Synthesis and characterization of Sr- and Mg-doped Lanthanum gallate electrolyte materials prepared via the Pechini method

Energy Technology Data Exchange (ETDEWEB)

Shi Min [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China)], E-mail: shimin@mail.hf.ah.cn; Xu Yudong; Liu Anping; Liu Ning; Wang Can [School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009 (China); Majewski, P.; Aldinger, F. [Max-Planck-Institut fur Metallforschung, Pulvermetallurgisches Laboratorium, Heisenbergstr. 5, D-70569 Stuttgart (Germany)

2009-03-15

The powders of Sr- and Mg-doped lanthanum gallate (La{sub 0.85}Sr{sub 0.15}Ga{sub 0.80}Mg{sub 0.2}O{sub 2.825}; LSGM) were synthesized by the Pechini method. The XRD pattern indicates that the main phase (LaGaO{sub 3}) exists in the uncalcined powders. The LSGM materials are composed of the main phase without secondary phases when calcined at 1400 deg. C. The LSGM materials contain fewer amounts of secondary phases than those prepared by the sol-gel method and solid-state reaction method at the same calcination temperature. TEM image of the powders indicate that the average grain size is about 80 nm. The conductivity increases with the testing temperature increasing. The curve of ln({sigma}T) vs 1/T exists two straight lines intersecting at T* (T* is about 602 deg. C). It indicates that activation energy of oxygen-vacancy motion at lower temperatures is greater than that at higher temperatures.

Low-temperature sintering and electrical properties of strontium- and magnesium-doped lanthanum gallate with V2O5 additive

Science.gov (United States)

Ha, Sang Bu; Cho, Yoon Ho; Ji, Ho-Il; Lee, Jong-Ho; Kang, Yun Chan; Lee, Jong-Heun

2011-03-01

The effects of a V2O5 additive on the low-temperature sintering and ionic conductivity of strontium- and magnesium-doped lanthanum gallate (LSGM: La0.8Sr0.2Ga0.8Mg0.2O2.8) are studied. The LSGM powders prepared by the glycine nitrate method are mixed with 0.5-2 at.% of VO5/2 and then sintered at 1100-1400 °C in air for 4 h. The apparent density and phase purity of the LSGM specimens are increased with increasing sintering temperature and VO5/2 concentration due to the enhanced sintering and mass transfer via the intergranular liquid phase. The 1 at.% VO5/2-doped LSGM specimen sintered at 1300 °C exhibits a high oxide ion conductivity of ∼0.027 S cm-1 at 700 °C over a wide range of oxygen partial pressure (PO2 =10-27 - 1 atm), thereby demonstrating its potential as a useful electrolyte for anode-supported solid oxide fuel cells (SOFCs) without the requirement for any buffer layer between the electrolyte and anode.

Influence of milling and calcination steps on phase assemblage of strontium and magnesium doped lanthanum gallate

International Nuclear Information System (INIS)

Reis, S.L.; Muccillo, E.N.S.

2011-01-01

Sr- and Mg- doped lanthanum gallate (La_1_-_xSr_xGa_1_-_yMg_yO_3_δ) is one of the most promising solid electrolyte and electrode components for solid oxide fuel cells operating at low-temperature, due to its high electric conductivity and stability over a wide range of oxygen partial pressures. In this work, La_0_,_9Sr_0_,_1Ga_0_,_8Mg_0_,_2O_2_,_85 was prepared by different solid state reaction routes. The main purpose is to determine a suitable processing route that enables high sintering density along with free or negligible secondary phase contents. Phase analysis was carried out by X-ray diffraction and the sintered density was obtained from the water immersion method. Results on X-ray diffraction showed negligible secondary phases formed even for sintering at relatively high temperatures. The apparent density obtained was higher than 95% of the theoretical value for all routes. The main difference observed among the studied routes is the final contents of secondary phases. (author)

Synthesis of pure and Sr-doped LaGaO3, LaFeO3 and LaCoO3 and Sr,Mg-doped LaGaO3 for ITSOFC application using different wet chemical routes

International Nuclear Information System (INIS)

Kumar, M.; Srikanth, S.; Ravikumar, B.; Alex, T.C.; Das, S.K.

2009-01-01

Pure and Sr-doped LaGaO 3 , LaFeO 3 and LaCoO 3 and Sr,Mg-doped LaGaO 3 were synthesized by various wet chemical routes, namely combustion, co-precipitation and citrate-gel methods. The effect of the various process parameters on the phase purity, particle size and surface area and morphology of the synthesized powders were determined by XRD, simultaneous TG-DTA, laser light scattering, BET and scanning electron microscopy. The stability of the synthesized pure phases in oxidizing and reducing atmosphere was also studied by thermogravimetry. It was observed that pure and Sr-doped single perovskite phases of lanthanum ferrite, cobaltite and gallate and Sr,Mg-doped lanthanum gallate could be synthesized by combustion and citrate-gel methods under suitable process conditions. Synthesis using the co-precipitation method yielded incomplete reaction irrespective of the calcination temperature adopted. The citrate-gel method yielded better powder properties in terms of particle size and morphology and surface area compared to combustion synthesis. It was found that pure and Sr-doped lanthanum ferrite, lanthanum cobaltite, lanthanum gallate and Sr,Mg-doped lanthanum gallate were stable in the oxidizing atmosphere. In the reducing atmosphere, pure and Sr-doped lanthanum ferrite and Sr,Mg-doped lanthanum gallate was found to be stable at least during the timeframe of the thermogravimetric experiment whereas pure and Sr-doped lanthanum cobaltite was partially reduced in hydrogen atmosphere

Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells

International Nuclear Information System (INIS)

Li Shuai; Li Zhicheng; Bergman, Bill

2010-01-01

The composite of doped lanthanum gallate (La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 , LSGM) and doped ceria (Ce 0.8 Sm 0.2 O 1.9 , CSO) was investigated as an electrolyte for solid oxide fuel cell (SOFC). The LSGM-CSO composite was examined by X-ray diffraction (XRD) and impedance spectroscopy. It was found that the sintered LSGM-CSO composite contains mainly fluorite CeO 2 phase and a minority impurity phase, Sm 3 Ga 5 O 12 . The LSGM-CSO composite electrolyte shows a small grain boundary response in the impedance spectroscopy as compared to LSGM and CSO pellets. The composite electrolyte exhibits the highest conductivity in the temperature range of 250-600 o C, compared to LSGM and CSO. The LSGM-CSO composite can be expected to be an attractive intermediate temperature electrolyte material for solid oxide fuel cells.

Synthesis of pure and Sr-doped LaGaO{sub 3}, LaFeO{sub 3} and LaCoO{sub 3} and Sr,Mg-doped LaGaO{sub 3} for ITSOFC application using different wet chemical routes

Energy Technology Data Exchange (ETDEWEB)

Kumar, M. [National Metallurgical Laboratory-Madras Center, CSIR Madras Complex, Chennai 600113 (India); Srikanth, S. [National Metallurgical Laboratory-Madras Center, CSIR Madras Complex, Chennai 600113 (India)], E-mail: s_srikanth_99@yahoo.com; Ravikumar, B.; Alex, T.C.; Das, S.K. [National Metallurgical Laboratory, Jamshedpur 831007 (India)

2009-02-15

Pure and Sr-doped LaGaO{sub 3}, LaFeO{sub 3} and LaCoO{sub 3} and Sr,Mg-doped LaGaO{sub 3} were synthesized by various wet chemical routes, namely combustion, co-precipitation and citrate-gel methods. The effect of the various process parameters on the phase purity, particle size and surface area and morphology of the synthesized powders were determined by XRD, simultaneous TG-DTA, laser light scattering, BET and scanning electron microscopy. The stability of the synthesized pure phases in oxidizing and reducing atmosphere was also studied by thermogravimetry. It was observed that pure and Sr-doped single perovskite phases of lanthanum ferrite, cobaltite and gallate and Sr,Mg-doped lanthanum gallate could be synthesized by combustion and citrate-gel methods under suitable process conditions. Synthesis using the co-precipitation method yielded incomplete reaction irrespective of the calcination temperature adopted. The citrate-gel method yielded better powder properties in terms of particle size and morphology and surface area compared to combustion synthesis. It was found that pure and Sr-doped lanthanum ferrite, lanthanum cobaltite, lanthanum gallate and Sr,Mg-doped lanthanum gallate were stable in the oxidizing atmosphere. In the reducing atmosphere, pure and Sr-doped lanthanum ferrite and Sr,Mg-doped lanthanum gallate was found to be stable at least during the timeframe of the thermogravimetric experiment whereas pure and Sr-doped lanthanum cobaltite was partially reduced in hydrogen atmosphere.

Lanthanum gallate and ceria composite as electrolyte for solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Li Shuai, E-mail: shuail@kth.s [Department of Materials Science and Engineering, School of Industrial Engineering and Management, Royal Institute of Technology, SE 10044 Stockholm (Sweden); Li Zhicheng [School of Materials Science and Engineering, Central South University, 410083 Changsha, Hunan (China); Bergman, Bill [Department of Materials Science and Engineering, School of Industrial Engineering and Management, Royal Institute of Technology, SE 10044 Stockholm (Sweden)

2010-03-04

The composite of doped lanthanum gallate (La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85}, LSGM) and doped ceria (Ce{sub 0.8}Sm{sub 0.2}O{sub 1.9}, CSO) was investigated as an electrolyte for solid oxide fuel cell (SOFC). The LSGM-CSO composite was examined by X-ray diffraction (XRD) and impedance spectroscopy. It was found that the sintered LSGM-CSO composite contains mainly fluorite CeO{sub 2} phase and a minority impurity phase, Sm{sub 3}Ga{sub 5}O{sub 12}. The LSGM-CSO composite electrolyte shows a small grain boundary response in the impedance spectroscopy as compared to LSGM and CSO pellets. The composite electrolyte exhibits the highest conductivity in the temperature range of 250-600 {sup o}C, compared to LSGM and CSO. The LSGM-CSO composite can be expected to be an attractive intermediate temperature electrolyte material for solid oxide fuel cells.

Impedance analysis of a disk-type SOFC using doped lanthanum gallate under power generation

Science.gov (United States)

Kato, Tohru; Nozaki, Ken; Negishi, Akira; Kato, Ken; Monma, Akihiko; Kaga, Yasuo; Nagata, Susumu; Takano, Kiyonami; Inagaki, Toru; Yoshida, Hiroyuki; Hosoi, Kei; Hoshino, Koji; Akbay, Taner; Akikusa, Jun

Impedance measurements were carried out under practical power generation conditions in a disk-type SOFC, which may be utilized as a small-scale power generator. The tested cell was composed of doped lanthanum gallate (La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ) as the electrolyte, Sm 0.5Sr 0.5CoO 3 as the cathode electrode and Ni/Ce 0.8Sm 0.2O 2 cermet as the anode electrode. The cell impedance was measured between 10 mHz and 10 kHz by varying the fuel utilization and gas flow rate and plotted in complex impedance diagrams. The observed impedance shows a large semi-circular pattern on the low frequency side. The semi-circular impedance, having a noticeably low characteristic frequency between 0.13 and 0.4 Hz, comes from the change in gas composition, originally caused by the cell reaction. The change in impedance with the fuel utilization (load current) and the gas flow rate agreed qualitatively well with the theoretical predictions from a simulation. This impedance was dominant under high fuel-utilization power-generation conditions. The impedance, which described the activation polarizations in the electrode reactions, was comparatively small and scarcely changed with the change in fuel utilization (load current) and gas flow rate.

Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate

Science.gov (United States)

Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar

2014-09-01

One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed.

Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate

International Nuclear Information System (INIS)

Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar

2014-01-01

One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed. (orig.)

Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate

Energy Technology Data Exchange (ETDEWEB)

Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar [Indian Institute of Technology (Banaras Hindu University), Department of Physics, Varanasi (India)

2014-09-15

One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-δ} (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed. (orig.)

Evaluation of GdBaCo{sub 2}O{sub 5+{delta}} as cathode material for doped lanthanum gallate electrolyte IT-SOFCs

Energy Technology Data Exchange (ETDEWEB)

Tarancon, A. [Department of Inorganic Chemistry, University of La Laguna, La Laguna, Tenerife (Spain); EME/XaRMAE/IN, Department of Electronics, University of Barcelona (Spain); Marrero-Lopez, D.; Ruiz-Morales, J.C.; Nunez, P. [Department of Inorganic Chemistry, University of La Laguna, La Laguna, Tenerife (Spain); Pena-Martinez, J.

2008-10-15

The layered perovskite GdBaCo{sub 2}O{sub 5+{delta}} (GBCO), recently proposed for intermediate temperature solid oxide fuel cell applications, was investigated and compared with Ba{sub 0.5}Sr{sub 0.5}Co{sub 0.8}Fe{sub 0.2}O{sub 3-{delta}} (BSCF) cathode material using La{sub 0.9}A{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85} (A=Sr,Ba) as electrolytes. Area-specific resistance was measured by impendance spectroscopy in symmetrical cells. The cobaltites were prepared by a modified citrate sol-gel route and tested as cathode materials for doped lanthanum gallate-based cells using dry H{sub 2} as fuel and air as oxidant, rendering power density values of 180 and 240 mW cm {sup -2} at 1,073 K (1 mm thick pellets) for GBCO and BSCF fuel cells, respectively. (Abstract Copyright [2008], Wiley Periodicals, Inc.)

Paramagnetic resonance of Mn4+ and Mn2+ centers in lanthanum gallate single crystals

Science.gov (United States)

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

2010-03-01

An increase in the manganese concentration in lanthanum gallate in the range 0.5-5.0% has been found to result in a complete replacement of individual Mn4+ ions by Mn2+ ions. The relative concentrations and binding energies of individual Mn4+, Mn3+, and Mn2+ ions have been determined. The spin Hamiltonians of the Mn2+ and Mn4+ centers in the rhombohedral and orthorhombic phases, respectively, have been constructed and the orientation of the principal axes of the fine-structure tensor of Mn4+ at room temperature has been found. The possibility of using electron paramagnetic resonance for determining the rotation angles of oxygen octahedra of lanthanum gallate with respect to the perovskite structure has been discussed.

Mixed ionic-electronic conduction in Ni doped lanthanum gallate perovskites

Energy Technology Data Exchange (ETDEWEB)

Long, N.J.; Tuller, H.L.

1998-07-01

Lanthanum gallate is a promising material for monolithic fuel cells or oxygen pumps, i.e., one in which the electrolyte and electrodes are formed from a common phase. The authors have investigated La{sub 1{minus}x}Sr{sub x}Ga{sub 1{minus}y}Ni{sub y}O{sub 3} (LSGN{sub x{minus}y}) with x = 0.1 and y = 0.2 and 0.5 as a potential cathode material for such an electrochemical device. The {sigma}(PO{sub 2},T) for LSGN{sub 10--20} points to a p-type electronic conductivity at high PO{sub 2} and predominantly ionic conductivity at low PO{sub 2}. LSGN{sub 10-50} has an electronic conductivity suitable for SOFC applications of approximately 50 S/cm in air at high temperature. AC impedance spectroscopy on an electron blocking cell of the form M/LSG/LSGN/LSG/M was used to isolate the ionic conductivity in the LSGN{sub 10--20} material. The ionic conductivity was found to have a similar magnitude and activation energy to that of undoped LSG material with {sigma}{sub i} = 0.12 S/cm at 800 C and E{sub A} = 1.0 {+-} 0.1 eV. Thermal expansion measurements on the LSGN materials were characterized as a function of temperature and dopant level and were found to match that of the electrolyte under operating conditions.

Ionic conductivity and fuel cell properties of apatite-type lanthanum silicates doped with Mg and containing excess oxide ions

Energy Technology Data Exchange (ETDEWEB)

Yoshioka, Hideki [Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira-cho, Suma-ku, Kobe 654-0037 (Japan); Nojiri, Yoshihiro [Kyushu University, Department of Mechanical Engineering Science, Faculty of Engineering, Motooka 744, Nishi-ku, Fukuoka 819-0935 (Japan); Tanase, Shigeo [National Institute of Advanced Industrial Science and Technology, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577 (Japan)

2008-11-30

Enhancement of the ionic conductivity of lanthanum silicate-based apatites is examined with emphasis on optimizing the La composition and the Mg doping level at the same time. La{sub 10}Si{sub 5.8}Mg{sub 0.2}O{sub 26.8} and La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} show the highest level of the ionic conductivities among apatite silicates, 8.8 and 7.4 x 10{sup -} {sup 2} S cm{sup -} {sup 1} at 800 C, respectively, with a very low level of activation energy (0.42-0.43 eV). Their conductivities are higher than yttria stabilized zirconia (YSZ) below 900 C and even comparable to Sr and Mg doped lanthanum gallate (LSGM) below 550 C. A solid oxide fuel cell using La{sub 9.8}Si{sub 5.7}Mg{sub 0.3}O{sub 26.4} as an electrolyte with Ni-ceria cermet anode and Sr doped lanthanum cobaltite cathode exhibits a remarkable improvement in power generation compared to previous data using Pt electrodes. Structural investigation by the Rietveld analysis on the powder X-ray diffraction pattern shows significant enlargement of the bottleneck triangle sizes of the conduction channel with the Mg doping. (author)

Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

Science.gov (United States)

Sandstrom, R. L.; Giess, E. A.; Gallagher, W. J.; Segmuller, A.; Cooper, E. I.

1988-11-01

It is demonstrated that lanthanum gallate (LaGaO3) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa2Cu3O(7-x), can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant and low dielectric losses. Epitaxial YBa2Cu3O(7-x) films grown on LaGaO3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K.

Lanthanum gallate substrates for epitaxial high-temperature superconducting thin films

International Nuclear Information System (INIS)

Sandstrom, R.L.; Giess, E.A.; Gallagher, W.J.; Segmueller, A.; Cooper, E.I.; Chisholm, M.F.; Gupta, A.; Shinde, S.; Laibowitz, R.B.

1988-01-01

We demonstrate that lanthanum gallate (LaGaO 3 ) has considerable potential as an electronic substrate material for high-temperature superconducting films. It provides a good lattice and thermal expansion match to YBa 2 Cu 3 O/sub 7-//sub x/, can be grown in large crystal sizes, is compatible with high-temperature film processing, and has a reasonably low dielectric constant (ε≅25) and low dielectric losses. Epitaxial YBa 2 Cu 3 O/sub 7-//sub x/ films grown on LaGaO 3 single-crystal substrates by three techniques have zero resistance between 87 and 91 K

Effect of noble metal doping on the structural properties of lanthanum cobaltite

International Nuclear Information System (INIS)

Dharmadhikari, Dipti V.; Athawal, Anjali A.

2016-01-01

Pristine and Noble metal (Ag and Pd) doped lanthanum cobaltite samples have been synthesised by Hydrothermal method. Lanthanum in the A-Site and Co at B-site of Lanthanum cobaltite (LaCoO 3 ) perovskites were partially doped by silver and palladium (4%). Crystal structure analysis revealed that the hydrothermal synthesis led to the formation of pure nanocrystalline perovskite structure. Morphological analysis of the samples shows that the noble metal doping affects the morphology of the samples. Pristine sample shows spherical to oval shaped particles while the doping results in the formation of irregular shaped, spherical and rod shaped particles. Silver doping results in the agglomeration of particles. The particles were observed to be fused with each other to form rod shaped structures in case of palladium doped samples. (author)

Local structure of gallate proton conductors

International Nuclear Information System (INIS)

Giannici, F; Messana, D; Martorana, A; Longo, A; Sciortino, L

2009-01-01

Lanthanum barium gallate proton conductors are based on disconnected GaO 4 groups. The insertion of hydroxyls in the LaBaGaO 4 network proceeds through self-doping with Ba 2+ , consequent O 2- vacancy formation to fulfill charge neutrality. With a structural investigation on self-doped LaBaGaO 4 oxides using synchrotron XRD and EXAFS on the Ga K-edge, we find that: (a) the GaO 4 tetrahedra retain their size throughout the whole series; (b) the GaO 4 tetrahedra rotate as rigid bodies on hydration, leading to the formation of a network of shorter O-O configurations that are stabilized by hydrogen bonds; (c) contraction of the lattice occurs along the a unit cell axis, as a consequence of an overall structural rearrangement of the hydrated solid.

Local structure of gallate proton conductors

Science.gov (United States)

Giannici, F.; Messana, D.; Longo, A.; Sciortino, L.; Martorana, A.

2009-11-01

Lanthanum barium gallate proton conductors are based on disconnected GaO4 groups. The insertion of hydroxyls in the LaBaGaO4 network proceeds through self-doping with Ba2+, consequent O2- vacancy formation to fulfill charge neutrality. With a structural investigation on self-doped LaBaGaO4 oxides using synchrotron XRD and EXAFS on the Ga K-edge, we find that: (a) the GaO4 tetrahedra retain their size throughout the whole series; (b) the GaO4 tetrahedra rotate as rigid bodies on hydration, leading to the formation of a network of shorter O-O configurations that are stabilized by hydrogen bonds; (c) contraction of the lattice occurs along the a unit cell axis, as a consequence of an overall structural rearrangement of the hydrated solid.

Relaxation effects in oxygen-conducting oxides on base of lanthanum gallate (La, Sr)(Ga, Me)O3, Me = Mg, Fe

International Nuclear Information System (INIS)

Glavatskikh, T.Yu.; Venskovskij, N.U.; Kaleva, G.M.; Mosunov, A.V.; Politova, E.D.; Stefanovich, S.Yu.

2003-01-01

The dielectric and electric conducting properties of the heterosubstituted perovskite-like solid solutions (La, Sr)(Ga, Me)O 3 , Me Mg, Fe are studied. The increase in the ceramics electric conductivity, conditioned by increase in the ion constituent at strengthening the nonstoichiometry by oxygen and electron constituent by the additional introduction of iron is observed by replacing the part of the lanthanum and gallium cations by strontium, magnesium and iron in the solid solutions on the basis of the lanthanum gallate. The ceramics relaxation behavior is identified; the applicability of the model of the vacational electron transfer for the dipole relaxation is established [ru

Silica doped with lanthanum sol–gel thin films for corrosion protection

International Nuclear Information System (INIS)

Abuín, M.; Serrano, A.; Llopis, J.; García, M.A.; Carmona, N.

2012-01-01

We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol–gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: ► Silica sol–gel films doped with lanthanum ions were synthesized. ► Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. ► La-acetate is an affordable chemical reactive preferred for the industry. ► Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. ► An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

The evolution mechanism of the dislocation loops in irradiated lanthanum doped cerium oxide

International Nuclear Information System (INIS)

Miao, Yinbin; Aidhy, Dilpuneet; Chen, Wei-Ying; Mo, Kun; Oaks, Aaron; Wolf, Dieter; Stubbins, James F.

2014-01-01

Cerium dioxide, a non-radioactive surrogate of uranium dioxide, is useful for simulating the radiation responses of uranium dioxide and mixed oxide fuel (MOX). Controlled additions of lanthanum can also be used to form various levels of lattice oxide or anion vacancies. In previous transmission electron microscopy (TEM) experimental studies, the growth rate of dislocation loops in irradiated lanthanum doped ceria was reported to vary with lanthanum concentration. This work reports findings of the evolution mechanisms of the dislocation loops in cerium oxide with and without lanthanum dopants based on a combination of molecular statics and molecular dynamics simulations. These dislocation loops are found to be b=1/3〈111〉 interstitial type Frank loops. Calculations of the defect energy profiles of the dislocation loops with different structural configurations and radii reveal the basis for preference of nucleation as well as the driving force of growth. Frenkel pair evolution simulations and displacement cascade overlaps simulations were conducted for a variety of lanthanum doping conditions. The nucleation and growth processes of the Frank loop were found to be controlled by the mobility of cation interstitials, which is significantly influenced by the lanthanum doping concentration. Competition mechanisms coupled with the mobility of cation point defects were discovered, and can be used to explain the lanthanum effects observed in experiments

Synthesis characterization and sintering of cobalt-doped lanthanum chromite powders for use in SOFCs

International Nuclear Information System (INIS)

Yamagata, Chieko; Mello-Castanho, Sonia R.H.

2009-01-01

Doped lanthanum chromite is a promising as interconnect material because of its good conductivity at high temperatures and its stability in oxidizing and reducing atmospheres. Perovskite oxide powders of Co-doped lanthanum chromite were synthesized by dispersing precursor metal salt solutions in a polymer matrix followed by a thermal treatment. XRD patterns showed that a highly crystalline cobalt-doped lanthanum chromite was obtained. Fine perovskite powder with a surface area of 6.15 m 2 g -1 calcined at 700 deg C for 1 h, were obtained. After the sample sintered at 1450 deg C for 3h, the powder reached high densities exceeding 97% of the theoretical density. The proposed here has proved to be a very promising technique for the synthesis of lanthanum chromite powders. (author)

Local structure of gallate proton conductors

Energy Technology Data Exchange (ETDEWEB)

Giannici, F; Messana, D; Martorana, A [Universita degli Studi di Palermo, Dipartimento di Chimica Inorganica ed Analitica, Viale delle Scienze, I-90128 Palermo (Italy); Longo, A [CNR, Istituto per lo studio dei materiali nanostrutturati, Via Ugo La Malfa 153, I-90146 Palermo (Italy); Sciortino, L, E-mail: sciortino@pa.ismn.cnr.i

2009-11-15

Lanthanum barium gallate proton conductors are based on disconnected GaO{sub 4} groups. The insertion of hydroxyls in the LaBaGaO{sub 4} network proceeds through self-doping with Ba{sup 2+}, consequent O{sup 2-} vacancy formation to fulfill charge neutrality. With a structural investigation on self-doped LaBaGaO{sub 4} oxides using synchrotron XRD and EXAFS on the Ga K-edge, we find that: (a) the GaO{sub 4} tetrahedra retain their size throughout the whole series; (b) the GaO{sub 4} tetrahedra rotate as rigid bodies on hydration, leading to the formation of a network of shorter O-O configurations that are stabilized by hydrogen bonds; (c) contraction of the lattice occurs along the a unit cell axis, as a consequence of an overall structural rearrangement of the hydrated solid.

Silica doped with lanthanum sol-gel thin films for corrosion protection

Energy Technology Data Exchange (ETDEWEB)

Abuin, M. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Serrano, A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); Llopis, J. [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain); Garcia, M.A. [Glass and Ceramic Institute, CSIC, C. Kelsen 5, 28049 Madrid (Spain); IMDEA Nanoscience, Fco. Tomas y Valiente 7, 28049 Madrid (Spain); Carmona, N., E-mail: n.carmona@fis.ucm.es [Department of Materials Physics, Complutense University at Madrid, Avda. Complutense sn, 28004 Madrid (Spain)

2012-06-01

We present here anticorrosive silica coatings doped with lanthanum ions for the protection of metallic surfaces as an alternative to chromate (VI)-based conversion coatings. The coatings were synthesized by the sol-gel method starting from silicon alkoxides and two different lanthanum precursors: La (III) acetate hydrate and La (III) isopropoxide. Artificial corrosion tests in acid and alkaline media showed their effectiveness for the corrosion protection of AA2024 aluminum alloy sheets for coating prepared with both precursors. The X-ray absorption Near Edge Structure and X-ray Absorption Fine Structure analysis of the coatings confirmed the key role of lanthanum in the structural properties of the coating determining its anticorrosive properties. - Highlights: Black-Right-Pointing-Pointer Silica sol-gel films doped with lanthanum ions were synthesized. Black-Right-Pointing-Pointer Films from lanthanum-acetate and La-alkoxide were prepared for comparison purposes. Black-Right-Pointing-Pointer La-acetate is an affordable chemical reactive preferred for the industry. Black-Right-Pointing-Pointer Films properties were explored by scanning electron microscopy and X-Ray absorption spectroscopy. Black-Right-Pointing-Pointer An alternative to anticorrosive pre-treatments for metallic surfaces is suggested.

Influence of milling and calcination steps on phase assemblage of strontium and magnesium doped lanthanum gallate; Influencia das etapas de calcinacao e moagem na composicao de fases do galato de lantanio contendo estroncio e magnesio

Energy Technology Data Exchange (ETDEWEB)

Reis, S.L.; Muccillo, E.N.S., E-mail: shirley.reis@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

Sr- and Mg- doped lanthanum gallate (La{sub 1-x}Sr{sub x}Ga{sub 1-y}Mg{sub y}O{sub 3δ}) is one of the most promising solid electrolyte and electrode components for solid oxide fuel cells operating at low-temperature, due to its high electric conductivity and stability over a wide range of oxygen partial pressures. In this work, La{sub 0,9}Sr{sub 0,1}Ga{sub 0,8}Mg{sub 0,2}O{sub 2,8}5 was prepared by different solid state reaction routes. The main purpose is to determine a suitable processing route that enables high sintering density along with free or negligible secondary phase contents. Phase analysis was carried out by X-ray diffraction and the sintered density was obtained from the water immersion method. Results on X-ray diffraction showed negligible secondary phases formed even for sintering at relatively high temperatures. The apparent density obtained was higher than 95% of the theoretical value for all routes. The main difference observed among the studied routes is the final contents of secondary phases. (author)

Strengthening and elongation mechanism of Lanthanum-doped Titanium-Zirconium-Molybdenum alloy

Energy Technology Data Exchange (ETDEWEB)

Hu, Ping, E-mail: huping1985@126.com [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Jinduicheng Molybdenum Co., Ltd., Xi’an 710068 (China); Hu, Bo-liang; Wang, Kuai-she; Song, Rui; Yang, Fan [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Yu, Zhi-tao [Ruifulai Tungsten & Molybdenum Co., Ltd., Xi’an 721914 (China); Tan, Jiang-fei [School of Metallurgy Engineering, Xi’an University of Architecture and Technology, Xi’an 710055 (China); Cao, Wei-cheng; Liu, Dong-xin; An, Geng [Jinduicheng Molybdenum Co., Ltd., Xi’an 710068 (China); Guo, Lei [Ruifulai Tungsten & Molybdenum Co., Ltd., Xi’an 721914 (China); Yu, Hai-liang [School of Mechanical, Materials and Mechatronics Engineering, University of Wollongong, NSW 2522 (Australia)

2016-12-15

The microstructural contributes to understand the strengthening and elongation mechanism in Lanthanum-doped Titanium-Zirconium-Molybdenum alloy. Lanthanum oxide particles not only act as heterogeneous nucleation core, but also act as the second phase to hinder the grain growth during sintering crystallization. The molybdenum substrate formed sub-grain under the effect of second phase when the alloy rolled to plate.

Chemical compatibility of alternative perovskite oxide SOFC cathodes with doped lanthanum gallate solid electrolyte

Energy Technology Data Exchange (ETDEWEB)

Kostogloudis, G.C.; Ftikos, C. [Laboratory of Inorganic Materials Technology, Department of Chemical Engineering, National Technical University of Athens, 9 Heroon Polytechniou Str., Zografou Campus, GR-15780 Athens (Greece); Ahmad-Khanlou, A.; Naoumidis, A.; Stoever, D. [Research Centre Juelich, Institute for Materials and Processes in Energy Systems IWV1, D-52425 Juelich (Germany)

2000-10-01

This paper reports on the investigations of the chemical compatibility between SOFC cathode materials with compositions Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Mn{sub 0.8}O{sub 3-{delta}}, Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}}, Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.3}Mn{sub 0.7}O{sub 3-{delta}} and Pr{sub 0.75}Sr{sub 0.2}Co{sub 0.2}Mn{sub 0.8}O{sub 3-{delta}} and the electrolyte materials with compositions La{sub 0.8}Sr{sub 0.2}Ga{sub 0.9}Mg{sub 0.1}O{sub 3-{delta}}, and La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}}. The lanthanum gallate electrolyte with 20 mol.% Sr contained two additional phases, namely, LaSrGa{sub 3}O{sub 7} and LaSrGaO{sub 4}, while that with 10 mol.% Sr was formed in nearly single phase. Two types of experiments were performed: (a) reactivity experiments of powder mixtures and (b) diffusion experiments in cathode/electrolyte double-layer pellets. No reaction products were detected by XRD. High Co diffusion into the electrolyte was identified with SEM/EDX in all diffusion experiments examined. The transition metals diffuse in the order Mn

Types of defect ordering in undoped and lanthanum-doped Bi2201 single crystals

International Nuclear Information System (INIS)

Martovitsky, V. P.

2006-01-01

Undoped and lanthanum-doped Bi2201 single crystals having a perfect average structure have been comparatively studied by x-ray diffraction. The undoped Bi2201 single crystals exhibit very narrow satellite reflections; their half-width is five to six times smaller than that of Bi2212 single crystals grown by the same technique. This narrowness indicates three-dimensional defect ordering in the former crystals. The lanthanumdoped Bi2201 single crystals with x = 0.7 and T c = 8-10 K exhibit very broad satellite reflections consisting of two systems (modulations) misoriented with respect to each other. The modulation-vector components of these two modulations are found to be q 1 = 0.237b* + 0.277c* and q 2 = 0.238b* + 0.037c*. The single crystals having a perfect average structure and a homogeneous average distribution of doping lanthanum consist of 70-to 80-A-thick layers that alternate along the c axis and have two different types of modulated superlattice. The crystals having a less perfect average structure also consist of alternating layers, but they have different lanthanum concentrations. The low value of T c in the undoped Bi2201 single crystals (9.5 K) correlates with three-dimensional defect ordering in them, and an increase in T c to 33 K upon lanthanum doping can be related to a thin-layer structure of these crystals and to partial substitution of lanthanum for the bismuth positions

Mixed conductivity in Co-doped lanthanum gallate

International Nuclear Information System (INIS)

Keppeler, F.M.; Nafe, H.; Aldinger, F.; Sammes, N.M.

1998-01-01

Materials of the composition La 0.8 Sr 0.2 Ga 0.85 Co x Mg 0.15 O 3-δ (x = 0 to 0.25) were synthesised using standard solid state technique resulting in phase purity and high density. Conductivity measurements at different temperatures and oxygen partial pressures revealed an ionic to metallic-like transition in conduction behaviour with rising Co amount. Samples with low Co contents (x=0.05) showed ionic behaviour with an average value of 0.15 S/cm at 900 deg C while heavy doping (x=0.25) resulted in metallic type conduction with a value of 5.43 S/cm at 900 deg C in air. Copyright (1998) Australasian Ceramic Society

Structural properties of Fe-doped lanthanum gallate

International Nuclear Information System (INIS)

Mori, Kazuhiro; Fukunaga, Toshiharu; Shibata, Koji; Iwase, Kenji; Harjo, Stefanus; Hoshikawa, Akinori; Itoh, Keiji; Kamiyama, Takashi; Ishigaki, Toru

2004-01-01

Structural characteristics of Fe-doped LaGaO 3-δ were studied by differential scanning calorimeter, neutron and high-temperature X-ray powder diffraction measurements. It was found that a phase transition temperature increases in proportion to an amount of Fe. The crystal structure could be described as a low-temperature orthorhombic phase (Pnma) and a high-temperature rhombohedral one (R3-bar c), respectively. Lattice parameters and bond lengths between M (=Ga/Fe) and O are monotonically expand with increasing Fe-content on both orthorhombic and rhombohedral phases. This means that a substitution of Ga 3+ with Fe 3+ leads to an electronic configuration of t 2g 3 e g 2 (high-spin state, HS)

Structural properties of Fe-doped lanthanum gallate

Science.gov (United States)

Mori, Kazuhiro; Fukunaga, Toshiharu; Shibata, Koji; Iwase, Kenji; Harjo, Stefanus; Hoshikawa, Akinori; Itoh, Keiji; Kamiyama, Takashi; Ishigaki, Toru

2004-10-01

Structural characteristics of Fe-doped LaGaO3-δ were studied by differential scanning calorimeter, neutron and high-temperature X-ray powder diffraction measurements. It was found that a phase transition temperature increases in proportion to an amount of Fe. The crystal structure could be described as a low-temperature orthorhombic phase (Pnma) and a high-temperature rhombohedral one (R 3 bar c), respectively. Lattice parameters and bond lengths between M (=Ga/Fe) and O are monotonically expand with increasing Fe-content on both orthorhombic and rhombohedral phases. This means that a substitution of Ga3+ with Fe3+ leads to an electronic configuration of t2g3eg2 (high-spin state, HS).

Structural phase transition in lanthanum gallate as studied by Raman and X-ray diffraction measurements

Energy Technology Data Exchange (ETDEWEB)

Dhak, P.; Pramanik, P. [Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India); Bhattacharya, S.; Roy, Anushree [Department of Physics, Indian Institute of Technology, Kharagpur 721302 (India); Achary, S.N.; Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2011-08-15

Lanthanum gallate (LaGaO{sub 3}) is known to undergo orthorhombic to rhombohedral first order phase transition at 150 C. In this article we have shown that by introducing 2% La deficiency in the system, coexistence of above two phases can be obtained at lower temperature and a complete phase transition occurs at 200 C. The evolution of structural parameters of the system with temperature is reported from X-ray diffraction measurements and Rietveld analysis of the diffraction patterns. The change in local octahedral distortion due to 2% La deficiency is revealed through the shift in the phonon modes of GaO{sub 6} octahedra, in both orthorhombic and rhombohedral phase. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Structural properties of Fe-doped lanthanum gallate

Energy Technology Data Exchange (ETDEWEB)

Mori, Kazuhiro [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)]. E-mail: kmori@rri.kyoto-u.ac.jp; Fukunaga, Toshiharu [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Shibata, Koji [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Iwase, Kenji [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Harjo, Stefanus [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Hoshikawa, Akinori [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Itoh, Keiji [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Kamiyama, Takashi [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Ishigaki, Toru [Department of Materials Science and Engineering, Muroran Institute for Technology, Muroran 050-8585 (Japan)

2004-10-30

Structural characteristics of Fe-doped LaGaO{sub 3-{delta}} were studied by differential scanning calorimeter, neutron and high-temperature X-ray powder diffraction measurements. It was found that a phase transition temperature increases in proportion to an amount of Fe. The crystal structure could be described as a low-temperature orthorhombic phase (Pnma) and a high-temperature rhombohedral one (R3-bar c), respectively. Lattice parameters and bond lengths between M (=Ga/Fe) and O are monotonically expand with increasing Fe-content on both orthorhombic and rhombohedral phases. This means that a substitution of Ga{sup 3+} with Fe{sup 3+} leads to an electronic configuration of t{sub 2g}{sup 3}e{sub g}{sup 2} (high-spin state, HS)

Mixed conductivity in Co-doped lanthanum gallate

Energy Technology Data Exchange (ETDEWEB)

Keppeler, F.M.; Nafe, H.; Aldinger, F. [Pulvermetallurgisches Laboratorium, Stuttgart (Germany). Max-Planck-Institut fur Metallforschung; Sammes, N.M. [The University of Waikato, Hamilton (New Zealand). Department of Technology

1998-12-31

Materials of the composition La{sub 0.8}Sr{sub 0.2}Ga{sub 0.85}Co{sub x}Mg{sub 0.15}O{sub 3-{delta}} (x = 0 to 0.25) were synthesised using standard solid state technique resulting in phase purity and high density. Conductivity measurements at different temperatures and oxygen partial pressures revealed an ionic to metallic-like transition in conduction behaviour with rising Co amount. Samples with low Co contents (x=0.05) showed ionic behaviour with an average value of 0.15 S/cm at 900 deg C while heavy doping (x=0.25) resulted in metallic type conduction with a value of 5.43 S/cm at 900 deg C in air. Copyright (1998) Australasian Ceramic Society 12 refs., 5 figs.

Deposition barium titanate (BaTiO3) doped lanthanum with chemical solution deposition

International Nuclear Information System (INIS)

Iriani, Y.; Nurhadi, N.; Jamaludin, A.

2016-01-01

Deposition of Barium Titanate (BaTiO 3 ) thin films used Chemical Solution Deposition (CSD) method and prepared with spin coater. BaTiO 3 is doped with lanthanum, 1%, 2%, and 3%. The thermal process use annealing temperature 900°C and holding time for 3 hours. The result of characterization with x-ray diffraction (XRD) equipment show that the addition of La 3+ doped on Barium Titanate caused the change of angle diffraction.The result of refine with GSAS software shows that lanthanum have been included in the structure of BaTiO 3 . Increasing mol dopant La 3+ cause lattice parameter and crystal volume become smaller. Characterization result using Scanning Electron Microscopy (SEM) equipment show that grain size (grain size) become smaller with increasing mole dopant (x) La 3+ . The result of characterization using Sawyer Tower methods show that all the samples (Barium Titanante and Barium Titanate doped lanthanum) are ferroelectric material. Increasing of mole dopant La 3+ cause smaller coercive field and remanent polarization increases. (paper)

Electrical behaviour of strontium-doped lanthanum manganite interfaces

DEFF Research Database (Denmark)

Koch, Søren; Hendriksen, P.V.; Jacobsen, Torben

2005-01-01

The contact resistance of strontium-doped lanthanum manganite (LSM) contact pairs is investigated by polarisation analysis at different temperatures and atmospheres. The ceramic contacts have a high contact resistance, and strongly nonlinear current–voltage behaviour is observed at low temperatur....... The nonlinear behaviour is ascribed to the presence of energy barriers at the contact interface. Generally, point contacts showed a more linear behaviour than plane contact interfaces....

