. Ca2+-doped CeBr3 exhibited little or no change in the peak fluorescence emission for 371 nm optical excitation for CeBr3. The structural, electronic, and optical properties of CeBr3 crystals were studied using the density functional theory within the generalized gradient approximation. Calculated lattice parameters are in agreement with the experimental data. The energy band structures and density of states were obtained. The optical properties of CeBr3, including the dielectric function, were calculated.

  13. Lake responses following lanthanum-modified bentonite clay (Phoslock) application: an analysis of water column lanthanum data from 16 case study lakes.

    PubMed

    Spears, Bryan M; Lrling, Miquel; Yasseri, Said; Castro-Castellon, Ana T; Gibbs, Max; Meis, Sebastian; McDonald, Claire; McIntosh, John; Sleep, Darren; Van Oosterhout, Frank

    2013-10-01

    Phoslock() is a lanthanum (La) modified bentonite clay that is being increasingly used as a geo-engineering tool for the control of legacy phosphorus (P) release from lake bed sediments to overlying waters. This study investigates the potential for negative ecological impacts from elevated La concentrations associated with the use of Phoslock() across 16 case study lakes. Impact-recovery trajectories associated with total lanthanum (TLa) and filterable La (FLa) concentrations in surface and bottom waters were quantified over a period of up to 60 months following Phoslock() application. Both surface and bottom water TLa and FLa concentrations were <0.001 mg L(-1) in all lakes prior to the application of Phoslock(). The effects of Phoslock() application were evident in the post-application maximum TLa and FLa concentrations reported for surface waters between 0.026 mg L(-1)-2.30 mg L(-1) and 0.002 mg L(-1) to 0.14 mg L(-1), respectively. Results of generalised additive modelling indicated that recovery trajectories for TLa and FLa in surface and bottom waters in lakes were represented by 2nd order decay relationships, with time, and that recovery reached an end-point between 3 and 12 months post-application. Recovery in bottom water was slower (11-12 months) than surface waters (3-8 months), most probably as a result of variation in physicochemical conditions of the receiving waters and associated effects on product settling rates and processes relating to the disturbance of bed sediments. CHEAQS PRO modelling was also undertaken on 11 of the treated lakes in order to predict concentrations of La(3+) ions and the potential for negative ecological impacts. This modelling indicated that the concentrations of La(3+) ions will be very low (<0.0004 mg L(-1)) in lakes of moderately low to high alkalinity (>0.8 mEq L(-1)), but higher (up to 0.12 mg L(-1)) in lakes characterised by very low alkalinity. The effects of elevated La(3+) concentrations following Phoslock() applications in lakes of very low alkalinity requires further evaluation. The implications for the use of Phoslock() in eutrophication management are discussed. PMID:23911225

  14. Structural and optical properties of La-doped BaSnO3 thin films grown by PLD

    NASA Astrophysics Data System (ADS)

    James, K. K.; Krishnaprasad, P. S.; Hasna, K.; Jayaraj, M. K.

    2015-01-01

    In this study the structural and optical properties of lanthanum-doped BaSnO3 powder samples and thin films deposited on fused silica were investigaed using laser ablation. Under an oxygen pressure of 510-4 mbar, phase pure BaSnO3 films with a lattice constant of 0.417 nm and grain size of 21 nm were prepared at 630 C. The band gap of BaSnO3 powder sample and thin films was calculated to be 3.36 eV and 3.67 eV, respectively. There was a progressive increase in conductivity for thin films of BaSnO3 doped with 0~7 at% of La. The highest conductivity, 9 Scm-1, was obtained for 7 at% La-doped BaSnO3. Carrier concentration, obtained from Burstein-Moss (B-M) shift, nearly matches the measured values except for 3 at% and 10 at% La-doped BaSnO3 thin films.

  15. Enhanced visible light activity of nano-titanium dioxide doped with multiple ions: Effect of crystal defects

    SciTech Connect

    Jaimy, Kanakkanmavudi B. [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India)] [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India); Ghosh, Swapankumar, E-mail: swapankumar.ghosh2@mail.dcu.ie [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India)] [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India); Gopakumar Warrier, Krishna, E-mail: wwarrierkgk@yahoo.co.in [National Institute for Interdisciplinary Science and Technology (NIIST), Council of Scientific and Industrial Research (CSIR), Trivandrum 695019 (India)

    2012-12-15

    Titanium dioxide photocatalysts co-doped with iron(III) and lanthanum(III) have been prepared through a modified sol-gel method. Doping with Fe{sup 3+} resulted in a relatively lower anatase to rutile phase transformation temperature, while La{sup 3+} addition reduced the crystal growth and thus retarded the phase transformation of titania nanoparticles. The presence of Fe{sup 3+} ions shifted the absorption profile of titania to the longer wavelength side of the spectrum and enhanced the visible light activity. On the other hand, La{sup 3+} addition improved the optical absorption of titania nanoparticles. Both the dopants improved the life time of excitons by proper transferring and trapping of photoexcited charges. In the present work, considerable enhancement in photocatalytic activity under visible light was achieved through synergistic effect of optimum concentrations of the two dopants and associated crystal defects. - Graphical abstract: Photocatalytic activity studies indicate a synergistic effect of dopants and crystal defects leading to an enhanced photochemical activity. Highlights: Black-Right-Pointing-Pointer An aqueous sol-gel synthesis of Fe{sup 3+} and La{sup 3+} co-doped TiO{sub 2} is being reported. Black-Right-Pointing-Pointer Optical and microstructural properties of titania were modified by co-doping. Black-Right-Pointing-Pointer Enhanced activity of titania by the crystal defects is being reported.

  16. Spectra of optical parameters in bulk and film amorphous alloys of the Se{sub 95}As{sub 5} system containing samarium (Sm) impurities

    SciTech Connect

    Djalilov, N. Z.; Damirov, G. M., E-mail: gafil@physics.ab.az [National Academy of Sciences of Azerbaijan, Institute of Physics (Azerbaijan)

    2011-09-15

    Reflectance spectra of bulk and film amorphous alloys of the Se{sub 95}As{sub 5} system containing samarium (Sm) impurities are studied in the energy range of 1-6 eV. Spectral dependences of optical constants and derivatives of optical dielectric functions are calculated by the Kramers-Kronig method. Changes in spectra of optical parameters depending on the content of impurities introduced into Se{sub 95}As{sub 5} and conditions of their preparation are explained based on the cluster model. According to the latter, changes in the electron density of states depends on changes in atomic configurations in clusters, i.e., short-range order changes.