Ductility of Mo–12Si–8.5B alloys doped with lanthanum oxide by the liquid–liquid doping method

Energy Technology Data Exchange (ETDEWEB)

Li, Wenhu [School of Materials Science & Engineering, Xi’an University of Technology, Xi’an 710048 (China); School of Materials Science & Engineering, Shaanxi University of Technology, Hanzhong 723000 (China); Zhang, Guojun, E-mail: zhangguojun@xaut.edu.cn [School of Materials Science & Engineering, Xi’an University of Technology, Xi’an 710048 (China); Wang, Shixiong [School of Materials Science & Engineering, Xi’an University of Technology, Xi’an 710048 (China); Li, Bin; Sun, Jun [State Key Laboratory for Mechanical Behavior of Materials, Xi’an Jiaotong University, Xi’an 710049 (China)

2015-09-05

Highlights: • Alloys doping lanthanum oxide by L–L doped method were prepared by hot pressing. • The compression strength of alloys are superior. • The fracture toughness of alloys is improved by L–L doped method. - Abstract: Mo–12Si–8.5B (Mo–Si–B) alloys doped with different mass fractions (0.3 wt%, 0.6 wt%, and 0.9 wt%) of lanthanum oxide (La{sub 2}O{sub 3}) were prepared by liquid–liquid (L–L) doping, mechanical alloying and hot pressing sintering techniques. The observation of the microstructures of the Mo–Si–B alloys reveals that the grain sizes of the alloys were refined with the increase in La{sub 2}O{sub 3} doping. The fracture toughness values of the alloys of over 10 MPa m{sup 1/2} reveal that the addition of La{sub 2}O{sub 3} via the L–L doping method can obviously improve the alloy fracture toughness compared to the alloys doped with La{sub 2}O{sub 3} via the solid–solid (S–S) doping method. In addition, compression tests indicate that the compression strength of the alloys was improved compared to Mo–12Si–8.5B alloys.

On the luminescence of perovskite type rare earth gallates

International Nuclear Information System (INIS)

Jianmei, Y.; Qingyuan, W.; Shuzhen, L.; Lianren, S.; Mingyu, C.

1985-01-01

It has been reported that perovskite type lanthanum gallates may be a good host material for laser and luminescence, but in the rare earth gallates studied, the numbers of perovskite type are less than that of the garnet type and there is less report on their spectroscopic properties in the literature. In this paper synthesis and spectroscopic properties of these compounds are studied

Thermoelectric power and electrical conductivity of strontium-doped lanthanum manganite

DEFF Research Database (Denmark)

Ahlgren, E.O.; Poulsen, F.W.

1996-01-01

Thermoelectric power and electrical conductivity of pure and 5, 10 and 20% strontium-doped lanthanum manganite are determined as function of temperature in air and of P-O2 at 1000 degrees C. At high temperatures the thermoelectric power is negative. Both thermoelectric power and conductivity...

Combined neutron and synchrotron X-ray diffraction study of Sr/Mg-doped lanthanum gallates up to high temperatures

Science.gov (United States)

Guenter, M. M.; Lerch, M.; Boysen, H.; Toebbens, D.; Suard, E.; Baehtz, C.

2006-08-01

Combined neutron diffraction and high-resolution synchrotron X-ray powder diffraction methods have been used to examine the crystal structures of two sample sets of Sr/Mg-doped Lanthanum gallate with the compositions La0.9Sr0.1Ga1-yMgyO3-0.5(0.1+y) (y=0, 0.1, 0.2) and La0.8Sr0.2Ga1-yMgyO3-0.5(0.2+y) (y=0.15, 0.2) up to 900 °C. At room temperature all samples of the first series exhibit orthorhombic structures with space group Imma: La0.9Sr0.1GaO2.95: a=5.4904(1)Å, b=7.7757(1)Å, c=5.5229(1)Å; La0.9Sr0.1Ga0.9Mg0.1O2.9: a=5.5100(1)Å, b=7.8080(1)Å, c=5.5411(1)Å; La0.9Sr0.1Ga0.8Mg0.2O2.85: a=5.5269(1)Å, b=7.8318(2)Å, c=5.5459(1)Å. The samples of the second series have the cubic perovskite structure with space group Pm3¯m at room temperature: La0.8Sr0.2Ga0.85Mg0.15O2.825: a=3.9160(1)Å; La0.8Sr0.2Ga0.8Mg0.20O2.80: a=3.9195(1)Å. Samples of the first series transform from the orthorhombic to a rhombohedral (Imma→R3¯c) structure at ˜170 °C for La0.9Sr0.1GaO2.95, at ˜430 °C for La0.9Sr0.1Ga0.9Mg0.1O2.9, and between 600 and 700 °C for La0.9Sr0.1Ga0.8Mg0.2O2.85. Both La0.8Sr0.2Ga0.85Mg0.15O2.825 and La0.8Sr0.2Ga0.8Mg0.2 show no structural deviations from the cubic aristotype over the whole temperature range. The room temperature Imma structures of the first series are justified by a domain model and are rationalized in terms of static disorder increasing with Mg content, thus driving the phase transition temperatures to higher values in agreement with tolerance factor considerations. The distortion of the rhombohedral high-temperature phases (octahedra tilting and compression) and the effect of phase transitions on the ionic conductivity are discussed.

Structural transition in lanthanum gallate and transformation of the fine structure of the EPR spectrum of a Gd3+ impurity center

Science.gov (United States)

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

2011-04-01

Abrupt changes in resonance positions, hysteretic temperature behavior, and coexistence of phases, which indicate a first-order phase transition, have been revealed from measurements of temperature dependences of the EPR spectra of Gd3+ and Mn4+ centers in the vicinity of the structural transition of lanthanum gallate. The transformation of monoclinic Gd3+ centers into trigonal Gd3+ centers upon the phase transition has been used to estimate the adequacy of two approximations of the superposition model for parameters of the zero-field splitting of the ground state.

The oxidation of carbon monoxide over transition metal doped lanthanum manganates nanoparticles

International Nuclear Information System (INIS)

Fal Desai, M.S.; Salker, A.V.

2012-01-01

Lanthanum manganates perovskites (ABO 3 ) has been widely studied and applied. Many perovskites with A and B sites doped with different metals show good catalytic activity in many oxidation reactions than the individual perovskite. In present study, an attempt has been made to show comparative account of CO oxidation by doping the B site with different cations using sol-gel method

Processing and electrical conductivity of lanthanum gallate core-shell heterostructures

Directory of Open Access Journals (Sweden)

Gomes, Eduarda

2006-06-01

Full Text Available The electrical properties of a lanthanum gallate solid electrolyte were modified by selectively doping the grain boundaries with Fe. This was achieved by sandwiching a La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM dense pellet between LaFeO3 samples. Annealing at 1550°C in air for several hours promoted Fe diffusion into LSGM via the grain boundaries. Scanning electron microscopy and energy-dispersive spectroscopy analyses showed that iron was located at the grain boundary while the grain bulk preserved the LSGM composition. Impedance spectra obtained at low temperature consist of the two usual bulk and grain boundary contributions. A significant increase in total conductivity was observed for the iron-doped samples, the effect being greater for the grain boundary contribution. The total conductivity measured for the iron-containing material revealed a slight decrease with decreasing oxygen partial pressure, suggesting the onset of p-type electronic conduction. Estimates of the p-type electronic conductivity (σp were obtained by fitting the low temperature impedance spectra to a simple equivalent circuit including one parallel electronic branch. The value for σp in air at 300°C is 3.1×10-6 S/cm and the activation energy is 75.1 kJ/mol between 300 and 400°C.

Las propiedades elécticas de un electrolito sólido de galato de lantano se han modificado mediante un dopado eléctrico de Fe en borde de grano. Esto se consiguió preparando una estructura de sandwich con una plantilla densa de La0.95Sr0.05Ga0.90Mg0.10O3-δ (LSGM entre las muestras de LaFeO3. Un tratamiento de varias horas a 1550ºC en aire favoreció la difusión de Fe a lo largo de los bordes de grano. Los análisis mediante microscopia electrónica de barrido y espectroscopía de energía dispersada muestran que el hierro se localiza en borde de grano mientras que se preserva la composición de LSGM en el interior de grano. En las muestras dopadas con hierro se observa un aumento de

Phase stability and processing of strontium and magnesium doped lanthanum gallate

Science.gov (United States)

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 +/- 2°C 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 1500°C for 2 hours. The doped material has higher oxygen ionic conductivity than

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

Science.gov (United States)

Guo, Weimin; Liu, Jiang

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 μm)/LSGM (19 μm)/LDC (13 μm) composite electrolyte film (designated as cell-A) shows the open-circuit voltages (OCVs) slightly higher than that of a cell with an LSGM (31 μm)/LDC (17 μm) electrolyte film (designated as cell-B) in the operating temperature range of 500-700 °C. The cell-A using Ag-YDB composition as cathode exhibits lower polarization resistance and ohmic resistance than those of a cell-B at 700 °C. The results show that the introduction of YDB to an anode-supported SOFC with a LSGM/LDC composite electrolyte film can effectively block electronic transport through the cell and thus increased the OCVs, and can help the cell to achieve higher power output.

Doping and temperature dependence of incommensurate antiferromagnetism in underdoped lanthanum cuprates

International Nuclear Information System (INIS)

Yuan Feng; Feng Shiping; Su Zhaobin; Yu Lu

2001-08-01

The doping, temperature and energy dependence of the dynamical spin structure factors of the underdoped lanthanum cuprates in the normal state is studied within the t-J model using the fermion-spin transformation technique. Incommensurate peaks are found at [(1±δ)π, π], [π, (1±δ)π] at relatively low temperatures with δ linearly increasing with doping at the beginning and then saturating at higher dopings. These peaks broaden and weaken in amplitude with temperature and energy, in good agreement with experiments. The theory also predicts a rotation of these peaks by π/4 at even higher temperatures, being shifted to [(1±δ/√2)π, (1±δ/√2)π]. (author)

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

International Nuclear Information System (INIS)

Cheng Jihong; Navrotsky, Alexandra

2004-01-01

LaGaO 3 perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol-gel method and characterized. Enthalpies of formation from constituent oxides at 298 K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three trends, LaGa 1-y Mg y O 3-δ (LGM), La 1-x Sr x Ga 1-y Mg y O 3-δ (LSGM), and La 1-x Ba x Ga 1-y Mg y O 3-δ (LBGM). They become less exothermic with increasing doping, suggesting a dominant destabilization effect from oxygen vacancies. The endothermic enthalpy of vacancy formation is 275±37, 166±18 and 138±12 kJ/mol of V O ·· for LGM, LBGM and LSGM, respectively. Tolerance factor and ion size mismatch also affect enthalpies. In terms of energetics, Sr is the best dopant for the La site and Mg for the Ga site, supporting earlier studies, including oxygen ion conductivity and computer modeling

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

Science.gov (United States)

Cheng, Jihong; Navrotsky, Alexandra

2004-01-01

LaGaO 3 perovskites doped with Sr or Ba at the La site and Mg at the Ga site were prepared by solid-state reaction or sol-gel method and characterized. Enthalpies of formation from constituent oxides at 298 K were determined by high-temperature oxide melt solution calorimetry. Energetic trends are discussed in terms of defect chemistry. As oxygen deficiency increases, formation enthalpies define three trends, LaGa 1- yMg yO 3- δ (LGM), La 1- xSr xGa 1- yMg yO 3- δ (LSGM), and La 1- xBa xGa 1- yMg yO 3- δ (LBGM). They become less exothermic with increasing doping, suggesting a dominant destabilization effect from oxygen vacancies. The endothermic enthalpy of vacancy formation is 275±37, 166±18 and 138±12 kJ/mol of VO·· for LGM, LBGM and LSGM, respectively. Tolerance factor and ion size mismatch also affect enthalpies. In terms of energetics, Sr is the best dopant for the La site and Mg for the Ga site, supporting earlier studies, including oxygen ion conductivity and computer modeling.

Photocatalytic degradation of the Paracetamol drug using Lanthanum doped ZnO nanoparticles and their in-vitro cytotoxicity assay

International Nuclear Information System (INIS)

Shakir, Mohammad; Faraz, Mohd; Sherwani, Mohd Asif; Al-Resayes, Saud I.

2016-01-01

The doping of semiconductor by rare earth metals nanoparticles is an effective way for increasing photocatalytic activity. Zinc oxide and Lanthanum doped Zinc oxide nanoparticles were synthesized by modifying the gel-combustion method. It was found that La can greatly enhance the cytotoxicity and photocatalytic activity of ZnO nanoparticles towards various cell lines and Paracetamol drug. These nanoparticles were characterized by various spectroscopic and other techniques which clearly revealed the presence of lanthanum ions. The absorption edge shifts towards the visible region after doping with La ions. This shift shows that the doping of La ions is favorable for absorbing the visible light. The comparative photocatalytic and cytotoxicity activity revealed that La doped ZnO nanoparticles remarkably enhanced activities as compared to the ZnO nanoparticles. The outcome of these studies offers valuable for planning La doped ZnO nanoparticles having cytotoxicity and photocatalytic activities helpful for the formulation of anticancer product and waste water remediation.

Photocatalytic degradation of the Paracetamol drug using Lanthanum doped ZnO nanoparticles and their in-vitro cytotoxicity assay

Energy Technology Data Exchange (ETDEWEB)

Shakir, Mohammad, E-mail: shakir078@yahoo.com [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Faraz, Mohd [Department of Chemistry, Aligarh Muslim University, Aligarh 202002 (India); Sherwani, Mohd Asif [Interdisciplinary Biotechnology Unit, Aligarh Muslim University, Aligarh 202002 (India); Al-Resayes, Saud I. [Department of Chemistry, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)

2016-08-15

The doping of semiconductor by rare earth metals nanoparticles is an effective way for increasing photocatalytic activity. Zinc oxide and Lanthanum doped Zinc oxide nanoparticles were synthesized by modifying the gel-combustion method. It was found that La can greatly enhance the cytotoxicity and photocatalytic activity of ZnO nanoparticles towards various cell lines and Paracetamol drug. These nanoparticles were characterized by various spectroscopic and other techniques which clearly revealed the presence of lanthanum ions. The absorption edge shifts towards the visible region after doping with La ions. This shift shows that the doping of La ions is favorable for absorbing the visible light. The comparative photocatalytic and cytotoxicity activity revealed that La doped ZnO nanoparticles remarkably enhanced activities as compared to the ZnO nanoparticles. The outcome of these studies offers valuable for planning La doped ZnO nanoparticles having cytotoxicity and photocatalytic activities helpful for the formulation of anticancer product and waste water remediation.

Intermediate temperature solid oxide fuel cell based on lanthanum gallate electrolyte

Science.gov (United States)

Inagaki, Toru; Nishiwaki, Futoshi; Yamasaki, Satoru; Akbay, Taner; Hosoi, Kei

The Kansai Electric Power Co. Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been developing intermediate temperature solid oxide fuel cells (IT-SOFCs) which are operable at a temperature range between 600 and 800 °C. There are some significant features in IT-SOFC of KEPCO-MMC: (1) highly conductive lanthanum gallate-based oxide is adopted as an electrolyte to realize high-performance disk-type electrolyte-supported cells; (2) the cell-stacks with seal-less structure using metallic separators allow residual fuel to burn around the stack and the combustion heat is utilized for thermally self-sustainable operation; (3) the separators have flexible arms by which separate compressive forces can be applied for manifold parts and interconnection parts. We are currently participating in the project by New Energy and Industrial Technology Development Organization (NEDO) to develop 10 kW-class combined heat and power (CHP) systems. In FY2006, a 10 kW-class module was developed, with which the electrical efficiency of 50%HHV was obtained based on DC 12.6 kW. In the first quarter of FY2007, the 10 kW-class CHP system using the module gave the electrical efficiency of 41%HHV on AC 10 kW and the overall efficiency of 82%HHV when exhaust heat was recovered as 60 °C hot water. Currently, the operation has been accumulated for about 2500 h to evaluate the long-term stability of the system.

Intermediate temperature solid oxide fuel cell based on lanthanum gallate electrolyte

Energy Technology Data Exchange (ETDEWEB)

Inagaki, Toru; Nishiwaki, Futoshi; Yamasaki, Satoru [The Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-choume, Amagasaki, Hyogo 661-0974 (Japan); Akbay, Taner; Hosoi, Kei [Mitsubishi Materials Corporation, Corporate Technology and Development Division, 1002-14 Mukohyama, Naka, Ibaraki 311-0102 (Japan)

2008-07-01

The Kansai Electric Power Co. Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been developing intermediate temperature solid oxide fuel cells (IT-SOFCs) which are operable at a temperature range between 600 and 800 C. There are some significant features in IT-SOFC of KEPCO-MMC: (1) highly conductive lanthanum gallate-based oxide is adopted as an electrolyte to realize high-performance disk-type electrolyte-supported cells; (2) the cell-stacks with seal-less structure using metallic separators allow residual fuel to burn around the stack and the combustion heat is utilized for thermally self-sustainable operation; (3) the separators have flexible arms by which separate compressive forces can be applied for manifold parts and interconnection parts. We are currently participating in the project by New Energy and Industrial Technology Development Organization (NEDO) to develop 10 kW-class combined heat and power (CHP) systems. In FY2006, a 10 kW-class module was developed, with which the electrical efficiency of 50%HHV was obtained based on DC 12.6 kW. In the first quarter of FY2007, the 10 kW-class CHP system using the module gave the electrical efficiency of 41%HHV on AC 10 kW and the overall efficiency of 82%HHV when exhaust heat was recovered as 60 C hot water. Currently, the operation has been accumulated for about 2500 h to evaluate the long-term stability of the system. (author)

Determination of the ionic transport numbers of lanthanum gallate materials by impedance spectroscopy and modified EMF method

Directory of Open Access Journals (Sweden)

Peña-Martínez, J.

2008-06-01

Full Text Available A combination of impedance spectroscopy and a modified electromotive force method (emf were used to evaluate the ionic transport numbers and the overall conductivity of several doped lanthanum gallate materials, i.e. La0.9Sr0.1Ga1-xMgxO3-δ (x=0.05-0.30, La0.9A0.1Ga0.8Mg0.2O3-δ (A=Sr, Ba and Ca and La0.9Sr0.1Ga0.8Mg0.2-yCoyO3-δ (y=0.015 and 0.045. La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM sample showed the maximum ionic transport number in the temperature range 900-1173 K, around 0.99 in both O2/air and H2/air gradients.

La conductividad total y los números de transporte iónico de las composiciones, basadas en el galato de lantano, La0,9Sr0,1Ga1-xMgxO3-δ (x=0,05-0,30, La0,9A0,1Ga0,8Mg0,2O3-δ (A=Sr, Ba, Ca y La0,9Sr0,1Ga0,8Mg0,2-yCoyO3-δ (y=0.015; 0,045 fueron estudiadas mediante una combinación de técnicas de espectroscopia de impedancia compleja y fuerza electromotriz (fem. La composición La0,9Sr0,1Ga0,8Mg0,2O2,85 (LSGM presenta el mayor número de transporte iónico, concretamente 0,99 en el rango de temperaturas 900-1173 K, tanto en gradiente de O2/aire como de H2/aire.

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

Energy Technology Data Exchange (ETDEWEB)

Guo, Weimin [School of Chemistry and Engineering, South China University of Technology, The Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education, Guangzhou 510640 (China); Department of Biological and Chemical Engineering, Guangxi University of Technology, Liuzhou 545006 (China); Liu, Jiang [School of Chemistry and Engineering, South China University of Technology, The Key Laboratory of Enhanced Heat Transfer and Energy Conservation, Ministry of Education, Guangzhou 510640 (China)

2010-12-15

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 {mu}m)/LSGM (19 {mu}m)/LDC (13 {mu}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 {mu}m)/LDC (17 {mu}m) electrolyte film (designated as cell-B) in the operating temperature range of 500-700 C. The cell-A using Ag-YDB composition as cathode exhibits lower polarization resistance and ohmic resistance than those of a cell-B at 700 C. The results show that the introduction of YDB to an anode-supported SOFC with a LSGM/LDC composite electrolyte film can effectively block electronic transport through the cell and thus increased the OCVs, and can help the cell to achieve higher power output. (author)

Twinning induced by the rhombohedral to orthorhombic phase transition in lanthanum gallate (LaGaO3)

Science.gov (United States)

Wang, W. L.; Lu, H. Y.

2006-10-01

Phase-transformation-induced twins in pressureless-sintered lanthanum gallate (LaGaO3) ceramics have been analysed using the transmission electron microscopy (TEM). Twins are induced by solid state phase transformation upon cooling from the rhombohedral (r, Rbar{3}c) to orthorhombic ( o, Pnma) symmetry at ˜145°C. Three types of transformation twins {101} o , {121} o , and {123} o were found in grains containing multiple domains that represent orientation variants. Three orthorhombic orientation variants were distinguished from the transformation domains converged into a triple junction. These twins are the reflection type as confirmed by tilting experiment in the microscope. Although not related by group-subgroup relation, the transformation twins generated by phase transition from rhombohedral to orthorhombic are consistent with those derived from taking cubic Pm {bar {3}}m aristotype of the lowest common supergroup symmetry as an intermediate metastable structure. The r→ o phase transition of first order in nature may have occurred by a diffusionless, martensitic-type or discontinuous nucleation and growth mechanism.

States of atoms and interatomic interactions in complex perovskite-like oxides. Communication XXIII. Magnetic dilution in the La(Sr)NiO3-LaGaO3

International Nuclear Information System (INIS)

Chezhina, N.V.; Bodritskaya, Eh.V.; Zhuk, N.A.

2008-01-01

Magnetic susceptibility of dilute solid solutions of lanthanum gallates doped with nickel and also with nickel and strontium was studied. Calculations showed that the main contribution into the exchange interactions in gallates doped with nickel is made by dimers formed by low-spin nickel(III) (J -20 cm -1 ), and in gallates doped with strontium and nickel the main contribution is due to dimers formed by high-and low-spin nickel (J 10 cm -1 ). Electrical conductivity measurements showed that the samples under study are electron and ion conductors [ru

Synthesis of calcium doped lanthanum manganite by mechanosynthesis

International Nuclear Information System (INIS)

Bolarin, A.M.; Sanchez, F.; Palomares, S.; Aguilar, J.A.; Torres-Villasenor, G.

2007-01-01

Lanthanum manganite doped with calcium, Ca 1/3 La 2/3 MnO 3-δ , was prepared by a high-energy ball milling. The precursors used were Mn 2 O 3 , La 2 O 3 and CaO, mixed in the stoichiometric ratio to obtain this manganite. The mechano-chemical process was performed at room temperature in a SPEX 8000D mixer/mill, using hardened steel balls and stainless steel vials, in air atmosphere. X-ray diffraction was used to elucidate the phase transformation as a function of the milling time. The Rietveld refinement was used in order to characterize structurally the manganites. The morphology and particle size of powder compound obtained were characterized by scanning electron microscope. The particle size of this powder material was measured with zeta size analyzer, and selected area electron diffraction (SAED) from TEM was used to elucidate the crystalline structure of this powder compound. The results showed that it is possible to obtain calcium doped lanthanum manganite by mechano-synthesis, using a weight ratio of ball to powder of 12:1, after 3 h of milling. The evolution of the phase transformation during the milling time is reported. Increases in milling time produce exponential decrease in the particle size, up to 680 nm after 1 h of milling. After the milling process it is obtained a powder compound with an orthorhombic structure (S.G. Pbnm). A prolonged milling time (>9 h) produce an important reduction in the particle size but this is accompanied with a high iron contamination caused by metallic residues originated from vial and balls and also, after 9 h of milling time, it was found an important distortion in orthorhombic structure, obtaining two types of parameters

Modification of TiO2 nanoparticles through lanthanum doping and PEG templating

Directory of Open Access Journals (Sweden)

Marija Milanovic

2014-12-01

Full Text Available Pure and lanthanum doped titania nanopowders were synthesized through a room temperature sol-gel method using a template of polyethylene glycol (PEG. The progress of the synthesis in terms of phase formation and size of nanoparticles was monitored by X-ray diffraction, FTIR spectroscopy and SEM analysis. After calcination at 450 °C in air, the results have shown the presence of small particles crystallized predominantly in the form of anatase phase, with significant agglomeration. Nitrogen adsorption-desorption measurements confirmed that all prepared powders are mesoporous with an average pore diameter in range 3.1–3.8 nm. The addition of lanthanum ions leads to the nanopowders with the highest specific surface (BET area (203 m2/g. The obtained powders were compared to TiO2 prepared without a template.

Growth and characterization of magnesium chloride and lanthanum chloride doped strontium tartrate crystals - gel method

International Nuclear Information System (INIS)

Kalaiarasi, S.; Jaikumar, D.

2014-01-01

Growth of single crystals of doped strontium tartrate by controlled diffusion of strontium chloride into the silica gel charged with tartaric acid at room temperature is narrated. In this study, we synthesized magnesium chloride (5% and 10%) doped strontium tartrate crystals and Lanthanum chloride (5%, 10% and 15%) doped strontium tartrate crystals are grown. The crystal structure of the compound crystals was confirmed by single crystal X-ray diffraction. The Fourier transform infrared spectrum of pure and doped crystals are recorded and analyzed. The UV-Vis-NIR spectrum analysis reveals that the optical study of the grown crystals. The second harmonic generation efficiency was measured by using Kurtz powder technique with Nd:YAG laser of wavelength 1064 nm. (author)

Summary of Research Activities Academic Departments 1980-1981.

Science.gov (United States)

1981-10-01

Na - salts of nickel (II) undecatungsto- gallate (III) were prepared and analyzed for all constituents except constitutional oxygen. The...Mary C. WINTERSGILL, Assistant Professor, "The Activation "olume for Type I Dipoles in Lanthanum Doped Strontium ioride," Journal of Physics C: Solid...State Physics 13 (1980) 3449-3455. The audio frequency complex dielectric constant has been measured for lanthanum -doped strontium fluoride at

The special features of the crystal structure and properties of oxides with mixed conductivity based on lanthanum gallate

Science.gov (United States)

Politova, E. D.; Ivanov, S. A.; Kaleva, G. M.; Mosunov, A. V.; Rusakov, V. S.

2008-10-01

The paper presents a review of works on the synthesis, structural composition effects, phase transitions, and electrical conductivity properties of multicomponent solid solutions based on heterosubstituted lanthanum gallate (La,A)(Ga,M)O3 - y . High-temperature phase transitions and structural and charge ordering effects were studied. The presence of iron cations in different valence states was proved; the relative contents of these cations depended on the x parameter and nonstoichiometry parameter y of the base composition. For M = Fe, antiferromagnetic ordering was observed; its temperature interval was determined by the concentration of iron cations in the high-spin state. The total conductivity was found to increase as the concentration of transition metal cations grew because of an increase in the electronic conductivity component. The data on structural parameters and dc and ac conductivity substantiated the conclusion that the highest ionic conductivity and permeability to oxygen were characteristic of iron-containing oxides. The results obtained are evidence that crystal chemical factors play a determining role in the formation of the ion-conducting properties of anion-deficient perovskite-like oxides.

Synthesis, thermal properties and growing of strontium and lanthanum aluminates and gallates and the phases on their basis

International Nuclear Information System (INIS)

Zimina, G.V.; Novoselov, A.V.; Filaretov, A.A.; Payachkovskaya, A.; Drobot, D.V.

2000-01-01

With the aim of manufacturing single crystal substrates for HTSC films a study is made into various ways of synthesis of strontium-lanthanum aluminate and gallate, as well as phases on their base. It is shown that the codeposition of difficulty soluble compounds with their subsequent heat treatment is an optimal method of synthesis for SrLaAlO 4 . For preparation of SrLaGaO 4 and SrLaAl x Ga 1-x O 4 a cryochemical method is shown to be best suited. High quality SrLaGaO 4 and SrLaAlO 4 single crystals are grown in [100] direction at oxygen pressure of 5 Pa. The formation of continuous series of solid solutions is revealed in the system of SrLaAlO 4 -SrLaGaO 4 . The compositions of SrLaAl 0.2 Ga 0.8 O 4 and SrLaAl 0.4 Ga 0.6 O 4 in the crystallochemical properties are marked to meet the requirements to the substrates [ru

Application of the Rietveld method in powders of strontium-doped lanthanum manganite calcined in different temperatures

International Nuclear Information System (INIS)

Chiba, R.; Vargas, R.A.; Martinez, L.G.; Andreoli, M.; Seo, E.S.M.

2010-01-01

The strontium-doped lanthanum manganite (LSM) is a ceramic material used as cathode in device called High Temperature Solid Oxide Fuel Cell. In this work, the LSM was synthesized by the citrate technique with the objective to get powders without the formation of secondary phases, such as lanthanum oxide and the lanthanum hydroxide, harmful for the functional performance of the device. The definitive calcination temperatures had been 700, 900 and 1100 deg C, due the decomposition of the polymeric precursors to present stabilization from 480 deg C. The analysis by X-ray diffraction of the calcined powders in different temperatures shows the formation only of phase LSM of hexagonal crystalline structure, type pseudo-perovskite. Using the refinement of Rietveld was determined the parameters and volumes of unity cells, atomic positions and occupations. These results confirm that the chemical compositions obtained are similar to the nominal. (author)

Structures, stabilities, and electronic properties for rare-earth lanthanum doped gold clusters

International Nuclear Information System (INIS)

Zhao, Ya-Ru

2015-01-01

The structures, stabilities, and electronic properties of rare-earth lanthanum doped gold La 2 Au n (n = 1-9) and pure gold Au n (n ≤ 11) clusters have been investigated by using density functional theory. The optimized geometries show that the lowest energy structures of La 2 Au n clusters favour the 3D structure at n ≥ 3. The lanthanum atoms can strongly enhance the stabilities of gold clusters and tend to occupy the most highly coordinated position. By analysing the gap, vertical ionization potential, and chemical hardness, it is found that the La 2 Au 6 isomer possesses higher stability for small-sized La 2 Au n clusters (n = 1-9). The charges in the La 2 Au n clusters transfer from La atoms to the Au n host. In addition, Wiberg bond indices analysis reveals that the intensity of different bonds of La 2 Au n clusters exhibits a sequence of La-La bond > La-Au bond > Au-Au bond.

Demonstration of high efficiency intermediate-temperature solid oxide fuel cell based on lanthanum gallate electrolyte

International Nuclear Information System (INIS)

Inagaki, Toru; Nishiwaki, Futoshi; Kanou, Jirou; Yamasaki, Satoru; Hosoi, Kei; Miyazawa, Takashi; Yamada, Masaharu; Komada, Norikazu

2006-01-01

The Kansai Electric Power Co., Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been jointly developing intermediate-temperature solid oxide fuel cells (SOFCs). The operation temperatures between 600 and 800 o C were set as the target, which enable SOFC to use less expensive metallic separators for cell-stacking and to carry out internal reforming of hydrocarbon fuels. The electrolyte-supported planar-type cells were fabricated using highly conductive lanthanum gallate-based electrolyte, La(Sr)Ga(Mg,Co)O 3-δ , Ni-(CeO 2 ) 1-x (SmO 1.5 ) x cermet anode, and Sm(Sr)CoO 3-δ cathode. The 1 kW-class power generation modules were fabricated using a seal-less stack of the cells and metallic separators. The 1 kW-class prototype power generation system with the module was developed with the high performance cell, which showed the thermally self-sustainability. The system included an SOFC module, a dc-ac inverter, a desulfurizer, and a heat recovery unit. It provided stable ac power output of 1 kW with the electrical efficiency of 45% LHV based on ac output by using city gas as a fuel, which was considered to be excellent for such a small power generation system. And the hot water of 90 o C was obtained using high temperature off-gas from SOFC

Demonstration of high efficiency intermediate-temperature solid oxide fuel cell based on lanthanum gallate electrolyte

Energy Technology Data Exchange (ETDEWEB)

Inagaki, Toru [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan)]. E-mail: inagaki@rdd.kepco.co.jp; Nishiwaki, Futoshi [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan); Kanou, Jirou [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan); Yamasaki, Satoru [Kansai Electric Power Co. Inc., Energy Use R and D Center, 11-20 Nakoji 3-chome, Amagasaki, Hyogo 661-0974 (Japan); Hosoi, Kei [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan); Miyazawa, Takashi [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan); Yamada, Masaharu [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan); Komada, Norikazu [Mitsubishi Materials Corporation, Central Research Institute, 1002-14 Mukohyama, Naka-machi, Naka-gun, Ibaraki 311-0102 (Japan)

2006-02-09

The Kansai Electric Power Co., Inc. (KEPCO) and Mitsubishi Materials Corporation (MMC) have been jointly developing intermediate-temperature solid oxide fuel cells (SOFCs). The operation temperatures between 600 and 800 {sup o}C were set as the target, which enable SOFC to use less expensive metallic separators for cell-stacking and to carry out internal reforming of hydrocarbon fuels. The electrolyte-supported planar-type cells were fabricated using highly conductive lanthanum gallate-based electrolyte, La(Sr)Ga(Mg,Co)O{sub 3-{delta}}, Ni-(CeO{sub 2}){sub 1-x}(SmO{sub 1.5}) {sub x} cermet anode, and Sm(Sr)CoO{sub 3-{delta}} cathode. The 1 kW-class power generation modules were fabricated using a seal-less stack of the cells and metallic separators. The 1 kW-class prototype power generation system with the module was developed with the high performance cell, which showed the thermally self-sustainability. The system included an SOFC module, a dc-ac inverter, a desulfurizer, and a heat recovery unit. It provided stable ac power output of 1 kW with the electrical efficiency of 45% LHV based on ac output by using city gas as a fuel, which was considered to be excellent for such a small power generation system. And the hot water of 90 {sup o}C was obtained using high temperature off-gas from SOFC.

Variation in band gap of lanthanum chromate by transition metals doping LaCr0.9A0.1O3 (A:Fe/Co/Ni)

International Nuclear Information System (INIS)

Naseem, Swaleha; Khan, Wasi; Saad, A. A.; Shoeb, M.; Ahmed, Hilal; Naqvi, A. H.; Husain, Shahid

2014-01-01

Transition metal (Fe, Co, Ni) doped lanthanum chromate (LaCrO 3 ) nanoparticles (NPs) were prepared by gel combustion method and calcinated at 800°C. 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 3 at about 315 nm. Influence of Fe, Co, Ni doping was studied and compared with pure lanthanum chromate nanoparticles

Sinterability and conductivity of barium doped aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} electrolyte of solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Cao Xiaoguo [Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, Guangdong (China); Jiang Sanping, E-mail: s.jiang@curtin.edu.au [Fuels and Energy Technology Institute and Department of Chemical Engineering, Curtin University, Perth, WA 6102 (Australia)

2012-05-15

Highlights: Black-Right-Pointing-Pointer Ba doping enhances the sintering and densification properties of aluminium lanthanum apatite. Black-Right-Pointing-Pointer Ba doping improves the oxide conductivity of aluminium lanthanum apatite. Black-Right-Pointing-Pointer The enhancement of Ba doping is mainly due to the significantly reduced grain boundary resistance of the aluminium lanthanum apatite. - Abstract: Apatite ceramics are interesting alternative solid oxide fuel cells (SOFCs) electrolytes because of their open structure for the transportation of oxide ions and their good chemical stability. This study reports the influence of barium doping on the microstructure, sinterability and oxide conductivity properties of the aluminium lanthanum oxyapatite La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5}. SEM results show that lanthanum substitution with barium improves the sinterability of apatite ceramics. The barium doping also enhances the conductivity of the aluminium lanthanum silicates. The oxygen ion conductivity of La{sub 9.5}Ba{sub 0.5}Si{sub 5.5}Al{sub 0.5}O{sub 26.5} sintered at 1600 Degree-Sign C is 2.21 Multiplication-Sign 10{sup -2} S cm{sup -1} at 800 Degree-Sign C, higher than 9.81 Multiplication-Sign 10{sup -3} S cm{sup -1} of La{sub 10}Si{sub 5}AlO{sub 26.5} sample prepared under the same conditions. The results in the present study demonstrate that doping Ba on the La site for aluminium lanthanum oxyapatite reduces the sintering temperature and improves the ion conductivity. The enhancement of Ba dopant is mainly on the improvement of the densification and thus substantially reduced grain boundary resistance of aluminium lanthanum oxyapatite particularly at low temperatures.

Synthesis and characterization of nanoporous strontium-doped lanthanum cobaltite thin film using metal organic chemical solution deposition

Energy Technology Data Exchange (ETDEWEB)

Park, Jun-Sik [Department of Mechanical Convergence Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Kim, Young-Beom, E-mail: ybkim@hanyang.ac.kr [Department of Mechanical Convergence Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of); Institute of Nano Science and Technology, Hanyang University, Seoul 133-791 (Korea, Republic of)

2016-01-29

By employing strontium as a dopant of lanthanum cobaltite (LaCoO{sub 3}), strontium-doped lanthanum cobaltite (La{sub 1−x}Sr{sub x}CoO{sub 3−δ}, LSC) thin film was fabricated using a metal organic chemical solution deposition (MOCSD) method. Lanthanum nitrate hexahydrate [La(NO{sub 3}){sub 3}6H{sub 2}O], strontium acetate [Sr(CH{sub 3}COO){sub 2}], and cobalt acetate tetrahydrate [Co(CH{sub 3}COO){sub 2}4H{sub 2}O] were used as precursors. The coating process was performed through a spin coating method on a substrate, which were then heat treated under various temperature conditions. Electrical properties, microstructures, and crystalline structures with respect to sintering temperature were analyzed. According to these analyses, the change in surface morphology, phase shift, and conductive properties were closely related, which could explain their respective behaviors. Furthermore, sintered strontium-doped lanthanum perovskite oxides showed various conductivities according to the amount of dopant. With the molar ratio of strontium that is stoichiometrically equivalent to lanthanum (La{sub 0.5}Sr{sub 0.5}CoO{sub 3−δ}) thin film showed the best conductivity in the sintering temperature range of 650–700 °C, with perovskite phases formed at this temperature condition. As the electrically conductive properties of the thin film are a function of thickness, the films were coated several times to a thickness of approximately 300 nm, with the lowest resistivity (approximately 9.06 × 10{sup −4} Ω cm) observed at the optimized sintering temperature and solution composition. - Highlights: • LSC thin film was fabricated by metal organic chemical solution deposition (MOCSD). • The film shows good agreement on the electrical conductivity of LSC by conventional methods. • The properties of LSC film are influenced by the surface morphology and crystalline phase. • Optimal molar ratio of strontium for the highest conductivity was investigated.

Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

Science.gov (United States)

Madhu, A.; Eraiah, B.

2018-04-01

Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

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)

Energy Technology Data Exchange (ETDEWEB)

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 800°C. 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.

Carbon doped lanthanum aluminate (LaAlO3:C) synthesized by solid state reaction for application in UV thermoluminescent dosimetry

International Nuclear Information System (INIS)

Alves, N.

2015-01-01

In this work we discuss the TL output for LaAlO 3 :C crystals grown by using three different combinations of Al 2 O 3 , La 2 O 3 and carbon atoms during the synthesis process. Recently, LaAlO 3 single crystals, co-doped with Ce 3+ and Dy 3+ rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO 3 synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce 3+ and Dy 3+ . It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO 3 by this solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO 3 crystallographic phase, however a small percentage (15%) of Al 2 O 3 has been also identified. The UV-Vis absorbance spectra were obtained and F and F + - center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

Medium-temperature solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Maffei, N.; Kuriakose, A.K. [Natural Resources Canada, Ottawa, ON (Canada). Materials Technology Lab

2000-07-01

The Materials Technology Laboratory (MTL) of Natural Resources Canada has been conducting research on the development of a solid oxide fuel cell (SOFC) for the past decade. Fuel cells convert chemical energy directly into electric energy in an efficient and environmentally friendly manner. SOFCs are considered to be good stationary power sources for commercial and residential applications and will likely be commercialized in the near future. The research at MTL has focused on the development of new electrolytes for use in SOFCs. In the course of this research, monolithic planar single cell SOFCs based on doubly doped ceria and lanthanum gallate have been fabricated and tested at 700 degrees C. This paper compared the performance characteristics of both these systems. The data suggested the presence of a significant electronic conductivity in the SOFC incorporating doubly doped ceria, resulting in lower than expected voltage output. The stability of the SOFC, however, did not appear to be negatively affected. The lanthanum gallate based SOFC performed well. It was concluded that reducing the operating temperature of SOFCs would improve their reliability and enhance their operating life. First generation commercial SOFCs will use a zirconium oxide-based electrolytes while second generation units might possibly use ceria-based and/or lanthanum gallate electrolytes. 24 refs., 6 figs.

Thermal expansion of doped lanthanum gallates

Indian Academy of Sciences (India)

Administrator

Since the components are in intimate mechanical contact, any stress generated due to their thermal expansion mis- match during thermal cycling could lead to catastrophic failure of the cell. The functional materials must have similar thermal expansions to avoid mechanical stresses. Hence it is useful to study the thermal ...

Cerium doped lanthanum halides: fast scintillators for medical imaging

International Nuclear Information System (INIS)

Selles, O.