  17. High pressure phase transition in samarium monochalcogenides SmX (X = S, Se, Te) and their alloy SmS1-xSex

    NASA Astrophysics Data System (ADS)

    Dubey, Ritu; Singh, Sadhna

    2013-11-01

    Phase transition pressures, relative volume changes, elastic and thermophysical properties of Samarium monochalcogenides SmX (X = S, Se, Te) have been studied. An improved interaction potential model has been developed which includes Coulomb, three-body interaction, polarizability effect and overlap repulsive interaction operative up to second neighbor ions. In addition, we have investigated the phase transition pressure and associated volume collapse in SmS1-xSex alloy (0 ? x ? 1) which shows transition from discontinuous to continuous as x is reduces. The present results are in general in good agreement with experimental data available for the end point members (x = 0 and x = 1). The results for the alloy counter parts are also in fair agreement with experimental data generated from the vegard's law.

  18. Ultimate intrinsic-coercivity samarium-cobalt magnet: An Earth-based feasibility study for space-shuttle missions. [containerless melts

    NASA Technical Reports Server (NTRS)

    Das, D. K.; Kumar, K.; Frost, R. T.; Chang, C. W.

    1980-01-01

    Techniques for containerless melting and solidification of the samarium-cobalt alloy without excessive oxidation were developed. The rationale for extending these experiments in a weightless environment is also discussed. The effect of oxygen content from 0.15 to 0.63 weight percent and grain size in the range of 2 to 10 micrometers has been examined on arc-plasma-sprayed SmCo5 magnets. Contrary to expectations, the larger grain sizes tended to improve the coercivities. This was attributed to an increase in homogeneity resulting from higher temperature treatments used to produce larger grain size. No significant differences in coercivity were observed on the basis of oxygen content in the range examined. It is expected that more meaningful data on the relationship between oxygen content and coercivity will be seen when the oxygen content can be lowered to less than 0.1 weight percent.

  19. Writing of nonlinear optical Sm{sub 2}(MoO{sub 4}){sub 3} crystal lines at the surface of glass by samarium atom heat processing

    SciTech Connect

    Abe, M.; Benino, Y.; Fujiwara, T.; Komatsu, T.; Sato, R. [Department of Chemistry, Nagaoka University of Technology, 1603-1 Kamitomioka-cho, Nagaoka 940-2188 (Japan); Department of Materials Engineering, Tsuruoka National College of Technology, Tsuruoka 997-8511 (Japan)

    2005-06-15

    Some glasses such as 21.25Sm{sub 2}O{sub 3}.63.75MoO{sub 3}.15B{sub 2}O{sub 3} (mol %) giving the formation of nonlinear optical Sm{sub 2}(MoO{sub 4}){sub 3} crystals through conventional crystallization in an electric furnace and through continuous-wave Nd: yttrium aluminum garnet (YAG) laser (wavelength: 1064 nm) irradiation (samarium atom heat processing) have been developed. It is proposed from x-ray diffraction analyses, micro-Raman-scattering spectra, and second-harmonic generation measurements that the crystal structure of Sm{sub 2}(MoO{sub 4}){sub 3} formed by the crystallization is the {beta}{sup '}-phase structure with an orthorhombic (noncentrosymmetric) symmetry. The lines consisting of nonlinear optical {beta}{sup '}-Sm{sub 2}(MoO{sub 4}){sub 3} crystals are written at the surface of glasses by YAG laser irradiation (laser power: P=0.4 W, laser scanning speed: S=1-10 {mu}m/s), and, in particular, homogeneous crystal lines are formed at the laser scanning speed of 1 {mu}m/s. Refractive index changes (not crystallization) are also induced by YAG laser irradiation of P=0.4 W and a high laser scanning speed of S=25 {mu}m/s. The crystallization mechanism in the laser-irradiated region has been proposed. The present study demonstrates that the samarium atom heat processing is a technique for the writing of rare earth containing optical nonlinear/ferroelectric crystal lines in glass.

  20. Room-temperature scintillation properties of cerium-doped REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I)

    SciTech Connect

    Eagleman, Yetta; Bourret-Courchesne, Edith; Derenzo, Stephen

    2010-12-10

    The scintillation properties of cerium-doped oxyhalides following the general formula REOX (RE=Y, La, Gd, and Lu; X=F, Cl, Br, and I) are reported. These materials were synthesized under dry conditions as microcrystalline powders from conventional solid state reactions. The room temperature X-ray excited emission and scintillation decay curves were measured and analyzed for each material. Additionally, the hygroscopic nature of the oxychlorides and oxybromides was compared to that of their corresponding rare earth halides. The yttrium, lanthanum, and gadolinium oxychlorides, and all of the oxybromides and oxyiodides are found to be activated by Ce{sup 3+}. GdOBr doped with 0.5% Ce{sup 3+} has the highest light output with a relative luminosity of about one-half that of LaBr{sub 3}: Ce{sup 3+}. It displays a single exponential decay of 30 ns.

  1. Rare earth elements and plant growth: II. Responses of corn and mungbean to low concentrations of lanthanum in dilute, continuously flowing nutrient solutions

    Microsoft Academic Search

    E. Diatloff; F. W. Smith; C. J. Asher

    1995-01-01

    Corn (Zea mays cv. Hycorn 82) and mungbean (Vigna radiata cv. Berken) plants were grown for 14 d in dilute nutrient solutions containing constant lanthanum (La) concentrations from 0 to 1.37 ?M. Solutions were maintained at pH 4.5 to prevent precipitation of La. Lanthanum at 0.63 ?M increased the root growth of corn by 36% and 0.19 ?M La increased

  2. Molecular doping of graphene.

    PubMed

    Wehling, T O; Novoselov, K S; Morozov, S V; Vdovin, E E; Katsnelson, M I; Geim, A K; Lichtenstein, A I

    2008-01-01

    Graphene is considered as one of the most promising materials for post silicon electronics, as it combines high electron mobility with atomic thickness [Novoselov et al. Science 2004, 306, 666-669. Novoselov et al. Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 10451-10453]. The possibility of chemical doping and related excellent chemical sensor properties of graphene have been demonstrated experimentally [Schedin et al. Nat. Mater. 2007, 6, 652-655], but a microscopic understanding of these effects has been lacking, so far. In this letter, we present the first joint experimental and theoretical investigation of adsorbate-induced doping of graphene. A general relation between the doping strength and whether adsorbates are open- or closed-shell systems is demonstrated with the NO2 system: The single, open shell NO2 molecule is found to be a strong acceptor, whereas its closed shell dimer N2O4 causes only weak doping. This effect is pronounced by graphene's peculiar density of states (DOS), which provides an ideal situation for model studies of doping effects in semiconductors. We show that this DOS is ideal for "chemical sensor" applications and explain the recently observed [Schedin et al. Nat. Mater. 2007, 6, 652-655] NO2 single molecule detection. PMID:18085811

  3. Lanthanum Tricyanide-Catalyzed Acyl Silane-Ketone Benzoin Additions and Kinetic Resolution of Resultant ?-Silyloxyketones

    PubMed Central

    Tarr, James C.

    2010-01-01

    We report the full account of our efforts on the lanthanum tricyanide-catalyzed acyl silane-ketone benzoin reaction. The reaction exhibits a wide scope in both acyl silane (aryl, alkyl) and ketone (aryl-alkyl, alkyl-alkyl, aryl-aryl, alkenyl-alkyl, alkynyl-alkyl) coupling partners. The diastereoselectivity of the reaction has been examined in both cyclic and acyclic systems. Cyclohexanones give products arising from equatorial attack by the acyl silane. The diastereoselectivity of acyl silane addition to acyclic ?-hydroxy ketones can be controlled by varying the protecting group to obtain either Felkin-Ahn or chelation control. The resultant ?-silyloxyketone products can be resolved with selectivity factors from 10 to 15 by subjecting racemic ketone benzoin products to CBS reduction. PMID:20392127

  4. Indirect determination of fluoride by EDTA back-titration of lanthanum.

    PubMed

    Murase, K; Nakagawa, G; Kodama, K; Shiraishi, N

    1977-01-01

    Semimicro to macro amounts of fluoride ion (0.4-100 mg) are determined rapidly and accurately by precipitation with an excess of lanthanum at pH 2.5-2.8 by digestion on a water-bath, cooling to room temperature, addition of excess of EDTA and back-titration of the excess with zinc solution to the Xylenol Orange end-point at ph 5.8-5..9. Large amounts of chloride, acetate and perchlorate, and small amounts of sulphate and silicate do not interfere, but phosphate does. This method is much superior to the usual thorium nitrate titration method and can be applied after preliminary separation of fluorine by steam distillation or pyrolysis. PMID:18962019

  5. Effect of Gun Current on Electrical Properties of Atmospheric Plasma-Sprayed Lanthanum Silicate Coatings

    NASA Astrophysics Data System (ADS)

    Gao, Wei; Liao, Han-Lin; Coddet, Christian

    2013-10-01

    Apatite-type lanthanum silicate (ATLS) electrolyte coatings for use in intermediate-temperature solid oxide fuel cells were deposited by atmospheric plasma spraying (APS). Plasma-sprayed coatings with typical composition La10(SiO4)6O3 exhibiting good densification and high oxide ionic conductivity were obtained by properly adjusting the spraying parameters, particularly the gun current. The highest obtained ionic conductivity value of 3.3 mS/cm at 1,173 K in air is comparable to other ATLS conductors. This work demonstrated empirically that utilization of the APS technique is feasible to synthesize dense La10(SiO4)6O3 electrolyte coatings using gun currents within an unusually broad range.

  6. Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface

    NASA Astrophysics Data System (ADS)

    Nichau, A.; Schnee, M.; Schubert, J.; Besmehn, A.; Rubio-Zuazo, J.; Breuer, U.; Bernardy, P.; Hollnder, B.; Mcklich, A.; Castro, G. R.; von Borany, J.; Buca, D.; Mantl, S.

    2013-04-01

    Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important.

  7. Photoemission spectroscopy study of the lanthanum lutetium oxide/silicon interface.

    PubMed

    Nichau, A; Schnee, M; Schubert, J; Besmehn, A; Rubio-Zuazo, J; Breuer, U; Bernardy, P; Hollnder, B; Mcklich, A; Castro, G R; von Borany, J; Buca, D; Mantl, S

    2013-04-21

    Rare earth oxides are promising candidates for future integration into nano-electronics. A key property of these oxides is their ability to form silicates in order to replace the interfacial layer in Si-based complementary metal-oxide field effect transistors. In this work a detailed study of lanthanum lutetium oxide based gate stacks is presented. Special attention is given to the silicate formation at temperatures typical for CMOS processing. The experimental analysis is based on hard x-ray photoemission spectroscopy complemented by standard laboratory experiments as Rutherford backscattering spectrometry and high-resolution transmission electron microscopy. Homogenously distributed La silicate and Lu silicate at the Si interface are proven to form already during gate oxide deposition. During the thermal treatment Si atoms diffuse through the oxide layer towards the TiN metal gate. This mechanism is identified to be promoted via Lu-O bonds, whereby the diffusion of La was found to be less important. PMID:23614438

  8. Cooperative downconversion in Yb3+/-RE3+ (RE=Tm or Pr) codoped lanthanum borogermanate glasses.

    PubMed

    Liu, Xiaofeng; Qiao, Yanbo; Dong, Guoping; Ye, Song; Zhu, Bin; Lakshminarayana, Gandham; Chen, Danping; Qiu, Jianrong

    2008-12-01

    We report on cooperative downconversion in Yb(3+)-RE(3+) (RE=Tm or Pr) codoped lanthanum borogermanate glasses (LBG), which are capable of splitting a visible photon absorbed by Tm(3+) or Pr(3+) ions into two near-infrared photons. The results indicate that Pr(3+)-Yb(3+) is a more efficient ion couple than Tm(3+)-Yb(3+) in terms of cooperative downconversion. We have obtained a highest quantum yield of 165% and 138% for Pr(3+)-Yb(3+) and Tm(3+)-Yb(3+) codoped LBG glasses under 468 nm excitation, respectively. However, ultraviolet light excitation to the charge transfer band of Yb(3+) does not result in quantum splitting as rapid relaxation from the charge transfer band to 4f(13) levels of Yb(3+) dominates. PMID:19037451

  9. Ba11La4Br34: a new barium lanthanum bromide

    PubMed Central

    Eagleman, Yetta; Wu, Guang; Gundiah, Gautam; Bourret-Courchesne, Edith; Derenzo, Stephen