2006-12-01

This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl 3 :Ce 3+ and LaBr 3 :Ce 3+ ).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce 3+ ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

Spectroscopic properties of Er/Nd co-doped yttrium lanthanum oxide transparent ceramics pumped at 980 nm

Energy Technology Data Exchange (ETDEWEB)

Shao, Yingjie; Yang, Qiuhong, E-mail: yangqiuhong@shu.edu.cn; Gui, Yan; Yuan, Ye; Lu, Qing

2016-05-15

(Er{sub 0.01}Nd{sub x}Y{sub 0.89-x}La{sub 0.1}){sub 2}O{sub 3} (x = 0, 0.001, 0.002, 0.005, 0.01) transparent ceramics were prepared by conventional ceramic processing. The Nd{sup 3+} content dependencies of mid-infrared, near infrared and up-conversion emission of Er{sup 3+} pumped at 980 nm were fully presented. Mechanism of energy transfer between Er{sup 3+} and Nd{sup 3+} was also demonstrated. The results showed that co-doping 0.1 at% Nd{sup 3+} into 1 at% Er{sup 3+} doped yttrium lanthanum oxide transparent ceramic enhanced the 2.7 μm emission significantly and meanwhile suppressed the 1.5 μm emission effectively which indicated an improvement in population inversion between Er:{sup 4}I{sub 11/2} and Er:{sup 4}I{sub 13/2}. Moreover, green up-conversion emission of Er{sup 3+} ion also showed a great improvement by co-doping 0.1 at% Nd{sup 3+}. Those great results were attributed to energy recycle from Er:{sup 4}I{sub 13/2} to Er:{sup 4}I{sub 11/2}. The energy recycle was mainly built by the two energy transfer between Er{sup 3+} and Nd{sup 3+} (one is from Er to Nd, another is in opposite way). So, Er/Nd co-doped yttrium lanthanum oxide transparent ceramic with Nd in low concentration can be considered as a promising laser material for ∼3 μm and up-conversion laser application. - Highlights: • (Er{sub 0.01}Nd{sub x}Y{sub 0.89-x}La{sub 0.1}){sub 2}O{sub 3} transparent ceramics were prepared. • The emission of 2.7 μm of Er{sup 3+} ion was significantly enhanced as x was 0.001. • The emission of 1.5 μm of Er{sup 3+} ion was suppressed greatly by co-doping Nd{sup 3+} ion. • Mechanism of Er–Nd energy transfer was discussed by the energy sketch.

Spectroscopic properties of Sm{sup 3+}-doped lanthanum borogermanate glass

Energy Technology Data Exchange (ETDEWEB)

Rajaramakrishna, R. [Department of Physics, Bangalore University, Bangalore 560056 (India); Knorr, Brian; Dierolf, Volkmar [Department of Physics, Lehigh University Bethlehem, PA 18015 (United States); Anavekar, R.V., E-mail: anavekar_271@yahoo.co.in [Department of Physics, Bangalore University, Bangalore 560056 (India); Jain, H. [Department of Materials Science and Engineering, Lehigh University Bethlehem, PA 18015 (United States)

2014-12-15

Ultraviolet–visible–near infrared (UV–vis–NIR) absorption and photoluminescence of (25−x) La{sub 2}O{sub 3}–25B{sub 2}O{sub 3}–50GeO{sub 2} glass series have been studied with different concentrations (x=0.1–1.0 wt%) of Sm{sub 2}O{sub 3} as an optically active dopant. The values of Judd–Ofelt (JO) parameters (Ω{sub t}) follow the trend Ω{sub 2}>Ω{sub 4}>Ω{sub 6}. Visible emission and decay times from the {sup 4}G{sub 5/2} level and its relative quantum efficiencies are measured. Intense reddish-orange emission corresponding to {sup 4}G{sub 5/2}→{sup 6}H{sub 7/2} transition has been observed in these glasses under 488 nm excitation. A decrease in the quantum yield is observed with increasing Sm{sup 3+} ion concentration beyond 1% doping level. - Highlights: • Lanthanum boro-germanate glasses doped with samarium ions are good laser host matrix. • These glasses show large emission cross-sections (σ{sub P}) values. • These glasses show large gain bandwidth and optical gain parameters. • These glasses are suitable candidate for reddish-orange laser applications.

Carbon doped lanthanum aluminate (LaAlO3:C) UV thermoluminescent properties synthesized by solid state reaction with three different mixing methodologies

International Nuclear Information System (INIS)

Alves, N.

2017-01-01

In this work we discuss the thermoluminescent (TL) response for LaAlO 3 :C crystals grown by using three different combinations of Al 2 O 3 , La 2 O 3 and carbon atoms during the synthesis process. Recently, LaAlO 3 single crystals, co-doped with Ce 3+ and Dy 3+ rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO 3 synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce 3+ and Dy 3+ . It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO 3 by the solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO 3 crystallographic phase, however a small percentage (15%) of Al 2 O 3 has been also identified. The UV-Vis absorbance spectra were obtained and F and F + - center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

Carbon doped lanthanum aluminate (LaAlO{sub 3}:C) UV thermoluminescent properties synthesized by solid state reaction with three different mixing methodologies

Energy Technology Data Exchange (ETDEWEB)

Alves, N., E-mail: neire.radiologia@yahoo.com.br, E-mail: farialo@cdtn.br [Universidade Federal do Estado de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Nuclear; Ferraz, W.B.; Faria, L.O., E-mail: ferrazw@cdtn.br [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2017-07-01

In this work we discuss the thermoluminescent (TL) response for LaAlO{sub 3}:C crystals grown by using three different combinations of Al{sub 2}O{sub 3}, La{sub 2}O{sub 3} and carbon atoms during the synthesis process. Recently, LaAlO{sub 3} single crystals, co-doped with Ce{sup 3+} and Dy{sup 3+} rare earth trivalent ions and grown under hydrothermal conditions, have been reported to show high thermoluminescent response (TL) when exposed to low levels of ultraviolet radiation (UVR). However, undoped LaAlO{sub 3} synthesized by solid state reaction method from the 1:1 mixture of aluminum and lanthanum oxide under reducing atmosphere revealed to have still higher thermoluminescent sensitivity to UV photon fields than the co-doped with Ce{sup 3+} and Dy{sup 3+}. It is well known that carbon doped aluminum oxide monocrystals have excellent TL and photoluminescent response properties for X-rays, UV and gamma radiation fields. Thus, we conducted three different syntheses of LaAlO{sub 3} by the solid state reaction method, doping the mixture with carbon. The lanthanum aluminate polycrystals were synthesized from the 1:1 mixture of aluminum and lanthanum oxide, adding 0.1wt.% carbon and annealed at 1700°C for two hours in hydrogen atmosphere. The X-ray diffraction analysis revealed the formation of rhombohedral LaAlO{sub 3} crystallographic phase, however a small percentage (15%) of Al{sub 2}O{sub 3} has been also identified. The UV-Vis absorbance spectra were obtained and F and F{sup +}- center were ascribed. The UV irradiations were carried out using a commercial 8W UV lamp. Thermoluminescence measurements were performed at a Harshaw 4500 TL reader. All compositions investigated have shown high TL sensitivity to UVR. (author)

Evolution of the local environment of lanthanum during simplified SON68 glass leaching

International Nuclear Information System (INIS)

Jollivet, P.; Delaye, J.M.; Den Auwer, C.; Simoni, E.

2007-01-01

The evolution of the short- and medium-range local environment of lanthanum was determined by L-III-edge X-ray absorption spectroscopy (XAS) during leaching of simplified SON68-type glasses. In glass without phosphorus, lanthanum is found in a silicate environment, and its first coordination sphere comprises eight oxygen atoms at a mean distance of 2.51 angstrom. When this glass was leached at a high renewal rate, the lanthanum local environment was significantly modified: it was present at hydroxy-carbonate and silicate sites with a mean La-O distance of 2.56 angstrom, and the second neighbors consisted of La atoms instead of Si for the glass. Conversely, in the gel formed at low renewal rates, lanthanum was found in a silicate environment similar to that of the glass. In phosphorus-doped glass, lanthanum is found in a phosphate environment, although the Si/P atomic ratio is 20:1. Lanthanum is surrounded by seven oxygen atoms at a mean distance of 2.37 angstrom. When phosphorus-doped glass is leached, regardless of the leaching solution flow rate, the short- and medium-range lanthanum local environment remains almost constant; the most significant change is a 0.05 angstrom increase in the La-O distance. (authors)

Linear Optical Properties of Zinc Borotellurite Glass Doped with Lanthanum Oxide Nanoparticles for Optoelectronic and Photonic Application

Directory of Open Access Journals (Sweden)

Faznny Mohd Fudzi

2017-01-01

Full Text Available Enhancing the optical properties of glasses for the sake of optical application in various fields is an ongoing challenge in materials science and technology. Thus, the optical properties of zinc borotellurite glass doped with lanthanum oxide nanoparticles (La2O3 NPs with the chemical composition of {[(TeO20.7(B2O30.3]0.7(ZnO0.3}1−x (La2O3 NPsx, where x = 0.01, 0.02, 0.03, 0.04, and 0.05 molar fraction, have been investigated. Characterization techniques such as x-ray diffraction, Fourier Transform Infrared Spectroscopy, and Ultraviolet-Visible Spectroscopy are employed to yield the structural properties and optical parameter of the glass. The amorphous nature of the fabricated glasses is confirmed with the presence of a broad hump via XRD diffraction pattern. The decreasing amount of high polarizable nonbridging oxygen as the concentration of La2O3 NPs increases has contributed to the increasing trend of energy band gap in the range of 2.70 to 3.52 eV and decreasing value of refractive index between 2.34 and 2.48. The fabricated glasses that have a higher refractive index than the widely used fiber material, pure silica glass, indicate that zinc borotellurite glass doped with lanthanum nanoparticles is a promising material to be applied as optical fibers.

Evaluating of electronic structure of Lanthanum chromite under doping of divalent ion using density functional theory

International Nuclear Information System (INIS)

Saievar, E.; Gharleghi, A.

2006-01-01

Doping Calcium in Lanthanum site of LaCrO 3 compound increasing the density of states in valance band and decreasing the band gap width because of increases of S electrons in valance band and variety of interaction energies from Cr +3 -Cr +4 couple in valance band. We have used Wien2k software for evaluating this mechanisms. Using of 0.25 percent of dopant and a kind of the space group of cell, let us to use one cell in calculations. We have used GGA approximation in this calculations.

Influence of zirconium doping in ceria lattice as an active electrode in amperometric electrochemical ammonia gas sensor using oxygen pumping current

International Nuclear Information System (INIS)

Sharan, R.; Dutta, Atanu; Roy, Mainak

2016-01-01

An amperometric electrochemical sensor using Ce-Zr system as ammonia gas detecting electrode is reported. Using lanthanum gallate based electrolyte La_0_._8Sr_0_._2Ga_0_._8Mg_0_._1Ni_0_._1O_3 (LSGMN) and lanthanum strontium cobaltite La_0_._5Sr_0_._5CoO_3 (LSC) as oxygen reduction electrode, the sensor was found to be highly sensitive to NH_3 gas down to few ppm level, when operated in the temperature range 300-450°C. Keeping LSC electrodecomposition same, when sensing properties were studied with the variation of Zr concentration in ceria for active electrode, sensor with 30 mol % Zr doped ceria showed highest sensitivity of 28μA/ decade at 400°C. For all active electrodecompositions Ce_1_-_xZr_xO_2 (x = 0 to 0.7) highest sensitivity was observed at 400°C. All the sensors performed reproducibly with time response and recovery time 40 and 120 seconds respectively. (author)

Phase constitution in Sr and Mg doped LaGaO3 system

International Nuclear Information System (INIS)

Zheng Feng; Bordia, Rajendra K.; Pederson, Larry R.

2004-01-01

Sr and Mg doped lanthanum gallate perovskites (La 1-x Sr x Ga 1-y Mg y O 3-δ , 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 2 O 3 -SrO-Ga 2 O 3 -MgO quaternary system at elevated temperature (1500 deg. C)

Preparation and luminescence properties of terbium-doped lanthanum oxide nanofibers by electrospinning

Energy Technology Data Exchange (ETDEWEB)

Song Lixin; Du Pingfan [Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University), Ministry of Education, Hangzhou 310018 (China); Xiong Jie, E-mail: jxiong@zstu.edu.cn [Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University), Ministry of Education, Hangzhou 310018 (China); Fan Xiaona; Jiao Yuxue [Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University), Ministry of Education, Hangzhou 310018 (China)

2012-01-15

Terbium-doped lanthanum oxide (La{sub 2}O{sub 3}:Tb{sup 3+}) nanofibers were prepared by electrospinning followed by calcination at high temperature. Thermogravimetric analyzer (TGA), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and photoluminescence (PL) were used to characterize the obtained fibers. The results reveal that the nanofibers have an average diameter of ca. 95{+-}25 nm and are composed of pure La{sub 2}O{sub 3} phase. Under the excitation of 274 nm light, the La{sub 2}O{sub 3}:Tb{sup 3+} nanofibers exhibit the characteristic emission resulting from the {sup 5}D{sub 4}{yields}{sup 7}F{sub J} (J=3, 4, 5, 6) transitions of Tb{sup 3+} ions. And the PL emission intensity is stronger than that of their nanoparticle counterparts. - Highlights: > Tb{sup 3+}-doped La{sub 2}O{sub 3} (La{sub 2}O{sub 3}:Tb{sup 3+}) fluorescent nanofibers were prepared via a simple electrospinning technique. > Luminescent properties and other characteristics of the nanofibers were investigated in details. > Potential applications of La{sub 2}O{sub 3}:Tb{sup 3+} nanofibers and electrospinning technique described in this paper are suggested.

Electrochemical corrosion of lanthanum chromite and yttrium chromite in coal slag

Energy Technology Data Exchange (ETDEWEB)

Marchant, D.D.; Bates, J.L.

1981-01-01

Lanthanum chromites have long been considered as electrodes for magnetohydrodynamic (MHD) generator channels. These chromites, when doped with divalent ions such as Ca, Mg or Sr, have adequate electronic and electrical conductivity (2), and melting points greater than 2500/sup 0/K. However, above approx. 1850/sup 0/K, selective vapor loss of chromium results in the formation of a La/sub 2/O/sub 3/ phase. The La/sub 2/O/sub 3/ is hydroscopic at room temperature, resulting in a large volume change and loss of mechanical integrity when exposed to H/sub 2/O. The analogous yttrium chromites have thermal and electrical properties similar to that for the lanthanum chromites. Although vapor loss of Cr results in the formation of Y/sub 2/O/sub 3/, this oxide does not hydrate. Corrosion studies of yttrium chromite compositions show that doped YCrO/sub 3/ may be a viable MHD electrode. An electrochemical corrosion study of both magnesium-doped lanthanum and yttrium chromites in synthetic coal slag electrolytes is described. Possible chemical and electrochemical degradation phenomena, as well as the relative rates of corrosion are emphasized.

Energy transfer driven tunable emission of Tb/Eu co-doped lanthanum molybdate nanophosphors

Science.gov (United States)

Thomas, Kukku; Alexander, Dinu; Sisira, S.; Gopi, Subash; Biju, P. R.; Unnikrishnan, N. V.; Joseph, Cyriac

2018-06-01

Tb3+/Eu3+ co-doped lanthanum molybdate nanophosphors were synthesized by conventional co-precipitation method. The Powder X-ray diffractogram revealed the formation of highly crystalline tetragonal nanocrystals with space group I41/a and the detailed analysis of the small variation of lattice parameters with Tb/Eu co-doping on the host lattice were carried out based on the ionic radii of the dopants. The FTIR spectra is employed to identify the fundamental vibrational modes in La2-x-y (MoO4)3:xTb, yEu nanocrystals. The formation of nanocrystals by oriented attachment was recognized from the HR TEM images and the d-spacing calculated was in accordance with that corresponding to highest intensity diffraction peak in the XRD patterns. The constituent elements present in the samples were identified with the aid of EDAX and elemental mapping analysis. The broad Mo6+- O2- CTB and the sharp excitation peaks of Tb and Eu identified from the UV-Vis absorption spectra facilitates the suitability of exciting the phosphors effectively over NUV and visible region of the spectra. The possibility of energy transfer from host to Tb3+/Eu3+ ions and from Tb3+ to Eu3+ ions were confirmed from the PL excitation spectra monitoring 5D0→7F2 transition of Eu3+ ions around 615 nm. The correlated analysis of PL emission spectra, life time measurements and CIE diagram, upon different excitation channels elucidate the excellent luminescent properties of La2-x-y (MoO4)3:xTb, yEu nanophosphors with tunable emission colours in a wide range varying from yellow green region to reddish orange region and the efficient energy transfer from Tb3+ to Eu3+ ions in lanthanum molybdate host lattice. The Tb→Eu energy transfer efficiency and probability were calculated from the decay measurements and the values were found to be satisfactory for exploiting the prepared nanophosphors for the development of multifunctional luminescent nanophosphors.

Organization of the Topical Meeting on Tunable Solid State Lasers Held in North Falmouth, Massachusetts on 1-3 May 1989

Science.gov (United States)

1989-08-30

p. 163) under 647 and 780-nm pumping. (p. 183) WB6 Growth and Characterization of Nd Doped Alumi- 2:15 PM nates and Gallates with the Melilite...Various phosphate glasses 14.5-15.1 Lithium- lanthanum phosphate glass 15.45 Lithium aluminium borate glass 16.4 118 TuB6-2 Alexandrite AI2.-. Cr.BeO...Salisbury SA 5108, Australia Summary The fluorescence spectrum of neodymium in BeL ( lanthanum beryllate) shows ?L reasonably strong line in the R-X

Influence of Lanthanum Doping on the Structural and Optical Properties of Hematite Nanopowders

Science.gov (United States)

Justus, J. Sharmila; Dharma Roy, S. Dawn; Raj, A. Moses Ezhil

2016-10-01

Rare-earth elements are an attractive class of dopant elements, as they give easily trivalent cations that possibly altering the structure and other properties of the parent nanoparticles and creating multifunctional materials because of their f-electronic configurations. Herein, experimental evidence has been given for a better understanding of the factors that dictate the interactions of La doping on the structure and optical properties of iron oxide nanoparticles. For that, lanthanum doped hematite (α-Fe2O3) nanoparticles were prepared by a facile solution method using iron (III) chloride (FeCl3) as starting precursor and sodium hydroxide (NaOH) as reducing agent without templates at low temperature. As-prepared powders were subsequently calcined in air for 3 hr at 800 °C. Xray diffraction (XRD) technique was used to study the nanocrystal formation of α-Fe2O3 and Fourier Transform Raman (FT-Raman) spectral information identified the chemical bond structure of the nanoparticles. Morphology study of the nanoparticles was identified using Scanning Electron Microscope (SEM) and the incorporated La content was recognized from the Energy Dispersive X-ray Spectroscopy (EDS) analysis. The optical absorption spectrum was recorded in the wavelength range of 200-2000 nm and the optical parameters such as absorption coefficient and optical band gap energy of pure and doped Fe2O3 nanoparticles were determined. Obtained results are interpreted by considering the impregnation of trivalent La cations that replaced Fe cations of the host structure.

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

International Nuclear Information System (INIS)

Onoda, Hiroaki; Matsui, Hironori; Tanaka, Isao

2007-01-01

Transition metal phosphates are used as inorganic pigments, however these materials had a weak point for acid and base resistance. Because lanthanum phosphate is insoluble in acidic and basic solution, the addition of lanthanum cation was tried for the improvement of the acid and base resistance of nickel phosphate pigment. The lanthanum-doped nickel phosphates were prepared from phosphoric acid, nickel nitrate, and lanthanum nitrate solution. The additional effects of lanthanum cation were studied on the chemical composition, particle shape and size distribution, specific surface area, color, acid and base resistance of the precipitations and their thermal products

Europium-Doped Lanthanum Hafnate Nanoparticles: Structure, Photoluminescence, and Radioluminescence

Science.gov (United States)

Wahid, Kareem; Pokhrel, Madhab; Mao, Yuanbing

Due to their novel physical properties, nanostructured phosphors are of interest for radiation-based imaging and therapeutics. Herein, the structural and luminescent properties of europium-doped lanthanum hafnate (La2Hf2O7:xmol%Eu3+, x = 0 - 35) nanoparticles are investigated for use as scintillators. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy confirm samples prepared through a combined co-precipitation and low-temperature molten salt synthetic process homogenously form spherical nanocrystals of 36 nm in the ordered pyrochlore phase. Ultraviolet and X-ray excitation of these samples induce strong red emissions in the 580 - 590 and 612 - 630 nm range corresponding to the 5D0->7 F1 magnetic dipole and 5D0->7 F2 electric dipole transitions of Eu3+. Optical response and quantum yield are optimized at 5% Eu3+; a proposed trade-off between quenching mechanisms (defect-states/cross-relaxation) and dopant concentration is discussed. Owing to their high density, large effective atomic number, and bright luminescence, these La2Hf2O7:xmol%Eu3+ nanoparticles warrant further investigation for scintillator applications. The authors thank the support from the Defense Threat Reduction Agency of the U.S. Department of Defense (award #HDTRA1- 10-1-0114).

Rare Earth Doped Lanthanum Calcium Borate Polycrystalline Red Phosphors

Directory of Open Access Journals (Sweden)

H. H. Xiong

2014-01-01

Full Text Available Single-phased Sm3+ doped lanthanum calcium borate (SmxLa2−xCaB10O19, SLCB, x=0.06 polycrystalline red phosphor was prepared by solid-state reaction method. The phosphor has two main excitation peaks located at 398.5 nm and 469.0 nm, which are nicely in accordance with the emitting wavelengths of commercial near-UV and blue light emitting diode chips. Under the excitation of 398.0 nm, the dominant red emission of Sm3+ in SLCB phosphor is centered at 598.0 nm corresponding to the transition of 4G5/2 → 6H7/2. The Eu3+ fluorescence in the red spectral region is applied as a spectroscopic probe to reveal the local site symmetry in the host lattice and, hence, Judd-Ofelt parameters Ωt  (t=2, 4 of Eu3+ in the phosphor matrix are derived to be 3.62×10-20 and 1.97×10-20 cm2, indicating a high asymmetrical and strong covalent environment around rare earth luminescence centers. Herein, the red phosphors are promising good candidates employed in white light emitting diodes (LEDs illumination.

Effect of lanthanum doping on electrical and electromechanical ...

Indian Academy of Sciences (India)

Unknown

temperature, Tc increased with the increase of lanthanum content. ... By adding oxide group softeners, hardeners and stabi- ... pressed with 2% polyvinyl alcohol as binder under a ... study are dependent on temperature and are shown in.

Bibliography of Soviet Laser Developments, Number 89, May-June 1987

Science.gov (United States)

1988-04-20

gratings. OPMPA, no. 6, 1987, 4-6. 672. Knvaz’kov, A.V. ; Lobanov, M.N. (LPI). Hologra~hic recording by non-actinic radiaticn in Pb-based lanthanum -doped...Vasil’tsiv, V.I.; Zakharko, Ya.M.; Merinov, B.V. (). Luminescence properties of calcium gallate single crystals activated by manganese. ZPSBA, v. 46, no. 5

Gelcasting of strontium doped lanthanum manganite for solid oxide fuel cell applications

International Nuclear Information System (INIS)

Abdul Haleem, B.; Bhuvana, R.; Udayakumar, A.

2009-01-01

Solid oxide fuel cells (SOFCs) are devices that offer high efficiency power output with negligible emissions. Cathode supported tubular SOFCs consist of porous cathode tubes made up of strontium doped lanthanum manganite, La 1-x Sr x MnO 3 (LSM) that work as functional component as well as structural support for the rest of the cell components. Gelcasting is one of the most suitable methods for the fabrication of porous ceramics. This paper describes the fabrication of porous LSM cathode by gelcasting process. Gelcasting parameters such as monomer concentration, powder volume fraction, pH of the slurry, etc were optimized. Slow drying of green specimens minimized warpage and cracking. Sintered specimens with controlled porosity were obtained by the use of suitable pore-forming agents. The coefficient of thermal expansion (CTE) of sintered specimens was measured, which was found matching with the CTE values of cell components reported in the literature. These results have shown the suitability of the gelcast generated LSM cathodes for SOFC applications. (author)

Suppression of cavitation in melted tungsten by doping with lanthanum oxide

International Nuclear Information System (INIS)

Yuan, Y.; Lu, G.H.; Xu, B.; Fu, B.Q.; Xu, H.Y.; Li, C.; Jia, Y.Z.; Qu, S.L.; Liu, W.; Greuner, H.; Böswirth, B.; Luo, G.-N.

2014-01-01

Melting and boiling behaviour of pure tungsten and 1 wt% lanthanum-oxide-doped tungsten (WL10) are investigated, focusing on the material selection with respect to material loss induced by cavitation. Melting experiments under high heat loads are carried out in the high heat flux facility GLADIS. Pulsed hydrogen neutral beams with heat flux of 10 and 23 MW m −2 are applied onto the adiabatically loaded samples for intense surface melting. Melt layer of the two tungsten grades exhibit different microstructure characteristics. Substantive voids owing to cavitation in the liquid phase are observed in pure W and lead to porous resolidified material. However, little cavitation bubbles can be found in the dense resolidified layer of WL10. In order to find out the gaseous sources, vapour collection is performed and the components are subsequently detected. Based on the observations and analyses, the microstructure evolutions corresponding to melting and vapourization behaviour of the two tungsten grades are tentatively described, and furthermore, the underlying mechanisms of cavitation in pure W and its suppression in WL10 are discussed. (paper)

Fabrication of lanthanum-doped thorium dioxide by high-energy ball milling and spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Scott, Spencer M.; Yao, Tiankai [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Lu, Fengyuan [Department of Mechanical & Industrial Engineering, Louisiana State University, Baton Rouge, LA 70803 (United States); Xin, Guoqing; Zhu, Weiguang [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States); Lian, Jie, E-mail: lianj@rpi.edu [Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy, NY 12180 (United States)

2017-03-15

Abstract: High-energy ball milling was used to synthesize Th{sub 1-x}La{sub x}O{sub 2-0.5x} (x = 0.09, 0.23) solid solutions, as well as improve the sinterability of ThO{sub 2} powders. Dense La-doped ThO{sub 2} pellets with theoretical density above 94% were consolidated by spark plasma sintering at temperatures above 1400 °C for 20 min, and the densification behavior and the non-equilibrium effects on phase and structure were investigated. A lattice contraction of the SPS-densified pellets occurred with increasing ball milling duration, and a secondary phase with increased La-content was observed in La-doped pellets. A dependence on the La-content and sintering duration for the onset of localized phase segregation has been proposed. The effects of high-energy ball milling, La-content, and phase formation on the thermal diffusivity were also studied for La-doped ThO{sub 2} pellets by laser flash measurement. Increasing La-content and high energy ball milling time decreases thermal diffusivity; while the sintering peak temperature and holding time beyond 1600 °C dramatically altered the temperature dependence of the thermal diffusivity beyond 600 °C. - Highlights: • Lanthanum incorporation into ThO{sub 2} by high energy ball milling and rapid consolidation by spark plasma sintering. • Elucidation of phase behavior of the La-doped ThO{sub 2} and the contributions of La incorporation and SPS sintering conditions. • Investigation of the effects of La incorporation and high energy ball milling on the thermal behavior of La-doped ThO{sub 2}.

Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO_3) ceramics

International Nuclear Information System (INIS)

Billah, Masum; Ahmed, A.; Rahman, Md. Miftaur; Mahbub, Rubbayat; Gafur, M. A.; Bashar, M. Shahriar

2016-01-01

In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La_2O_3) doped Barium Titanate (BaTiO_3) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO_3 with 0.3, 0.5 and 0.7 mole% La_2O_3 under different sintering parameters. The raw materials used were La_2O_3 nano powder of ~80 nm grain size and 99.995% purity and BaTiO_3 nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO_3 ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La_2O_3) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La_2O_3 with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La"3"+ concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO_3 ceramics.

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

Science.gov (United States)

Das, Soma; Dey, T. K.

2006-08-01

The magnetocaloric effect (MCE) in fine grained perovskite manganites of the type La1-xKxMnO3 (0value of 3.00 J kg-1 K-1 at 310 K amongst the compounds investigated. Moreover, the maximum magnetic entropy change exhibits a linear dependence with applied magnetic field. The estimated adiabatic temperature change at TC and at 1 T field also increases with K doping, being a maximum of 2.1 K for the La0.85K0.15MnO3 compound. The relative cooling power (RCP) of La1-xKxMnO3 compounds is estimated to be about one-third of that of the prototype magnetic refrigerant material (pure Gd). However, La1-xKxMnO3 compounds possess an MCE around room temperature, which is comparable to that of Gd. Further, tailoring of their TC, higher chemical stability, lower eddy current heating and lower cost of synthesis are some of the attractive features of K doped lanthanum manganites that are advantageous for a magnetic refrigerant. The temperature dependence of the magnetic entropy change (ΔSM) measured under various magnetic fields is explained fairly well using the Landau theory of phase transitions. Contributions of magnetoelastic and electron interaction are found to have a strong influence in the magnetocaloric effect of manganites.

The effect of samarium doping on structure and enhanced thermionic emission properties of lanthanum hexaboride fabricated by spark plasma sintering

Energy Technology Data Exchange (ETDEWEB)

Zhou, Shenlin; Hu, Qianglin [College of Mathematics and Physics, Jinggangshan University, Jian (China); Zhang, Jiuxing; Liu, Danmin [Key Laboratory of Advanced Functional Materials, Ministry of Education, College of Materials Science and Engineering, Beijing University of Technology, Beijing (China); Huang, Qingzhen [NIST Center for Neutron Research, National Institute of Standards and Technology, MD (United States)

2014-03-15

Single-phase polycrystalline solid solutions (La{sub 1-x}Sm{sub x})B{sub 6} (x = 0, 0.2, 0.4, 0.8, 1) are fabricated by spark plasma sintering (SPS). This study demonstrates a systematic investigation of structure-property relationships in Sm-doped LaB{sub 6} ternary rare-earth hexaborides. The microstructure, crystallographic orientation, electrical resistivity, and thermionic emission performance of these compounds are investigated. Analysis of the results indicates that samarium (Sm) doping has a noticeable effect on the structure and performance of lanthanum hexaboride (LaB{sub 6}). The analytical investigation of the electron backscatter diffraction confirms that (La{sub 0.6}Sm{sub 0.4})B{sub 6} exhibits a clear (001) texture that results in a low work function. Work functions are determined by pulsed thermionic diode measurements at 1500-1873 K. The (La{sub 0.6}Sm{sub 0.4})B{sub 6} possesses improved thermionic emission properties compared to LaB{sub 6}. The current density of (La{sub 0.6}Sm{sub 0.4})B{sub 6} is 42.4 A cm{sup -2} at 1873 K, which is 17.5% larger than that of LaB{sub 6}. The values of Φ{sub R} for (La{sub 0.6}Sm{sub 0.4})B{sub 6} and LaB{sub 6} are 1.98 ± 0.03 and 1.67 ± 0.03 eV, respectively. Furthermore, the Sm substitution of lanthanum (La) effectively increases the electrical resistivity. These results reveal that Sm doping lead to significantly enhanced thermionic emission properties of LaB{sub 6}. The compound (La{sub 0.6}Sm{sub 0.4})B{sub 6} appears most promising as a future emitter material. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Oxygen ion transference number of doped lanthanum gallate

Energy Technology Data Exchange (ETDEWEB)

Wang, Shizhong; Wu, Lingli; Gao, Jie; He, Qiong [Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Liu, Meilin [School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332-0245 (United States)

2008-12-01

The transference numbers for oxygen ion (t{sub O}) in several LaGaO{sub 3}-based materials are determined from oxygen concentration cells using the materials as the electrolyte, including La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM8282), La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3-{delta}} (LSGMC5) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.115}Co{sub 0.085}O{sub 3-{delta}} (LSGMC8.5). Analysis indicates that the accuracy in determination of oxygen ion transference number depends on the electrode polarization resistances of the concentration cell as well as the transport properties of the materials studied. For example, the ratio of open cell voltage to Nernst potential is a good approximation to the ionic transference number for LSGM8282. However, this approximation is no longer adequate for LSGMC5 and LSGMC8.5; the effect of electrode polarization resistances must be taken into consideration in estimation of the ionic transference numbers. In particular, the ionic transference number for LSGMC5 is as high as 0.99, suggesting that it is a promising electrolyte material for low-temperature solid-state electrochemical applications. (author)

Oxygen ion transference number of doped lanthanum gallate

Science.gov (United States)

Wang, Shizhong; Wu, Lingli; Gao, Jie; He, Qiong; Liu, Meilin

The transference numbers for oxygen ion (t O) in several LaGaO 3-based materials are determined from oxygen concentration cells using the materials as the electrolyte, including La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5). Analysis indicates that the accuracy in determination of oxygen ion transference number depends on the electrode polarization resistances of the concentration cell as well as the transport properties of the materials studied. For example, the ratio of open cell voltage to Nernst potential is a good approximation to the ionic transference number for LSGM8282. However, this approximation is no longer adequate for LSGMC5 and LSGMC8.5; the effect of electrode polarization resistances must be taken into consideration in estimation of the ionic transference numbers. In particular, the ionic transference number for LSGMC5 is as high as 0.99, suggesting that it is a promising electrolyte material for low-temperature solid-state electrochemical applications.

Phase transformations in lead zirconate-titanate doped with lanthanum

Energy Technology Data Exchange (ETDEWEB)

Ishchuk, V M; Morozov, E M

1979-07-01

Presented are the results of studies on the character of phase transitions of the lead-lanthanum zirconate-titanate (LLZT) system. The replacement of lead by lanthanum leads to the expansion of the region of antisegnetoelectric (ASE) states of solid solutions of lead zirconate-titanate (LZT) in the direction of PbTiO/sub 3/ concentration growth. An intermediate region is revealed between segnetoelectric (SE) and ASE states, material properties in which depend on their prehistory: annealed samples are in the ASE state, whereas the application of electric field exceeding some critical value induces the SE state. A family of phase diagrams obtained at consequent replacement of lead by lanthanum permits to identify phase states in any series of LLZT with a constant ratio of Zr:Ti, in the x/65/35 series in particular. Thermally depolarized state of materials of this series at x<6.5 is shown to be antisegnetoelectric at all the temperatures below the Curie point Tsub(c), and heating causes phase transition of ASE..-->..PE (paraelectric state) at Tsub(c). Polarized samples being heated, a successiveness of phase transitions of SE..-->..ASE takes place at T/sub 0/, and that of ASE reversible PE at Tsub(C) (Tsub(0)..ASE phase transition in the LZT system.

Improvement of the optoelectronic properties of tin oxide transparent conductive thin films through lanthanum doping

Energy Technology Data Exchange (ETDEWEB)

Mrabet, C., E-mail: chokri.mrabet@hotmail.com; Boukhachem, A.; Amlouk, M.; Manoubi, T.

2016-05-05

This work highlights some physical investigations on tin oxide thin films doped with different lanthanum content (ratio La–to-Sn = 0–3%). Such doped thin films have been successfully grown by spray pyrolysis onto glass substrates at 450 °C. X-ray diffraction (XRD) patterns showed that SnO{sub 2}:La thin films were polycrystalline with tetragonal crystal structure. The preferred orientation of crystallites for undoped SnO{sub 2} thin film was along (110) plane, whereas La-doped ones have rather preferential orientations along (200) direction. Although the grain size values exhibited a decreasing tendency with increasing doping content confirming the role of La as a grain growth inhibitor, dislocation density and microstrain values showed an increasing tendency. Also, Raman spectroscopy shows the bands corresponding to the tetragonal structure for the entire range of La doping. The same technique confirms the presence of La{sub 2}O{sub 3} as secondary phase. Moreover, SEM images showed a porous architecture with presence of big clusters with different sizes and shapes resulting from the agglomeration of small grains round shaped. Photoluminescence spectra of SnO{sub 2}:La thin films exhibit a decrease in the emission intensity with La concentration due to the decrease in grain size. Optical transmittance spectra of the films showed high transparency (∼80%) in the visible region. The dispersion of the refractive index is discussed using both Cauchy model and Wemple–Di-Domenico method. The optical band gap values vary slightly with La doping and were found to be around 3.8 eV. It has been found that La doping causes a pronounced decrease in the sheet resistance by up to two orders of magnitude and allows improving the Haacke's figure of merit (Φ) of the sprayed thin films. Moreover, we have introduced for a first time a new figure of merit for qualifying photo-thermal conversion applications. The obtained high conducting and transparent SnO{sub 2}:La

Microstructure evolution and electrical characterization of Lanthanum doped Barium Titanate (BaTiO{sub 3}) ceramics

Energy Technology Data Exchange (ETDEWEB)

Billah, Masum, E-mail: masum.buet09@gmail.com; Ahmed, A., E-mail: jhinukbuetmme@gmail.com; Rahman, Md. Miftaur, E-mail: miftaurrahman@mme.buet.ac.bd [Department of Materials & Metallurgical Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Mahbub, Rubbayat, E-mail: rubayyatm@gce.buet.ac.bd [Department of Glass and Ceramic Engineering, Bangladesh University of Engineering and Technology, Dhaka-1000 (Bangladesh); Gafur, M. A., E-mail: d-r-magafur@bcsir.gov.bd [Bangladesh Council of Scientific & Industrial Research (BCSIR), Dhaka-1205 (Bangladesh); Bashar, M. Shahriar, E-mail: bashar@agni.com [Institute of Fuel Research & Development, Bangladesh Council of Scientific & Industrial Research (BCSIR), Dhaka-1205 (Bangladesh)

2016-07-12

In the current work, we investigated the structural and dielectric properties of Lanthanum oxide (La{sub 2}O{sub 3}) doped Barium Titanate (BaTiO{sub 3}) ceramics and established a correlation between them. Solid state sintering method was used to dope BaTiO{sub 3} with 0.3, 0.5 and 0.7 mole% La{sub 2}O{sub 3} under different sintering parameters. The raw materials used were La{sub 2}O{sub 3} nano powder of ~80 nm grain size and 99.995% purity and BaTiO{sub 3} nano powder of 100 nm grain size and 99.99% purity. Grain size distribution and morphology of fracture surface of sintered pellets were examined by Field Emission Scanning Electron Microscope and X-Ray Diffraction analysis was conducted to confirm the formation of desired crystal structure. The research result reveal that grain size and electrical properties of BaTiO{sub 3} ceramic significantly enhanced for small amount of doping (up to 0.5 mole% La{sub 2}O{sub 3}) and then decreased with increasing doping concentration. Desired grain growth (0.80-1.3 µm) and high densification (<90% theoretical density) were found by proper combination of temperature, sintering parameters and doping concentration. We found the resultant stable value of dielectric constant was 10000-12000 at 100-300 Hz in the temperature range of 30°-50° C for 0.5 mole% La{sub 2}O{sub 3} with corresponding shift of curie temperature around 30° C. So overall this research showed that proper La{sup 3+} concentration can control the grain size, increase density, lower curie temperature and hence significantly improve the electrical properties of BaTiO{sub 3} ceramics.

Radiation defects in some oxide compounds

International Nuclear Information System (INIS)

Kaczmarek, S.M.

1999-01-01

Yttrium aluminium garnets, yttrium aluminium perovskite, strontium and barium lanthanum and gadolinium gallates, lithium niobate and tantalate as-grown crystals and doped by diffusion with rare-earth (Nd, Dy, Er, Tm, Ho, Pr, Ce, Eu) and ions of the first transition series (Mn, Cr, Cu, Fe) were investigated optically and using electron spin resonance method before and after gamma, electron and proton irradiation. (author)

Lanthanum chromite colloidal processing

International Nuclear Information System (INIS)

Setz, Luiz Fernando Grespan

2009-01-01

Lanthanum chromite (LaCrO 3 ) is currently the most studied material for applications such as solid oxide fuel cell inter connector (HTSOFC). The complexity of microstructures and geometries of HTSOFC devices, require a precise control of processing parameters to get the desired combination of properties and this, the use of techniques involving concentrated ceramic slips conformation are appropriate, therefore, is well controlled, assist in obtaining homogeneous parts, reproductive and complex geometries. Thus, studies involving the surface chemistry, the stability conditions and slips flow behaviour in the forming conditions, provide important elements for processes control in the inter connectors manufacture, where more applied settings have slots and channels for the gases passage. Thus, surface chemistry, stability and rheological behaviour of strontium and cobalt doped LaCrO 3 (La) 0.80 Sr 0. 2 0 Cr 0.92 Co 0.08 O 3 ) slips prepared with ethanol and water, were studied. The doped lanthanum chromite was produced by combustion synthesis in the IPEN/SP labs. The influence of parameters: pH (water), dispersant concentration, homogenization times and conditions, solid concentration, different ratios binder:plasticizer in the stability and the flow behavior of ceramic suspensions prepared were evaluated. The La) 0.80 Sr 0. 2 0 Cr 0.92 Co 0.08 O 3 products obtained by casting aqueous slips in a plaster mould, using alkaline pH and anionic polyelectrolyte and tapes obtained by using ethanol as a dispersant medium, after sintering at 1600 degree C/4 hours presented theoretical density > 94%, suitable for use as HTSOFC inter connector. (author)

Synthesis, processing and characterization of the solid oxide half-cells cathode/electrolyte of strontium-doped lanthanum manganite/Yttria-stabilized zirconia

International Nuclear Information System (INIS)

Chiba, Rubens

2010-01-01

The ceramic films of strontium-doped lanthanum manganite (LSM) and strontium doped lanthanum manganite/Yttria-stabilized zirconia (LSM/YSZ) are used as cathodes of the high temperature solid oxide fuel cells (HTSOFC). These porous ceramic films had been deposited on the YSZ dense ceramic substrate, used as electrolyte, structural component of the module, thus conferring a configuration of half-cell called auto-support. The study of the half-cell it is basic, therefore in the interface cathode/electrolyte occurs the oxygen reduction reaction, consequently influencing in the performance of the HTSOFC. In this direction, the present work contributes for the processing of thin films, using the wet powder spraying technique, adopted for the conformation of the ceramic films for allowing the attainment of porous layers with thicknesses varied in the order of micrometers. The LSM powders were synthesized by the citrate technique and the LSM/YSZ powders synthesized by the solid mixture technique. In the stage of formation were prepared organic suspensions of LSM and LSM/YSZ fed by gravity in a manual aerograph. For the formation of the YSZ substrate was used a hydraulic uniaxial press. The attainment of solid oxide half-cells cathode/electrolyte was possible of crystalline structures hexagonal for phase LSM and cubic for phase YSZ. The half-cells micrographs show that the YSZ substrate is dense, enough to be used as solid electrolyte, and the LSM and LSM/YSZ films are presented porous with approximately 30 μm of thickness and good adherence between the cathodes and the electrolyte. The presence of composite cathode between the LSM cathode and YSZ substrate, presented an increase in the electrochemical performance in the oxygen reduction reaction. (author)

Effect of sintering time on structural, microstructural and chemical composition of Ni-doped lanthanum gallate perovskites

Science.gov (United States)

Colomer, M. T.; Kilner, J. A.