    2011-01-01

    The structure of the title compound, barium lanthanum bromide (11/4/34), can be derived from the fluorite structure. The asymmetric unit contains two Ba sites (one with site symmetry 4/m..), one La site (site symmetry 4..), one mixed-occupied Ba and La site (ratio 1:1, site symmetry m..) and six Br sites (one with site symmetry \\=4.., one with 2.., one with m.., the latter being disordered over two positions with a 0.86:0.14 ratio). The fundamental building units of the structure are edge-sharing polyhedral clusters made up of Ba and La bromide clusters interconnected to BaBr8 square prisms and BaBr10 groups. PMID:22064368

  10. The lanthanum(III) molybdate(VI) La4Mo7O27

    PubMed Central

    van der Wolf, Benjamin; Held, Peter; Becker, Petra

    2009-01-01

    Crystals of the orthorhombic phase La4Mo7O27 (lanthanum molybdenum oxide) were obtained from a non-stoichiometric melt in the pseudo-ternary system La2O3MoO3B2O3. In the crystal structure, distorted square-antiprismatic [LaO8] and monocapped square-antiprismatic [LaO9] polyhedra are connected via common edges and faces into chains along [010]. These chains are arranged in layers that alternate with layers of [MoO4] and [MoO5] polyhedra parallel to (001). In the molybdate layers, a distorted [MoO5] trigonal bipyramid is axially connected to two [MoO4] tetrahedra, forming a [Mo3O11] unit. PMID:21583295

  11. Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

    DOEpatents

    Leung, Ka-Ngo (Hercules, CA); Gordon, Keith C. (Berkeley, CA); Kippenham, Dean O. (Castro Valley, CA); Purgalis, Peter (San Francisco, CA); Moussa, David (San Francisco, CA); Williams, Malcom D. (Danville, CA); Wilde, Stephen B. (Pleasant Hill, CA); West, Mark W. (Albany, CA)

    1989-01-01

    A large area directly heated lanthanum hexaboride (LaB.sub.6) cathode system (10) is disclosed. The system comprises a LaB.sub.6 cathode element (11) generally circular in shape about a central axis. The cathode element (11) has a head (21) with an upper substantially planar emission surface (23), and a lower downwardly and an intermediate body portion (26) which diminishes in cross-section from the head (21) towards the base (22) of the cathode element (11). A central rod (14) is connected to the base (22) of the cathode element (11) and extends along the central axis. Plural upstanding spring fingers (37) are urged against an outer peripheral contact surface (24) of the head end (21) to provide a mechanical and electrical connection to the cathode element (11).

  12. Stabilization of ambient sensitive atomic layer deposited lanthanum aluminates by annealing and in situ capping

    NASA Astrophysics Data System (ADS)

    Swerts, J.; Gielis, S.; Vereecke, G.; Hardy, A.; Dewulf, D.; Adelmann, C.; Van Bael, M. K.; Van Elshocht, S.

    2011-03-01

    We have studied the effect of air exposure on lanthanum aluminates (LaAlOx) deposited by atomic layer deposition. Fourier transform infrared spectroscopy and thermal desorption spectroscopy of as-deposited LaAlOx showed that H2O is absorbed during air exposure and that the amount of absorbed H2O increases with increasing La atomic percent. C was found to be incorporated already during deposition in the form of carbonates. H2O and CO2 are outgassed during postdeposition annealing in an inert atmosphere. After a 700 C postdeposition anneal, the LaAlOx becomes resistant against H2O absorption due to film densification. Alternatively, in situ capping of the LaAlOx with a 2 nm thin Al2O3 film protects the LaAlOx against H2O absorption, but it also hinders the outgassing of the C contaminants during a postdeposition anneal.

  13. Deposition of sol-gel derived lanthanum zirconate titanate thin films on copper substrates.

    SciTech Connect

    Narayanan, M.; Kwon, D. K.; Ma, B.; Balchandran, U.; Energy Systems

    2008-06-23

    Lead lanthanum zirconate titanate (PLZT) thin films were directly deposited on copper substrates by chemical solution deposition and crystallized at temperatures of {approx_equal} 650 C under low pO{sub 2} conditions. Although the crystallization conditions used are conducive for copper oxidation, a thin layer ({approx}115 nm) of PLZT was sufficient to protect the underlying copper from oxidation. Films exhibited well saturated hysteresis loops with remanent polarization {approx}24 {micro}C/cm{sup 2} and dielectric constants {approx}730. Indirect evidence suggests that the oxygen vacancies created during the high temperature processing are responsible for the degradation of the electrical properties of these thin films. Techniques for avoiding this problem are proposed.

  14. Enhanced lithium ion conductivity in lithium lanthanum titanate solid electrolyte nanowires prepared by electrospinning

    NASA Astrophysics Data System (ADS)

    Yang, Ting; Li, Ying; Chan, Candace K.

    2015-08-01

    Solid electrolytes have great potential to address the safety issues of Li-ion batteries, but better synthesis methods are still required for ceramics such as lithium lanthanum titanate (LLTO) since current techniques require high-temperature calcination for long times. Here we report a new approach that utilizes electrospinning to prepare phase-pure polycrystalline LLTO nanowires with well-crystallized tetragonal structure after only 3 h calcination at 1000 C. Pellets prepared from the electrospun LLTO nanowires had higher density, less void space, and higher Li+ conductivity compared to those comprised of LLTO prepared with conventional sol-gel methods. This work demonstrates the potential that electrospinning can provide towards improving the properties of sol-gel derived ceramics.

  15. Crystal growth of lanthanum calcium borate (LCB) single crystals from melt and its characterization

    NASA Astrophysics Data System (ADS)

    Senthi lkumar, M.; Kalidasan, M.; Sugan; Dhanasekaran, R.

    2013-01-01

    Non-linear optical lanthanum calcium borate (LCB) single crystals were grown by the melt growth method using the Czohralski technique. The polycrystalline LCB compound is synthesized using the solid state reaction method. The grown crystals were characterized by XRD, EDAX, DTA, HRXRD, specific heat, dielectric and NLO studies. The powder XRD pattern revealed the formation of LCB compound and the lattice parameters of the grown crystals were identified through single crystal XRD studies. The melting point of the LCB compound is analyzed by the DTA measurements. Good crystalline nature of the grown crystal is observed from HRXRD analysis. Specific heat measurements in the temperature range 50-550 C are carried out for the as grown crystal samples. The results obtained by the dielectric and NLO studies are also presented.

  16. Effect of R(3+) ions on the structure and properties of lanthanum borate glasses

    NASA Technical Reports Server (NTRS)

    Chakraborty, I. N.; Day, D. E.