2015-08-01

This work reports the effect of two different sintering times, 6 and 48 h on the structural, microstructural, and chemical features of Ni-doped La0.90Sr0.10GaO3.00-δ. Independently of the sintering time, La0.90Sr0.10Ga1-xNixO3.00-δ (where x=0.10, and 0.20 (mol)) presents a rhombohedral symmetry with a lattice volume that decreases when NiO dopant increases. Besides the perovskite, LaSrGa3.00O7.00 (nominal composition) is present as second phase in all cases. When the samples are doped with NiO, the peaks of this second phase are shifted with respect to the peaks of the pure phase. These shifts suggest that this second phase could admit some Ni ions in its structure. According to the XRD patterns, the amount of the latter phase is larger when sintering time is increased. Electron probe microanalysis (EPMA) indicated that the matrix of the samples sintered for 6 h is constituted by a perovskite with an experimental composition very close to the nominal one. However, when the samples are sintered for 48 h the matrix of each sample is constituted by two perovskites; both with compositional deviations with respect to their nominal one. In particular, a significant Sr depletion compensated by a La increment in the A site is observed. Those compositional deviations could be mainly due to the diffusion of the cations in the bulk and/or from the bulk to the surface of the samples. That diffusion can favour the formation, not only, of a second perovskite with a different composition in relation with the first one formed, but also, the formation of second phases. In addition, a very slight broadening of Bragg peaks of the perovskites sintered for 48 h is observed by XRD and can be related to the presence of two different perovskites in each sample according to EPMA results. By BSEM and EPMA analyses La4.00Ga2.00O9.00 (nominal composition) is also observed as second phase when samples are treated for 48 h.

Lanthanum and yttrium oxysulfides activated by europium: (Ln1-x Eux)2 O2 S - Synthesis and characterization

International Nuclear Information System (INIS)

Luiz, J.M.

1989-01-01

The synthesis of lanthanum and yttrium oxysulfides activated by europium were obtained by thermal decomposition of lanthanum and yttrium oxalates doped with europium, under an argon and sulphur atmosphere. The thermal decomposition of these compounds is studied by differential thermal analysis (DTA). The characterization of these oxysulfides were made by chemical analyses, infrared spectroscopy, X-ray diffraction, scanning electron microscopy and emission spectroscopy. (M.V.M.)

Cerium doped lanthanum halides: fast scintillators for medical imaging; Halogenures de lanthane dopes cerium des scintillateurs rapides pour l'imagerie medicale

Energy Technology Data Exchange (ETDEWEB)

Selles, O

2006-12-15

This work is dedicated to two recently discovered scintillating crystals: cerium doped lanthanum halides (LaCl{sub 3}:Ce{sup 3+} and LaBr{sub 3}:Ce{sup 3+}).These scintillators exhibit interesting properties for gamma detection, more particularly in the field of medical imaging: a short decay time, a high light yield and an excellent energy resolution. The strong hygroscopicity of these materials requires adapting the usual experimental methods for determining physico-chemical properties. Once determined, these can be used for the development of the industrial manufacturing process of the crystals. A proper comprehension of the scintillation mechanism and of the effect of defects within the material lead to new possible ways for optimizing the scintillator performance. Therefore, different techniques are used (EPR, radioluminescence, laser excitation, thermally stimulated luminescence). Alongside Ce{sup 3+} ions, self-trapped excitons are involved in the scintillation mechanism. Their nature and their role are detailed. The knowledge of the different processes involved in the scintillation mechanism leads to the prediction of the effect of temperature and doping level on the performance of the scintillator. A mechanism is proposed to explain the thermally stimulated luminescence processes that cause slow components in the light emission and a loss of light yield. Eventually the study of afterglow reveals a charge transfer to deep traps involved in the high temperature thermally stimulated luminescence. (author)

Structural stability of the smectite-doped lanthanum under high pressures and high temperatures

International Nuclear Information System (INIS)

Stefani, Vicente Fiorini

2012-01-01

Smectites are phyllosilicates that have a tetrahedron: octahedron structure ratio of 2:1, with high cation exchange capacity (CEC) in the interlayers. For these and other features, smectites have been used in many parts of the world as secondary barriers with the goal of containing a possible leak of radioactive elements in final disposal facilities for radioactive waste through cation exchange. Our aim in this work is to reach the cation exchange in calcium montmorillonite (smectite dioctahedral) by lanthanum to simulate trivalent radionuclides and to study the stability of this structure under high pressure and high temperature. To achieve high pressure it was used two different technique: DAC (Diamond Anvil Cell), achieving pressures up to 12GPa at room temperature and hydraulic press with a toroidal chamber profile to achieve pressures up to 7,7GPa and temperatures up to 900 degree C. The heating is achieved simultaneously by an electric system coupled in the hydraulic press. The outcomes show that the smectite structure doped with lanthanum remains stable under 12GPa at room temperature and 2.5GPa at 200 degree C. However, above 300 degree C at 2.5GPa the structure becomes a new phase of muscovite-like, rich of La, where it loses its interlayer water and turns out to be irreversible. Furthermore, it is important to point out that the higher temperature the better ordered is the structure and it is still stable under 7.7GPa and 900 degree C. Moreover, after all experiments the structure continues being dioctahedral. The new phase of muscovite-like, rich of La, in contact with a calcium solution remains partially unchanged, whereas the other part returns to the original structure (montmorillonite-Ca). The following analyses were performed: X-ray diffraction (XRD) for evaluating the spatial structure; Fourier transform infrared spectroscopy (FTIR) for getting information about the vibrational modes; scanning electron microscopy with dispersive Xray spectroscopy

Photoluminescence properties of cerium oxide nanoparticles as a function of lanthanum content

International Nuclear Information System (INIS)

Deus, R.C.; Cortés, J.A.; Ramirez, M.A.; Ponce, M.A.; Andres, J.; Rocha, L.S.R.

2015-01-01

Highlights: • CeO 2 nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO 2 and La-doped CeO 2 particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in the cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission

State of atoms and interatomic interactions in complex perovskite-like oxides. Communication XVIII. Magnetic dilution in the LaCrO3-LaGaO3 system

International Nuclear Information System (INIS)

Chezhina, N.V.; Zolotukhina, N.V.; Bodritskaya, Eh.V.

2005-01-01

Solid solutions LaCr x Ga 1-x O 3 (0.01 ≤ x ≤ 0.10) were synthesized using the ceramic technique and characterized by X-ray powder diffraction and chemical analysis. Magnetic susceptibility of dilute solid solutions of lanthanum chromate in lanthanum gallate was studied in the temperature range 77-400 K. The calculated antiferromagnetic exchange parameter and distribution of chromium atoms over the diamagnetic matrix gave evidence for enhanced chromium aggregation and weakened magnetic exchange in lanthanum gallate compared to lanthanum aluminate [ru

On magnetic ordering in heavily sodium substituted hole doped lanthanum manganites

Energy Technology Data Exchange (ETDEWEB)

Sethulakshmi, N. [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India); Unnimaya, A.N. [Centre for Materials for Electronic Technology (CMET), Thrissur 680581, Kerala (India); Al-Omari, I.A.; Al-Harthi, Salim [Department of Physics, Sultan Qaboos University, PC 123 Muscat (Oman); Sagar, S. [Government College for Women, Thiruvananthapuram 695014, Kerala (India); Thomas, Senoy [Materials Science and Technology Division, National Institute for Interdisciplinary Science and Technology, Thiruvananthapuram 695019, Kerala (India); Srinivasan, G. [Department of Physics, Oakland University, Rochester (United States); Anantharaman, M.R., E-mail: mraiyer@yahoo.com [Department of Physics, Cochin University of Science and Technology, Cochin 682022, Kerala (India)

2015-10-01

Mixed valence manganite system with monovalent sodium substituted lanthanum manganites form the basis of the present work. Lanthanum manganites belonging to the series La{sub 1−x}Na{sub x}MnO{sub 3} with x=0.5–0.9 were synthesized using modified citrate gel method. Variation of lattice parameters and unit cell volume with Na concentration were analyzed and the magnetization measurements indicated ferromagnetic ordering in all samples at room temperature. Low temperature magnetization behavior indicated that all samples exhibit antiferromagnetism along with ferromagnetism and it has also been observed that antiferromagnetic ordering dominates ferromagnetic ordering as concentration is increased. Evidence for such a magnetic inhomogeneity in these samples has been confirmed from the variation in Mn{sup 3+}/Mn{sup 4+} ion ratio from X-ray Photoelectron Spectroscopy and from the absorption peak studies using Ferromagnetic Resonance Spectroscopy. - Highlights: • Higher substitution of more than 50 percent of monovalent ion, sodium for La sites in lanthanum manganites scarce in literature. • Structural studies using XRD and further structure refinement by Rietveld refinement confirmed orthorhombic pbnm spacegroup. • Ferromagnetic behavior at room temperature with saturation magnetization decreasing with increase in sodium concentration. • M vs T measurements using FC ZFC proved coexisting FM/AFM behavior arising from exchange interactions between different valence states of Mn ions. • Disparity in ratio of Mn valence ions indicated presence of vacancies providing the role of vacancies and oxygen stoichiometry in deciding magnetic inhomogeneity.

Lanthanum-doped mesostructured strontium titanates synthesized via sol–gel combustion route using citric acid as complexing agent

Energy Technology Data Exchange (ETDEWEB)

Sukpanish, Polthep [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Lertpanyapornchai, Boontawee [Program in Petrochemistry, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Yokoi, Toshiyuki [Division of Catalytic Chemistry, Chemical Resources Laboratory, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Ngamcharussrivichai, Chawalit, E-mail: Chawalit.Ng@chula.ac.th [Department of Chemical Technology, Faculty of Science, Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand); Center of Excellence on Petrochemical and Materials Technology (PETROMAT), Chulalongkorn University, Patumwan, Bangkok 10330 (Thailand)

2016-09-15

In the present work, a series of lanthanum-doped mesostructured strontium titanate (LMST) materials with different La/Sr ratios were synthesized via a sol–gel combustion method in the presence of citric acid as a complexing agent and Pluronic P123 as a templating agent. The effects of the amount of doped La and calcination temperature on the physicochemical properties of the LMSTs were examined using various techniques. Powder X-ray diffraction confirmed the substitution of La{sup 3+} into the SrTiO{sub 3} lattice, generating cubic perovskite La{sub x}Sr{sub 1−x}TiO{sub 3}, for the LMST materials calcined at 600 °C. The purity and crystallinity of the desired perovskite phase were enhanced by citric acid addition. The solubility limit of La{sup 3+} substitution at an La/Sr ratio of 0.43 was determined by structural and morphological studies. Increasing the La doping amount decreased the crystallinity and compositional homogeneity, because an La-rich amorphous phase segregated on the surface, but improved the mesoporosity. N{sub 2} physisorption measurements indicated that the LMSTs had a bimodal pore size distribution, of which the larger one was characterized by the crystallite size of mixed oxides, and the specific surface area of 24.9–37.3 m{sup 2} g{sup −1}. The formation of mesopores in the LMST materials synthesized via sol–gel combustion was explained based on a combination of soft- and hard-templating chemistries. - Highlights: • La-doped mesoporous SrTiO{sub 3} (LMST) was prepared first time via sol-gel combustion. • Pluronic P123 triblock copolymer was used as a cheap templating agent. • Citric acid as a complexing agent enhanced the purity and crystallinity of SrTiO{sub 3}. • The textural properties of LMST were improved by increasing the La doping amount. • Mesopore formation was explained by a combined soft- and hard-templating route.

La doping effect on TZM alloy oxidation behavior

International Nuclear Information System (INIS)

Yang, Fan; Wang, Kuai-She; Hu, Ping; He, Huan-Cheng; Kang, Xuan-Qi; Wang, Hua; Liu, Ren-Zhi; Volinsky, Alex A.

2014-01-01

Highlights: • The oxidation can be resisted by doping La into TZM alloy. • La doped TZM alloy has more compact organization. • It can rise the starting temperature of severe oxidation reaction by more than 50 °C. • Effectively slow down the oxidation rate. • Provide guidance for experiments of improving high-temperature oxidation resistance. - Abstract: Powder metallurgy methods were utilized to prepare lanthanum-doped (La-TZM) and traditional TZM alloy plates. High temperature oxidation experiments along with the differential thermal analysis were employed to study the oxidation behavior of the two kinds of TZM alloys. An extremely volatile oxide layer was generated on the surface of traditional TZM alloy plates when the oxidation started. Molybdenum oxide volatilization exposed the alloy matrix, which was gradually corroded by oxygen, losing its quality with serious surface degradation. The La-TZM alloy has a more compact structure due to the lanthanum doping. The minute lanthanum oxide particles are pinned at the grain boundaries and refine the grains. Oxide layer generated on the matrix surface can form a compact coating, which effectively blocks the surface from being corroded by oxidation. The oxidation resistance of La-TZM alloys has been enhanced, expanding its application range

Photoluminescence properties of cerium oxide nanoparticles as a function of lanthanum content

Energy Technology Data Exchange (ETDEWEB)

Deus, R.C. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Cortés, J.A., E-mail: leandrosrr89@gmail.com [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ramirez, M.A. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); Ponce, M.A. [Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA) (CONICET-Universidad Nacional de Mar del Plata), Juan B. Justo 4302, 7600 Mar del Plata (Argentina); Andres, J. [Laboratório Interdisciplinar em Cerâmica, Instituto de Química, Universidade Estadual Paulista, P.O. Box 355, 14801-907 Araraquara, São Paulo (Brazil); Rocha, L.S.R. [Universidade Estadual Paulista, Unesp —Faculdade de Engenharia de Guaratinguetá, Av. Dr Ariberto Pereira da Cunha 333, Bairro Pedregulho, P.O. Box 355, 12.516-410 Guaratinguetá, São Paulo, Brazil, (Brazil); and others

2015-10-15

Highlights: • CeO{sub 2} nanoparticles were obtained by microwave-hydrothermal method. • Rietveld refinement reveals a cubic structure. • KOH mineralizer agent exhibit weak agglomeration at low temperature and shorter time. - Abstract: The structural and photoluminescent properties at room temperature of CeO{sub 2} and La-doped CeO{sub 2} particles were undertaken. The obtained particles were synthesized by a microwave-assisted hydrothermal method (MAH) under different lanthanum contents. X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Fourier transform Raman (FT-Raman), Ultra-violet spectroscopy (UV–vis) and photoluminescence (PL) measurements were carried out. XRD revealed that the powders are free of secondary phases and crystallize in the cubic structure. Raman data show that increasing La doping content increase oxygen vacancies due to lattice expansion. The UV/vis absorption spectroscopy suggested the presence of intermediate energy levels in the band gap of structurally ordered powders. Lanthanum addition creates oxygen vacancies and shifts the photoluminescence in the low energy range leading to intense PL emission.

Electrical properties of Ba doped LSGM for electrolyte material of solid oxide fuel cells

Science.gov (United States)

Raghvendra, Singh, Prabhakar; Singh, Rajesh Kumar

2013-02-01

We report our investigations on Lanthanum Strontium Magnesium Gallate, LSGM, La0.8Sr0.2Ga0.8Mg0.2O3-δ doped with Barium at Strontium site having composition La0.8(Sr0.1Ba0.1)Ga0.8Mg0.2O3-δ (LSBGM). The pure cubic phase along with some additional phase was confirmed by XRD pattern. Electrical properties of the Composition LSBGM [La0.8(Sr0.1Ba0.1)Ga0.8Mg0.2O3-δ] prepared by solid state route, was studied employing impedance spectroscopy in the temperature range 573 K-993 K and frequency range 20 Hz-1MHz. The total ionic conductivity of the composition was found to be 0.072 S.cm-1 at 953 K and the activation energy from Arrhenius plot was found to be 1.16 eV in the measured temperature range. This confirms oxygen ion conductivity in the system. SEM micrograph shows the uniform densed particle morphology with gains of average size 200 nm.

The lanthanum gallate-based mixed conducting perovskite ceramics

Science.gov (United States)

Politova, E. D.; Stefanovich, S. Yu.; Aleksandrovskii, V. V.; Kaleva, G. M.; Mosunov, A. V.; Avetisov, A. K.; Sung, J. S.; Choo, K. Y.; Kim, T. H.

2005-01-01

The structure, microstructure, dielectric, and transport properties of the anion deficient perovskite solid solutions (La,Sr)(Ga,Mg,M)O3- with M=Fe, Ni have been studied. Substitution of iron and nickel for gallium up to about 20 and 40 at.% respectively, leads to the perovskite lattice contraction due to the cation substitutions by the transition elements. The transition from pure ionic to mixed ionic-electronic conductivity was observed for both the systems studied. Both the enhancement of total conductivity and increasing in the thermal expansion coefficient values has been proved to correlate with the increasing amount of weakly bounded oxygen species in the Fe or Ni-doped ceramics. The oxygen ionic conductivity has been estimated from the kinetic experiments using the dc-conductivity and dilatometry methods under the condition of the stepwise change of the atmosphere from nitrogen to oxygen.

Superconducting Electronic Film Structures

Science.gov (United States)

1991-02-14

Segmuller, A., Cooper, E.I., Chisholm, M.F., Gupta, A. Shinde, S., and Laibowitz, R.B. Lanthanum gallate substrates for epitaxial high-T superconducting thin...M. F. Chisholm, A. Gupta, S. Shinde, and R. B. Laibowitz, " Lanthanum Gallate Substrates for Epitaxial High-T c Superconducting Thin Films," Appl...G. Forrester and J. Talvacchio, " Lanthanum Copper Oxide Buffer Layers for Growth of High-T c Superconductor Films," Disclosure No. RDS 90-065, filed

Lanthanum doped titania decorated with silver plasmonic nanoparticles with enhanced photocatalytic activity under UV-visible light

Science.gov (United States)

Dal'Toé, Adrieli T. O.; Colpani, Gustavo Lopes; Padoin, Natan; Fiori, Márcio Antônio; Soares, Cíntia

2018-05-01

Lanthanum doped titanium dioxide decorated with silver plasmonic nanoparticles (Ag-La/TiO2 NPs) materials were prepared using a simple ultrasound-assisted wet impregnation method followed by silver photodeposition. The obtained photocatalysts with different Ag contents were characterized by XRD, FE-SEM, EDX, TEM, BET, XPS, DRS and PL techniques. Moreover, the size distribution of the nanoparticles aggregates was assessed. The characterization analysis revealed that La doping slightly changed the crystalline phase of TiO2, increased the amount of surface hydroxyl groups and interacted with TiO2 nanoparticles via Ti-O-La bond, while Ag photodeposition enhanced the absorption of visible light due to the effects of localized surface plamon resonance and significantly decreased electronic recombination rate by the Schottky junction. Furthermore, the combination of Ag-La induced the formation of oxygen vacancies, which increased the amount of adsorbed surface hydroxyl groups in Ag-La/TiO2. In addition, Ag-La possibly decreased the semiconductor surface energy, which acted positively in the reduction of NPs aggregation. These features along with better textural properties (greater surface areas) played a fundamental role in the enhancement of the photocatalytic activity of Ag-La/TiO2 composites for the decolorization of methylene blue under UV-visible irradiation compared to the mono-metallic (La/TiO2 and Ag/TiO2) modified photocatalysts. Finally, a mechanism for the transfer of charge carriers in Ag-La/TiO2 photocatalyst under UV-visible irradiation was proposed.

Fabrication of Lanthanum Strontium Cobalt Ferrite-Gadolinium-Doped Ceria Composite Cathodes Using a Low-Price Inkjet Printer.

Science.gov (United States)

Han, Gwon Deok; Choi, Hyung Jong; Bae, Kiho; Choi, Hyeon Rak; Jang, Dong Young; Shim, Joon Hyung

2017-11-15

In this work, we have successfully fabricated lanthanum strontium cobalt ferrite (LSCF)-gadolinium-doped ceria (GDC) composite cathodes by inkjet printing and demonstrated their functioning in solid oxide fuel cells (SOFCs). The cathodes are printed using a low-cost HP inkjet printer, and the LSCF and GDC source inks are synthesized with fluidic properties optimum for inkjet printing. The composition and microstructure of the LSCF and GDC layers are successfully controlled by controlling the color level in the printed images and the number of printing cycles, respectively. Anode-support type SOFCs with optimized LSCF-GDC composite cathodes synthesized by our inkjet printing method have achieved a power output of over 570 mW cm -2 at 650 °C, which is comparable to the performance of a commercial SOFC stack. Electrochemical impedance analysis is carried out to establish a relationship between the cell performance and the compositional and structural characteristics of the printed LSCF-GDC composite cathodes.

The lanthanum gallate-based mixed conducting perovskite ceramics

International Nuclear Information System (INIS)

Politova, E.D.; Stefanovich, S.Yu.; Aleksandrovskii, V.V.; Kaleva, G.M.; Mosunov, A.V.; Avetisov, A.K.; Sung, J.S.; Choo, K.Y.; Kim, T.H.

2005-01-01

The structure, microstructure, dielectric, and transport properties of the anion deficient perovskite solid solutions (La,Sr)(Ga,Mg,M)O 3-δ with M=Fe, Ni have been studied. Substitution of iron and nickel for gallium up to about 20 and 40 at.% respectively, leads to the perovskite lattice contraction due to the cation substitutions by the transition elements. The transition from pure ionic to mixed ionic-electronic conductivity was observed for both the systems studied. Both the enhancement of total conductivity and increasing in the thermal expansion coefficient values has been proved to correlate with the increasing amount of weakly bounded oxygen species in the Fe or Ni-doped ceramics. The oxygen ionic conductivity has been estimated from the kinetic experiments using the dc-conductivity and dilatometry methods under the condition of the stepwise change of the atmosphere from nitrogen to oxygen. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

The lanthanum gallate-based mixed conducting perovskite ceramics

Energy Technology Data Exchange (ETDEWEB)

Politova, E.D.; Stefanovich, S.Yu.; Aleksandrovskii, V.V.; Kaleva, G.M.; Mosunov, A.V.; Avetisov, A.K. [L.Ya. Karpov Institute of Physical Chemistry, Vorontsovo pole 10, 105064 Moscow (Russian Federation); Sung, J.S.; Choo, K.Y.; Kim, T.H. [Korea Institute of Energy Research, 71-2 Jang-dong Yooseong, Daejeon (Korea)

2005-01-01

The structure, microstructure, dielectric, and transport properties of the anion deficient perovskite solid solutions (La,Sr)(Ga,Mg,M)O{sub 3-{delta}} with M=Fe, Ni have been studied. Substitution of iron and nickel for gallium up to about 20 and 40 at.% respectively, leads to the perovskite lattice contraction due to the cation substitutions by the transition elements. The transition from pure ionic to mixed ionic-electronic conductivity was observed for both the systems studied. Both the enhancement of total conductivity and increasing in the thermal expansion coefficient values has been proved to correlate with the increasing amount of weakly bounded oxygen species in the Fe or Ni-doped ceramics. The oxygen ionic conductivity has been estimated from the kinetic experiments using the dc-conductivity and dilatometry methods under the condition of the stepwise change of the atmosphere from nitrogen to oxygen. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Thermal decomposition pathway of undoped and doped zinc layered gallate nanohybrid with Fe 3+, Co 2+ and Ni 2+ to produce mesoporous and high pore volume carbon material

Science.gov (United States)

Ghotbi, Mohammad Yeganeh; bin Hussein, Mohd Zobir; Yahaya, Asmah Hj; Abd Rahman, Mohd Zaki

2009-12-01

A series of brucite-like materials, undoped and doped zinc layered hydroxide nitrate with 2% (molar) Fe 3+, Co 2+ and Ni 2+ were synthesized. Organic-inorganic nanohybrid material with gallate anion as a guest, and zinc hydroxide nitrate, as an inorganic layered host was prepared by the ion-exchange method. The nanohybrid materials were heat-treated at various temperatures, 400-700 °C. X-ray diffraction, thermal analysis and also Fourier transform infrared results showed that incorporation of the doping agents within the zinc layered hydroxide salt layers has enhanced the heat-resistivity of the nanohybrid materials in the thermal decomposition pathway. Porous carbon materials can be obtained from the heat-treating the nanohybrids at 600 and 700 °C. Calcination of the nanohybrids at 700 °C under nitrogen atmosphere produces mesoporous and high pore volume carbon materials.

Elastic, piezoelectric and dielectric properties of La3Ga5.5Nb0.5O14 crystals

International Nuclear Information System (INIS)

Sil'vestrova, I.M.; Pisarevskij, Yu.V.; Kaminskij, A.A.; Mill', B.V.

1987-01-01

The results of investigation into piezoelectric, electric, acoustic and dielectric properties of monocrystals of niobium lanthanum gallate La 3 Ga 5.5 Nb 0.5 O 14 at room temperature are presented. It is concluded that niobium lanthanum gallate belongs to moderate strong piezoelectrics with a comparatively low level of acoustic losses up to hypersound frequencies

X-ray photoelectron spectroscopy study of the surface of solid electrolyte La0.88Sr0.12Ga0.82Mg0.18O3-α

International Nuclear Information System (INIS)

Shkerin, S.N.; Kalashnikova, N.A.; Kuznetsov, M.V.

2003-01-01

The composition and chemical state of elements on the surface of solid oxygen-conducting electrolyte La 0.88 Sr 0.12 Ga 0.82 Mg 0.18 O 3-α prior to and after high-temperature annealing (T = 973 K) in CO 2 atmosphere were studied by the method of X-ray photoelectron spectroscopy. It is shown that products of interaction between doped lanthanum gallate and carbon dioxide are localized in the surface layer 8-10 nm thick. Annealing in CO 2 atmosphere does not involve formation of carbon chemical compounds with metals on the electrolyte surface. Surface layers both in the initial electrolyte and after allowance to stay in CO 2 were enriched by strontium oxide, lanthanum hydroxide being present on the surface [ru

Synthesis, structural, optical and Raman studies of pure and lanthanum doped ZnSe nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Kumar, Pushpendra, E-mail: push.nac@gmail.com [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 11529, Taiwan (China); Singh, Jai [Department of Physics, Faculty of Science, Banaras Hindu University, Varanasi 221005 (India); Department of Materials Science and Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Pandey, Mukesh Kumar [Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 11529, Taiwan (China); Jeyanthi, C.E. [Research and Development Centre, Bharathiar University, Coimbatore 641 046 (India); Siddheswaran, R. [Department of Materials Science and Engineering, University of Concepcion, Concepcion (Chile); Paulraj, M. [Department of Physics, Faculty of Physical sciences and Mathematics, University of Concepcion, Casilla 160, Concepcion (Chile); Hui, K.N. [Department of Materials Science and Engineering, Pusan National University, 30 Jangjeon-dong, Geumjeong-gu, Busan 609-735 (Korea, Republic of); Hui, K.S., E-mail: kshui@hanyang.ac.kr [Department of Mechanical Engineering, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of)

2014-01-01

Graphical abstract: - Highlights: • Template-free synthesis of ZnSe and ZnSe:La nanoparticles was developed at low temperature 100 °C. • Cubic ZnSe and ZnSe:La nanoparticles were obtained by chemical route. • As-synthesized ZnSe:La nanoparticles showed higher emission intensity than ZnSe nanoparticles. • Band gap (E{sub g}) of ZnSe nanoparticles was bigger than ZnSe nanoparticles due to nanosized effect. - Abstract: In this work, a simple, effective and reproducible chemical synthetic route for the production of high-quality, pure ZnSe nanoparticles (NPs), and lanthanum-doped ZnSe (ZnSe:La) NPs is presented. The wide bandgap, luminescent pure ZnSe and ZnSe:La NPs has been synthesized at a low temperature (100 °C) in a single template-free step. The size and optical bandgap of the NPs was analyzed from powder X-ray diffraction (XRD), UV–visible (UV–vis) spectroscopy, transmission electron microscopy (TEM), and high resolution transmission electron microscopy (HRTEM). A broad photoluminescence (PL) emission across the visible spectrum has been demonstrated by a systematic blue-shift in emission due to the formation of small nanoparticles. Here, contribution to emission intensity from surface states of NPs increases with La doping. TEM data revealed that the average size of ZnSe and ZnSe:La NPs is 14 and 8 nm, respectively. On the other hand, band gap energy E{sub g} of ZnSe and ZnSe:La NPs were found to be 3.59 eV and 3.65 eV, respectively. Results showed that hydrazine hydrate played multiple roles in the formation of ZnSe and ZnSe:La NPs. A possible reaction mechanism for the growth of NPs is also discussed.

Gallate Contact Dermatitis: Product Update and Systematic Review.

Science.gov (United States)

Holcomb, Zachary E; Van Noord, Megan G; Atwater, Amber Reck

Allergic contact dermatitis related to cosmetic use can result from allergens not routinely evaluated by standard patch test protocols. Propyl, octyl, and dodecyl gallates are commonly used antioxidant preservatives with reports of associated allergic contact dermatitis in the literature. The objectives of this review were to investigate the role of gallates in allergic contact dermatitis and to explore products containing these preservatives. A systematic review of the literature through April 2016 was performed to explore cases of reported gallate allergy. Food and cosmetic product databases were searched for products containing gallates. Seventy-four cases of gallate contact allergy have been reported. In addition, a variety of commercially available cosmetic products and foods contain gallate chemicals. Propyl gallate is the most commonly reported gallate contact allergen and often causes facial and/or hand dermatitis.

Effect of sintering time on structural, microstructural and chemical composition of Ni-doped lanthanum gallate perovskites

International Nuclear Information System (INIS)

Colomer, M.T.; Kilner, J.A.

2015-01-01

This work reports the effect of two different sintering times, 6 and 48 h on the structural, microstructural, and chemical features of Ni-doped La 0.90 Sr 0.10 GaO 3.00−δ . Independently of the sintering time, La 0.90 Sr 0.10 Ga 1−x Ni x O 3.00−δ (where x=0.10, and 0.20 (mol)) presents a rhombohedral symmetry with a lattice volume that decreases when NiO dopant increases. Besides the perovskite, LaSrGa 3.00 O 7.00 (nominal composition) is present as second phase in all cases. When the samples are doped with NiO, the peaks of this second phase are shifted with respect to the peaks of the pure phase. These shifts suggest that this second phase could admit some Ni ions in its structure. According to the XRD patterns, the amount of the latter phase is larger when sintering time is increased. Electron probe microanalysis (EPMA) indicated that the matrix of the samples sintered for 6 h is constituted by a perovskite with an experimental composition very close to the nominal one. However, when the samples are sintered for 48 h the matrix of each sample is constituted by two perovskites; both with compositional deviations with respect to their nominal one. In particular, a significant Sr depletion compensated by a La increment in the A site is observed. Those compositional deviations could be mainly due to the diffusion of the cations in the bulk and/or from the bulk to the surface of the samples. That diffusion can favour the formation, not only, of a second perovskite with a different composition in relation with the first one formed, but also, the formation of second phases. In addition, a very slight broadening of Bragg peaks of the perovskites sintered for 48 h is observed by XRD and can be related to the presence of two different perovskites in each sample according to EPMA results. By BSEM and EPMA analyses La 4.00 Ga 2.00 O 9.00 (nominal composition) is also observed as second phase when samples are treated for 48 h. - Graphical abstract: Typical

Effect of sintering time on structural, microstructural and chemical composition of Ni-doped lanthanum gallate perovskites

Energy Technology Data Exchange (ETDEWEB)

Colomer, M.T., E-mail: tcolomer@icv.csic.es [Instituto de Cerámica y Vidrio, CSIC, C/ Kelsen no. 5, 28049 Madrid (Spain); Kilner, J.A. [Department of Materials, Imperial College, Prince Consort Road, London SW7 2BP (United Kingdom)

2015-08-15

This work reports the effect of two different sintering times, 6 and 48 h on the structural, microstructural, and chemical features of Ni-doped La{sub 0.90}Sr{sub 0.10}GaO{sub 3.00−δ}. Independently of the sintering time, La{sub 0.90}Sr{sub 0.10}Ga{sub 1−x}Ni{sub x}O{sub 3.00−δ} (where x=0.10, and 0.20 (mol)) presents a rhombohedral symmetry with a lattice volume that decreases when NiO dopant increases. Besides the perovskite, LaSrGa{sub 3.00}O{sub 7.00} (nominal composition) is present as second phase in all cases. When the samples are doped with NiO, the peaks of this second phase are shifted with respect to the peaks of the pure phase. These shifts suggest that this second phase could admit some Ni ions in its structure. According to the XRD patterns, the amount of the latter phase is larger when sintering time is increased. Electron probe microanalysis (EPMA) indicated that the matrix of the samples sintered for 6 h is constituted by a perovskite with an experimental composition very close to the nominal one. However, when the samples are sintered for 48 h the matrix of each sample is constituted by two perovskites; both with compositional deviations with respect to their nominal one. In particular, a significant Sr depletion compensated by a La increment in the A site is observed. Those compositional deviations could be mainly due to the diffusion of the cations in the bulk and/or from the bulk to the surface of the samples. That diffusion can favour the formation, not only, of a second perovskite with a different composition in relation with the first one formed, but also, the formation of second phases. In addition, a very slight broadening of Bragg peaks of the perovskites sintered for 48 h is observed by XRD and can be related to the presence of two different perovskites in each sample according to EPMA results. By BSEM and EPMA analyses La{sub 4.00}Ga{sub 2.00}O{sub 9.00} (nominal composition) is also observed as second phase when samples are

Encephalopathy caused by lanthanum carbonate.

Science.gov (United States)

Fraile, Pilar; Cacharro, Luis Maria; Garcia-Cosmes, Pedro; Rosado, Consolacion; Tabernero, Jose Matias

2011-06-01

Lanthanum carbonate is a nonaluminum, noncalcium phosphate-binding agent, which is widely used in patients with end-stage chronic kidney disease. Until now, no significant side-effects have been described for the clinical use of lanthanum carbonate, and there are no available clinical data regarding its tissue stores. Here we report the case of a 59-year-old patient who was admitted with confusional syndrome. The patient received 3750 mg of lanthanum carbonate daily. Examinations were carried out, and the etiology of the encephalopathy of the patient could not be singled out. The lanthanum carbonate levels in serum and cerebrospinal fluid were high, and the syndrome eased after the drug was removed. The results of our study confirm that, in our case, the lanthanum carbonate did cross the blood-brain barrier (BBB). Although lanthanum carbonate seems a safe drug with minimal absorption, this work reveals the problem derived from the increase of serum levels of lanthanum carbonate, and the possibility that it may cross the BBB. Further research is required on the possible pathologies that increase serum levels of lanthanum carbonate, as well as the risks and side-effects derived from its absorption.

Priprava lantanovega galata iz mešanega sistema reducentov in nitrata:

OpenAIRE

Kapun, Barbara; Maček, Jadran; Pejovnik, Stane; Zupan, Klementina

2004-01-01

Lanthanum-gallate-based material is a candidate for the electrolyte in a new generation of low-temperature ceramic fuel cells due to its good ionic and negligible electronic conductivity. Lantn!an!um gallate is one of two compounds in the binary system La2O3-Ga2O3 together with La4Ga2O9. Undoped lanthanum gallate was prepared using combustion synthesis from metal nitrates and a reducing agent (urea and/or citric acid). In the mixed-fuel-type system the reaction intensifies and higer temperatu...

Paramagnetic resonance of LaGaO3: Mn single crystals grown by floating zone melting

Science.gov (United States)

Vazhenin, V. A.; Potapov, A. P.; Artyomov, M. Yu.; Salosin, M. A.; Fokin, A. V.; Gil'mutdinov, I. F.; Mukhamedshin, I. R.

2016-02-01

The EPR spectrum of Mn-doped lanthanum gallate single crystals grown by floating zone melting with optical heating has been studied. In contrast to the crystals grown according to the Czochralski method, no manganese is found in these crystals even after high-temperature annealing in air. The spectral characteristics of Fe3+ and Gd3+ centers in crystals prepared by various methods have been compared in the rhombohedral phase, and the fourth-rank nondiagonal parameters of the Fe3+ trigonal centers have been determined, as well.

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

Energy Technology Data Exchange (ETDEWEB)

Yan Bing [Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092 (China)]. E-mail: byan@tongji.edu.cn; Chen Xi [Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092 (China); Wu Jianhua [Department of Chemistry, Tongji University, Siping Road 1239, Shanghai 200092 (China)

2007-08-31

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

Nd3+-doped lanthanum lead boro-tellurite glass for lasing and amplification applications

Science.gov (United States)

Madhu, A.; Eraiah, B.; Manasa, P.; Srinatha, N.

2018-01-01

Nd3+-doped lanthanum lead boro-tellurite glass samples were prepared by conventional melt quenching method and their structural, thermal, fluorescence, and decay times of the glasses were investigated. Prepared glass samples exhibits amorphous nature and shows good thermal stability in the temperature range of 100-800 °C. Judd-Ofelt (JO) analysis was carried out and the intensity parameters (Ωλ = 2, 4, 6) also spontaneous radiative probability and stimulated-.emission cross-sections were estimated. The magnitude of Ωλ confirms the covalency nature. The near infrared emission spectra were measured by 808 nm excitation in which the emission intensity is found to be high at 1060 nm for the 4F3/2 → 4F11/2 transition. The stimulated cross section, effective band width and branching ratios are found to be 8.910 × 10-20 cm2, 21.57 nm and 53.72 % respectively, for 4F3/2 → 4F11/2 transition. The derived gain bandwidth, figure of merit, threshold and saturation intensity found to be comparable to some of the glass systems. Furthermore, the time decay rate found to decrease from 100 μs to 27 μs when the concentration increased from 0.1 to 3.0 mol% of Nd3+ ions and also all follow the single exponential behaviour which is attributed to the self quenching effect due to the cross-relaxation channels.

Perovskite-related oxide materials for oxygen-permeable electrochemical membrans

OpenAIRE

Naumovich, E. N.; Yaremchenko, A. A.; Viskup, A. P.; Kharton, V. V.

2003-01-01

This brief review is focused on the studies of mixed ionic-electronic conductors on the basis of lanthanum gallate doped with transition metal cations in the В sublattice. The substitution of gallium with iron, cobalt or nickel results in greater electronic conductivity, simultaneously keeping high level of the oxy-gen ionic transport. In particular, La0 90Sr0 10Ga0 65Ni0 20Mg0 1503d perovskite exhib-its attractive oxygen permeability, which is quite similar to that of La2Ni04- and (...

Applied and theoretical study of textural and structural evolution of pure and doped zircon powders

International Nuclear Information System (INIS)

Methivier, A.

1992-02-01

Using different preparation methods, undoped zircon constituted of quadratic and monoclinic phases, and quadratic phase zircon doped with lanthanum, magnesium or silicon were obtained and characterized. An applied kinetic study of the influence of the gaseous phase, and of the doping on pre-sintering shows an accelerating effect of water vapour, an important stabilization effect of lanthanum or silicon additions and a little effect of magnesium additions. This kinetic study leads to a model giving two parallel types of matter transport: one using water vapour catalytic effect, and the other oxygen diffusion

Interactions between lanthanum gallate based solid electrolyte and ceria

Energy Technology Data Exchange (ETDEWEB)

Hrovat, M.; Ahmad-Khanlou, A.; Samardzija, Z.; Holc, J.

1999-10-01

Possible interactions between La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85} and Gd{sub 2}O{sub 3}-doped CeO{sub 2} (solid electrolyte and anode binding materials, respectively, for solid oxide fuel cells (SOFC)) at 1,300 C were studied with diffusion couples and fired powder mixtures. The SrLaGa{sub 3}O{sub 7} compound was detected and its formation was attributed to the diffusion of La{sub 2}O{sub 3} from La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85} into Ce{sub 1{minus}x}La{sub x}O{sub 2{minus}x/2} solid solution. As the resistivity of SrLaGa{sub 3}O{sub 7} is rather high, around 1 M{center_dot}ohm at 800 C, its presence in the solid electrolyte/anode interface could significantly increase the internal resistivity of an SOFC.

Thermophysical Properties of Matter - The TPRC Data Series. Volume 6. Specific Heat - Nonmetallic Liquids and Gases

Science.gov (United States)

1970-01-01

hexahydrate (ErClj-6H201 Erbium gallate (see Trierbium p«ntagallium dodecaoxide) Trierbium pentagallium dodecaoxide lErjGajO« (Garnet) J Erbium oxide (E...Freon 22) Isotron 113 (see Freon 113) Isotron 114 (see Freon 114) J odium (see Iodine) Kalium (see Potassium) Krypton Lanthana (see Lanthanum ...oxide) Lanthanum Lanthanum oxide (LajOj) Lanthanum sesquioxide (see Lanthanum oxide) Dilantanum trioxide (see Lanthanum oxide) T auehing gas (see

High Temperature Superconducting Films and Multilayers for Electronics

Science.gov (United States)

1994-04-19

Vol. 1292 (1990). U Chisholm, A. Gupta, S. Shinde and R.B. Bnidges. GAN. Connell and 1B. Boyce, Laibowitz, " Lanthanum Gallate Sub- "Properties of...aluminate or gallate ..._.........102 24 - 2:2:4:5 structure ........................ 115 IN - Interface reactions ............ 93 #M - MgO substrates...Draper with the measure- High-Tc Superconductors,’ Physica C. on Lanthanum Aluminate Subsbates." in ments of surface resistance; T.T. Vol. 153-155,19M8 pp

n-Octyl gallate as inhibitor of pyruvate carboxylation and lactate gluconeogenesis.

Science.gov (United States)

Eler, Gabrielle Jacklin; Santos, Israel Souza; de Moraes, Amarilis Giaretta; Comar, Jurandir Fernando; Peralta, Rosane Marina; Bracht, Adelar

2015-04-01

The alkyl gallates are found in several natural and industrial products. In the latter products, these compounds are added mainly for preventing oxidation. In the present work, the potencies of methyl gallate, n-propyl gallate, n-pentyl gallate, and n-octyl gallate as inhibitors of pyruvate carboxylation and lactate gluconeogenesis were evaluated. Experiments were done with isolated mitochondria and the isolated perfused rat liver. The potency of the gallic acid esters as inhibitors of pyruvate carboxylation in isolated mitochondria obeyed the following decreasing sequence: n-octyl gallate > n-pentyl gallate > n-propyl gallate > methyl gallate. A similar sequence of decreasing potency for lactate gluconeogenesis inhibition in the perfused liver was found in terms of the portal venous concentration. Both actions correlate with the lipophilicity of the compounds. The effects are harmful at high concentrations. At appropriate concentrations, however, octyl gallate should act therapeutically because its inhibitory action on gluconeogenesis will contribute further to its proposed antihyperglycemic effects. © 2014 Wiley Periodicals, Inc.

Microstructural development and characterization of lanthanum chromite-based ceramics to application in solid oxide fuel cells; Desenvolvimento microestrutural e caracterizacao de ceramicas a base de cromita de lantanio para aplicacao em celulas a combustivel de oxido solido

Energy Technology Data Exchange (ETDEWEB)

Oliveira, R.N.; Furtado, J.G. de M.; Soares, C.M.; Serra, E.T. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)], e-mail: rnunes@cepel.br

2006-07-01

This work has for objective to investigate and to characterize the microstructural development of lanthanum chromite-based ceramics (LaCrO{sub 3}) doped with earth alkaline metals, correlating the microstructural parameters (mainly the densification level) and processing parameters with the electrothermal properties reached. Lanthanum chromite-based ceramic systems doped with earth-alkaline metals (Ca, Mg and Sr) had been produced from respective metallic nitrates by solid state reactions process. The phase compositions were evaluated by X-ray diffraction and the densification level by Archimedes method. The microstructural characterization was effected by scanning electron microscopy, energy dispersive X-ray spectroscopy and thermal analysis techniques. Electrical tests were used to evaluate the electrical conductivity of the studied ceramics. The obtained results corroborate the literature comments concerning the difficulty of lanthanum chromite-based ceramics with high densification level and evidence the great influence of the nature of the dopants on the sintering mechanism and the microstructural and electric characteristics of the produced ceramics. The best ones results, in terms of densification and electrical conductivity, had been gotten through multiple doping with calcium and strontium, and in sintering temperature conditions lower that the normally considered to pure or monodoped lanthanum chromite-based ceramics. (author)

An epitaxial transparent conducting perovskite oxide: double-doped SrTiO3

NARCIS (Netherlands)

Ravichandran, Jayakanth; Siemons, W.; Heijmerikx, Herman; Huijben, Mark; Majumdar, Arun; Ramesh, Ramamoorthy

2010-01-01

Epitaxial thin films of strontium titanate doped with different concentrations of lanthanum and oxygen vacancies were grown on LSAT substrates by pulsed laser deposition technique. Films grown with 5−15% La doping and a critical growth pressure of 1−10 mTorr showed high transparency (>70−95%) in the

Lanthanum additions and the toughness of ultra-high strength steels and the determination of appropriate lanthanum additions

International Nuclear Information System (INIS)

Garrison, Warren M.; Maloney, James L.

2005-01-01

Studies of commercial heats of AF1410 steel suggest that under appropriate conditions additions of rare-earth elements can significantly enhance fracture toughness. This improvement in toughness is not due to an extremely low inclusion volume fraction but is apparently due to the formation of larger and more widely spaced inclusions. The purpose of this work is to discuss our experience in using rare-earth additions to laboratory scale vacuum induction melted and subsequently vacuum arc remelted heats of ultra-high strength steels to achieve inclusion distributions similar to those observed in commercial heats modified with lanthanum additions. The results indicate that lanthanum additions of 0.015 wt.% to low sulfur steels which have been well deoxidized using carbon-vacuum deoxidation can result in lanthanum rich inclusions which are similar in size, volume fraction and spacing to those obtained in commercially produced heats of ultra-high strength steel to which lanthanum has been added. The heat of steel to which lanthanum additions of 0.015 wt.% were made had significantly higher toughness than did the heat of the same steel in which the sulfur had been gettered as small and closely spaced particles of MnS and which had an inclusion volume fraction similar to that of the heat modified by the addition of 0.015 wt.% lanthanum. This improvement in toughness was attributed to an increase in inclusion spacing. An addition of 0.06 wt.% lanthanum was excessive. Such an addition of lanthanum resulted in a huge volume fraction of large cuboidal inclusions which primarily contain lanthanum and oxygen and which are extremely detrimental to toughness

Performance of strontium- and magnesium-doped lanthanum gallate electrolyte with lanthanum-doped ceria as a buffer layer for IT-SOFCs

Energy Technology Data Exchange (ETDEWEB)

Lee, Dokyol; Han, Ju-Hyeong; Kim, Eun-Gu [Department of Materials Science and Engineering, Korea University, 5-1 Anam-dong, Seongbuk-gu, Seoul 136-713 (Korea); Song, Rak-Hyun; Shin, Dong-Ryul [Hydrogen and Fuel Cell Research Department, Korea Institute of Energy Research, 71-2 Jang-dong, Yuseong-gu, Daejeon 305-600 (Korea)

2008-10-15

La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.8} (LSGM8080) powder, showing the highest electrical conductivity among LSGMs of various compositions, is synthesized using the glycine nitrate process (GNP) and used as the electrolyte for an intermediate-temperature solid oxide fuel cell (IT-SOFC). The LDC (Ce{sub 0.55}La{sub 0.45}O{sub 1.775}) powder is synthesized by a solid-state reaction and employed as the material for a buffer layer to prevent the reaction between the anode and electrolyte materials. The LDC also serves as the skeleton material for the anode. An anode-supported single cell with an active area of 1 cm{sup 2} is constructed for performance evaluation. A single-cell test is performed at 750 and 800 C. The maximum power density of the cell 459 and 664 mW cm{sup -2} at 750 and 800 C, respectively. (author)

Performance of strontium- and magnesium-doped lanthanum gallate electrolyte with lanthanum-doped ceria as a buffer layer for IT-SOFCs

Science.gov (United States)

Lee, Dokyol; Han, Ju-Hyeong; Kim, Eun-Gu; Song, Rak-Hyun; Shin, Dong-Ryul

La 0.8Sr 0.2Ga 0.8Mg 0.2O 2.8 (LSGM8080) powder, showing the highest electrical conductivity among LSGMs of various compositions, is synthesized using the glycine nitrate process (GNP) and used as the electrolyte for an intermediate-temperature solid oxide fuel cell (IT-SOFC). The LDC (Ce 0.55La 0.45O 1.775) powder is synthesized by a solid-state reaction and employed as the material for a buffer layer to prevent the reaction between the anode and electrolyte materials. The LDC also serves as the skeleton material for the anode. An anode-supported single cell with an active area of 1 cm 2 is constructed for performance evaluation. A single-cell test is performed at 750 and 800 °C. The maximum power density of the cell 459 and 664 mW cm -2 at 750 and 800 °C, respectively.

Lanthanum

Science.gov (United States)

... levels of phosphate in the blood can cause bone problems. Lanthanum is in a clsas of medications ... to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in ...

Defects in doped LaGaO3 anionic conductors: linking NMR spectral features, local environments, and defect thermodynamics.

Science.gov (United States)

Blanc, Frédéric; Middlemiss, Derek S; Gan, Zhehong; Grey, Clare P

2011-11-09

Doped lanthanum gallate perovskites (LaGaO(3)) constitute some of the most promising electrolyte materials for solid oxide fuel cells operating in the intermediate temperature regime. Here, an approach combining experimental multinuclear NMR spectroscopy with density functional theory total energy and GIPAW NMR calculations yields a comprehensive understanding of the structural and defect chemistries of Sr- and Mg-doped LaGaO(3) anionic conductors. The DFT energetics demonstrate that Ga-V(O)-Ga (V(O) = oxygen vacancy) environments are favored (vs Ga-V(O)-Mg, Mg-V(O)-Mg and Mg-O-Mg-V(O)-Ga) across a range y = 0.0625, 0.125, and 0.25 of fractional Mg contents in LaGa(1-y)Mg(y)O(3-y/2). The results are interpreted in terms of doping and mean phase formation energies (relative to binary oxides) and are compared with previous calculations and experimental calorimetry data. Experimental multinuclear NMR data reveal that while Mg sites remain six-fold coordinated across the range of phase stoichiometries, albeit with significant structural disorder, a stoichiometry-dependent minority of the Ga sites resonate at a shift consistent with Ga(V) coordination, demonstrating that O vacancies preferentially locate in the first anion coordination shell of Ga. The strong Mg-V(O) binding inferred by previous studies is not observed here. The (17)O NMR spectra reveal distinct resonances that can be assigned by using the GIPAW NMR calculations to anions occupying equatorial and axial positions with respect to the Ga(V)-V(O) axis. The disparate shifts displayed by these sites are due to the nature and extent of the structural distortions caused by the O vacancies.

Preparation of Ho3+/Tm3+ Co-doped Lanthanum Tungsten Germanium Tellurite Glass Fiber and Its Laser Performance for 2.0 μm

Science.gov (United States)

Zhou, Dechun; Bai, Xuemei; Zhou, Hang

2017-03-01

Ho3+/Tm3+ co-doped 50TeO2-25GeO2-3WO3-5La2O3-3Nb2O5-5Li2O-9BaF2 glass fiber is prepared with the rod-tube drawing method of 15 μm core diameter and 125 μm inner cladding diameter applied in the 2.0 μm-infrared laser. The 2.0 μm luminescence properties of the core glass are researched and the fluorescence intensity variation for different Tm3+ doping concentration is systematically analyzed. The results show that the 2.0 μm luminescence of Ho3+ is greatly influenced by the doping concentration ratio of Ho3+ to Tm3+ and that the maximum fluorescence intensity of the core glass can be obtained and its emission cross section can reach 0.933 × 10-21 cm2 when the sensitized proportion of holmium to thulium is 0.3 to 0.7 (mol%). Simultaneously, the maximum phonon energy of the core glass sample is 753 cm-1, which is significantly lower than that of silicate, gallate and germanate glass and the smaller matrix phonon energy can be conductive to the increase 2.0 μm-band emission intensity. The continuous laser with the maximum laser output power of 0.993 W and 2051 nm -wavelength of 31.9%-slope efficiency is output within the 0.5 m glass fiber and the experiment adopts 1560 nm erbium-doped fiber laser(EDFL) as the pump source and the self-built all-fiber laser. Therefore, the glass fiber has excellent laser characteristics and it is suitable for the 2.0 μm-band laser.

High performance electrodes for reduced temperature solid oxide fuel cells with doped lanthanum gallate electrolyte. I. Ni-SDC cermet anode

Science.gov (United States)

Ohara, S.; Maric, R.; Zhang, X.; Mukai, K.; Fukui, T.; Yoshida, H.; Inagaki, T.; Miura, K.

A Ni-samaria-doped ceria (SDC) cermet was selected as the anode material for reduced temperature (800°C) solid oxide fuel cells. The NiO-SDC composite powder, synthesized by spray pyrolysis, was employed as the starting anode powder in this study. The influence of Ni content in Ni-SDC cermets on the electrode performance was investigated in order to create the most suitable microstructures. It was found that anodic polarization was strongly influenced by the Ni content in Ni-SDC cermets. The best results were obtained for anode cermets with Ni content of around 50 vol.%; anodic polarization was about 30 mV at a current density of 300 mA/cm 2. This high performance seems to be attributable to the microstructure, in which Ni grains form a skeleton with well-connected SDC grains finely distributed over the Ni grains surfaces; such microstructure was also conducive to high stability of the anode.

Effects of rapid thermal annealing on structural, chemical, and electrical characteristics of atomic-layer deposited lanthanum doped zirconium dioxide thin film on 4H-SiC substrate

International Nuclear Information System (INIS)

Lim, Way Foong; Quah, Hock Jin; Lu, Qifeng; Mu, Yifei; Ismail, Wan Azli Wan; Rahim, Bazura Abdul; Esa, Siti Rahmah; Kee, Yeh Yee; Zhao, Ce Zhou

2016-01-01

Graphical abstract: - Highlights: • Studies of RTA temperatures on La doped ZrO2 atomic layer deposited on 4HSiC. • Oxygen vacancies improved insulating and catalytic properties of La doped ZrO2. • 700 °C annealed sample showed the highest EB, k value, and sensitivity on O2. • La doped ZrO2 was proposed as a potential metal reactive oxide on 4H-SiC. - Abstract: Effects of rapid thermal annealing at different temperatures (700–900 °C) on structural, chemical, and electrical characteristics of lanthanum (La) doped zirconium oxide (ZrO_2) atomic layer deposited on 4H-SiC substrates have been investigated. Chemical composition depth profiling analysis using X-ray photoelectron spectroscopy (XPS) and cross-sectional studies using high resolution transmission electron microscopy equipped with energy dispersive X-ray spectroscopy line scan analysis were insufficient to justify the presence of La in the investigated samples. The minute amount of La present in the bulk oxide was confirmed by chemical depth profiles of time-of-flight secondary ion mass spectrometry. The presence of La in the ZrO_2 lattice led to the formation of oxygen vacancies, which was revealed through binding energy shift for XPS O 1s core level spectra of Zr−O. The highest amount of oxygen vacancies in the sample annealed at 700 °C has yielded the acquisition of the highest electric breakdown field (∼ 6.3 MV/cm) and dielectric constant value (k = 23) as well as the highest current–time (I–t) sensor response towards oxygen gas. The attainment of both the insulating and catalytic properties in the La doped ZrO_2 signified the potential of the doped ZrO_2 as a metal reactive oxide on 4H-SiC substrate.

Lanthanum chromite colloidal processing; Processamento coloidal de cromito de lantanio

Energy Technology Data Exchange (ETDEWEB)

Setz, Luiz Fernando Grespan

2009-07-01

Lanthanum chromite (LaCrO{sub 3}) is currently the most studied material for applications such as solid oxide fuel cell inter connector (HTSOFC). The complexity of microstructures and geometries of HTSOFC devices, require a precise control of processing parameters to get the desired combination of properties and this, the use of techniques involving concentrated ceramic slips conformation are appropriate, therefore, is well controlled, assist in obtaining homogeneous parts, reproductive and complex geometries. Thus, studies involving the surface chemistry, the stability conditions and slips flow behaviour in the forming conditions, provide important elements for processes control in the inter connectors manufacture, where more applied settings have slots and channels for the gases passage. Thus, surface chemistry, stability and rheological behaviour of strontium and cobalt doped LaCrO{sub 3} (La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3}) slips prepared with ethanol and water, were studied. The doped lanthanum chromite was produced by combustion synthesis in the IPEN/SP labs. The influence of parameters: p H (water), dispersant concentration, homogenization times and conditions, solid concentration, different ratios binder:plasticizer in the stability and the flow behavior of ceramic suspensions prepared were evaluated. The La{sub 0.80}Sr{sub 0.20}Cr{sub 0.92}Co{sub 0.08}O{sub 3} products obtained by casting aqueous slips in a plaster mould, using alkaline p H and anionic polyelectrolyte and tapes obtained by using ethanol as a dispersant medium, after sintering at 1600 deg C/4h presented theoretical density > 94%, suitable for use as HTSOFC inter connector. (author)

Electrical, electrochemical and isotopic exchange measurements on lanthanum gallate based ceramics

Energy Technology Data Exchange (ETDEWEB)

Bronin, D.I.; Gorelov, V.P. [RAS, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry]|[Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Kuzin, B.L.; Kurumchin, E.Kh.; Vdovin, G.K.; Sokolova, Ju.V.; Beresnev, S.M. [RAS, Ekaterinburg (Russian Federation). Inst. of High-Temperature Electrochemistry; Keppeler, M.; Naefe, H.; Aldinger, F. [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany)

2000-07-01

The solubility limits of Sr and Mg in La{sub 1-x}Sr{sub x}Ga{sub 1-y}Mg{sub y}O{sub 3-{delta}} (LSGM) and the electrical conductivity of LSGM and La{sub 1-x}Sr{sub x}Ga{sub 1-y-z}Mg{sub y}Co{sub z}O{sub 3-{delta}} (LSGMC) were studied. By electrochemical and isotopic exchange measurements on both LSGM material and on an LSGM pellet whose surface was modified by Co-doping, it was shown that the oxygen exchange rate between the solids and the surrounding gas phase is much higher in the case of the modified electrolyte material. A single fuel cell with an LSGM electrolyte was constructed and tested. (orig.)

Lanthanum Containing Polymer's Modification to PP

Institute of Scientific and Technical Information of China (English)

Dai Shaojun; Zhang Ming

2004-01-01

Polypropylene (PP)'s low impact strength limits its usages. Adding some a rare earth polymer can enhance PP's tensile strength and impact strength. Acrylic lanthanum was prepared by the reaction between lanthanum oxide and acrylic acid. The IR spectrum prove that and optimum reacting conditions are that the bulk ratio of La(AA) 3 and MMA is not less than one and temperature is about 80 ℃. Lanthanum containing Polymer were added into PP. When percent of addition only was 3%, strength were enhanced 10% , and impact strength 40%. SEM shows the compatibility of rare earth polymer and PP; lanthanum containing polymer can form physical crosslinking between PP's molecules, then every particle's surface connect with several PP molecules and the PP mechanical property were enhanced.

Sintering and electrical properties of strontium-doped lanthanum manganite

Energy Technology Data Exchange (ETDEWEB)

Tarrago, Diego Pereira; Sousa, Vania Caldas de [Universidade Federal do Rio Grande do Sul (LABIOMAT/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Biomateriais], Email: dptarrago@gmail.com; Moreno Buriel, Berta; Chinarro Martini, Eva; Jurado Egea, Jose Ramon [Consejo Superior de Investigaciones Cientificas (ICV/CSIC), Madrid (Spain). Inst. de Ceramica y Vidrio; Malfatti, Celia de Fraga [Universidade Federal do Rio Grande do Sul (LAPEC/PPGEM/UFRGS), Porto Alegre, RS (Brazil). Programa de Pos-Graduacao em Engenharia de Minas, Metalurgica e de Materiais. Lab. de Pesquisa em Corrosao

2010-07-01

Lanthanum strontium manganites (LSM) are potential materials for cathode applications in solid oxide fuel cells (SOFC) due to their good catalytic activity, chemical stability and compatibility with electrolyte materials in high temperatures. The sinterability of single phase La{sub 1-x}Sr{sub x}Mn{sub O3} (x=0.18) perovskite powders and the electrical properties of the resulting samples are analyzed in this study. Using a heating microscope, the powders were pressed and sintered at different pressures and temperatures, resulting in an open porosity of 33.36% when compacted at 125 MPa and sintered at 1200 degree C. Top and cross-section s canning electron microscopy (SEM) micrographs revealed interconnected pores in the sintered body and, hence, a suitable microstructure for the application. The activation energy for conductance was 0.04 eV and the tested LSM bulk started to exhibit adequate electrical properties at about 500 degree C. (author)

Corrosion and electrochemical properties of lanthanum

International Nuclear Information System (INIS)

Tomashov, N.D.; Matveeva, T.V.

The kinetics of the corrosion rate of lanthanum at 25 0 in air of different relative humidities, distilled water, sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, potassium hydroxide of different concentrations and at 100 0 C in distilled water and potassium hydroxide have been studied. In air at 22--100% relative humidity, the corrosion rate of lanthanum increases with time and with increasing humidity. In distilled water and in potassium hydroxide solutions, the corrosion rate of lanthanum increases with time and decreasees when the concentration of alkali exceeds 20%. With increasing concentration of the acids, the corrosion rate of lanthanum increases in hydrochloric acid and nitric acid and passes through a maximum in sulfuric acid (20%) and phosphoric acid (60%). The values of the corrosion rates of lanthanum in 40% nitric acid, 35% hydrochloric acid, 20% sulfuric acid, 60% phosphoric acid, and 40% hydrofluoric acid are 8 x 10 5 ; 4.4 x 10 4 ; 1.3 x 10 3 ; 9 g/m 2 h respectively

Antioxidant activity of alkyl gallates and glycosyl alkyl gallates in fish oil in water emulsions: relevance of their surface active properties and of the type of emulsifier.

Science.gov (United States)

González, María J; Medina, Isabel; Maldonado, Olivia S; Lucas, Ricardo; Morales, Juan C

2015-09-15

The antioxidant activity of gallic acid and a series of alkyl gallates (C4-C18) and glycosylated alkyl gallates (C4-C18) on fish oil-in-water emulsions was studied. Three types of emulsifiers, lecithin, Tween-20 and sodium dodecyl sulphate (SDS) were tested. A nonlinear behavior of the antioxidant activity of alkyl gallates when increasing alkyl chain length was observed for emulsions prepared with lecithin. Medium-size alkyl gallates (C6-C12) were the best antioxidants. In contrast, for emulsions prepared with Tween-20, the antioxidants seem to follow the polar paradox. Glucosyl alkyl gallates were shown previously to be better surfactants than alkyl gallates. Nevertheless, they exhibited a worse antioxidant capacity than their corresponding alkyl gallates, in emulsions prepared with lecithin or Tween-20, indicating the greater relevance of having three OH groups at the polar head in comparison with having improved surfactant properties but just a di-ortho phenolic structure in the antioxidant. Copyright © 2015 Elsevier Ltd. All rights reserved.

Complexometric determination of lanthanum and calcium in lanthanum chromite

International Nuclear Information System (INIS)

Novoselova, I.M.

1989-01-01

Methods of complexometric determination of lanthanum and calcium in lanthanum chromite, based on sequential titration of La and Ca by EDTA solution, where as an indicator eriochrome brack T with NaCl mixture in the ratio of 1:100 is used, are determined. Cr (3) effect was removed by its oxidation up to Cr (6) with perchloric acid; at first La was determined in presence of urotropine buffer, then Ca at pH 9.5-10 in presence of ammonia buffer. For reaction acceleration method of back titration of EDTA excess by zinc salt solution was used. Standard deviation in La and Ca determination is not over 0.2 and 0.1 % respectively

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

Energy Technology Data Exchange (ETDEWEB)

Setz, L.F.G. [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); 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); Moreno, R. [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.

Electrical and stability performance of anode-supported solid oxide fuel cells with strontium- and magnesium-doped lanthanum gallate thin electrolyte

International Nuclear Information System (INIS)

Guo Weimin; Liu Jiang; Zhang Yaohui

2008-01-01

Anode-supported solid oxide fuel cells (SOFCs) comprising NiO-samarium-doped ceria (SDC) (Sm 0.2 Ce 0.8 O 1.9 ) composite anode, thin tri-layer electrolyte, and La 0.6 Sr 0.4 Co 0.8 Fe 0.2 O 3 (LSCF)-La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 3-δ (LSGM) composite cathode were fabricated. The thin tri-layer consisting of an 11-μm thick LSGM electrolyte layer and a 12-μm thick La 0.4 Ce 0.6 O 1.8 (LDC) layer on each side of the LSGM was prepared by centrifugal casting and co-firing technique. The performance of the cells operated with humidified H 2 as fuel and ambient air as oxidant showed a maximum power density of 1.23 W cm -2 at 800 deg. C. A stability test of about 100 h was carried out and some deterioration of output power was observed, while the open circuit voltage (OCV) kept unchanged. Impedance measurements showed that both the electrolyte ohmic resistance and the electrode polarization increased with time and the latter dominated the degradation

Vaporization of Sr- and Mg- doped lanthanum gallate and implications for SOFC

OpenAIRE

Kuncewicz-Kupczyk, W.; Kobertz, D.; Miller, M.; Singheiser, L.; Hilpert, K.

2001-01-01

© The Electrochemical Society, Inc. 2001. All rights reserved. Except as provided under U.S. copyright law, this work may not be reproduced, resold, distributed, or modified without the express permission of The Electrochemical Society (ECS). The archival version of this work was published in Journal of the Electrochemical Society, 148 (2001), E276 - E281.

Elastic properties of Sr- and Mg-doped lanthanum gallate at elevated temperature

Science.gov (United States)

Okamura, T.; Shimizu, S.; Mogi, M.; Tanimura, M.; Furuya, K.; Munakata, F.

The elastic moduli, i.e., Young's modulus, shear modulus and Poisson's ratio, of a sintered La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ bulk have been experimentally determined in the temperature range from room temperature to 1373 K using a resonance technique. Anomalous elastic properties were observed over a wide temperature range from 473 to 1173 K. In the results for internal friction and in X-ray diffraction measurements at elevated temperature, two varieties of structural changes were seen in La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ in the examined temperature range. The results agreed with the findings of a previous crystallographic study of the same composition system by Slater et al. In addition, the temperature range in which a successive structural change occurred in La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ was the same as that exhibiting the anomalous elastic properties. Taking all the results together, it can be inferred that the successive structural change in the significant temperature range is responsible for the elastic property anomaly of La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ.

High performance electrodes for reduced temperature solide oxide fuel cells with doped lanthanum gallate electrolyte. Pt. 1. Ni-SDC cermet anode

Energy Technology Data Exchange (ETDEWEB)

Ohara, S.; Maric, R.; Zhang, X.; Mukai, K.; Fukui, T. [Japan Fine Ceramics Center, Nagoya (Japan); Yoshida, H.; Inagaki, T. [The Kansai Electroc Power Co. Inc., Hyogo (Japan); Miura, K. [Kanden Kakou Co. Ltd., Hyogo (Japan)

2000-03-01

A Ni-samaria-doped ceria (SDC) cermet was selected as the anode material for reduced temperature (800 C) solid oxide fuel cells. The NiO-SDC composite powder, synthesized by spray pyrolysis, was employed as the starting anode powder in this study. The influence of Ni content in Ni-SDC cermets on the electrode performance was investigated in order to create the most suitable microstructures. It was found that anodic polarization was strongly influenced by the Ni content in Ni-SDC cermets. The best results were obtained for anode cermets with Ni content of around 50 vol.%; anodic polarization was about 30 mV at a current density of 300 mA/cm{sup 2}. This high performance seems to be attributable to the microstructure, in which Ni grains form a skeleton with well-connected SDC grains finely distributed over the Ni grains surfaces; such microstructure was also conducive to high stability of the anode. (orig.)

Materiais a base de oxidos com estrutura do tipo perovskite e compositos como anodos de PCES: Propriedades Funcionais e Comportamento Eletroquimico em Celulas com Eletrolitos Solidos a Base de Galatos e Silicatos

Science.gov (United States)

Kolotygin, Vladislav

This work was focused on the analysis of transport, thermomechanical and electrochemical properties of a series of perovskite-like oxide materials and composites for potential applications as anodes of intermediate-temperature solid oxide fuel cells (SOFCs) with lanthanum gallate and silicate solid electrolytes. The primary attention was centered on A(Mn,Nb)O3-delta (A = Sr, Ca) and (La,Sr)(Mn,Ti)O3-based systems, lanthanum chromite substituted with acceptor-type and variable-valence cations, and various Ni-containing cermets. Emphasis was given to phase stability of the materials, their crystal structure, microstructure of porous electrode layers and dense ceramics, electronic conductivity, Seebeck coefficient, oxygen permeability, thermal and chemical induced expansion, and anodic overpotentials of the electrodes deposited onto (La,Sr)(Ga,Mg)O3- and La10(Si,Al)6O27-based electrolyte membranes. In selected cases, roles of oxygen diffusivity, states of the transition metal cations relevant for the electronic transport, catalytically active additives and doped ceria protective interlayers introduced in the model electrochemical cells were assessed. The correlations between transport properties of the electrode materials and electrochemical behavior of porous electrodes showed that the principal factors governing anode performance include, in particular, electronic conduction of the anode compositions and cation interdiffusion between the electrodes and solid electrolytes. The latter is critically important for the silicatebased electrolyte membranes, leading to substantially worse anode properties compared to the electrochemical cells with lanthanum gallate solid electrolyte. The results made it possible to select several anode compositions exhibiting lower area-specific electrode resistivity compared to known analogues, such as (La,Sr)(Cr,Mn)O3-delta.

Electrical and stability performance of anode-supported solid oxide fuel cells with strontium- and magnesium-doped lanthanum gallate thin electrolyte

Energy Technology Data Exchange (ETDEWEB)

Guo Weimin [College of Chemistry, South China University of Technology, Guangzhou 510640, Guangdong (China); Liu Jiang [College of Chemistry, South China University of Technology, Guangzhou 510640, Guangdong (China)], E-mail: jiangliu@scut.edu.cn; Zhang Yaohui [College of Chemistry, South China University of Technology, Guangzhou 510640, Guangdong (China)

2008-05-20

Anode-supported solid oxide fuel cells (SOFCs) comprising NiO-samarium-doped ceria (SDC) (Sm{sub 0.2}Ce{sub 0.8}O{sub 1.9}) composite anode, thin tri-layer electrolyte, and La{sub 0.6}Sr{sub 0.4}Co{sub 0.8}Fe{sub 0.2}O{sub 3} (LSCF)-La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM) composite cathode were fabricated. The thin tri-layer consisting of an 11-{mu}m thick LSGM electrolyte layer and a 12-{mu}m thick La{sub 0.4}Ce{sub 0.6}O{sub 1.8} (LDC) layer on each side of the LSGM was prepared by centrifugal casting and co-firing technique. The performance of the cells operated with humidified H{sub 2} as fuel and ambient air as oxidant showed a maximum power density of 1.23 W cm{sup -2} at 800 deg. C. A stability test of about 100 h was carried out and some deterioration of output power was observed, while the open circuit voltage (OCV) kept unchanged. Impedance measurements showed that both the electrolyte ohmic resistance and the electrode polarization increased with time and the latter dominated the degradation.

Growth and physical properties of highly oriented La-doped (K,Na)NbO3 ferroelectric thin films

International Nuclear Information System (INIS)

Vendrell, X.; Raymond, O.; Ochoa, D.A.; García, J.E.; Mestres, L.

2015-01-01

Lead-free (K,Na)NbO 3 (KNN) and La doped (K,Na)NbO 3 (KNN-La) thin films are grown on SrTiO 3 substrates using the chemical solution deposition method. The effect of adding different amounts of Na and K excess (0–20 mol%) is investigated. The results confirm the necessity of adding 20 mol% excess amounts of Na and K precursor solutions in order to avoid the formation of the secondary phase, K 4 Nb 6 O 17 , as confirmed by X-ray diffraction and Raman spectroscopy. Moreover, when adding a 20 mol% of alkaline metal excess, the thin films are highly textured with out-of-plane preferential orientation in the [100] direction of the [100] orientation of the substrate. Doping with lanthanum results in a decrease of the leakage current density at low electric field, and an increase in the dielectric permittivity across the whole temperature range (80–380 K). Although the (100)-oriented KNN and KNN-La films exhibited rounded hysteresis loops, at low temperatures the films show the typical ferroelectric hysteresis loops. - Highlights: • (K 0.5 Na 0.5 )NbO 3 and [(K 0.5 Na 0.5 ) 0.985 La 0.005 ]NbO 3 thin films have been prepared. • The obtained thin films show an excellent (100) preferred orientation. • Doping with lanthanum results in a decrease of the leakage current density. • The dielectric properties are enhanced when doping with lanthanum

High Tc superconductor-gallate crystal structures

International Nuclear Information System (INIS)

Gallagher, W.J.; Giess, E.A.; Gupta, A.; Laibowitz, R.B.; O'Sullivan, E.J.; Sandstrom, R.L.

1990-01-01

This patent describes a superconductive combination. It comprises a crystalline gallate layer, including a rare earth element or another element selected from the group consisting of Y, La, Bi, and Sc, or combinations of a rare earth element and at least one of the another elements. A superconductive layer thereon, the superconductive layer having a transition temperature in excess of 77 degrees K. and being an oxide material having Cu-O planes whose Cu and O atoms align with Ga and O atoms in the gallate layer

Thermoelectric properties of non-stoichiometric lanthanum sulfides

International Nuclear Information System (INIS)

Shapiro, E.; Danielson, L.R.

1983-01-01

The lanthanum sulfides are promising candidate materials for high-efficiency thermoelectric applications at temperatures up to 1300 0 C. The nonstoichiometric lanthanum sulfides (LaS /SUB x/ , where 1.33 2 //rho/ can be chosen. The thermal conductivity remains approximately constant with stoichiometry, so a material with an optimum value of α 2 //rho/ should possess the optimum figure-of-merit. Data for the Seebeck coefficient and electrical resistivity of non-stoichiometric lanthanum sulfides is presented, together with structural properties of these materials

Adsorption of lithium-lanthanum films on the (100) tungsten face

International Nuclear Information System (INIS)

Gupalo, M.S.; Smereka, T.P.; Babkin, G.V.; Palyukh, B.M.

1982-01-01

The method of contact potential difference is used to investigate combined adsorption of lithium-lanthanum on the (100) tungsten face. The data on work functions and thermal stability of mixed lithium-lanthanum films are obtained. The presence of lanthanum on the W(100) surface leads to appearance of minimum of work functions unobserved for the Li-W(100) system, minimum work functions and optimum lithium concentration in a mixed film are decreased at initial lanthanum coating increase. The presence of lanthanum on the W(100) face leads to lithium adsorption heat decrease

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

Science.gov (United States)

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

2015-02-03

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.

Lanthanum deposition corresponds to white lesions in the stomach.

Science.gov (United States)

Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Kawano, Seiji; Kawahara, Yoshiro; Kimoto, Katsuhiko; Okada, Hiroyuki

2018-05-23

Although lanthanum deposition in the stomach has been most frequently reported to occur as white lesions, no study has investigated whether the white lesions observed during esophagogastroduodenoscopy are truly lanthanum-related. Here, we retrospectively investigated the amount of lanthanum in endoscopic biopsy specimens. We reviewed four patients showing gastric white spots or annular whitish mucosa in the gastric white lesions (Bw) and peripheral mucosa where the white substance was not endoscopically observed (Bp) during biopsy. We also reviewed three patients with diffuse whitish mucosa and three patients with no whitish lesions. We performed scanning electron microscopy and energy dispersive X-ray spectrometry to quantify the lanthanum elements (wt%) in the biopsy specimens. The amount of lanthanum in the Bw ranged from 0.15-0.31 wt%, whereas that of Bp was 0.00-0.13 wt%. The difference was statistically significant (P < 0.05). The amount of lanthanum in the Bw, endoscopically presented with white spots or annular whitish mucosa, was significantly higher than that of no whitish lesions (0.05-0.14 wt%, P < 0.05). The amount of lanthanum was also higher in the diffuse whitish mucosa (0.21-0.23 wt%) compared with no whitish lesions (P < 0.01). This study is the first to reveal that pathological lanthanum deposition corresponds to the endoscopically observed white lesions in the gastric mucosa. Therefore, during esophagogastroduodenoscopy, physicians should pay attention to possible presence of white lesions in patients treated with oral lanthanum carbonate to ensure prompt identification of associated issues. Copyright © 2018 Elsevier GmbH. All rights reserved.

Mechanical properties of dense to porous alumina/lanthanum hexaaluminate composite ceramics

International Nuclear Information System (INIS)

Negahdari, Zahra; Willert-Porada, Monika; Pfeiffer, Carolin

2010-01-01

For development of new composite materials based on lanthanum hexaaluminate and alumina ceramics, a better understanding of the microstructure-properties relationship is essential. In this paper, attention was focused on the evaluation of mechanical properties of lanthanum hexaaluminate/alumina particulate composite. It was found out that the lanthanum hexaaluminate content plays a critical role in determination of the microstructure and mechanical properties of the composite ceramics. In situ formation of plate-like lanthanum hexaaluminate in the ceramic matrix was accompanied with formation of pores so that the microstructure shifted from dense to porous. Increasing the lanthanum hexaaluminate content up to a certain value enhanced the fracture toughness, increased the hardness, and increased the elastic modulus of the composite materials. Further increase in the lanthanum hexaaluminate content degraded the hardness as well as the elastic modulus of composite ceramics. The influence of lanthanum hexaaluminate on mechanical properties was described by means of microstructure, porosity, and intrinsic characteristics of lanthanum hexaaluminate.

Applications of Superconductivity to Avionics: Proceedings of a Conference Held in Bath, England on May 7-8, 1990 (Les Applications de la Supraconductivite dans le Domains de l’Avionique)

Science.gov (United States)

1990-10-01

old. Lanthanum Gallate may avoid this problem. The progress has been rapid since the discovery Sapphire has also been studied, but results were of...surface resistance 43 times lower than that of Cryostat copper has been measured by this method for YBCO deposited on Lanthanum Aluminate (Ref. 5...temperature and 10 GHz. It At the present time, Lanthanum Aluminate seems varies like the square root of the frequency while to be the best candidate. Its

Electrical characterization and impedance response of lanthanum doped barium titanate ceramics

Directory of Open Access Journals (Sweden)

Mančić D.

2008-01-01

Full Text Available The dielectric permittivity and dissipation factor of La-doped and undoped BaTiO3 were investigated as a function of frequency and temperature. The impedance response was used to study the electrical properties of La-doped BaTiO3 over the temperature range from room temperature (RT to 350°C. La-doped and undoped BaTiO3, obtained by a modified Pechini method, were sintered in air at 1300°C for 2 and 16 hours. The impedance spectra were analyzed in terms of equivalent circuits involving resistors, capacitors and constant phase elements (CPE. The most suitable electrical circuit for the interpretation of experimental results is found to be the equivalent circuit consisting of resistors and CPE elements which replace the capacitor elements. The contribution of grain boundary resistance to the total resistance of a system is remarkable at low temperature. Dielectric permittivity of doped BaTiO3 was in the range of 8000 to 12000 at 1 kHz and the dissipation factor was less than 1%.

Electrochemical properties of lanthanum nitride with calcium nitride additions

International Nuclear Information System (INIS)

Lesunova, R.P.; Fishman, L.S.

1986-01-01

This paper reports on the electrochemical properties of lanthanum nitride with calcium nitride added. The lanthanum nitride was obtained by nitriding metallic lanthanum at 870 K in an ammonia stream. The product contained Cl, Pr, Nd, Sm, Fe, Ca, Cu, Mo, Mg, Al, Si, and Be. The calcium nitride was obtained by nitriding metallic calcium in a nitrogen stream. The conductivity on the LaN/C 3 N 2 system components are shown as a function of temperature. A table shows the solid solutions to be virtually electronic conductors and the lanthanum nitride a mixed conductor

Review on dielectric properties of rare earth doped barium titanate

International Nuclear Information System (INIS)

Ismail, Fatin Adila; Osman, Rozana Aina Maulat; Idris, Mohd Sobri

2016-01-01

Rare earth doped Barium Titanate (BaTiO_3) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO_3 (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO_3 downshifted the Curie temperature (T_C). Transition temperature also known as Curie temperature, T_C where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-doped BaTiO_3, Er-doped BaTiO_3, Sm-doped BaTiO_3, Nd-doped BaTiO_3 and Ce-doped BaTiO_3 had been proved to increase and the transition temperature or also known as T_C also lowered down to room temperature as for all the RE doped BaTiO_3 except for Er-doped BaTiO_3.

Kinetic Monte Carlo model of defect transport and irradiation effects in La-doped CeO2

International Nuclear Information System (INIS)

Oaks, Aaron; Yun Di; Ye Bei; Chen Weiying; Stubbins, James F.

2011-01-01

A generalized Kinetic Monte Carlo code was developed to study oxygen mobility in UO 2 type nuclear fuels, using lanthanum doped CeO 2 as a surrogate material. Molecular Statics simulations were performed using interatomic potentials for CeO 2 developed by Gotte, Minervini, and Sayle to calculate local configuration-dependent oxygen vacancy migration energies. Kinetic Monte Carlo simulations of oxygen vacancy diffusion were performed at varying lanthanum dopant concentrations using the developed generalized Kinetic Monte Carlo code and the calculated configuration-dependent migration energies. All three interatomic potentials were found to confirm the lanthanum trapping effect. The results of these simulations were compared with experimental data and the Gotte potential was concluded to yield the most realistic diffusivity curve.