    1985-01-01

    The present investigation of glass formation in the (mole percent) systems 25La2O3 (x)R2O3 (75-x)B2O3, where R = Al, Ga, and (25-x)La2O3 (x)Ln2O3 75B2O3, where Ln = Gd, Er, Y, notes that up to 25 mol pct Al2O3 or Ga2O3 can be substituted for B2O3, while no more than about 5 mol pct Ln2O3, substituted for La2O3, caused macro-phase separation. The substitution of either R2O3 or Ln2O3 in the lanthanum borate system changes the separation distance between adjacent B3O6 chains. The effect of this structural change on the molar volume, transformation temperature, thermal expansion coefficient, and transformation-range viscosity is discussed.

  17. Large area directly heated lanthanum hexaboride cathode structure having predetermined emission profile

    DOEpatents

    Leung, Ka-Ngo; Gordon, K.C.; Kippenhan, D.O.; Purgalis, P.; Moussa, D.; Williams, M.D.; Wilde, S.B.; West, M.W.

    1987-10-16

    A large area directly heated lanthanum hexaboride (LaB/sub 6/) cathode system is disclosed. The system comprises a LaB/sub 6/ cathode element generally circular in shape about a central axis. The cathode element has a head with an upper substantially planar emission surface, and a lower downwardly and an intermediate body portion which diminishes in cross-section from the head towards the base of the cathode element. A central rod is connected to the base of the cathode element and extends along the central axis. Plural upstanding spring fingers are urged against an outer peripheral contact surface of the head end to provide a mechanical and electrical connection to the cathode element. 7 figs

  18. Neurotoxicological evaluation of long-term lanthanum chloride exposure in rats.

    PubMed

    He, Xiao; Zhang, Zhiyong; Zhang, Haifeng; Zhao, Yuliang; Chai, Zhifang

    2008-06-01

    With their widespread application in industry, agriculture, medicine, and daily life, rare earth elements (REEs) are widely used in various fields and eventually accumulated in human body. Therefore, understanding the effects of REEs on health has become more and more important. In this work, the neurotoxicity of lanthanum (La) was evaluated. Wistar rats were exposed to lanthanum chloride through oral administration at 0, 0.1, 2, and 40 mg/kg doses from gestation day 0 through 6 months of age. Experiments were carried out to reveal the effects of La exposure on brain functions from four aspects including behavioral performance, [Ca2+](i) level and the activity of Ca2+-ATPase (adenosine triphosphatase) in hippocampal cells, oxidative stress, and Nissl staining. Adverse effects were observed in 2 and 40 mg/kg dose groups and increased with dose. Morris water maze test showed that La exposure at 2 and 40 mg/kg could significantly impair the behavioral performance. (The preference for the target quadrant decreased by 16.6% and 19.4% versus control, respectively.) The neurotoxicological consequences demonstrated that the alteration in homeostasis of [Ca2+](i)/Ca2+-ATPase (the ratio of [Ca2+](i) vs. Ca2+-ATPase activity increased by 44% in rats of 40 mg/kg group), the inhibition to activities of antioxidant enzymes, and the subsequent cell damage (18% and 23% cell loss in CA3 subregion of rats in 2 and 40 mg/kg group, respectively) might be involved in the neurological adverse effects of REEs exposure. PMID:18319242

  19. The combination of lanthanum chloride and the calcimimetic calindol delays the progression of vascular smooth muscle cells calcification

    SciTech Connect

    Ciceri, Paola; Volpi, Elisa; Brenna, Irene; Elli, Francesca [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy)] [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy); Borghi, Elisa [Dipartimento di Salute Pubblica, Microbiologia e Virologia, Universita di Milano, Milan (Italy)] [Dipartimento di Salute Pubblica, Microbiologia e Virologia, Universita di Milano, Milan (Italy); Brancaccio, Diego [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy)] [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy); Cozzolino, Mario, E-mail: mario.cozzolino@unimi.it [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy)] [Renal Division and Laboratory of Experimental Nephrology, Dipartimento di Medicina e Chirurgia, Universita di Milano, Milan (Italy)

    2012-02-24

    Highlights: Black-Right-Pointing-Pointer Lanthanum reduces the progression of high phosphate-induced calcium deposition. Black-Right-Pointing-Pointer Calcium receptor agonists and the calcimimetic calindol reduce calcium deposition. Black-Right-Pointing-Pointer Lanthanum and calindol cooperate on reducing calcium deposition. Black-Right-Pointing-Pointer Lanthanum and calindol may interact with the same receptor. -- Abstract: Phosphate (Pi)-binders are commonly used in dialysis patients to control high Pi levels, that associated with vascular calcification (VC). The aim of this study was to investigate the effects of lanthanum chloride (LaCl{sub 3}) on the progression of high Pi-induced VC, in rat vascular smooth muscle cells (VSMCs). Pi-induced Ca deposition was inhibited by LaCl{sub 3}, with a maximal effect at 100 {mu}M (59.0 {+-} 2.5% inhibition). Furthermore, we studied the effects on VC of calcium sensing receptor (CaSR) agonists. Gadolinium chloride, neomycin, spermine, and the calcimimetic calindol significantly inhibited Pi-induced VC (55.9 {+-} 2.2%, 37.3 {+-} 4.7%, 30.2 {+-} 5.7%, and 63.8 {+-} 5.7%, respectively). To investigate the hypothesis that LaCl{sub 3} reduces the progression of VC by interacting with the CaSR, we performed a concentration-response curve of LaCl{sub 3} in presence of a sub-effective concentration of calindol (10 nM). Interestingly, this curve was shifted to the left (IC{sub 50} 9.6 {+-} 2.6 {mu}M), compared to the curve in the presence of LaCl{sub 3} alone (IC{sub 50} 19.0 {+-} 4.8 {mu}M). In conclusion, we demonstrated that lanthanum chloride effectively reduces the progression of high phosphate-induced vascular calcification. In addition, LaCl{sub 3} cooperates with the calcimimetic calindol in decreasing Ca deposition in this in vitro model. These results suggest the potential role of lanthanum in the treatment of VC induced by high Pi.