Preparation and Characterization of Lanthanum Carbonate Octahydrate for the Treatment of Hyperphosphatemia

Directory of Open Access Journals (Sweden)

Anqi He

2013-01-01

Full Text Available We proposed a new approach to prepare lanthanum carbonate via reactions between lanthanum chloride and NaHCO3. In the reaction, small amount of NaHCO3 solution was firstly added to the acidic lanthanum chloride solution to generate lanthanum carbonate nuclei and then NaHCO3 is added to the lanthanum chloride at a constant speed. This approach makes both precipitation reaction and neutralization reaction take place simultaneously. Consequently, lanthanum carbonate is produced at low pH environment (pH below 4.0 so that the risk of generating lanthanum carbonate hydroxide is reduced. The product of the above reaction is validated by EDTA titration, elemental analysis, and XRD characterization. In addition, we established a FTIR spectroscopic method to identify La(OHCO3 from La2(CO32·8H2O. Lanthanum carbonate exhibits considerable ability to bind phosphate.

Preparation of lanthanum sulfide nanoparticles by thermal decomposition of lanthanum complex

Institute of Scientific and Technical Information of China (English)

LI Peisen; LI Huanyong; JIE Wanqi

2011-01-01

γ-La2S3 nanoparticles were successfully prepared by thermal decomposition of lanthanum complex La(Et2S2CN)3·phen at low temperature. The obtained sample was characterized by the X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and element analysis. The decomposition mechanism of lanthanum complex was studied by thermogravimetric analyses (TGA). The results showed that the obtained samples were cubic phase particles with uniform sizes among 10-30 nm and γ-La2S3 was prepared by decomposition of La(Et2S2CN)3 phen via La4(Et2S2CN)3 as an intermediate product. The band gap of γ-La2S3 was 2.97 eV, which was bigger than bulk crystal because of pronounced quantum confinement effect.

Kinetics of the transformation of n-propyl gallate and structural analogs in the perfused rat liver

International Nuclear Information System (INIS)

Eler, Gabrielle Jacklin; Santos, Israel Souza; Giaretta de Moraes, Amarilis; Mito, Márcio Shigueaki; Comar, Jurandir Fernando; Peralta, Rosane Marina; Bracht, Adelar

2013-01-01

n-Propyl gallate and its analogs are used in foods and other products to prevent oxidation. In the liver the compound exerts several harmful effects, especially gluconeogenesis inhibition. The mode of transport and distribution of n-propyl gallate and its kinetics of biotransformation have not yet been investigated. To fill this gap the transformation, transport and distribution of n-propyl gallate and two analogs were investigated in the rat liver. Isolated perfused rat liver was used. n-Propyl gallate, methyl gallate, n-octyl gallate and transformation products were quantified by high pressure-liquid chromatography coupled to fluorescence detection. The interactions of n-propyl gallate and analogs with the liver presented three main characteristics: (1) the hydrolytic release of gallic acid from n-propyl gallate and methyl gallate was very fast compared with the subsequent transformations of the gallic acid moiety; (2) transport of the esters was very fast and flow-limited in contrast to the slow and barrier-limited transport of gallic acid; (3) the apparent distribution volume of n-propyl gallate, but probably also of methyl gallate and n-octyl gallate, greatly exceeded the water space in the liver, contrary to the gallic acid space which is smaller than the water space. It can be concluded that at low portal concentrations (< 50 μM) the gallic acid esters are 100% extracted during a single passage through the liver, releasing mainly gallic acid into the systemic circulation. For the latter a considerable time is required until complete biotransformation. The exposure of the liver to the esters, however, is quite prolonged due to extensive intracellular binding. - Highlights: • The liver binds very strongly n-propyl gallate and releases basically gallic acid. • n-propyl gallate and analogs undergo concentrative flow-limited distribution. • Gallic acid undergoes barrier-limited distribution and is slowly transformed. • The long residence time of n

Kinetics of the transformation of n-propyl gallate and structural analogs in the perfused rat liver

Energy Technology Data Exchange (ETDEWEB)

Eler, Gabrielle Jacklin; Santos, Israel Souza; Giaretta de Moraes, Amarilis; Mito, Márcio Shigueaki; Comar, Jurandir Fernando; Peralta, Rosane Marina; Bracht, Adelar, E-mail: adebracht@uol.com.br

2013-11-15

n-Propyl gallate and its analogs are used in foods and other products to prevent oxidation. In the liver the compound exerts several harmful effects, especially gluconeogenesis inhibition. The mode of transport and distribution of n-propyl gallate and its kinetics of biotransformation have not yet been investigated. To fill this gap the transformation, transport and distribution of n-propyl gallate and two analogs were investigated in the rat liver. Isolated perfused rat liver was used. n-Propyl gallate, methyl gallate, n-octyl gallate and transformation products were quantified by high pressure-liquid chromatography coupled to fluorescence detection. The interactions of n-propyl gallate and analogs with the liver presented three main characteristics: (1) the hydrolytic release of gallic acid from n-propyl gallate and methyl gallate was very fast compared with the subsequent transformations of the gallic acid moiety; (2) transport of the esters was very fast and flow-limited in contrast to the slow and barrier-limited transport of gallic acid; (3) the apparent distribution volume of n-propyl gallate, but probably also of methyl gallate and n-octyl gallate, greatly exceeded the water space in the liver, contrary to the gallic acid space which is smaller than the water space. It can be concluded that at low portal concentrations (< 50 μM) the gallic acid esters are 100% extracted during a single passage through the liver, releasing mainly gallic acid into the systemic circulation. For the latter a considerable time is required until complete biotransformation. The exposure of the liver to the esters, however, is quite prolonged due to extensive intracellular binding. - Highlights: • The liver binds very strongly n-propyl gallate and releases basically gallic acid. • n-propyl gallate and analogs undergo concentrative flow-limited distribution. • Gallic acid undergoes barrier-limited distribution and is slowly transformed. • The long residence time of n

Small polaron conduction in lead modified lanthanum ferrite ceramics

Energy Technology Data Exchange (ETDEWEB)

Bhargav, K.K.; Ram, S.; Majumder, S.B., E-mail: subhasish@matsc.iitkgp.ernet.in

2015-07-25

Highlights: • La{sub 0.8}Pb{sub 0.2}FeO{sub 3} (ε{sub r} ∼ 30,000) shows higher dielectric constant than LaFeO{sub 3} (∼14,000). • Lower A-site dopant content, the dielectric maxima shift to higher temperature. • The frequency dependence of ε{sub r} and tan δ vs. temperature exhibit CDC like behavior. • R{sub g} and R{sub gb} of Pb modified LaFeO{sub 3} follow small polaron hopping conduction model. - Abstract: In the present work we have illustrated the physics of the electrical characteristics of nanocrystalline La{sub 1−x}Pb{sub x}FeO{sub 3,} (0 ⩽ x ⩽ 0.2) powder prepared using auto-combustion synthesis. The effect of lead doping on the dielectric, impedance and ac conductivity characteristics of lanthanum ferrite has systematically been investigated. The synthesized powders were phase pure and crystallized into centro-symmetric Pnma space group. As compared to pure LaFeO{sub 3} ceramics (dielectric constant ∼ 14,000), the dielectric constant is grossly increased (∼30,000) in Pb doped LaFeO{sub 3}. The temperature dependence of dielectric constant of 10.0 at.% Pb doped LaFeO{sub 3} exhibits dielectric maxima similar to that observed in ferroelectric ceramics with non-centrosymmetric point group. For La{sub 0.8}Pb{sub 0.2}FeO{sub 3} ceramics, the frequency dependence of the dielectric constant and loss tangent at various temperatures (300–450 K) exhibit typical colossal dielectric constant (CDC) like behavior. From the impedance spectroscopy we have estimated the grain and grain boundary resistance and capacitance of Pb doped LaFeO{sub 3} that follow a small polaron hopping conduction model. Long range movement of the charge carriers govern the CDC behavior.

Process for obtaining cobalt and lanthanum nickelate

International Nuclear Information System (INIS)

Tapcov, V.; Samusi, N.; Gulea, A.; Horosun, I.; Stasiuc, V.; Petrenco, P.

1999-01-01

The invention relates to the process for obtaining polycrystalline ceramics of cobalt and lanthanum nickelate with the perovskite structure from coordinative hetero metallic compounds. The obtained products can be utilized in the industry in the capacity of catalysts. Summary of the invention consists in obtaining polycrystalline ceramics LaCoO 3 and LaNiO 3 with the perovskite structure by pyrolysis of the parent compounds, namely, the coordinative hetero metallic compounds of the lanthanum cobalt or lanthanum nickel. The pyrolysis of the parent compound runs during one hour at 800 C. The technical result of the invention consists in lowering the temperature of the parent compound pyrolysis containing the precise ratio of metals necessary for ceramics obtaining

Thermophysical Properties of Matter - the TPRC Data Series. Volume 5. Specific Heat - Nonmetallic Solids

Science.gov (United States)

1970-01-01

114 35 Lanthanum Oxide La 2O3 . . . . . . . . . . . . . . . .. . . . 118 xviii Grouping of Materials and List of Figures and Tables 2. OXIDES...triebloride hiexahyc rate (Er Cls 611 20 5 822 Freon 20 (see Chloroform) Erbium gallate (see Trierbium pentagallium dodecaoxide) Freon 21 (Cl 2CHr) 6 212...FexSe) 5 530 Kalium (see Potassium) Iron silicides: Krypton 6 34 FeSi 5 577 Lanthana (see Lanthanum oxide) Fe3Si 5 583 Lanthanum 4 110 Fe6Si3 5 580

Antitumor evaluation of epigallocatechin gallate by colorimetric methods

Energy Technology Data Exchange (ETDEWEB)

Baek, Soon Ok [Korean Ginseng and Tobacco Research institute, Daejon (Korea, Republic of); Kim, Il Kwang; Baek, Seung Hwa; Han, Du Seok [Wonkwang Unvi., Iksan (Korea, Republic of)

1998-08-01

In the present study, we were evaluated cytotoxic effects of epigallocatechin gallate in human skin melanoma cells such as HTB-69. The light microscopic study showed morphological changes of the treated cells. Disruptions in cell organelles were determined by colorimetric methods; 3-(4,5-dimethyl thiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, neutral red (NR) assay and sulforhodamine B protein (SRB) as-say. These results suggest that epigallocatechin gallate retains a potential antitumor activity.

Methyl gallate is a natural constituent of maple (Genus Acer) leaves.

Science.gov (United States)

Abou-Zaid, Mamdouh M; Lombardo, Domenic A; Nozzolillo, Constance

2009-01-01

Methyl gallate was found in ethanolic extracts of red maple (Acer rubrum L.), silver maple (A. saccharinum L.) and sugar maple (A. saccharum Marsh) leaves, but more was present in methanolic extracts. The increased amount of methyl gallate in methanolic extracts was accompanied by a disappearance of m-digallate. It is concluded that only some of the methyl gallate detected in methanolic extracts is an artefact as a result of methanolysis of m-digallate. Its presence in ethanolic extracts is evidence that it is also a natural constituent of maple leaves.

High-temperature corrosion of lanthanum in equimole mixture of sodium and potassium chlorides

International Nuclear Information System (INIS)

Kochergin, V.P.; Obozhina, R.N.; Dragoshanskaya, T.I.; Startsev, B.P.

1984-01-01

Results of investigation into the process of lanthanum corrosion in the molted equimole NaCl-KCl mixture after the change of test time, temperature and lanthanum trichloride were summarized. It was shown that polarization of lanthanum anode in equimole NaCl-KCl melt is controlled by La 3+ diffusion from near-electrode layer to electrolyte depth, which results in decrease of corrosion rate in time. The established electrochemical properties of metallic lanthanum in equimole NaCl-KCl mixture must be considered when improving the technology of electrochemical production of lanthanum or its alloys of molten chlorides of lanthanum and alkaline metals

Separation of lanthanum from nuclear fuel solutions by high performance liquid chromatography

International Nuclear Information System (INIS)

Lazar, G. C.; Petre, M.; Androne, G.; Benga, A.

2016-01-01

This paper presents the separation of uranium, praseodymium and lanthanum from nuclear fuel solutions by high performance liquid chromatography (HPLC). The aim of this study is to establish a minimum concentration of lanthanum which can be analyzed by high performance liquid chromatography, and also to study the effect of uranium concentration on the separation of praseodymium and lanthanum. Optimum gradient mode was established for mixture standard stoc solutions with uranium in a concentration of 1 mg/ml, praseodymium and lanthanum in a concentration range of 1-5 μg/ml from each element. These conditions were applied for the separation of lanthanum from a nuclear fuel solution in which praseodymium and lanthanum were added in a concentration of 3 μg/ml from each element. The elution behavior of lanthanum as a function of the pH and the concentration of the mobile phase, using a mixture of 1-octanesulfonic acid sodium salt with a-hidroxyisobutiric acid is presented. (authors)

The effect of lanthanum applications on drought tolerance in barley

International Nuclear Information System (INIS)

Buckingham, S.; Maheswaran, J.; Peverill, K.; Meehan, B.; Stokes, J.

1998-01-01

Full text: Glasshouse investigations carried out by the authors on both perlite and soil, have repeatedly shown that several plant species, when treated with lanthanum, retain greater amounts of moisture under water stressed conditions. Dry matter increases under water stress have been observed in some cases. Barley plants watered to 50% field capacity, and show-ing signs of water stress, yielded 18% more dry matter when treated with 5 kg/ha and 10 kg/ha of lanthanum than control plants (P<0.05). The results of these experiments suggest that increased dry matter production in crops under periods of water stress, is likely when previously treated with lanthanum. Consequently, it is conceivable that lanthanum may have potential as an agent that induces drought tolerance in grain crops, grown in low rainfall areas. Subsequent field trials using barley as a test crop at Walpeup, in the Mallee region of Victoria have shown that in a below average rainfall year, combined soil and foliar applications of lanthanum can significantly increase grain yield. This effect was not evident when barley grown on the same soil type was treated with lanthanum under above average rainfall conditions

Rare earth doped nanoparticles in organic and inorganic host materials for application in integrated optics

NARCIS (Netherlands)

Dekker, R.; Hilderink, L.T.H.; Diemeer, Mart; Stouwdam, J.W.; Sudarsan, V; van Veggel, F.C.J.M.; Driessen, A.; Worhoff, Kerstin; Misra, D; Masscher, P.; Sundaram, K.; Yen, W.M.; Capobianco, J.

2006-01-01

The preparation and the optical properties of lanthanum fluoride (LaF3) nanoparticles doped with erbium and neodymium will be discussed. Organic and inorganic materials in the form of polymers and sol-gels were used to serve as the hosts for the inorganic nanoparticles, respectively. The organic

Characterization of the perovskite La0,9Sr0,1Ga0,2O2,85 prepared by cation complexation

International Nuclear Information System (INIS)

Reis, S.L.; Grosso, R.L.; Muccillo, E.N.S.

2012-01-01

Strontium and magnesium doped lanthanum gallate exhibits perovskite-type structure and high ionic conductivity. Other features of this ceramic material are large electrolytic regime and negligible electronic conductivity. These characteristics are responsible for the potential use of this solid electrolyte in solid oxide fuel cells operating at intermediate temperatures (~∼500-700 deg C). In this work, the composition La 0.9 Sr 0.1 Ga 0.8 Mg 0.2 O 2.85 was prepared by the cation complexation technique aiming to obtain powder and sintered specimens with good chemical and structural homogeneities. X-ray diffraction results evidence that single phase was obtained, within the limitations of the technique, in samples sintered at 1350 deg C/4 h, with relative density above 92%. (author)

Substitutional Doping for Aluminosilicate Mineral and Superior Water Splitting Performance

Science.gov (United States)

Zhang, Yi; Fu, Liangjie; Shu, Zhan; Yang, Huaming; Tang, Aidong; Jiang, Tao

2017-07-01

Substitutional doping is a strategy in which atomic impurities are optionally added to a host material to promote its properties, while the geometric and electronic structure evolution of natural nanoclay mineral upon substitutional metal doping is still ambiguous. This paper first designed an efficient lanthanum (La) doping strategy for nanotubular clay (halloysite nanotube, HNT) through the dynamic equilibrium of a substitutional atom in the presence of saturated AlCl3 solution, and systematic characterization of the samples was performed. Further density functional theory (DFT) calculations were carried out to reveal the geometric and electronic structure evolution upon metal doping, as well as to verify the atom-level effect of the La doping. The CdS loading and its corresponding water splitting performance could demonstrate the effect of La doping. CdS nanoparticles (11 wt.%) were uniformly deposited on the surface of La-doped halloysite nanotube (La-HNT) with the average size of 5 nm, and the notable photocatalytic hydrogen evolution rate of CdS/La-HNT reached up to 47.5 μmol/h. The results could provide a new strategy for metal ion doping and constructive insight into the substitutional doping mechanism.

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

Science.gov (United States)

Singh, Prabhakar; Ruka, Roswell J.

1995-01-01

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

Lanthanum trilactate: Vibrational spectroscopic study - infrared/Raman spectroscopy

Czech Academy of Sciences Publication Activity Database

Švecová, M.; Novák, Vít; Bartůněk, V.; Člupek, M.

2016-01-01

Roč. 87, Nov (2016), s. 123-128 ISSN 0924-2031 Institutional support: RVO:61388963 Keywords : lanthanum trilactate * tris(2-hydroxypropanoato-O1,O2) * lanthanum tris[2-(hydroxy-kappa O)propanoato-kappa O] * Raman spectra * infrared spectra * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.740, year: 2016

Microstructural characterization of composite cobaltite and lanthanum-based ceria for use as fuel cell cathodes

International Nuclear Information System (INIS)

Rodrigues, E.R.T.; Nascimento, R.M.; Miranda, A.C. de; Lima, A.M. de; Macedo, D.A.

2016-01-01

Fuel cells are devices that convert chemical energy into electricity via redox reactions. In this work, the lanthanum cobaltite doped with strontium and iron (La_0_,_6Sr_0_,_4Co_0_,_2Fe_0_,_8O_3 - LSCF) a traditional cathodes material of the fuel cell was mixed with an electrolyte material (composite) to the base ceria doped with gadolinia and a eutectic mixture of lithium carbonates and sodium (CGO-NLC). The powders of LSCF and CGO-NLC were obtained by the citrate method and mixed to obtain a composite cathode. Samples obtained by uniaxial pressure between 5 and 10 MPa were sintered at 1100°C and investigated by X-ray diffraction, scanning electron microscopy and micro hardness test. A symmetric cell cathode / electrolyte / cathode, obtained by co-pressing and co-sintering was investigated by electron microscopy. The results indicated that the composite is chemically stable up to the sintering temperature used. The hardness ranged between 51 and 227 HV. (author)

Hydrophilic block copolymer-directed growth of lanthanum hydroxide nano-particles

Energy Technology Data Exchange (ETDEWEB)

Bouyer, F.; Sanson, N.; Gerardin, C. [Laboratoire de Materiaux Catalytiques et Catalyse en Chimie Organique, UMR 5618 CNRS-ENSCM-UM1, FR 1878, Institut Gerhardt, 34 - Montpellier (France); Destarac, M. [Centre de Recherches Rhodia Aubervilliers, 93 - Aubervilliers (France)

2006-03-15

Stable hairy lanthanum hydroxide nano-particles were synthesized in water by performing hydrolysis and condensation reactions of lanthanum cations in the presence of double hydrophilic poly-acrylic acid-b-polyacrylamide block copolymers (PAA-b-PAM). In the first step, the addition of asymmetric PAA-b-PAM copolymers (M{sub w,PAA} {<=} M{sub w,PAM}) to lanthanum salt solutions, both at pH = 5.5, induces the formation of monodispersed micellar aggregates, which are predominantly isotropic. The core of the hybrid aggregates is constituted of a lanthanum polyacrylate complex whose formation is due to bidentate coordination bonding between La{sup 3+} and acrylate groups, as shown by ATR-FTIR experiments and pH measurements. The size of the micellar aggregates depends on the molecular weight of the copolymer but is independent of the copolymer to metal ratio in solution. In the second step, the hydrolysis of lanthanum ions is induced by addition of a strong base such as sodium hydroxide. Either flocculated suspensions or stable anisotropic or spherical nano-particles of lanthanum hydrolysis products were obtained depending on the metal complexation ratio [acrylate]/[La]. The variation of that parameter also enables the control of the size of the core-corona nano-particles obtained by lanthanum hydroxylation. The asymmetry degree of the copolymer was shown to influence both the size and the shape of the particles. Elongated particles with a high aspect ratio, up to 10, were obtained with very asymmetric copolymers (M{sub w,PAM}/M{sub w,PAA}{>=}10) while shorter rice grain-like particles were obtained with a less asymmetric copolymer. The asymmetry degree also influences the value of the critical metal complexation degree required to obtain stable colloidal suspensions of polymer-stabilized lanthanum hydroxide. (authors)

Cytocompatibility of a free machining titanium alloy containing lanthanum.

Science.gov (United States)

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

2009-09-01

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

A Density Functional Theory Study of Doped Tin Monoxide as a Transparent p-type Semiconductor

KAUST Repository

Bianchi Granato, Danilo

2012-05-01

In the pursuit of enhancing the electronic properties of transparent p-type semiconductors, this work uses density functional theory to study the effects of doping tin monoxide with nitrogen, antimony, yttrium and lanthanum. An overview of the theoretical concepts and a detailed description of the methods employed are given, including a discussion about the correction scheme for charged defects proposed by Freysoldt and others [Freysoldt 2009]. Analysis of the formation energies of the defects points out that nitrogen substitutes an oxygen atom and does not provide charge carriers. On the other hand, antimony, yttrium, and lanthanum substitute a tin atom and donate n-type carriers. Study of the band structure and density of states indicates that yttrium and lanthanum improves the hole mobility. Present results are in good agreement with available experimental works and help to improve the understanding on how to engineer transparent p-type materials with higher hole mobilities.

Nanostructured Lanthanum Halides and CeBr3 for Nuclear Radiation and Detection

International Nuclear Information System (INIS)

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

2010-01-01

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 3 :Ce oleic acid-based nanocomposite exhibits a photopeak when exposed to 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 3 :Ce-loaded sample have been made using 137 Cs sources. Figure 2 shows an energy spectrum acquired for CeF 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 3 crystals do not have a self-activity component as strong as the lanthanum halides. The radioactive 0.090% 138 La component of lanthanum leads to significant self-activity, which will be a problem for very large detector volumes. Yet a significant

Epitaxial Garnets and Hexagonal Ferrites.

Science.gov (United States)

1982-04-20

guide growth of the epitaxial YIG films. Aluminum or gallium substitu- tions for iron were used in combination with lanthanum substitutions for yttrium... gallate spinel sub- strates. There was no difficulty with nucleation in the melt and film quality appeared to be similar to that observed previously...hexagonal ferrites. We succeeded in growing the M-type lead hexaferrite (magnetoplumbite) on gallate spinel substrates. We found that the PbO-based

Method of microbially producing metal gallate spinel nano-objects, and compositions produced thereby

Science.gov (United States)

Duty, Chad E.; Jellison, Jr., Gerald E.; Love, Lonnie J.; Moon, Ji Won; Phelps, Tommy J.; Ivanov, Ilia N.; Kim, Jongsu; Park, Jehong; Lauf, Robert

2018-01-16

A method of forming a metal gallate spinel structure that includes mixing a divalent metal-containing salt and a gallium-containing salt in solution with fermentative or thermophilic bacteria. In the process, the bacteria nucleate metal gallate spinel nano-objects from the divalent metal-containing salt and the gallium-containing salt without requiring reduction of a metal in the solution. The metal gallate spinel structures, as well as light-emitting structures in which they are incorporated, are also described.

Influence of La doping on structural and dielectric properties of SrBi2Nb2O9 ceramics

Science.gov (United States)

Verma, Maya; Sreenivas, K.; Gupta, Vinay

2009-01-01

Lanthanum doped SrBi2Nb2O9 ceramics with the chemical formula SrBi2-xLaxNb2O9 (SBLN) (x =0-0.5) have been prepared through conventional solid state route. X-ray diffraction reveals the shrinkage of unit cell of strontium bismuth niobate with incorporation of La3+ dopant, having no lone pair electrons. Shifting of Raman phonon modes indicates the reduced rattling space of NbO6 octahedra with increase in La doping concentration. 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 °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).

Influence of La doping on structural and dielectric properties of SrBi2Nb2O9 ceramics

International Nuclear Information System (INIS)

Verma, Maya; Sreenivas, K.; Gupta, Vinay

2009-01-01

Lanthanum doped SrBi 2 Nb 2 O 9 ceramics with the chemical formula SrBi 2-x La x Nb 2 O 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 3+ dopant, having no lone pair electrons. Shifting of Raman phonon modes indicates the reduced rattling space of NbO 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)

Conductivity and hydration trends in disordered fluorite and pyrochlore oxides: A study on lanthanum cerate–zirconate based compounds

DEFF Research Database (Denmark)

Besikiotis, Vasileios; Ricote, Sandrine; Jensen, Molly Hjorth

2012-01-01

In the present contribution we discuss the influence of order/disorder on the concentration and mobility of ionic charge carriers in undoped and acceptor (calcium) doped fluorite and pyrochlore structured lanthanum cerate–zirconate solid solutions: (La1−yCay)2(Ce1−xZrx)2O7−δ (y=0, 0.02, 0.10; x=0...... enthalpy becomes more exothermic with higher cerium content, i.e. with more disordered materials. The proton conductivity decreases upon acceptor substitution of La3+ with Ca2+ which is attributed to trapping of the charge carriers by the effectively negative acceptor....

Electron paramagnetic resonance of V4+ in the lanthanum and cerium orthophosphates

International Nuclear Information System (INIS)

Lima, J.C. de.

1983-11-01

The Electron Paramagnetic Resonance (EPR) spectrum of V 4+ was investigated in polycrystalline samples of lanthanum orthophosphate (LaPO 4 ) and cerium orthophosphate (CePO 4 ) doped with 0.2 wt % vanadium pentoxide (V 2 O 5 ). Measurements were performed at room temperature and 9.5 GHz. In LaPO 4 , two non-equivalent axial sites were inferred from the EPR spectra. The most stable of these two sites is probably substitutional. In CePO 4 , a single axial spectrum was observed. It was attributed to V 4+ in substitutional sites. A central, wide line was also seen; it was attributed to ferromagnetic clusters of vanadium ions. Photoacoustic absorption spectra were also recorded for the two compounds. The EPR and photoacoustic absorption data, when analyzed using the molecular orbital theory, show that for both lanthanum orthophosphate and cerium orthophosphate the ground orbital (d sub(x) 2 sub(-y) 2) of the unpainred electron is purely ionic, while the excited orbitals d sub(xy) and d sub(xz,yz) are partly covalent. The degree of covalency is higher for the d sub(xy) orbital. Finally, it should be pointed out that part of the theory used for the interpretation of the EPR and photoacoustic absorption spectra (study of the ligand field splitting of a d orbital in a site of distorted capped antiprism structure) was developed by the author in the present work and is therefore an original contribution. (Author) [pt

Bio-accumulation of lanthanum from lanthanum modified bentonite treatments in lake restoration

NARCIS (Netherlands)

Waajen, G.; Van Oosterhout, F.; Lürling, M.

2017-01-01

Abstract Lanthanum (La) modified bentonite (LMB) is one of the available mitigating agents used for the reduction of the phosphorus (P) recycling in eutrophic lakes. The potential toxicity of the La from LMB to aquatic organisms is a matter of concern. In this study the accumulation of La was

Electrochemical reduction of lanthanum trichloride in a molten equimolar mixture of sodium and potassium chlorides

Energy Technology Data Exchange (ETDEWEB)

Glagolevskaya, A.L.; Kuznetsov, S.A.; Polyakov, E.G.; Stangrit, P.T.

1987-09-20

The authors used linear voltamperometry for the investigation of the mechanism for the cathodic reduction of lanthanum. The mechanism for the cathodic reduction of lanthanum chloride in molten equimolar NaCl-KCl may be seen as consisting of a slow irreversible electrode reaction with a subsequent rapid irreversible chemical reaction. Lanthanum ions in a lower oxidation state were not found upon the prolonged maintenance of metallic lanthanum in molten NaCl-KCl-LaCl/sub 3/. Only an increase in the concentration of lanthanum(III) chloride in the melt was noted. The appearance of oxygen anions in the melt does not lead to a change in the mechanism of the cathodic reduction of lanthanum chloride but reduces the concentration of this chloride due to the formation of lanthanum oxochloride which is insoluble in the melt.

Uncovering the Lactobacillus plantarum WCFS1 Gallate Decarboxylase Involved in Tannin Degradation

Science.gov (United States)

Jiménez, Natalia; Curiel, José Antonio; Reverón, Inés; de las Rivas, Blanca

2013-01-01

Lactobacillus plantarum is a lactic acid bacterium able to degrade tannins by the subsequent action of tannase and gallate decarboxylase enzymes. The gene encoding tannase had previously been identified, whereas the gene encoding gallate decarboxylase is unknown. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of gallic-acid induced L. plantarum extracts showed a 54-kDa protein which was absent in the uninduced cells. This protein was identified as Lp_2945, putatively annotated UbiD. Homology searches identified ubiD-like genes located within three-gene operons which encoded the three subunits of nonoxidative aromatic acid decarboxylases. L. plantarum is the only bacterium in which the lpdC (lp_2945) gene and the lpdB and lpdD (lp_0271 and lp_0272) genes are separated in the chromosome. Combination of extracts from recombinant Escherichia coli cells expressing the lpdB, lpdC, and lpdC genes demonstrated that LpdC is the only protein required to yield gallate decarboxylase activity. However, the disruption of these genes in L. plantarum revealed that the lpdB and lpdC gene products are essential for gallate decarboxylase activity. Similar to L. plantarum tannase, which exhibited activity only in esters derived from gallic and protocatechuic acids, purified His6-LpdC protein from E. coli showed decarboxylase activity against gallic and protocatechuic acids. In contrast to the tannase activity, gallate decarboxylase activity is widely present among lactic acid bacteria. This study constitutes the first genetic characterization of a gallate decarboxylase enzyme and provides new insights into the role of the different subunits of bacterial nonoxidative aromatic acid decarboxylases. PMID:23645198

Characterization of the perovskite La{sub 0,9}Sr{sub 0,1}Ga{sub 0,2}O{sub 2,85} prepared by cation complexation; Caracterizacao da perovsquita La{sub 0,9}Sr{sub 0,1}Ga{sub 0,2}O{sub 2,85} preparada pela tecnica de complexacao de cations

Energy Technology Data Exchange (ETDEWEB)

Reis, S.L.; Grosso, R.L.; Muccillo, E.N.S., E-mail: shirley.reis@usp.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2012-07-01

Strontium and magnesium doped lanthanum gallate exhibits perovskite-type structure and high ionic conductivity. Other features of this ceramic material are large electrolytic regime and negligible electronic conductivity. These characteristics are responsible for the potential use of this solid electrolyte in solid oxide fuel cells operating at intermediate temperatures (~∼500-700 deg C). In this work, the composition La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85} was prepared by the cation complexation technique aiming to obtain powder and sintered specimens with good chemical and structural homogeneities. X-ray diffraction results evidence that single phase was obtained, within the limitations of the technique, in samples sintered at 1350 deg C/4 h, with relative density above 92%. (author)

Structural and electrochemical properties of La 0.8Sr 0.2Ga 1-xFe xO 3

Science.gov (United States)

Mori, Kazuhiro; Onodera, Yohei; Kiyanagi, Ryoji; Richardson, James W.; Itoh, Keiji; Sugiyama, Masaaki; Kamiyama, Takashi; Fukunaga, Toshiharu

2009-02-01

Mixed ionic-electronic conductor of Fe doped lanthanum gallate, La 0.8Sr 0.2Ga 1-xFe xO 3, has been studied by the dc four-probe method and the neutron powder diffraction. In the electrical conductivity measurement at RT, insulator-metal transition-like phenomenon was observed at around x˜0.35; this suggests an existence of the percolation limit for the electronic conductivity. Simultaneously, a bond length between O atoms, lO-O, in a MO 6 octahedron (M dbnd Ga 1-xFe x) drastically expands over x˜0.4, according to the result of crystal structure refinement based on the hexagonal phase. Such a drastic expansion in the lO-O would induce the decrease in the oxygen ionic conductivity.

Densification of LSGM electrolytes using activated microwave sintering

Science.gov (United States)

Kesapragada, S. V.; Bhaduri, S. B.; Bhaduri, S.; Singh, P.

Lanthanum gallate doped with alkaline rare earths (LSGM) powders were densified using an activated microwave sintering process for developing a dense stable electrolyte layer for applications in intermediate temperature-solid oxide fuel cells (IT-SOFCs). Due to heat generation in situ, the process of sintering gets activated with faster kinetics compared to a conventional sintering process. The effect of various microwave process parameters on the microstructure and phase formation was studied. The sintered pellets were characterized using scanning electron microscopy-energy dispersive analysis (SEM-EDAX), and X-ray diffraction (XRD). The density of LSGM pellets microwave sintered at 1350 °C for 20 min is greater than 95% theoretical density with a fine grained microstructure (˜2-3 μm) and without the presence of other phase(s).

Preparation and Characterization of High Temperature Superconductor Film Surfaces

Science.gov (United States)

1993-10-27

Lanthanum Strontium Copper Oxide (LSCO) was also tested as a normal metal overlayer because of its compatibility with the high deposition temperature for...fabricate YBCO/ISCO SEB junctions using a variety of step heights (110 nm - 330 nm) on Neodymium Gallate (NGO) substrates. NGO was chosen as a...substrate because of its excellent lattice match to YBCO and its lack of crystal twinning Twinning had been a drawback of Lanthanum Aluminate (LAO)- L

Thermophysical Properties of Matter - The TPRC Data Series. Volume 4. Specific Heat - Metallic Elements and Alloys

Science.gov (United States)

1971-01-01

Indium—Indium alloys—Iron—iron alloys— lanthanum — load—lead alloys—lithium—lithium alloya—«agnaslum—magnaalum alloys—manganas^ —naoganasa alloys—marcury...Germanium 21 Gold 22 Hafnium 23 Holmium 24 Indium 25 Iridium 26 Iron 27 Lanthanum 28 Lead 29 Lithium 30 Lutetium 31 Magnesium 32 Manganese 33...hexahydrate (ErC^-eHjO Erbium gallate (see Trierbium pentagallium 1 dodecaoxide) 4 5 65 822 Freon 10 (see Carbon tetrachloride) Freon 11

LANTHANUM STAINING OF THE SURFACE COAT OF CELLS

Science.gov (United States)

Shea, Stephen M.

1971-01-01

Among the techniques which have been reported to stain the surface coat of cells, for electron microscopy, is lanthanum staining en bloc. Similarly, the presence of the cationic dye, Alcian blue 8GX, in a primary glutaraldehyde fixative has been reported to improve the preservation of the surface coat of cells of many types; however, the preserved coat is not very electron opaque unless thin sections are counterstained. The present paper shows that for several rat tissues lanthanum staining en bloc is an effective electron stain for the cell surface, giving excellent contrast, if combined sequentially with prefixation in an aldehyde fixative containing Alcian blue. The cationic substance cetylpyridinium chloride was found to have a similar effect to that of Alcian blue in enhancing the lanthanum staining of the surface coat material of the brush border of intestinal epithelial cells. The patterns of lanthanum staining obtained for the tissues studied strikingly resemble those reported in the literature where tissues are stained by several standard methods for demonstrating mucosubstances at the ultrastructural level. This fact and the reproduction of the effect of Alcian blue by cetylpyridinium chloride constitute a persuasive empirical argument that the material visualized is a mucopolysaccharide or mucopolysaccharide-protein complex. PMID:4108476

Determination of main components in lanthanum titanates blend

International Nuclear Information System (INIS)

Sizonenko, T.N.; Timchenko, A.K.

1981-01-01

Conditions for complexonometric determination of lanthanum in the presence of titanium using the disguising of the latter are studied. A method is suggested for lanthanum and titanium determination in a blend of lanthanum titanate which is used to grow monocrystals. Sulfosalicylic acid is chosen as a disguising agent. La has been determined by complexonometric titration using EDTA with xylenol orange in urotropin. The total contents of La and Ti have been determined by titration of EDTA excess with standard solution of zinc sulfate. Ti content has been calculated from the difference between the first two determinations. Reproducibility of Ti and La determination in the blend (n=21) is characterized by the following: at 19.73% La and 57.21% Ti there are (19.72+-0.16)% La and (57.10+-0.22)% Ti, Sr equals 0.0071 and 0.0034, respectively

Effect of ‘A’-site non stoichiometry in strontium doped lanthanum ferrite based solid oxide fuel cell cathodes

Energy Technology Data Exchange (ETDEWEB)

Banerjee, Koyel; Mukhopadhyay, Jayanta, E-mail: jayanta_mu@cgcri.res.in; Barman, Madhurima; Basu, Rajendra N., E-mail: rnbasu@cgcri.res.in

2015-12-15

Highlights: • La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2 system varying La-site (0.6–0.54) are studied. • Combustion synthesis technique is used to prepare the powder samples. • Highest electrical conductivity observed with largest A-site deficit composition. • Lowest cathode polarization is found with the same composition (0.02 Ω cm{sup 2}). • Composition with largest A-site deficiency exhibits best performance (2.84 A cm{sup −2}). - Abstract: Effect of A-site non-stoichiometry in strontium doped lanthanum cobalt ferrite (La{sub 1−x}Sr{sub x}Co{sub y}Fe{sub 1−y}O{sub 3−δ}, x = 0.4; y = 0.2) is studied in a systematic manner with variation of ‘A’ site stoichiometry from 1 to 0.94. The perovskite based cathode compositions are synthesized by combustion synthesis. Powder characterizations reveal rhombohedral crystal structure with crystallite size ranging from 29 to 34 nm with minimum lattice spacing of 0.271 nm. Detailed sintering studies along with total DC electrical conductivities are evaluated in the bulk form with variation of sintering temperatures. The electrode polarizations are measured in the symmetric cell configuration by impedance spectroscopy which is found to be the lowest (0.02 Ω cm{sup 2} at 800 °C) for cathode having highest degree of ‘A’-site deficiency. The same cathode composition exhibits a current density of 2.84 A cm{sup −2} (at 0.7 V, 800 °C) in anode-supported single cell. An attempt has been made to correlate the trend of electrical behaviour with increasing ‘A’-site deficiency for such cathode compositions.

Cyan-white-red luminescence from europium doped Al2O3-La2O3-SiO2 glasses.

Science.gov (United States)

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.

Effect of La doping on crystalline orientation, microstructure and dielectric properties of PZT thin films

Energy Technology Data Exchange (ETDEWEB)

Xu, Wencai; Li, Qi; Wang, Xing [Dalian Univ. of Technology, Dalian (China). School of Mechanical Engineering; Yin, Zhifu [Jilin Univ., Changchun (China). Faculty of the School of Mechanical Science and Engineering; Zou, Helin [Dalian Univ. of Technology, Dalian (China). Key Lab. for Micro/Nano Systems and Technology

2017-11-01

Lanthanum (La)-modified lead zirconate titanate (PLZT) thin films with doping concentration from 0 to 5 at.-% have been fabricated by sol-gel methods to investigate the effects of La doping on crystalline orientation, microstructure and dielectric properties of the modified films. The characterization of PLZT thin films were performed by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and precision impedance analysis. XRD analysis showed that PLZT films with La doping concentration below 4 at.-% exhibited (100) preferred orientation. SEM results indicated that PLZT films presented dense and columnar microstructures when La doping concentration was less than 3 at.-%, while the others showed columnar microstructures only at the bottom of the cross section. The maximum dielectric constant (1502.59 at 100 Hz) was obtained in a 2 at.-% La-doped film, which increased by 53.9 % compared with undoped film. Without introducing a seed layer, (100) oriented PLZT thin films were prepared by using conventional heat treatment process and adjusting La doping concentration.

Calcium and lanthanum solid base catalysts for transesterification

Science.gov (United States)

Ng, K. Y. Simon; Yan, Shuli; Salley, Steven O.

2015-07-28

In one aspect, a heterogeneous catalyst comprises calcium hydroxide and lanthanum hydroxide, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g. In another aspect, a heterogeneous catalyst comprises a calcium compound and a lanthanum compound, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g, and a total basicity of about 13.6 mmol/g. In further another aspect, a heterogeneous catalyst comprises calcium oxide and lanthanum oxide, wherein the catalyst has a specific surface area of more than about 10 m.sup.2/g. In still another aspect, a process for preparing a catalyst comprises introducing a base precipitant, a neutral precipitant, and an acid precipitant to a solution comprising a first metal ion and a second metal ion to form a precipitate. The process further comprises calcining the precipitate to provide the catalyst.

Spark plasma sintering of hydrothermally derived ultrafine Ca doped lanthanum chromite powders

Directory of Open Access Journals (Sweden)

Rendón-Angeles, J. C.

2006-08-01

Full Text Available Lanthanum chromite nano-particles, with a composition of La0.9Ca0.1CrO3 and La0.8Ca0.2CrO3, were produced by 1 h of hydrothermal reaction at 400 and 425°C respectively. The sintering of the powders was conducted using a spark plasma apparatus over the temperature range 1300-1550ºC for 1 min with a constant loading pressure of 45 MPa. Additional sintering experiments using conventional firing were carried out for comparison. Fully densified (98 % r.d. lanthanum chromite pellets with fine equiaxial grains 2.3 μm in size were obtained using the SPS (spark plasma sintering method. In contrast, a maximum relative density of 97 % was produced using La0.8Ca0.2CrO3 sintered conventionally at 1400ºC for 300 min, and the average grain size of the resulting sintered sample was 6 μm.

Partículas ultrafinas de cromita de lantano, con una composición de La0.9Ca0.1CrO3 y La0.8Ca0.2CrO3, se obtuvieron después de 1 hora de síntesis hidrotermal a las temperaturas de 400 y 425°C respectivamente. Los compuestos obtenidos, con un tamaño de partícula de ~ 200 nm, se caracterizaron utilizando las técnicas de DRX, MEB y MET. La sinterización de estos polvos se efectuó en un equipo de chispa de plasma en el rango de temperatura de 1300-1500°C durante 1 min, y a una presión de compactación de 45 MPa. Ambos polvos también se sinterizaron siguiendo un tratamiento térmico convencional, en aire, con el propósito de comparar ambos métodos de sinterización. Las muestras de cromita de lantano sinterizadas por plasma presentaban una densidad relativa del 98 % (/t; y una microestructura monofásica con granos equaxiales con un tamaño medio de grano menor de 2.3 μm. En contraste, la composición La0.8Ca0.2CrO3, sinterizada a 1400°C/300 min, por métodos convencionales alcanzó una densidad relativa máxima del 97 % y su microestructura estaba formada por una sola fase con un tamaño medio de grano de 6 μm.

Color centers inside crystallic active media

Science.gov (United States)

Mierczyk, Zygmunt; Kaczmarek, Slawomir M.; Kopczynski, Krzysztof

1995-03-01

This paper presents research results on color centers induced by radiation of a xenon lamp in non doped crystals of yttrium aluminum garnet Y3Al5O12 (YAG), strontium- lanthanum aluminate SrLaAlO4 (SLAO), strontium-lanthanum gallate SrLaGa3O7 (SLGO), and in doped crystals: Nd:YAG, Cr, Tm, Ho:YAG (CTH:YAG), Nd:SLAO and Nd:SLGO. In all these investigated crystals under the influence of intensive exposure by xenon lamp radiation additional bands connected with centers O-2, O2 and centers F came up near the short-wave absorption edge. In the case of doped crystals the observed processes are much more complicated. In crystals CTH:YAG the greatest perturbations in relation to basic state are present at the short-wave absorption edge, as well as on areas of absorption bands of ions Cr+3 and Tm+3 conditioning the sensibilization process of ions Ho+3. These spectral structure disturbances essentially influence the efficiency of this process, as proven during generating investigations. In the case of SrLaGa3O7:Nd+3 under the influence of exposure substantial changes of absorption spectrum occurred on spectral areas 346 divided by 368 nm, 429 divided by 441 nm and 450 divided by 490 nm. Those changes have an irreversible character. They disappear not before the plate is being held at oxidizing atmosphere. Investigations of laser rods Nd:SLGO, CTH:YAG, and Nd:YAG in a free generation demonstrated that the color centers of these crystals are induced by pomp radiation from the spectral area up to 450 nm.

DISSOLUTION OF LANTHANUM FLUORIDE PRECIPITATES

Science.gov (United States)

Fries, B.A.

1959-11-10

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

Adsorption of lithium-lanthanum films on W (112) face

International Nuclear Information System (INIS)

Gupalo, M.S.; Smereka, T.P.; Palyukh, B.M.; Babkin, G.V.

1986-01-01

The method of contact potential difference is employed to study the electron adsorption properties (the work function phi and adsorption heat q) lithium films on a lanthanized W(112) surface. It is found that the work function of mixed lithium-lanthanum films is intermediate between phi of the summands. The presence of lanthanum on a W(112) face reduces the adsorption heat of lithium

Study of magnetic and electrical properties of La doped Mn-Zn nanoferrites synthesized by co-precipitation technique

International Nuclear Information System (INIS)

Panwar, Neena; Thakur, Atul; Thakur, Preeti

2013-01-01

Lanthanum manganese zinc ferrite powder of the composition Mn 0.4 Zn 0.6 La 0.4 Fe 1.6 O 4 were synthesized via co-precipitation technique. Metallic chlorides of manganese, zinc and iron in which Lanthanum is doped were taken. Sodium hydroxide (NaOH) base was used as precipitant agent. The calcinations (presintering) were performed at 700℃ for 3h and sintering at different temperatures 900℃, 850℃, 800℃ also for 3h. The structural investigation of the prepared sample was performed with X-ray diffraction (XRD) and scanning electron microscope (SEM). For studying magnetic properties vibrating sample magnetometer (VSM) are used. Electrical properties were studied by DC resistivity set up. (author)

Synthesis and Luminescence Properties of Novel Ce(3+)- and Eu(2+)-Doped Lanthanum Bromothiosilicate La3Br(SiS4)2 Phosphors for White LEDs.

Science.gov (United States)

Lee, Szu-Ping; Liu, Shuang-De; Chan, Ting-Shan; Chen, Teng-Ming

2016-04-13

Novel Ce(3+)- and Eu(2+)-doped lanthanum bromothiosilicate La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors were prepared by solid-state reaction in an evacuated and sealed quartz glass ampule. The La3Br(SiS4)2:Ce(3+) phosphor generates a cyan emission upon excitation at 375 nm, whereas the La3Br(SiS4)2:Eu(2+) phosphor could be excited with extremely broad range from UV to blue region (300 to 600 nm) and generates a reddish-orange broadband emission centered at 640 nm. In addition, thermal luminescence properties of La3Br(SiS4)2:Ce(3+)and La3Br(SiS4)2:Eu(2+) phosphors from 20 to 200 °C were investigated. The combination of a 450 nm blue InGaN-based LED chip with the red-emitting La3Br(SiS4)2:Eu(2+) phosphor, and green-emitting BOSE:Eu(2+) commercial phosphor produced a warm-white light with the CRI value of ∼95 and the CCT of 5,120 K. Overall, these results show that the prepared phosphors may have potential applications in pc-WLED.

Laser Spectroscopy Characterization of Materials for Frequency Agile Solid State Laser Systems

Science.gov (United States)

1991-03-15

Received 30 November 1987; revised manuscript received 29 January 1988) Single crystals of lanthanum lutetium gallium garnet (LaLuGaG) were grown by...group may be realized it gar- dleternte itf other materials can be found with spectral nets formed with lanthanum occupying tile dodecaliedrial ,1nl...array-pumped Nd: YAG and Nd: Lu: YAG lasers," Opt. inates and gallates with the malilite structure," in Tunable Lett. 14, 116-118 (1989). Solid State

Characterization of Lanthanum Ferric Cobaltite doped with Strontium (LSCF) films deposited by spray-pyrolysis for application as cathode in PaCOS-TI; Caracterizacao de filmes de CFLE depositados por spray-pirolise para utilizacao como catodo em PaCOS-TI

Energy Technology Data Exchange (ETDEWEB)

Almeida, L.S.; Guimaraes, V.F.; Paes Junior, H.R. [Universidade Estadual do Norte Fluminense Darcy Ribeiro (UENF), Campos dos Goytacazes, RJ (Brazil). Lab. de Materiais Avancados], Emails: laryssadsa@yahoo.com.br, valtencyguimaraes@yahoo.com.br, herval@uenf.br

2010-07-01

The lanthanum ferric cobaltite doped with strontium (LSCF) is a ceramic material with the perovskite structure that stands out in the field of research for its use as cathode in solid oxide fuel cells at intermediate temperatures (IT-SOFC). The films were synthesized by spray-pyrolysis technique on 8% mol Yttria stabilized zirconia (YSZ) substrates. It was studied the influence of heat treatment temperatures (600-1000 deg C) on the properties of the films under the conditions of treatment during four hours. Samples were tested electrically by measuring the variation of electrical conductivity with temperature, structurally by X-ray diffraction (XRD) and morphologically by scanning electron microscopy (SEM). The films heat treated at 700 deg C for 4 hours showed better performance for application as cathode. (author)

Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

Energy Technology Data Exchange (ETDEWEB)

Camargo, Emerson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: camargo@ufscar.br; Barrado, Cristiano M. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil); Ribeiro, Caue [EMBRAPA Instrumentacao Agropecuaria, Rua XV de Novembro 1452, Sao Carlos SP 13560-970 (Brazil)], E-mail: caue@cnpdia.embrapa.br; Longo, Elson [Department of Biochemistry, Chemistry Institute of Araraquara, UNESP-Sao Paulo State University, Rua Francisco Degni, CP 355, Araraquara SP 14801-907 (Brazil)], E-mail: elson@iq.unesp.br; Leite, Edson R. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Department of Chemistry, UFSCar-Federal University of Sao Carlos, Rod.Washingtin Luis km 235, CP 676, Sao Carlos SP 13565-9905 (Brazil)], E-mail: derl@power.ufscar.br

2009-05-05

For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm{sup -1} and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

Nanosized lead lanthanum titanate (PLT) ceramic powders synthesized by the oxidant peroxo method

International Nuclear Information System (INIS)

Camargo, Emerson R.; Barrado, Cristiano M.; Ribeiro, Caue; Longo, Elson; Leite, Edson R.

2009-01-01

For the first time it is reported the synthesis of lead titanate modified with rare earth by the oxidant-peroxo method (OPM). Lanthanum was added up to 20% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of a solution of lead and lanthanum nitrate into an aqueous solution of titanium peroxo complexes. The amorphous precipitate formed was heat-treated at different temperatures in the range from 400 to 900 deg. C for crystallization. Powders were characterized by Raman spectroscopy and X-ray diffraction. Tetragonal perovskite structure was observed for the samples up to 15% of lanthanum substitution and cubic perovskite for sample with 20% of lanthanum. Crystallographic domains calculated by Scherrer equation showing a probable suppression of the crystallite growth in function of lanthanum content. It was observed shifting to lower frequencies of Raman modes in the range between 100 and 400 cm -1 and the vanishing of the A1(2TO) and E(1LO) modes could be attributed to transition phase from tetragonal to cubic. Electronic microscopy image revealed that the powders annealed at height temperature are spherical with sharp size distribution.

Distribution of lanthanum and neodymium in Di(2-ethlhexyl) phosphoric acid and tributylphosphate

International Nuclear Information System (INIS)

Kraikaew, J.; Suparith, N.; Pruantonsai, P.

1994-01-01

Lanthanum and neodymium are among the high quantity elements in mixed rare earth from monazite processing. The popular rare earth separation process is liquid-liquid extraction. This research was carried out to study lanthanum and neodymium distribution in two extractants, di(2-ethylhexyl) phosphoric acid and tributylphosphate. The experimental results show that neodymium distributes in both extractants better than lanthanum. The distribution of both elements are higher at low acidity than at high acidity. Quick and rough investigation by calculating the ratio of distribution coefficient of neodymium to lanthanum in each extractant indicated that La-nd separation efficiency of Di(2-ethylhexyl) phosphoric acid is higher than that of tributylphosphate

Molecular interactions between (--epigallocatechin gallate analogs and pancreatic lipase.

Directory of Open Access Journals (Sweden)

Shihui Wang

Full Text Available The molecular interactions between pancreatic lipase (PL and four tea polyphenols (EGCG analogs, like (--epigallocatechin gallate (EGCG, (--gallocatechin gallate (GCG, (--epicatechin gallate (ECG, and (--epigallocatechin (EC, were studied from PL activity, conformation, kinetics and thermodynamics. It was observed that EGCG analogs inhibited PL activity, and their inhibitory rates decreased by the order of EGCG>GCG>ECG>EC. PL activity at first decreased rapidly and then slowly with the increase of EGCG analogs concentrations. α-Helix content of PL secondary structure decreased dependent on EGCG analogs concentration by the order of EGCG>GCG>ECG>EC. EGCG, ECG, and EC could quench PL fluorescence both dynamically and statically, while GCG only quenched statically. EGCG analogs would induce PL self-assembly into complexes and the hydrodynamic radii of the complexes possessed a close relationship with the inhibitory rates. Kinetics analysis showed that EGCG analogs non-competitively inhibited PL activity and did not bind to PL catalytic site. DSC measurement revealed that EGCG analogs decreased the transition midpoint temperature of PL enzyme, suggesting that these compounds reduced PL enzyme thermostability. In vitro renaturation through urea solution indicated that interactions between PL and EGCG analogs were weak and non-covalent.

Simple preparation of fluorescent composite films based on cerium and europium doped LaF3 nanoparticles

Science.gov (United States)

Secco, Henrique de L.; Ferreira, Fabio F.; Péres, Laura O.

2018-03-01

The combination of materials to form hybrids with unique properties, different from those of the isolated components, is a strategy used to prepare functional materials with improved properties aiming to allow their application in specific fields. The doping of lanthanum fluoride with other rare earth elements is used to obtain luminescent particles, which may be useful to the manufacturing of electronic devices' displays and biological markers, for instance. The application of the powder of nanoparticles has limitations in some fields; to overcome this, the powder may be incorporated in a suitable polymeric matrix. In this work, lanthanum fluoride nanoparticles, undoped and doped with cerium and europium, were synthesized through the co-precipitation method in aqueous solution. Aiming the formation of solid state films, composites of nanoparticles in an elastomeric matrix, the nitrile rubber (NBR), were prepared. The flexibility and the transparency of the matrix in the regions of interest are advantages for the application of the luminescent composites. The composites were applied as films using the casting and the spin coating techniques and luminescent materials were obtained in the samples doped with europium and cerium. Scanning electron microscopy images showed an adequate dispersion of the particles in the matrix in both film formation techniques. Aggregates of the particles were detected in the samples which may affect the uniformity of the emission of the composites.

Pressure behaviour of the superconducting transition temperature of lanthanum

International Nuclear Information System (INIS)

Glocker, R.

1977-01-01

The dissertation has the following chapters: 1) Introduction, 2) Fundamentals of the microscopic theory of superconductivity, 3) Calculation of the first momentum of the Eliashberg function, 4) Determination of the average values of frequency, 5) The relativistic cellular method and its application to lanthanum, 6) Results of the calculation of the electron-phonon coupling cosntants for f.c.c. lanthanum, 7) Phonon dispersion and phonon state density. (orig.) [de

Functionalization of lanthanum hydroxide nanowires by atom transfer radical polymerization

International Nuclear Information System (INIS)

Zhou Mi; Yuan Jinying; Yuan Weizhong; Yin Yingwu; Hong Xiaoyin

2007-01-01

Atom transfer radical polymerization (ATRP) has been used to prepare a core-shell hybrid nanostructure successfully: a hard core of single-crystalline lanthanum hydroxide nanowires and a soft shell of polystyrene (PS) brushes. Transmission electron microscopy (TEM) images indicated that the resulting products presented special structures and different thicknesses of polymer layers. The chemical components and grafted PS quantities of the samples were measured by Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analysis (TGA). The polymers showed narrow polydispersity, which proved that the lanthanum hydroxide nanowires initiated the 'living'/controlled polymerization of styrene. With the modifiability of lanthanum hydroxide nanowires, the solubility increased, which affords a new way to functionalize nanowires

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

Energy Technology Data Exchange (ETDEWEB)

Singh, Prabhakar [Univ. of Connecticut, Storrs, CT (United States); Mahapatra, Manoj [Univ. of Connecticut, Storrs, CT (United States); Ramprasad, Rampi [Univ. of Connecticut, Storrs, CT (United States); Minh, Nguyen [Univ. of California, San Diego, CA (United States); Misture, Scott [Alfred Univ., NY (United States)

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.

Spectrophotometric study of the complexation equilibria of lanthanum(III) with 1,4-bis(4'-methylanilino)anthraquinone and the determination of lanthanum(III)

International Nuclear Information System (INIS)

Idriss, K.A.-R; El-Shahawy, A.S.; Sedaira, H.; Harfoush, A.A.

1985-01-01

The complexation equilibria of lanthanum(III) with 1,4-bis(4'-methylanilino)anthraquinone (Quinizarin Green) were studied spectrophotometrically in 40% V/V dimethylformamide using graphical analysis of the absorbance curves. The reaction mechanism of lanthanum with the bisarylaminoanthraquinone dye within the pH range 6 to 9.25 was demonstrated. The thermodynamic stabilities and the molar absorptivities of the complexes formed were determined. The optimum conditions for the spectrophotometric determination of La(III) with this reagent were found. (author)

Fabrication of mesoporous and high specific surface area lanthanum carbide-carbon nanotube composites

International Nuclear Information System (INIS)

Biasetto, L.; Carturan, S.; Maggioni, G.; Zanonato, P.; Bernardo, P. Di; Colombo, P.; Andrighetto, A.; Prete, G.

2009-01-01

Mesoporous lanthanum carbide-carbon nanotube composites were produced by means of carbothermal reaction of lanthanum oxide, graphite and multi-walled carbon nanotube mixtures under high vacuum. Residual gas analysis revealed the higher reactivity of lanthanum oxide towards carbon nanotubes compared to graphite. After sintering, the composites revealed a specific surface area increasing with the amount of carbon nanotubes introduced. The meso-porosity of carbon nanotubes was maintained after thermal treatment.

Effects of the wet air on the properties of the lanthanum oxide and lanthanum aluminate thin films

International Nuclear Information System (INIS)

Jun, Jin Hyung; Choi, Doo Jin

2006-01-01

Lanthanum oxide and lanthanum aluminate thin films were deposited on Si substrates. The as-grown films were stored in wet ambient and dry ambient for days and annealed after storage and also the structural and the electrical properties of the films were investigated. As the storage time increased, the La 2 O 3 films stored in wet ambient showed rapid reaction with moisture and the properties degraded. In case of the LAO films, although the thickness of the film also increased during hydration, the properties of the film did not so much changed due to the role of the incorporated aluminum. The LAO films showed better hydration resistance characteristics and so more suitable for conventional wet cleaning process in semiconductor fabrication

Structural and electrochemical properties of La{sub 0.8}Sr{sub 0.2}Ga{sub 1-x}Fe{sub x}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Mori, Kazuhiro [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)], E-mail: kmori@rri.kyoto-u.ac.jp; Onodera, Yohei [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Kiyanagi, Ryoji; Richardson, James W. [Intense Pulsed Neutron Source Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Itoh, Keiji; Sugiyama, Masaaki [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan); Kamiyama, Takashi [Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801 (Japan); Fukunaga, Toshiharu [Research Reactor Institute, Kyoto University, Kumatori-cho, Sennan-gun, Osaka 590-0494 (Japan)

2009-02-21

Mixed ionic-electronic conductor of Fe doped lanthanum gallate, La{sub 0.8}Sr{sub 0.2}Ga{sub 1-x}Fe{sub x}O{sub 3}, has been studied by the dc four-probe method and the neutron powder diffraction. In the electrical conductivity measurement at RT, insulator-metal transition-like phenomenon was observed at around x{approx}0.35; this suggests an existence of the percolation limit for the electronic conductivity. Simultaneously, a bond length between O atoms, l{sub O-O}, in a MO{sub 6} octahedron (M=Ga{sub 1-x}Fe{sub x}) drastically expands over x{approx}0.4, according to the result of crystal structure refinement based on the hexagonal phase. Such a drastic expansion in the l{sub O-O} would induce the decrease in the oxygen ionic conductivity.

Ceramic membrane technologies for gas separation

International Nuclear Information System (INIS)

Badwal, S.P.S.; Ciacchi, F.T.

2000-01-01

Solid state electrochemical cells based on oxygen-ion or proton conduction (pure ionic or mixed ionic/electronic conductors) allow selective transport of oxygen (oxygen-ion conducting materials) or hydrogen (for proton conducting materials) in the form of ionic flux at high temperatures. Thus these systems can act as filters for molecular oxygen or hydrogen and can be used for both generation or removal of these gases selectively. The usage of such devices are numerous including control of atmosphere in industrial environments to production of power and chemicals, in petroleum and medical industries, and in combustion processes. In this paper, a brief overview of the technology has been given and various doped materials for construction of such devices, such as zirconia, ceria, bismuth oxides or lanthanum gallates have been briefly reviewed. Copyright (2000) The Australian Ceramic Society

Analyzing relation between the radioactivity in lanthanum products and the origins of RE chlorides

International Nuclear Information System (INIS)

Wan Rongsheng

2004-01-01

Objective: To analyze the relation between the radioactivity in Lanthanum products and the origins of RE Chlorides. Methods: Using JY-38 plus sequential ICP spectrometer to examine the content of the uranium in the RE Chlorides. Using FJ-2603 low background alpha, beta measurement apparatus to measure total alpha and total beta activities of Lanthanum products. Results: The content of the uranium in the RE Chlorides is much lower in Baotou's than Hunan's. The radioactivity in Lanthanum products are made from the RE Chlorides of Baotou is much lower than that in Hunan's too. The radioactivity in Lanthanum products depends on the origins of RE Chlorides. Conclusion: The basic data were provided for radioactivity in Lanthanum products which are made from RE Chlorides of different places of China. The mathematical model was founded for the reasonable use of resource RE Chlorides

Microwave-assisted synthesis of lanthanum conversion coating on Mg-Li alloy and its corrosion resistance

International Nuclear Information System (INIS)

Song Dalei; Jing Xiaoyan; Wang Jun; Lu Shanshan; Yang Piaoping; Wang Yanli; Zhang Milin

2011-01-01

Graphical abstract: Highlights: → The method of microwave is used to synthesize lanthanum conversion coating. → Lanthanum conversion coating on Mg-Li alloy was studied. → Different conditions between room temperature and microwave were compared. → The corrosion behavior of lanthanum conversion coatings was studied. → The corrosion mechanism of lanthanum conversion coatings was studied. - Abstract: Lanthanum-based conversion coating on Mg-Li alloy has been prepared by a microwave-assisted method. X-ray diffractions (XRD) indicate that the intermetallic compounds of lanthanum are formed on Mg-Li alloy surface. Scanning electron microscopy (SEM) images show that the coating has different morphologies and special structures. The corrosion resistance was assessed by means of potentiodynamic polarization curves and electrochemical impedance spectra (EIS). The results indicate that this coating significantly reduces the corrosion rate of Mg-Li alloy in NaCl solution. A comparing experiment indicates that the coating prepared by microwave-assisted process has superior corrosion resistance to the coating obtained at room temperature.

21 CFR 184.1660 - Propyl gallate.

Science.gov (United States)

2010-04-01

... alcohol. (b) The ingredient meets the specifications of the “Food Chemicals Codex,” 3d Ed. (1981), pp. 257... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Propyl gallate. 184.1660 Section 184.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN...

Electrical conductivity studies of nanocrystalline lanthanum silicate synthesized by sol-gel route

International Nuclear Information System (INIS)

Nallamuthu, N.; Prakash, I.; Satyanarayana, N.; Venkateswarlu, M.

2011-01-01

Research highlights: → Nanocrystalline La 10 Si 6 O 27 material was synthesized by sol-gel method. → TG/DTA curves predicted the thermal behavior of the material. → FTIR spectra confirmed the formation of SiO 4 and La-O network in the La 10 Si 6 O 27 . → XRD patterns confirmed the formation of pure crystalline La 10 Si 6 O 27 phase. → The grain interior and the grain boundary conductivities are evaluated. - Abstract: Nanocrystalline apatite type structured lanthanum silicate (La 10 Si 6 O 27 ) sample was synthesized by sol-gel process. Thermal behavior of the dried gel of lanthanum silicate sample was studied using TG/DTA. The structural coordination of the dried gel of lanthanum silicate, calcined at various temperatures, was identified from the observed FTIR spectral results. The observed XRD patterns of the calcined dried gel were compared with the ICDD data and confirmed the formation of crystalline lanthanum silicate phase. The average crystalline size of La 10 Si 6 O 27 was calculated using the Scherrer formula and it is found to be ∼80 nm. The observed SEM images of the lanthanum silicate indicate the formation of the spherical particles and the existence of O, Si and La in the lanthanum silicate are confirmed from the SEM-EDX spectrum. The grain and grain boundary conductivities are evaluated by analyzing the measured impedance data, using winfit software, obtained at different temperatures, of La 10 Si 6 O 27 sample. Also, the observed grain and grain boundary conductivity behaviors of the La 10 Si 6 O 27 sample are analysed using brick layer model. The electrical permittivity and electrical modulus were calculated from the measured impedance data and were analyzed by fitting through the Havriliak and Negami function to describe the dielectric relaxation behavior of the nanocrystalline lanthanum silicate.

Antibacterial activity of alkyl gallates is a combination of direct targeting of FtsZ and permeabilization of bacterial membranes

NARCIS (Netherlands)

Krol, Ewa; de Sousa Borges, Anabela; da Silva, Isabel; Polaquini, Carlos; Regasini, Luis; Ferreira, Henrique; Scheffers, Dirk

2015-01-01

Alkyl gallates are compounds with reported antibacterial activity. One of the modes of action is binding of the alkyl gallates to the bacterial membrane and interference with membrane integrity. However, alkyl gallates also cause cell elongation and disruption of cell division in the important plant

Management of hyperphosphatemia in patients with end-stage renal disease: focus on lanthanum carbonate

Directory of Open Access Journals (Sweden)

Veerle P Persy

2009-04-01

Full Text Available Veerle P Persy, Geert J Behets, Marc E De Broe, Patrick C D’HaeseLaboratory of Pathophysiology, University of Antwerp, BelgiumAbstract: Elevated serum phosphate levels as a consequence of chronic kidney disease (CKD contribute to the increased cardiovascular risk observed in dialysis patients. Protein restriction and dialysis fail to adequately prevent hyperphosphatemia, and in general treatment with oral phosphate binding agents is necessary in patients with advanced CKD. Phosphate plays a pivotal role in the development of vascular calcification, one of the factors contributing to increased cardiovascular risk in CKD patients. Treatment of hyperphosphatemia with standard calcium-based phosphate binders and vitamin D compounds can induce hypercalcemic episodes, increase the Ca × PO4 product and thus add to the risk of ectopic mineralization. In this review, recent clinical as well as experimental data on lanthanum carbonate, a novel, non-calcium, non-resin phosphate binding agent are summarized. Although lanthanum is a metal cation no aluminium-like toxicity is observed since the bioavailability of lanthanum is extremely low and its metabolism differs from that of aluminium. Clinical studies now document the absence of toxic effects of lanthanum for up to 6 years of follow-up. The effects of lanthanum on bone, vasculature and brain are discussed and put in perspective with lanthanum pharmacokinetics.Keywords: lanthanum carbonate, phosphate binding, chronic kidney disease

Study of behaviour of lanthanum- and yttrium electrodes in chloride melts

International Nuclear Information System (INIS)

Shkol'nikov, S.I.; Tolypin, E.S.; Yur'ev, B.P.

1984-01-01

A study was made on the lanthanum- and yttrium behaviour in a mixture of molten potassium- and sodium chlorides at various temperatures. It is shown that the lanthanum- and yttrium behaviour in KCl-NaCl melt is similar to the behaviour of other metals. Their corrosion rate is much higher as compared to other metals and it grows rapidly with increasing melt temperature. The temperature growth by 200 deg C results in an increase in the corrosion rate almost by an order. The potentials of lanthanum- and yttrium electrodes at the instant they are immersed in the melt have more negative values than the potentials of alkali metals under similar conditions

Electrochemical Deposition of Lanthanum Telluride Thin Films and Nanowires

Science.gov (United States)

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.

Epigallocatechin-3-gallate Promotes Osteoblastic Activity in Human ...

African Journals Online (AJOL)

Keywords: Epigallocatechin-3-gallate, Osteoporosis, Osteoclast, Proliferation, Estrogen receptor. Tropical Journal of Pharmaceutical Research is indexed by Science Citation Index (SciSearch), Scopus,. International Pharmaceutical Abstract, Chemical Abstracts, Embase, Index Copernicus, EBSCO, African. Index Medicus ...

Protective effect of (-)-epigallocatechin gallate on ultraviolet b ...

African Journals Online (AJOL)

Purpose: To investigate the protective effect of green tea (-)-epigallocatechin gallate (EGCg) on ultraviolet B (UV-B)-induced skin damages in hairless mice in order to develop a natural sunscreen ... hydrophilic cream has also showed high.

THE EFFECT OF GREEN TEA EXTRACT - EPIGALLOCATECHIN GALLATE (EGCG ON PORCINE OVARIAN GRANULOSA CELL

Directory of Open Access Journals (Sweden)

Attila Kádasi

2014-02-01

Full Text Available The aim of our study was to elucidate the potential effect of green tea substance on basic ovarian functions. For this purpose, we examined the action of green tea bioactive molecule, epigallocatechin gallate (given at doses 0, 1, 10, 100 μg/mL, on cultured porcine ovarian granulosa cell functions - proliferation, apoptosis and steroidogenesis. Accumulation of PCNA (marker of proliferation, BAX (marker of apoptosis and the release of steroid hormones (progesterone and testosterone were analysed by immunocytochemistry and RIA respectively. It was observed that epigallocatechin gallate addition decreased the percentage of proliferative (PCNA-positive cells at all used doses (1, 10 and 100 μg/mL. The percentage of apoptotic (BAX-positive cells was increased at the highest used dose (100 μg/mL, but not a lower doses. Epigallocatechin gallate stimulated progesterone release (at 10 μg/mL but not at 1 and 100 μg/mL and diminished testosterone release (at 1 μg/mL but not at 10 and 100 μg/mL by porcine granulosa cells. Our results suggest a direct effect of epigallocatechin gallate on proliferation, apoptosis and steroidogenesis in porcine ovaries. Taken together, these data suggest that green tea molecule epigallocatechin gallate can negatively affect reproductive (ovarian functions – suppress ovarian cell proliferation, promote their apoptosis and alter release of steroid hormones.

Properties of gallium lanthanum sulphide glass

OpenAIRE

Bastock, P.; Craig, C.; Khan, K.; Weatherby, E.; Yao, J.; Hewak, D.W.

2015-01-01

A series of gallium lanthanum sulphide (GLS) glasses has been studied in order to ascertain properties across the entire glass forming region. This is the first comprehensive study of GLS glass over a wide compositional range.

Preventive effects of a major component of green tea, epigallocathechin-3-gallate, on hepatitis-B virus DNA replication.

Science.gov (United States)

Karamese, Murat; Aydogdu, Sabiha; Karamese, Selina Aksak; Altoparlak, Ulku; Gundogdu, Cemal

2015-01-01

Hepatitis B virus infection is one of the major world health problems. Epigallocatechin-3 gallate is the major component of the polyphenolic fraction of green tea and it has an anti-viral, anti-mutagenic, anti- tumorigenic, anti-angiogenic, anti-proliferative, and/or pro-apoptotic effects on mammalian cells. In this study, our aim was to investigate the inhibition of HBV replication by epigallocatechin-3 gallate in the Hep3B2.1-7 hepatocellular carcinoma cell line. HBV-replicating Hep3B2.1-7 cells were used to investigate the preventive effects of epigallocatechin-3 gallate on HBV DNA replication. The expression levels of HBsAg and HBeAg were determined using ELISA. Quantitative real-time-PCR was applied for the determination of the expression level of HBV DNA. Cytotoxicity of epigallocathechin-3-gallate was not observed in the hepatic carcinoma cell line when the dose was lower than 100 μM. The ELISA method demonstrated that epigallocatechin-3 gallate have strong effects on HBsAg and HBeAg levels. Also it was detected by real-time PCR that epigallocatechin-3 gallate could prevent HBV DNA replication. The obtained data pointed out that although the exact mechanism of HBV DNA replication and related diseases remains unclear, epigallocatechin-3 gallate has a potential as an effective anti-HBV agent with low toxicity.

Surface spin effects in La-doped CoFe.sub.2./sub.O.sub.4./sub. nanoparticles prepared by microemulsion route

Czech Academy of Sciences Publication Activity Database

Burianová, Simona; Poltierová Vejpravová, Jana; Holec, Petr; Plocek, J.; Nižňanský, D.

2011-01-01

Roč. 110, č. 7 (2011), "073902-1"-"073902-7" ISSN 0021-8979 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40320502 Keywords : CoFe 2 O 4 nanoparticles * lanthanum doping * microemulsion route * high coercivity * surface spin effects Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.168, year: 2011

DFT Studies on Interaction between Lanthanum and Hydroxyamide

Science.gov (United States)

Pati, Anindita; Kundu, T. K.; Pal, Snehanshu

2018-03-01

Extraction and separation of individual rare earth elements has been a challenge as they are chemically very similar. Solvent extraction is the most suitable way for extraction of rare earth elements. Acidic, basic, neutral, chelating are the major classes of extractants for solvent extraction of rare earth elements. The coordination complex of chelating extractants is very selective with positively charged metal ion. Hence they are widely used. Hydroxyamide is capable of forming chelates with metal cations. In this present study interactions of hydroxyamide ligand with lanthanum have been investigated using density functional theory (DFT). Two different functional such as raB97XD and B3LYP are applied along with 6-31+G(d,p) basis set for carbon, nitrogen, hydrogen and SDD basis set for lanthanum. Stability of formed complexes has been evaluated based on calculated interaction energies and solvation energies. Frontier orbital (highest occupied molecular orbital or HOMO and lowest unoccupied molecular orbital or LUMO) energies of the molecule have also been calculated. Electronegativity, chemical hardness, chemical softness and chemical potential are also determined for these complexes to get an idea about the reactivity. From the partial charge distribution it is seen that oxygen atoms in hydroxyamide have higher negative charge. The double bonded oxygen atom present in the hydroxyamide structure has higher electron density and so it forms bond with lanthanum but the singly bonded oxygen atom in the hydroxyamide structure is weaker donor atom and so it is less available for interaction with lanthanum.

New doped tungsten cathodes. Applications to power grid tubes

International Nuclear Information System (INIS)

Cachard, J. de; Cadoret, K; Martinez, L.; Veillet, D.; Millot, F.

2001-01-01

Thermionic emission behavior of tungsten/tungsten carbide modified with rare earth (La, Ce, Y) oxides is examined on account of suitability to deliver important current densities in a thermo-emissive set up and for long lifetime. Work functions of potential cathodes have been determined from Richardson plots for La 2 O 3 doped tungsten and for tungsten covered with variable compositions rare earth tungstates. The role of platinum layers covering the cathode was also examined. Given all cathodes containing mainly lanthanum oxides were good emitters, emphasis was put on service lifetime. Comparisons of lifetime in tungsten doped with rare earth oxides and with rare earth tungstates show that microstructure of the operating cathodes may play the major role in the research of very long lifetime cathodes. Based on these results, tests still running show lifetime compatible with power grid tubes applications. (author)

PMR investigation into complexes of lanthanum and lutetium with ethylenediaminediacetic acid

International Nuclear Information System (INIS)

Kostromina, N.A.; Novikova, L.B.

1975-01-01

Proton resonance spectra of ethylendiaminediacetic acid (EDDA) and EDDA mixtures with La and Lu as function of pH of solution was studied. Sequence of EDDA (A 2- ) protonation was established; cations H 3 A + and H 4 A 2+ were found; dissociation constants of above mentioned cations were determined. Formation of H 2 LnA 3+ , HLnA 2+ and LnA + complexes in EDDA-Ln (1:1) system was found. Difference in the bonds mobility of lanthanum and lutetium complexes was determined: lanthanum forms complexes with labile, lutetium with non-labile bonds. Information on complexes structure is collected. Acid dissociation constants of protonated complexes of lanthanum with EDDA were determined

Proceedings of the Annual Symposium on Frequency Control (45th) held in Los Angeles, California on May 29 -31, 1991

Science.gov (United States)

1991-05-31

material gallium silicate of 0 80 lanthanum . Electronic Engineering, Series "Radiodetails and Components",issue 2(63), 1986. Fig. 4: TCF curves of... lanthanum (La 3 Ga5 SiO1 4 )(LGS) yzb/-170-cut operating in thickness which had been first grown up and inves- shear mode are of considerable... gallates with the struc- ture of Ca3 Ga2 GeO1 4 , Reports of the USSR Academy of Science, v.264, No.6 p.1385, 1982. (In Russian5 . 216 FORTY-FIFTH

Quantum efficiencies of near-infrared emission from Ni2+-doped glass-ceramics

International Nuclear Information System (INIS)

Suzuki, Takenobu; Arai, Yusuke; Ohishi, Yasutake

2008-01-01

A systematic method to evaluate potentials of Ni 2+ -doped transparent glass-ceramics as a new broadband optical gain media is presented. At first, near-infrared emission of various ceramics were investigated to explore the suitable crystalline phase to be grown in the glass-ceramics. The quantum efficiency of Ni 2+ near-infrared emission estimated by the Struck-Fonger analysis was higher than 95% for spinel-type structure gallate crystals MgGa 2 O 4 and LiGa 5 O 8 at room temperature. Transparent glass-ceramics containing Ni 2+ :LiGa 5 O 8 could be prepared and the quantum efficiency for the glass-ceramics was measured to be about 10%. This value shows a potential of Ni-doped transparent glass-ceramics as a broadband gain media

Studies on the promotion of nickel—alumina coprecipitated catalysts: II. Lanthanum oxide

NARCIS (Netherlands)

Lansink Rotgerink, H.G.J.; Paalman, R.P.A.M.; van Ommen, J.G.; Ross, J.R.H.

1988-01-01

Two series of lanthanum promoted nickel—alumina catalysts have been prepared by coprecipitation of the metal nitrates, using potassium carbonate. The molar ratio between nickel and the sum of aluminium and lanthanum was kept constant at 2.5 or 9.0 within each series. The calcination and reduction of

Removal of Lanthanum (III) From Aqueous Solution Using Non-Living Water Hyacinth Roots

International Nuclear Information System (INIS)

Aly, A.; Amer, H.A.; Shawky, S.; Shawky, S.; Kandil, A.T.

2013-01-01

Removal of lanthanum (III) from aqueous solution using dried roots of water hyacinth (Eichhornia crassipes) has been investigated. The roots have been characterized by determining the ash percentage, the ph of the slurry, the elemental composition, the thermal gravimetric analysis, the surface area, the pore size, the zeta potential and ph of zero point charge. A surface area of 128 m 2 /g has been found and the micropore structure of the roots has been confirmed. Zeta potential and ph of zero point charge of the roots surfaces showed that they are positively charged within the ph range from 2 to 7.5. Sorption is rapid and depends on ph, weight of roots, concentration of lanthanum (III) and ionic strength. The sorption of lanthanum (III) was confirmed by scanning electron microscope, energy dispersive spectroscopy and the release of Ca +2 , Mg +2 and K +1 after sorption of lanthanum (III) have been indicated an ion exchange mechanism. Fourier transform infrared spectra indicated surface complexation mechanism, and sorption isotherms and kinetics were discussed. The roots were tested for removal of radioactive lanthanum ( 140 La) from simulated radioactive waste. Accepted June 2013.

Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

Energy Technology Data Exchange (ETDEWEB)

Pinto, Alexandre H. [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Souza, Flavio L., E-mail: flavio.souza@ufabc.edu.br [Centro de Ciencias Naturais e Humanas, Universidade Federal do ABC, Rua Santa Adelia 166, Bangu, Santo Andre, SP 09210-170 (Brazil); Chiquito, Adenilson J., E-mail: chiquito@df.ufscar.br [Departamento de Fisica, UFSCar-Federal University of Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Longo, Elson, E-mail: elson@iq.unesp.br [Instituto de Quimica de Araraquara, UNESP-Universidade Estadual Paulista, Rua Francisco Degni, CP 355 Araraquara, SP 14801-907 (Brazil); Leite, Edson R., E-mail: derl@power.ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil); Camargo, Emerson R., E-mail: camargo@ufscar.br [LIEC-Laboratorio Interdisciplinar de Eletroquimica e Ceramica, Departamento de Quimica, UFSCar-Universidade Federal de Sao Carlos, Rod.Washington Luis km 235, CP 676 Sao Carlos, SP 13565-905 (Brazil)

2010-12-01

Nanosized powders of lead lanthanum titanate (Pb{sub 1-x}La{sub x}TiO{sub 3}) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

Characterization of dense lead lanthanum titanate ceramics prepared from powders synthesized by the oxidant peroxo method

International Nuclear Information System (INIS)

Pinto, Alexandre H.; Souza, Flavio L.; Chiquito, Adenilson J.; Longo, Elson; Leite, Edson R.; Camargo, Emerson R.

2010-01-01

Nanosized powders of lead lanthanum titanate (Pb 1-x La x TiO 3 ) were synthesized by means of the oxidant-peroxo method (OPM). Lanthanum was added from 5 to 30% in mol through the dissolution of lanthanum oxide in nitric acid, followed by the addition of lead nitrate to prepare a solution of lead and lanthanum nitrates, which was dripped into an aqueous solution of titanium peroxo complexes, forming a reactive amorphous precipitate that could be crystallized by heat treatment. Crystallized powders were characterized by FT-Raman spectroscopy and X-ray powder diffraction, showing that tetragonal perovskite structure is obtained for samples up to 25% of lanthanum and cubic perovskite for samples with 30% of lanthanum. Powders containing 25 and 30% in mol of lanthanum were calcined at 700 deg. C for 2 h, and in order to determine the relative dielectric permittivity and the phase transition behaviour from ferroelectric-to-paraelectric, ceramic pellets were prepared and sintered at 1100 or 1150 deg. C for 2 h and subjected to electrical characterization. It was possible to observe that sample containing 25% in mol of La presented a normal behaviour for the phase transition, whereas the sample containing 30% in mol of La presented a diffuse phase transition and relaxor behaviour.