  20. Characterization of doped La 0.7A 0.3Cr 0.5Mn 0.5O 3 ? ? (A = Ca, Sr, Ba) electrodes for solid oxide fuel cells

    Microsoft Academic Search

    Lan Zhang; Xinbing Chen; San Ping Jiang; Hong Quan He; Yan Xiang

    2009-01-01

    Doped lanthanum manganese chromite based perovskite, La0.7A0.3Cr0.5Mn0.5O3?? (LACM, A=Ca, Sr, Ba), on yttria-stabilized zirconia (YSZ) electrolyte is investigated as potential electrode materials for solid oxide fuel cells (SOFCs). The electrical conductivity and electrochemical activity of LACM depend on the A-site dopant. The best electrochemical activity is obtained on the La0.7Ca0.3Cr0.5Mn0.5O3??\\/YSZ (LCCM\\/YSZ) composite electrodes. The conductivity of LCCM is 29.9S cm?1

  1. Characterization of Sm-Doped Ceria Ceramics Synthesized by Two Different Methods

    NASA Astrophysics Data System (ADS)

    Arabaci, Aliye; Serin, zgn

    2015-06-01

    Ceria-based materials have attracted much attention as electrolyte materials for low and intermediate temperature solid oxide fuel cells (SOFCs). In this study, we examined the effect of synthesis method on the microstructure and the ionic conductivity of ceria-based electrolytes. Sm0.2Ce0.8O1.9 (SDC) electrolytes for SOFCs were prepared using the Pechini and cellulose templating (CT) methods. Microstructures of the calcined and sintered samples were characterized by XRD and SEM techniques. The XRD results indicate that a single-phase fluorite structure formed at the relatively low calcination temperature of 500 C. The relative densities of the sintered pellets were higher than 90%, which was proved by the SEM images. Calcined powders were characterized by FTIR technique. The electrical properties of the samarium-doped ceria electrolytes were analyzed by electrochemical impedance spectroscopy. The total ionic conductivities are 3.02 10-2 and 3.42 10-2 S/cm at 750 C for the SDC electrolytes prepared by the Pechini method and the CT method, respectively.

  2. Photoluminescence and energy transfer properties of Sm 3+ doped CFB glasses

    NASA Astrophysics Data System (ADS)

    Suresh Kumar, J.; Pavani, K.; Sasikala, T.; Sreenivasa Rao, A.; Giri, Neeraj Kumar; Rai, S. B.; Rama Moorthy, L.

    2011-08-01

    The present paper describes the optical absorption, photoluminescence and lifetime measurements of trivalent samarium doped calcium fluoroborate (CFB) glasses. From the observed energy levels, the free-ion energy level parameters for the 4f 5 electronic configuration of Sm 3+ ion have been evaluated using H FI model. The experimental oscillator strengths of absorption bands have been analyzed to determine the Judd-Ofelt (J-O) parameters. From the evaluated J-O parameters and luminescence data, the radiative parameters such as AR, ?R and ?e values were obtained from the excited 4G 5/2 level to different lower energy levels. The decay curves of 4G 5/2 ? 6H 7/2 transition were analyzed by the Inokuti-Hirayama model assuming dipole-dipole interaction between the dopant ions. The decrease of fluorescence intensities as well as measured lifetimes at higher concentrations has been explained based on energy transfer process through cross-relaxation between Sm 3+ ions.

  3. Mn and Sm doped lead titanate ceramic fibers and fiber/epoxy 13 composites

    NASA Astrophysics Data System (ADS)

    Li, Kun; Pang, Geoffrey; Wa Chan, Helen Lai; Choy, Chung Loong; Li, Jin-hua

    2004-05-01

    Manganese and samarium doped lead titanate [Pb0.85Sm0.10(Ti0.98Mn0.02)O3, PSmT] fibers were prepared by sol-gel method. The micrographs obtained using scanning electron microscope show that PSmT ceramic fibers are round and dense. The diameter of the fibers was in the range of 30-35 ?m. The crystalline grains size is 2.5 ?m. The micrographs obtained using transmission electron microscope also unveiled the layer-by-layer 90 domains in the grains. X-ray diffraction patterns of the fibers show that PSmT ceramics have a pure perovskite structure. The c/a ratio of the unit cell was 1.04. The PSmT fiber/epoxy 1-3 composites were fabricated by filling the ceramic fiber bundle with epoxy. The dielectric permittivity ?, electromechanical coefficient kt, and the piezoelectric constant d33 of PSmT fiber/epoxy 1-3 composites with 68% fiber loading were 118, 0.51, and 48 pC/N, respectively. The hysteresis loop of the composites was measured by the Sawyer-Tower method. It was also found that the composites could withstand an electric field of 15 kV/mm at room temperature.

  4. Asymmetric catalysis with self-organized chiral lanthanum complexes: practical and highly enantioselective epoxidation of alpha,beta-unsaturated ketones.

    PubMed

    Daikai, Kazuhiro; Hayano, Tetsuji; Kino, Rie; Furuno, Hiroshi; Kagawa, Takumi; Inanaga, Junji

    2003-01-01

    A highly efficient and practical method for obtaining alpha,beta-epoxy ketones with high optical purities was developed. The chiral lanthanum complex self-organized in situ from lanthanum triisopropoxide, (R)-BINOL, triarylphosphine oxide, and alkyl hydroperoxide (1:1:1:1) was found to catalyze the epoxidation of alpha,beta-unsaturated ketones with tert-butyl hydroperoxide or cumene hydroperoxide at room temperature to give the corresponding epoxy ketones in high enantioselectivities (up to >99% enantiomeric excess (ee)). A remarkably high asymmetric amplification, a positive nonlinear effect, was observed in the epoxidation of chalcone, which strongly suggests the formation of a dinuclear peroxide-involved mu-complex as the active catalyst. PMID:12467048

  5. Doped zinc oxide microspheres

    DOEpatents

    Arnold, Jr., Wesley D. (Oak Ridge, TN); Bond, Walter D. (Knoxville, TN); Lauf, Robert J. (Oak Ridge, TN)

    1993-01-01

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel.

  6. Doped zinc oxide microspheres

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-12-14

    A new composition and method of making same for a doped zinc oxide microsphere and articles made therefrom for use in an electrical surge arrestor which has increased solid content, uniform grain size and is in the form of a gel. 4 figures.

  7. Dope, Fiends, and Myths.

    ERIC Educational Resources Information Center

    Reasons, Charles E.

    Since the social reality of the drug problem has largely emanated from the diffuse conceptions of the drug user, an analysis of the history of the "dope fiend" mythology is presented in this paper in an attempt to assess the manner in which certain publics are informed about the problem. A content analysis of drug-related imagery was made from

  8. Thin Lanthanum Oxide and Rare-Earth Oxide Films by Pecvd of beta-DIKETONATE Chelate Complexes

    Microsoft Academic Search

    A. Weber; H. Suhr

    1989-01-01

    A method for the deposition of lanthanum oxide and rare-earth (Re) oxide films using the tris[2,2,6,6-tetramethyl-3,5-heptanedionato] chelate complexes is reported. The films were characterized by metal analysis, carbon analysis, FTIR spectra, XPS and SEM micrographs. The film composition strongly depends on experimental parameters. Films deposited in an oxygen plasma at a substrate temperature of 400C and a power density of

  9. High Sensitive Sensor Based on Carbon Nanotube Electrode for Determination of Lanthanum in the Presence of Calcon Carboxylic Acid

    Microsoft Academic Search

    Sayed Mehdi Ghoreishi; Mohsen Behpour; Samaneh Mazaheri; Mohammadhassan Motaghedifard

    2012-01-01

    In this paper we have investigated the electrochemical activity of lanthanum chloride (La (III)) in the presence of calcon carboxylic acid (CCA) using a multi-walled carbon nano tube\\/carbon paste electrode (CNT\\/CPE). The peak current increases linearly with increasing of the La (III) concentration. For this purpose, a few electrochemical methods such as cyclic, differential pulse voltammetry, linear sweep and hydrodynamic

  10. Effects of lanthanum ion-implantation on microstructure of oxide film formed on Co-Cr alloy

    Microsoft Academic Search

    Huiming JIN; Xiaowei ZHOU; Linnan ZHANG

    2008-01-01

    Isothermal and cyclic oxidizing behavior of Co-40Cr alloy and its lanthanum ion-implanted samples were studied at 1000 C in the air by thermal-gravimetric analysis (TGA). Scanning electronic microscopy (SEM) and transmission electronic microscopy (TEM) were used to examine the morphology and structure of oxide film after oxidation. Secondary ion mass spectrum (SIMS) method was used to examine the binding energy

  11. Effects of lanthanum addition on NiB\\/?-Al 2O 3 amorphous alloy catalysts used in anthraquinone hydrogenation

    Microsoft Academic Search

    Yongjiang Hou; Yaquan Wang; Fei He; Wanliang Mi; Zhenhua Li; Zhentao Mi; Wei Wu; Enze Min

    2004-01-01

    A series of amorphous Ni-B\\/?-Al2O3 catalysts with different La loadings were prepared by KBH4 reduction, characterized by inductively coupled plasma (ICP), DSC, H2-TPD, X-ray photoelectron spectroscopy (XPS) and H2-chemisorption, and studied in the hydrogenation of anthraquinone (AQ). In comparison with the catalyst without La loadings, the presence of proper amounts of lanthanum in the supported amorphous alloy catalyst leads to

  12. The selective catalytic reduction of nitric oxide with methane over scandium oxide, yttrium oxide and lanthanum oxide

    Microsoft Academic Search

    Mark D Fokema; Jackie Y Ying

    1998-01-01

    The selective catalytic reduction of nitric oxide with methane over nanocrystalline Group IIIB metal oxides was investigated between 400C and 675C. Scandium oxide and yttrium oxide are better catalysts than lanthanum oxide because they have a greater specific activity and selectivity. The activity of yttrium oxide is 75% of that of Co-ZSM-5 at 600C and yttrium oxide was also found

  13. Effects of lanthanum(III) on nitrogen metabolism of soybean seedlings under elevated UV-B radiation

    Microsoft Academic Search

    Rui CAO; Xiao-hua HUANG; Qing ZHOU; Xiao-ying CHENG

    2007-01-01

    The hydroponic culture experiments of soybean bean seedlings were conducted to investigate the effect of lanthanum (La) on nitrogen metabolism under two different levels of elevated UV-B radiation (UV-B, 280320 nm). The whole process of nitrogen metabolism involves uptake and transport of nitrate, nitrate assimilation, ammonium assimilation, amino acid biosynthesis, and protein synthesis. Compared with the control, UV-B radiation with

  14. Prediction of transport properties of new functional materials based on lanthanum-strontium cuprates: Molecular mechanics calculations

    Microsoft Academic Search

    A. K. Ivanov-Shits; G. N. Mazo; S. N. Savvin; S. N. Putilin; A. S. Samokhin

    2008-01-01

    The method of molecular dynamics is used for prediction of properties of new functional materials based on lanthanum-strontium\\u000a cuprates La2 ? x\\u000a Sr\\u000a x\\u000a CuO4 ? ? as new materials of the solid state ionics. The most interesting phases are synthesized to test the obtained calculation\\u000a data and their electrophysical and thermomechanical characteristics are studied. It is shown that the

  15. Experimental investigation on the concentration and voltage effects on the characteristics of deposited magnesium-lanthanum powder

    NASA Astrophysics Data System (ADS)

    Sahli, M.; Chetehouna, K.; Faubert, F.; Bariki, C.; Gascoin, N.; Bellel, N.

    2015-06-01

    In this paper, magnesium-lanthanum powders were synthesized by an electrodeposition technique using an aqueous solution, based on magnesium chloride hexahydrate and lanthanum nitrate for different values of voltage and La weight percentage. A copper cathode plate and a tungsten thread anode were used for the preparation of the Mg-La layers. The as-deposited powders were characterized by energy dispersive spectroscopy (EDS) to determine the chemical composition, scanning electron microscope to describe the morphology, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectra in order to define the chemical structure. EDS analyses indicate the presence of three elements (Mg, La and O) in the different deposited layers, and the major one is O (51-74.2 at.%). The two other elements, Mg and La, are, respectively, ranked 2 and 3 in the different powders. Morphological description reveals the formation of heterogeneous chemical structures on the surfaces of specimens. They are characterized by aggregates with different sizes. The dark aggregates are associated with magnesium, and the bright ones are attributed to lanthanum. X-ray results showed the existence of two distinct phases in the obtained deposits which are magnesium hydroxide (Mg(OH)2) and lanthanum hydroxide (La(OH)3). FTIR analyses confirm the presence of the two phases identified in XRD diffractograms, and they can be exhibited by clear peaks. In the studied ranges of voltage and La weight percentage, their peak transmittances have non-monotonic behaviors. A design of experiments was used to determine the influence of these two processing parameters and their interaction on the products formation. The parameter effects were ranked as follow: The first was the voltage then the interaction between the two parameters and finally the La content.

  16. Chemical Aproximate Quantity Container Size Notes Lanthanum (La) Metal 2x 25g 2 x 25g

    E-print Network

    Wager, John F.

    Chemical Aproximate Quantity Container Size Notes Lanthanum (La) Metal 2x 25g 2 x 25g Aluminum (Al) evaporation pellets 10g 25g Strontium (Sr) Metal 25g 50g Sb g 5g Zn g 10g Selenium Powder 35g 50g Tellurium Powder 2 x 5g 2 x 25g Si Metal 3g 5g Indium (III) Isopropoxide Trace 0.5g MSB2675, H.W. Sands Corp

  17. Computational termochemistry study of the C?? isomers and their endo lanthanum complexes by applying homodesmotic and isodesmic reactions.

    PubMed

    Rios, Citlalli; Salcedo, Roberto

    2012-01-01

    C?? is a fullerene species which appears in different isomeric configurations. A general homodesmotic reaction previously designed to study the energy of fullerenes was implemented, in order to analyze the energy of this family of isomers. These results concur with some of the experimental data, but energy differences referring to all the configurations yield novel propositions about their particular behavior. The corresponding lanthanum complexes are also analyzed here and a new isodesmic reaction was designed for this particular case. PMID:23222905

  18. Photoluminescence of Valence-Changed Samarium Ions in Sintered BaSO4 Induced by X-ray Radiation

    NASA Astrophysics Data System (ADS)

    Maeda, K.; Kumeda, T.; Arimura, K.; Sakai, K.; Ikari, T.

    2015-06-01

    The conversion of ionic valence induced by X-ray irradiation can possibly be applied in X-ray imaging devices. Here, we report the X-ray irradiation time dependence of the valence change of Sm ions doped in a BaSO4 matrix. The samples were prepared by sintering a mixture of BaSO4 and Sm2O3 powder. The as-prepared sample consisted mainly of Sm3+. Sm2+ and Sm3+ were detected by using the photoluminescence (PL) spectral shapes. After X-ray irradiation (? = 0.154 nm), the PL intensity of the Sm2+ increased proportionally to the X-ray irradiation time from 4 to 1000 s. The intensity began to saturate at more than 1000 s. The intensity of Sm3+ was constant regardless of the increasing Sm2+ intensity.

  19. Samarium and yttrium codoped BaCeO? proton conductor with improved sinterability and higher electrical conductivity.

    PubMed

    Shi, Zhen; Sun, Wenping; Wang, Zhongtao; Qian, Jing; Liu, Wei

    2014-04-01

    Acceptor-doped barium cerate is considered as one of the state-of-the-art high temperature proton conductors (HTPCs), and the proton conductivity of such HTPCs is heavily dependent on the dopant. In this work, a codoping strategy is employed to improve the electrical conductivity and sinterability of BaCeO3-based HTPC. BaCe0.8Sm(x)Y(0.2-x)O(3-?) (0 ? x ? 0.2) powders are synthesized by a typical citrate-nitrate combustion method. The XRD and Raman spectra reveal all the compounds have an orthorhombic perovskite structure. The effects of Sm and/or Y doping on the sinterability and electrical conductivity under different atmospheres are carefully investigated. The SEM results of the sintered BaCe0.8Sm(x)Y(0.2-x)O(3-?) pellets indicate a significant sintering enhancement with increasing Sm concentration. BaCe0.8Sm0.1Y0.1O(3-?) exhibits the highest electrical conductivity in hydrogen among the BaCe0.8Sm(x)Y(0.2-x)O(3-?) pellets. Anode-supported BaCe0.8Sm0.1Y0.1O(3-?) electrolyte membranes are also fabricated via a drop-coating process, and the corresponding single cell exhibits desirable power performance and durability at low temperatures. The results demonstrate that BaCe0.8Sm0.1Y0.1O(3-?) is a promising proton conductor with high conductivity and sufficient sinterability for proton-conducting solid oxide fuel cells operating at reduced temperatures. PMID:24646030

  20. Synthesis of lanthanum zirconium oxide nanomaterials through composite-hydroxide-mediated approach

    SciTech Connect

    Jin, Hongyun [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China) [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Huang, Dan [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China)] [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China); Gao, Qiang [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China) [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Li, Li [Qinghai Entry-Exit Inspection and Quarantine Bureau (China)] [Qinghai Entry-Exit Inspection and Quarantine Bureau (China); Wang, Ning [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China)] [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China); Wang, Yongqian [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China) [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Hou, Shuen, E-mail: jincug@yahoo.com.cn [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China) [Faculty of Material Science and Chemistry Engineering, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China)

    2012-01-15

    Graphical abstract: Lanthanum zirconium oxide (La{sub 2}Zr{sub 2}O{sub 7}) with cubic pyrochlore structure thermal barrier coatings (TBCs) materials have been synthesized through composite-hydroxide-mediated method at 200 Degree-Sign C. Compared with YSZ TBCs material, La{sub 2}Zr{sub 2}O{sub 7} showed more excellent thermal stability and lower thermal conductivity. Highlights: Black-Right-Pointing-Pointer La{sub 2}Zr{sub 2}O{sub 7} TBCs were synthesized through composite-hydroxide-mediated method. Black-Right-Pointing-Pointer The XRD patterns showed a single phase for La{sub 2}Zr{sub 2}O{sub 7} after treated at 1300 Degree-Sign C. Black-Right-Pointing-Pointer The thermal conductivity value of La{sub 2}Zr{sub 2}O{sub 7} was lower than that of YSZ. Black-Right-Pointing-Pointer La{sub 2}Zr{sub 2}O{sub 7} showed more excellent stability and lower thermal conductivity than YSZ. -- Abstract: A novel thermal barrier coating material, lanthanum zirconium oxide (La{sub 2}Zr{sub 2}O{sub 7}) has been synthesized through the composite-hydroxide-mediated method at low temperature. The phase structures, morphology, thermal stability and thermal conductivity of the as-synthesized La{sub 2}Zr{sub 2}O{sub 7} were investigated systematically. The X-ray diffraction (XRD) patterns revealed a single phase with cubic pyrochlore structure for La{sub 2}Zr{sub 2}O{sub 7} after treated at 1300 Degree-Sign C for 100 h. The transmission electron microscope (TEM) and scanning electron microscope (SEM) analyses showed that the sample was made up of sphere-like nanoparticles with the size between 50 and 100 nm. Furthermore, the thermal analysis result demonstrated the La{sub 2}Zr{sub 2}O{sub 7} sample had high thermal stability even at 1300 Degree-Sign C. As the temperature increased to 1200 Degree-Sign C, the thermal conductivity value could be as low as 1.75 W m{sup -1} K{sup -1}. Due to the high-temperature stability and lower thermal conductivity, the La{sub 2}Zr{sub 2}O{sub 7} material is expected to be a promising candidate for the use of thermal barrier coatings.