MATERIAL AND PROCESS DEVELOPMENT LEADING TO ECONOMICAL HIGH-PERFORMANCE THIN-FILM SOLID OXIDE FUEL CELLS. Final Technical Report (October 2000 - December 2003)

International Nuclear Information System (INIS)

Jie Guan; Nguyen Minh

2003-01-01

This report summarizes the results of the work conducted under the program: ''Material and Process Development Leading to Economical High-Performance Thin-Film Solid Oxide Fuel Cells'' under contract number DE-AC26-00NT40711. The program goal is to advance materials and processes that can be used to produce economical, high-performance solid oxide fuel cells (SOFC) capable of achieving extraordinary high power densities at reduced temperatures. Under this program, anode-supported thin electrolyte based on lanthanum gallate (LSMGF) has been developed using tape-calendering process. The fabrication parameters such as raw materials characteristics, tape formulations and sintering conditions have been evaluated. Dense anode supported LSGMF electrolytes with thickness range of 10-50 micron have been fabricated. High performance cathode based on Sr 0.5 Sm 0.5 CoO 3 (SSC) has been developed. Polarization of ∼0.23 ohm-cm 2 has been achieved at 600 C with Sr 0.5 Sm 0.5 CoO 3 cathode. The high-performance SSC cathode and thin gallate electrolyte have been integrated into single cells and cell performance has been characterized. Tested cells to date generally showed low performance because of low cell OCVs and material interactions between NiO in the anode and lanthanum gallate electrolyte

Signal amplification of dopamine using lanthanum hexacyanoferrate ...

Indian Academy of Sciences (India)

rare earth metal hexacyanoferrates, for e.g., lanthanum ... to facilitate the electrochemical reactions of biological molecules.9,10 In general ... bic acid and potassium hexacyanoferrate (Merck) were ... were prepared using doubly distilled water.

Leaching behavior of lanthanum, nickel and iron from spent catalyst using inorganic acids

Science.gov (United States)

Astuti, W.; Prilitasari, N. M.; Iskandar, Y.; Bratakusuma, D.; Petrus, H. T. B. M.

2018-01-01

Highly technological applications of rare earth metals (REs) and scarcity of supply have become an incentive torecover the REs from various resources, which include high grade and low grade ores, as well as recycledwaste materials. Spent hydrocracking catalyst contain lanthanum and a variety of valuable metals such as nickel and iron. This study investigated the recovery of lanthanum, nickel and iron from spent hydrocracking catalyst by leaching using various inorganic acid (sulfuric acid, hydrochloric acid, and nitric acid). The effect of acid concentration, type of acid and leaching temperature was conducted to study the leaching behavior of each valuable metal from spent-catalyst. It has been shown that it is possible to recover more than 90% of lanthanum, however the leaching efficiency of nickel and iron in this process was very low. It can be concluded that the leaching process is selective for lanthanum recovery from hydrocracking spent-catalyst.

Eutrophication management in surface waters using lanthanum modified bentonite

DEFF Research Database (Denmark)

Copetti, Diego; Finsterle, Karin; Marziali, Laura

2016-01-01

This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales. The availa......This paper reviews the scientific knowledge on the use of a lanthanum modified bentonite (LMB) to manage eutrophication in surface water. The LMB has been applied in around 200 environments worldwide and it has undergone extensive testing at laboratory, mesocosm, and whole lake scales....... The available data underline a high efficiency for phosphorus binding. This efficiency can be limited by the presence of humic substances and competing oxyanions. Lanthanum concentrations detected during a LMB application are generally below acute toxicological threshold of different organisms, except in low...... alkalinity waters. To date there are no indications for long-term negative effects on LMB treated ecosystems, but issues related to La accumulation, increase of suspended solids and drastic resources depletion still need to be explored, in particular for sediment dwelling organisms. Application of LMB...

High-temperature, Knudsen cell-mass spectroscopic studies on lanthanum oxide/uranium dioxide solid solutions

International Nuclear Information System (INIS)

Sunder, S.; McEachern, R.; LeBlanc, J.C.

2001-01-01

Knudsen cell-mass spectroscopic experiments were carried out with lanthanum oxide/uranium oxide solid solutions (1%, 2% and 5% (metal at.% basis)) to assess the volatilization characteristics of rare earths present in irradiated nuclear fuel. The oxidation state of each sample used was conditioned to the 'uranium dioxide stage' by heating in the Knudsen cell under an atmosphere of 10% CO 2 in CO. The mass spectra were analyzed to obtain the vapour pressures of the lanthanum and uranium species. It was found that the vapour pressure of lanthanum oxide follows Henry's law, i.e., its value is directly proportional to its concentration in the solid phase. Also, the vapour pressure of lanthanum oxide over the solid solution, after correction for its concentration in the solid phase, is similar to that of uranium dioxide. (authors)

Scanning Auger microscopy study of lanthanum partitioning in sphene-based glass-ceramics

International Nuclear Information System (INIS)

Hocking, W.H.; Hayward, P.J.; Watson, D.G.; Allen, G.C.

1984-01-01

Glass-ceramics are being investigated as possible hosts for the radioactive wastes that would result from recycling irradiated nuclear fuels. The partitioning of lanthanum in sphene-based glass-ceramics has been studied by scanning Auger electron microscopy for lanthanum concentrations from 0.2 to 2.0 mol.%. Sphene crystals (CaTiSiO 5 ) were located in the silica-rich glass matrix by recording digital Auger images of the calcium and titanium distributions. The sphene crystals were typically 0.5 to 5 μm in size and occupied approximately 40% of the total specimen volume. Auger spot analyses revealed that lanthanum was strongly partitioned into the sphene phase of phosphorus-free glass-ceramics; however, when a small amount of phosphorus was included in the glass-ceramic composition as a crystal nucleating agent, the lanthanum was concentrated in a third minor phase which also contained calcium, phosphorus and oxygen. Chemical shift effects in the Auger spectra of silicon, titanium and phosphorus showed evidence for electron-stimulated desorption of oxygen. (author)

Photocatalytic degradation of Reactive Black 5 and Malachite Green with ZnO and lanthanum doped nanoparticles

International Nuclear Information System (INIS)

Kaneva, N; Bojinova, A; Papazova, K

2016-01-01

Here we report the preparation of ZnO particles with different concentrations of La 3 + doping (0, 0.5 and 1 wt%) via sol-gel method. The nanoparticles are synthesized directly from Zn(CH 3 COO) 2 .2H 2 O in the presence of 1-propanol and triethylamine at 80°C. The conditions are optimized to obtain particles of uniform size, easy to isolate and purify. The nanoparticles are characterized by SEM, XRD and UV-Vis analysis. The photocatalytic properties of pure and La-doped ZnO are studied in the photobleaching of Malachite Green (MG) and Reactive Black 5 (RB5) dyes in aqueous solutions upon UV illumination. It is observed that the rate constant increases with the La loading up to 1 wt%. The doping helps to achieve complete mineralization of MG within a short irradiation time. 1 wt% La-doped ZnO nanoparticles show highest photocatalytic activity. The La 3+ doped ZnO particles degrade faster RB5 than MG. The reason is weaker N=N bond in comparison with the C-C bond between the central carbon atom and N,N-dimethylaminobenzyl in MG. The as-prepared ZnO particles can find practical application in photocatalytic purification of textile wastewaters. (paper)

Bifunctional lanthanum phosphate substrates as novel adsorbents and biocatalyst supports for perchlorate removal

International Nuclear Information System (INIS)

Sankar, Sasidharan; Prajeesh, Gangadharan Puthiya Veetil; Anupama, Vijaya Nadaraja; Krishnakumar, Bhaskaran; Hareesh, Padinhattayil; Nair, Balagopal N.; Warrier, Krishna Gopakumar; Hareesh, Unnikrishnan Nair Saraswathy

2014-01-01

Graphical abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign thermal gelation process, performed the role of dual functional sorbent facilitating perchlorate adsorption and bioremediation through the growth of perchlorate reducing microbial colonies. - Highlights: • Lanthanum phosphate monoliths as efficient perchlorate adsorbents. • And also as substrates for biofilm (perchlorate reducing bacteria) growth. • Environmentally benign thermal gelation process for substrate fabrication. • 98% adsorption efficiency for perchlorate concentrations up to 100 μg/L. • The regenerated monoliths show nearly 100% reusability. - Abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign colloidal forming process employing methyl cellulose, are reported here as excellent adsorbents of perchlorate with >98% efficiency and with 100% reusability. Additionally, the effectiveness of such substrates as biocatalyst supports that facilitate biofilm formation of perchlorate reducing microbes (Serratia marcescens NIIST 5) is also demonstrated for the first time. The adsorption of perchlorate ions is attributed to the pore structure of lanthanum phosphate substrate and the microbial attachment is primarily ascribed to its intrinsic hydrophobic property. Lanthanum phosphate thus emerges as a dual functional material that possesses an integrated adsorption/bioremediation property for the effective removal of ClO 4 − which is an increasingly important environmental contaminant

Bifunctional lanthanum phosphate substrates as novel adsorbents and biocatalyst supports for perchlorate removal

Energy Technology Data Exchange (ETDEWEB)

Sankar, Sasidharan [Materials Science and Technology Division (India); Prajeesh, Gangadharan Puthiya Veetil; Anupama, Vijaya Nadaraja [Process Engineering and Environmental Technology Division, CSIR – National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019 (India); Krishnakumar, Bhaskaran [Process Engineering and Environmental Technology Division, CSIR – National Institute for Interdisciplinary Science and Technology, Industrial Estate P.O., Thiruvananthapuram 695019 (India); Academy of Scientific and Industrial Research (AcSIR) (India); Hareesh, Padinhattayil [Materials Science and Technology Division (India); Nair, Balagopal N. [R and D Centre, Noritake Co. Ltd., Aichi (Japan); Warrier, Krishna Gopakumar [Materials Science and Technology Division (India); Academy of Scientific and Industrial Research (AcSIR) (India); Hareesh, Unnikrishnan Nair Saraswathy, E-mail: hareesh@niist.res.in [Materials Science and Technology Division (India); Academy of Scientific and Industrial Research (AcSIR) (India)

2014-06-30

Graphical abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign thermal gelation process, performed the role of dual functional sorbent facilitating perchlorate adsorption and bioremediation through the growth of perchlorate reducing microbial colonies. - Highlights: • Lanthanum phosphate monoliths as efficient perchlorate adsorbents. • And also as substrates for biofilm (perchlorate reducing bacteria) growth. • Environmentally benign thermal gelation process for substrate fabrication. • 98% adsorption efficiency for perchlorate concentrations up to 100 μg/L. • The regenerated monoliths show nearly 100% reusability. - Abstract: Porous lanthanum phosphate substrates, obtained by an environmentally benign colloidal forming process employing methyl cellulose, are reported here as excellent adsorbents of perchlorate with >98% efficiency and with 100% reusability. Additionally, the effectiveness of such substrates as biocatalyst supports that facilitate biofilm formation of perchlorate reducing microbes (Serratia marcescens NIIST 5) is also demonstrated for the first time. The adsorption of perchlorate ions is attributed to the pore structure of lanthanum phosphate substrate and the microbial attachment is primarily ascribed to its intrinsic hydrophobic property. Lanthanum phosphate thus emerges as a dual functional material that possesses an integrated adsorption/bioremediation property for the effective removal of ClO{sub 4}{sup −} which is an increasingly important environmental contaminant.

Methyl Gallate Inhibits Osteoclast Formation and Function by Suppressing Akt and Btk-PLCγ2-Ca2+ Signaling and Prevents Lipopolysaccharide-Induced Bone Loss.

Science.gov (United States)

Baek, Jong Min; Kim, Ju-Young; Lee, Chang Hoon; Yoon, Kwon-Ha; Lee, Myeung Su

2017-03-07

In the field of bone research, various natural derivatives have emerged as candidates for osteoporosis treatment by targeting abnormally elevated osteoclastic activity. Methyl gallate, a plant-derived phenolic compound, is known to have numerous pharmacological effects against inflammation, oxidation, and cancer. Our purpose was to explore the relation between methyl gallate and bone metabolism. Herein, we performed screening using methyl gallate by tartrate resistant acid phosphatase (TRAP) staining and revealed intracellular mechanisms responsible for methyl gallate-mediated regulation of osteoclastogenesis by Western blotting and quantitative reverse transcription polymerase chain reaction (RT-PCR). Furthermore, we assessed the effects of methyl gallate on the characteristics of mature osteoclasts. We found that methyl gallate significantly suppressed osteoclast formation through Akt and Btk-PLCγ2-Ca 2+ signaling. The blockade of these pathways was confirmed through transduction of cells with a CA-Akt retrovirus and evaluation of Ca 2+ influx intensity (staining with Fluo-3/AM). Indeed, methyl gallate downregulated the formation of actin ring-positive osteoclasts and resorption pit areas. In agreement with in vitro results, we found that administration of methyl gallate restored osteoporotic phenotype stimulated by acute systemic injection of lipopolysaccharide in vivo according to micro-computed tomography and histological analysis. Our data strongly indicate that methyl gallate may be useful for the development of a plant-based antiosteoporotic agent.

Methyl Gallate Inhibits Osteoclast Formation and Function by Suppressing Akt and Btk-PLCγ2-Ca2+ Signaling and Prevents Lipopolysaccharide-Induced Bone Loss

Directory of Open Access Journals (Sweden)

Jong Min Baek

2017-03-01

Full Text Available In the field of bone research, various natural derivatives have emerged as candidates for osteoporosis treatment by targeting abnormally elevated osteoclastic activity. Methyl gallate, a plant-derived phenolic compound, is known to have numerous pharmacological effects against inflammation, oxidation, and cancer. Our purpose was to explore the relation between methyl gallate and bone metabolism. Herein, we performed screening using methyl gallate by tartrate resistant acid phosphatase (TRAP staining and revealed intracellular mechanisms responsible for methyl gallate-mediated regulation of osteoclastogenesis by Western blotting and quantitative reverse transcription polymerase chain reaction (RT-PCR. Furthermore, we assessed the effects of methyl gallate on the characteristics of mature osteoclasts. We found that methyl gallate significantly suppressed osteoclast formation through Akt and Btk-PLCγ2-Ca2+ signaling. The blockade of these pathways was confirmed through transduction of cells with a CA-Akt retrovirus and evaluation of Ca2+ influx intensity (staining with Fluo-3/AM. Indeed, methyl gallate downregulated the formation of actin ring-positive osteoclasts and resorption pit areas. In agreement with in vitro results, we found that administration of methyl gallate restored osteoporotic phenotype stimulated by acute systemic injection of lipopolysaccharide in vivo according to micro-computed tomography and histological analysis. Our data strongly indicate that methyl gallate may be useful for the development of a plant-based antiosteoporotic agent.

Separation of lanthanum (3) and samarium (3) extraction with tributylphosphate in the solvent presence of solid phase

International Nuclear Information System (INIS)

Korotkevich, I.B.; Kolesnikov, A.A.; Bomshtejn, V.E.

1990-01-01

Lanthanum (3) and samarium (3) extraction from nitric acid solutions by tributylphosphate in the presence of solid phase has been investigated. An increase in samarium α-nitrate distribution factor in the presence of solid phase with a decrease in its concentration in the initial solution and with lanthanum nitrate concentration increase is detected. The greatest effect of separation is observed in samarium nitrate microregion. The method of quantitative extraction of samarium from lanthanum nitrate solutions with samarium-lanthanum separation factor exceeding 50 has been suggested

Lanthanum benzoyl acetonates: an IR and mass spectrometric study of the composition and structure

International Nuclear Information System (INIS)

Kostyuk, N.N.; Dik, T.A.; Tereshko, N.V.

2005-01-01

IR spectroscopy and mass spectrometry were used to study the structure of lanthanum chelates of benzoyl acetone (1-phenyl-1,3-butadione, HBA) of the following compositions: La(BA) 3 · EtOH, La(BA) 2 , La(BA) 2 · CH 3 CN, and La(BA) 2 · HDA, where EtOH = ethanol, HDA = nonadecanoic acid. It is demonstrated that a quasi-aromatic metalloring is formed in lanthanum chelates studied. Stable metal-containing fragments of the molecular ions of lanthanum bis- and tris-benzoylacetonate were identified [ru

Synthesis and Biological Testing of Novel Glucosylated Epigallocatechin Gallate (EGCG Derivatives

Directory of Open Access Journals (Sweden)

Xin Zhang

2016-05-01

Full Text Available Epigallocatechin gallate (EGCG is the most abundant component of green tea catechins and has strong physiological activities. In this study, two novel EGCG glycosides (EGCG-G1 and EGCG-G2 were chemoselectively synthesized by a chemical modification strategy. Each of these EGCG glycosides underwent structure identification, and the structures were assigned as follows: epigallocatechin gallate-4′′-O-β-d-glucopyranoside (EGCG-G1, 2 and epigallocatechin gallate-4′,4′′-O-β-d-gluco-pyranoside (EGCG-G2, 3. The EGCG glycosides were evaluated for their anticancer activity in vitro against two human breast cell lines (MCF-7 and MDA-MB-231 using MTT assays. The inhibition rate of EGCG glycosides (EGCG-G1 and EGCG-G2 is not obvious. The EGCG glycosides are more stable than EGCG in aqueous solutions, but exhibited decreasing antioxidant activity in the DPPH radical-scavenging assay (EGCG > EGCG-G2 > EGCG-G1. Additionally, the EGCG glycosides exhibited increased water solubility: EGCG-G2 and EGCG-G1 were 15 and 31 times as soluble EGCG, respectively. The EGCG glycosides appear to be useful, and further studies regarding their biological activity are in progress.

Synthesis and characterization of lanthanum incorporated mesoporous molecular sieves

International Nuclear Information System (INIS)

Pesquera, C.; Gonzalez, F.; Blanco, C.; Sanchez, L.

2004-01-01

A series of mesoporous materials under reflux conditions have been synthesized with two silicon sources (fumed silica and sodium silicate) and lanthanum added. The following Si/La molar ratio was used in the samples: 100; 75; 50 and 25. The calcined products were characterized by means of X-ray diffraction, nitrogen adsorption isotherms and energy dispersive X-ray spectrometry (EDS). The BET surface area gradually decreases with an increase in the lanthanum content of the LaxMCM-41 samples. Moreover, the average pore size tends to decrease along with the increase in the La content in the samples

Physiological responses in barley to applications of lanthanum

International Nuclear Information System (INIS)

Reddy, N.; Maheswaran, J.; Peverill, K.; Meehan, B.

1998-01-01

Full text: Chinese research and glasshouse investigations carried out in Victoria by the authors have shown that several plant species, when treated with Rare Earth Elements (REEs), retain greater amounts of moisture under water stressed conditions. The physiological adaptation of the plant to retain moisture in response to REE treatment however, has not been investigated. A glasshouse trial is currently in progress to study the physiological and agronomic responses of barley (cv. Schooner) grown in pots to application of lanthanum (0, 5 and 10 kg/ha), at a concentration of 0.05%, under well-watered (field capacity) and water-deficit (25 - 30% field capacity) conditions. Lanthanum was applied both directly to the soil and as a foliar spray. The physiological measurements include, photosynthetic rate, leaf water potential, osmotic potential, relative water content, stomatal conductance and water use efficiency. Measured agronomic parameters include plant height, tiller production, leaf area development, total grain weight, total biomass, root and shoot ratio and harvest index. Analysis of plant tissue for N, P, K, Ca, Mg, Zn and La to study the relationship between application of REE and nutrient uptake is also being carried out. The paper discusses physiological and agronomic changes in barley plants in response to treatment with lanthanum, under conditions of water stress

Characteristics and performance of lanthanum gallate electrolyte-supported SOFC under ethanol steam and hydrogen

Science.gov (United States)

Huang, Bo; Zhu, Xin-Jian; Hu, Wan-Qi; Yu, Qing-Chun; Tu, Heng-Yong

This study is focused on the electrochemical performance of perovskite-type materials based on doped LaGaO 3. La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC) were used as electrolytes and (Pr 0.7Ca 0.3) 0.9MnO 3 (PCM) and La 0.75Sr 0.25Cr 0.5Mn 0.5O 3- δ (LSCM) as cathode and anode material, respectively. LSGM and LSGMC electrolytes were prepared by tape casting with a thickness of about 600 μm. The performance of LSCM/LSGMC/PCM was slightly superior to that obtained on LSCM/LSGM/PCM at different temperatures in both humidified hydrogen and ethanol steam atmospheres, good values of power output in LSCM/LSGMC/PCM were 182 and 169 mW cm -2 using humidified hydrogen and ethanol steam as fuel, respectively, and oxygen as oxidant at 850 °C. Cell stability tests indicate no significant degradation in performance after 60 h of cell testing when LSCM anode was exposed to ethanol steam at 750 °C. Almost no carbon deposits were detected after testing in ethanol steam at 750 °C for >60 h on the LSCM anodes, suggesting that carbon deposition was limited during cell operation.

Formulation and Assessment of a Wash-Primer Containing Lanthanum "Tannate" for Steel Temporary Protection

Science.gov (United States)

D'Alessandro, Oriana; Selmi, Gonzalo J.; Deyá, Cecilia; Di Sarli, Alejandro; Romagnoli, Roberto

2018-02-01

Tannins are polyphenols synthesized by plants and useful for the coating industry as corrosion inhibitors. In addition, lanthanum salts have a great inhibitory effect on steel corrosion. The aim of this study was to obtain lanthanum "tannate" with adequate solubility to be incorporated as the corrosion inhibitor in a wash-primer. The "tannate" was obtained from commercial "Quebracho" tannin and 0.1 M La(NO3)3. The soluble tannin was determined by the Folin-Denis reagent, while the concentration of Lanthanum was obtained by a gravimetric procedure. The protective action of "tannate" on SAE 1010 steel was evaluated by linear polarization curves and corrosion potential measurements. Lanthanum "tannate" was incorporated in a wash-primer formulation and tested by corrosion potential and ionic resistance measurements. The corrosion rate was also determined by the polarization resistance technique. Besides, the primer was incorporated in an alkyd paint system and its anticorrosion performance assessed in the salt spray cabinet and by electrochemical impedance spectroscopy. Results showed that lanthanum "tannate" primer inhibits the development of deleterious iron oxyhydroxides on the steel substrate and incorporated into a paint system had a similar behavior to the primer formulated with zinc tetroxychromate.

Separation of lanthanum (3) and neodymium (3) by tributyl phosphate extraction in the presence of solid phase

International Nuclear Information System (INIS)

Korotkevich, I.B.; Kolesnikov, A.A.; Bomshtejn, V.E.; Shikhaleeva, N.N.

1987-01-01

Lanthanum (3) and neodymium (3) extraction from nitric acid solutions by tributyl phosphate in the presence of solid phase of the element nitrates is investigated. An increase in distribution of neodymium nitrate in the presence of solid phase with the decrease in its concentration in the initial solution and with the increase in lanthanum nitrate concentration is detected. The highest effect of extractive-crystallizational separation is observed in the range of neodymium nitrate microconcentrations. A method of neodymium quantitative extraction from lanthanum nitrate solutions with neodymium - lanthanum separation coefficient exceeding 25 is suggested

Epigallocatechin gallate ameliorates chronic fatigue syndrome in mice: behavioral and biochemical evidence.

Science.gov (United States)

Sachdeva, Anand Kamal; Kuhad, Anurag; Tiwari, Vinod; Chopra, Kanwaljit

2009-12-28

Three decades after the coining of the term chronic fatigue syndrome, the diagnosis of this illness is still symptom based and the aetiology remains elusive. Chronic fatigue syndrome pathogenesis seems to be multifactorial and the possible involvement of immune system is supported. The present study was designed to evaluate the effects of the epigallocatechin gallate in a mouse model of immunologically induced chronic fatigue. On 19th day, after lipopolysaccharide/Brucella abortus administration, the mice showed significant increase in immobility period, post swim fatigue and thermal hyperalgesia. Behavioral deficits were coupled with enhanced oxidative-nitrosative stress as evident by increased lipid peroxidation, nitrite levels and decreased endogenous antioxidant enzymes (superoxide dismutase, reduced glutathione and catalase) and inflammation (increased levels of tumor necrosis factor-alpha and tissue growth factor-beta). Chronic treatment with epigallocatechin gallate restored these behavioral and biochemical alterations in mice. The present study points out towards the beneficial effect of epigallocatechin gallate in the amelioration of chronic fatigue syndrome and thus may provide a new, effective and powerful strategy to treat chronic fatigue syndrome.

Study of strontium- and magnesium-doped lanthanum gallate solid electrolyte surface by X-ray photoelectron spectroscopy

International Nuclear Information System (INIS)

Datta, Pradyot; Majewski, Peter; Aldinger, Fritz

2008-01-01

The chemical states of the surface of the oxygen ion conducting solid electrolyte La 0.9 Sr 0.1 Ga 0.85 Mg 0.15 O 3-δ (LSGM 1015) as prepared by solid-state synthesis was analyzed by X-ray photoelectron spectroscopy. It was found that adventitious carbon did not interact with any of the constituent elements of LSGM 1015. Ga and La were found to exist in trivalent states. But, due to ionic bombardment presence of Mg could not be detected in the electrolyte surface

New calcium gallates of lanthanum and neodymium

International Nuclear Information System (INIS)

Ismatov, A.A.; Azimov, Sh.Yu.; Ismatov, T.A.

1982-01-01

CaLaGa 3 O 7 and CaNdGa 3 O 7 gallium-containing analogs of helenite were synthesized. The dependence of their physical (density, specific resistance, thermal expansion coefficient and other) and crystallochemical (crystal habitus, parameters and volumes of unit cells) properties on rare earth nature was established

Processing of strontium-doped lanthanum manganite suspensions for cathode production of the solid oxide fuel cell; Processamento das suspensoes de manganito de lantanio dopado com estroncio para fabricacao do catodo da celula a combustivel de oxido solido

Energy Technology Data Exchange (ETDEWEB)

Chiba, R.; Vargas, R.A.; Andreoli, M.; Seo, E.S.M. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil). Centro de Ciencia e Tecnologia de Materiais. Lab. de SOFC - Insumos e Componentes

2008-07-01

The ceramic material, strontium-doped lanthanum manganite (La{sub 0,85}Sr{sub 0,15}MnO{sub 3} - LSM), has been used as cathode in Solid Oxide Fuel Cells (SOFCs). The cathode attainment as component of the SOFCs has been studied for diverse routes of synthesis and thin films forming in Yttria-stabilized zirconia (ZrO{sub 2}/Y{sub 2}O{sub 3} - YSZ) electrolyte. In this work, the LSM was synthesized by the citrate technique and deposited in YSZ substrate using the forming technique wet powder spraying. Rheological studies of suspensions and chemical, physical and microstructural characterizations of LSM powders were made, aiming at the deposition for thin films formation until 50 mum. The half unit cells LSM/YSZ sintered were characterized by scanning electron microscopy, for verification of porosity and adherence. In this sense, this work is a contribution for production of porous cathode using the forming technique wet powder spraying in the SOFCs. (author)

Reactivity and interdiffusion of alternative SOFC cathodes with yttria stabilized zirconia, gadolinia doped ceria and doped lanthanum gallate solid electrolytes

Energy Technology Data Exchange (ETDEWEB)

Kostogloudis, G.C.; Tsiniarakis, G.; Riza, F.; Ftikos, C. [National Tech. Univ. of Athens (Greece)

2000-07-01

The chemical compatibility between the cathode composition Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} and the electrolyte compositions yttria stabilized zirconia (YSZ), Ce{sub 0.8}Gd{sub 0.2}O{sub 1.9} (CGO) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.9}Mg{sub 0.1}O{sub 3-{delta}} (LSGM) was investigated. Also, the influence of the substitution of Al for Fe on the reactivity of the cathode with YSZ was examined. All oxides were single-phase materials except for LSGM, which contained two additional phases, namely LaSrGa{sub 3}O{sub 7} and LaSrGaO{sub 4}. Two types of experiments were performed: (a) reactivity experiments by XRD in cathode/electrolyte powder mixtures and (b) diffusion experiments by SEM/EDX analysis in cathode/electrolyte double-layer pellets. Pr{sub 2}Zr{sub 2}O{sub 7}, SrZrO{sub 3} and CoFe{sub 2}O{sub 4} were formed by the interaction of the cathode materials with YSZ. Substitution by Al at the B-site of the perovskite cathode led to a decrease of its reactivity with YSZ. No reaction products were formed for powder mixtures of Pr{sub 0.8}Sr{sub 0.2}Co{sub 0.2}Fe{sub 0.8}O{sub 3-{delta}} and CGO or LSGM electrolytes. High Co and Fe diffusion into LSGM was identified. Pr, La and Ga show a smaller tendency for diffusion. The diffusion of transition metal cations into LSGM electrolyte caused the destabilisation and disappearance of the second phases in the interdiffusion zone. (orig.)

Develop techniques for ion implantation of PLZT [lead-lanthanum-zirconate-titanate] for adaptive optics

International Nuclear Information System (INIS)

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

1987-09-01

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 0 C. This report summarizes the research and provides a sampling of the data taken during the report period

The influence of propyl gallate and α-tocopherol on the survival time of rats during fasting

NARCIS (Netherlands)

Tonkelaar, E.M. den; Verschuuren, H.G.; Kroes, R.; Esch, G.J. van

1968-01-01

A toxicological investigation was carried out in order to repeat and extend the findings of Bukhman (Vop. Pitan. 1962, 21, 68) concerning the toxicity of propyl gallate in fasting rats. Rats were given a diet containing 0·002 or 0·004% propyl gallate or α-tocopherol. After 13 wk some of the animals

Preparation of lanthanum ferrite powder at low temperature

Energy Technology Data Exchange (ETDEWEB)

Andoulsi, R.; Horchani-Naifer, K.; Ferid, M., E-mail: karima_horchani@yahoo.com [Physical Chemistry Laboratory of Mineral Materials and their Applications, Hammam-Lif (Tunisia)

2012-01-15

Single lanthanum ferrite phase was successfully prepared at low processing temperature using the polymerizable complex method. To implement this work, several techniques such as differential scanning calorimetry, X-ray diffraction, Fourier Transform Infrared Spectroscopy, scanning electron microscopy and BET surface area measurements were used. Throw the obtained results, it was shown that steps of preparing the powder precursor and temperature of its calcination are critical parameters for avoiding phase segregation and obtaining pure lanthanum ferrite compound. Thus, a single perovskite phase was obtained at 600 deg C. At this temperature, the powder was found to be fine and homogeneous with an average crystallite size of 13 nm and a specific surface area of 12.5 m{sup 2}.g{sup -1}. (author)

Synthesis of Ni nanoparticles in lanthanum chromite ceramic matrix

International Nuclear Information System (INIS)

Tinti, Victor Buratto; Florio, Daniel Zanetti de; Fonseca, Fabio Coral

2016-01-01

Full text: Lanthanum chromite is a well-known interconnector for solid oxide fuel cells. It presents electronic conductivity at high temperatures. Moreover it is very stable in oxidizing and reducing atmospheres. Due to its high stability this material is a promising matrix to produce and stabilize nanoparticles by exothermal reaction. The objective of the present work is to synthesize and stabilize nickel nanoparticles in a stable ceramic matrix. Compounds of (La 1-x Sr x ) a (Cr 1-y Ni y )O 3 (x and y = 0, 0.1, and 0.2; a = 1, and 0.8) were synthesized by Pechini method. The powders were heat treated in air at 1300 °C and 1600°C in attempt to solubilise NiO in the matrix. Then the samples were exposed to a reducing treatment in H 2(g) flux at 900°C per 8 hours. XRD measurements were made using a D8 Focus, Bruker AXS. The data was acquired in a range of 2θ from 20° to 90°, with a step of 0,02° per second. Magnetic properties were investigated utilizing a SQUIDVSM from Quantum Design. Magnetic moment at constant magnetic field (100 Oe and 1000 Oe) was measured in a range of 2K to 300K. Analyses with variable magnetic field were performed at 2K, 196K and 390K in a rage from -5 up to 5 T. Samples were observed using TEM technique. The XRD results showed that the stoichiometric samples achieved desiderate phase. Compounds without Sr and non-stoichiometric lanthanum site showed an incomplete nickel solid solution. The addition of 10% of Sr decreases the Neel temperature from 289 K to 285K. Ni doping created a stronger effect, lowering the temperature down to 267 K , in the sample with 10% of dopant. After reduction is possible to observe peaks of Ni in the XRD, indicating that nickel was exoluted form the matrix. Images of TEM confirm the presence of nanoparticles with an approximate diameter of 3 nm. The reducing treatment increased the magnetic response. (author)

Trimethylphosphide isomerization in lanthanum ions presence

International Nuclear Information System (INIS)

Zacharias, M.A.; Massabni, A.M.G.

1984-01-01

The integration between the trimethilphosphide and the lanthanum ions carry to the formation of solid complexes in a relation of 6:1 where the ligand is the phosphonate what is resultant of the isomerization of trimetylphosphite. By the RMN -1 H and infra-red spectra the products were characterized. (L.M.J.) [pt

The air oxidation behavior of lanthanum ion implanted zirconium at 500 deg. C

CERN Document Server

Peng, D Q; Chen, X W; Zhou, Q G

2003-01-01

The beneficial effect of lanthanum ion implantation on the oxidation behavior of zirconium at 500 deg. C has been studied. Zirconium specimens were implanted by lanthanum ions using a MEVVA source at energy of 40 keV with a fluence range from 1x10 sup 1 sup 6 to 1x10 sup 1 sup 7 ions/cm sup 2 at maximum temperature of 130 deg. C, The weight gain curves were measured after being oxidized in air at 500 deg. C for 100 min, which showed that a significant improvement was achieved in the oxidation behavior of zirconium ion implanted with lanthanum compared with that of the as-received zirconium. The valence of the oxides in the scale was analyzed by X-ray photoemission spectroscopy; and then the depth distributions of the elements in the surface of the samples were obtained by Auger electron spectroscopy. Glancing angle X-ray diffraction at 0.3 deg. incident angles was employed to examine the modification of its phase transformation because of the lanthanum ion implantation in the oxide films. It was obviously fou...

AB initio energetics of lanthanum substitution in ferroelectric bismuth titanate

International Nuclear Information System (INIS)

Shah, S.H.

2012-01-01

Density functional theory based electronic structure calculations play a vital role in understanding, controlling and optimizing physical properties of materials at microscopic level. In present study system of interest is bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/)/(BIT) which has wide range of applications such as a high temperature piezoelectric and one of the best material for memory devices. However, it also suffers from serious issues such as oxygen vacancies which degrade its performance as a memory element and piezoelectric material. In this context, the bulk and defect properties of orthorhombic bismuth titanate (Bi/sub 4/Ti/sub 3/O/sub 12/) and bismuth lanthanum titanate (Bi/sub 3.25/La/sub 0.75/Ti/sub 3/O/sub 12/)/(BLT, x=0.75) were investigated by using first principles calculations and atomistic thermodynamics. Heats of formation, valid chemical conditions for synthesis, lanthanum substitution energies and oxygen and bismuth vacancy formation energies were computed. The study improves understanding of how native point defects and substitutional impurities influence the ferroelectric properties of these layered perovskite materials. It was 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 for 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. (orig./A.B.)

Synthesis and luminescence studies of novel rare earth activated lanthanum pentaborate

International Nuclear Information System (INIS)

Nagpure, P.A.; Bajaj, N.S.; Omanwar, S.K.; Sonekar, R.P.

2011-01-01

The lanthanum pentaborate (LaB 5 O 9 ) is a novel material which exhibits excellent luminescence when doped with rare earth ions. It was prepared by a novel technique which is a slight variation of solution combustion synthesis. The synthesis is based on the exothermic reaction between the fuel (urea) and oxidizer (ammonium nitrate). The structure of the prepared material was confirmed by powder XRD technique. The photoluminescence of rare earth ions (Ce 3+ , Eu 3+ ) and sensitized luminescence of Gd 3+ (Pr 3+ -Gd 3+ and Bi 3+ -Gd 3+ ) in LaB 5 O 9 have been studied. LaB 5 O 9 :Ce 3+ shows broad band UV emission at 317 nm and LaB 5 O 9 :Eu 3+ shows orange red emission. LaB 5 O 9 : Pr 3+ -Gd 3+ and LaB 5 O 9 : Bi 3+ -Gd 3+ exhibit efficient luminescence of Gd 3+ in narrow UVB region at 310 nm. The material (La 0.5 Pr 0.4 )B 5 O 9 :Gd 0.1 exhibits intense narrow band UVB emission at 310 nm and could be a potential candidate for UVB phosphors used in phototherapy lamps. (author)

Phase segregation in cerium-lanthanum solid solutions

NARCIS (Netherlands)

Belliere, V.; Joorst, G; Stephan, O; de Groot, FMF; Weckhuysen, BM

2006-01-01

Electron energy-loss spectroscopy (EELS) in combination with scanning transmission electron microscopy ( STEM) reveals that the La enrichment at the surface of cerium-lanthanum solid solutions is an averaged effect and that segregation occurs in a mixed oxide phase. This separation occurs within a

Polarization characteristics of composite electrodes in electrochemical cells with solid electrolytes based on CeO2 and LaGaO3

International Nuclear Information System (INIS)

Yaroslavtsev, I. Yu.; Kuzin, B. L.; Bronin, D. I.; Bogdanovich, N. M.

2005-01-01

For two types of electrochemical cells with oxygen-conducting solid electrolytes based on lanthanum gallate (LSGM) and cerium oxide (SDC) studied are the temperature dependences of the polarization conductivity of air electrodes prepared from lanthanum strontium manganite (LSM) and composites LSM-LSGM, LSM-SDC, and LSM-SSZ (SSZ is zirconium dioxide-based electrolyte). Effect of praseodymium oxide, added into these electrodes as a modifier, on their electrochemical properties is examined. Electrochemical systems with an LSM/LSGM interface exhibit low electrochemical activity toward the oxygen reaction, because during the formation of electrodes, LSM interacts with LSGM to form a poorly conducting product [ru

Characteristics and performance of lanthanum gallate electrolyte-supported SOFC under ethanol steam and hydrogen

Energy Technology Data Exchange (ETDEWEB)

Huang, Bo; Zhu, Xin-Jian; Yu, Qing-Chun; Tu, Heng-Yong [Institute of Fuel Cell, Shanghai Jiaotong University, 800 Dongchuan Road, Shanghai 200240 (China); Hu, Wan-Qi [Institute of Process Engineering, Chinese Academy of Sciences (China)

2009-01-01

This study is focused on the electrochemical performance of perovskite-type materials based on doped LaGaO{sub 3}. La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.115}Co{sub 0.085}O{sub 3-{delta}} (LSGMC) were used as electrolytes and (Pr{sub 0.7}Ca{sub 0.3}){sub 0.9}MnO{sub 3} (PCM) and La{sub 0.75}Sr{sub 0.25}Cr{sub 0.5}Mn{sub 0.5}O{sub 3-{delta}} (LSCM) as cathode and anode material, respectively. LSGM and LSGMC electrolytes were prepared by tape casting with a thickness of about 600 {mu}m. The performance of LSCM/LSGMC/PCM was slightly superior to that obtained on LSCM/LSGM/PCM at different temperatures in both humidified hydrogen and ethanol steam atmospheres, good values of power output in LSCM/LSGMC/PCM were 182 and 169 mW cm{sup -2} using humidified hydrogen and ethanol steam as fuel, respectively, and oxygen as oxidant at 850 C. Cell stability tests indicate no significant degradation in performance after 60 h of cell testing when LSCM anode was exposed to ethanol steam at 750 C. Almost no carbon deposits were detected after testing in ethanol steam at 750 C for >60 h on the LSCM anodes, suggesting that carbon deposition was limited during cell operation. (author)

As-Deposited (La1-xSrx)(Ga1-y-zMgyCoz)O3-(x+y+z)/2 Crystallized Thin Films Prepared by Pulsed Laser Deposition for Application to Solid Oxide Fuel Cell Electrolyte

Science.gov (United States)

Mitsugi, Fumiaki; Kanazawa, Seiji; Ohkubo, Toshikazu; Nomoto, Yukiharu; Ishihara, Tatsumi; Takita, Yusaku

2004-01-01

Doped lanthanum gallate (La1-xSrx)(Ga1-y-zMgyCoz)O3-(x+y+z)/2 (LSGMCO) perovskite oxide films were deposited on a quartz glass, LaAlO3 single-crystal substrate and porous anode electrode of a solid oxide fuel cell (SOFC) by pulsed laser deposition. It was necessary to increase the substrate temperature up to 800°C for a crystallization of the LSGMCO films. The film deposited on the LaAlO3 single-crystal substrate grew along the c-axis. The as-deposited LSGMCO thick film fabricated on the porous substrate at 800°C and at an oxygen pressure of 20Pa was formed from polycrystal columns and showed a high conductivity of 0.7S/cm at a measurement temperature of 800°C. The activation energies were 0.72 eV at 600-800°C and 1.05 eV at 400-600°C.

Structural characterization and properties of lanthanum film as chromate replacement for tinplate

International Nuclear Information System (INIS)

Huang Xingqiao; Li Ning

2007-01-01

Sulfide-stain resistance of La-passivated, unpassivated and Cr-passivated tinplate was measured using a cysteine tarnish test. Corrosion behavior of these tinplates was investigated using electrochemical impedance spectroscopy (EIS) measurement. The morphology, composition and thickness of lanthanum film were studied by atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and X-ray fluorescence spectrometry (XRF), respectively. La-passivation treatment remarkably enhances sulfide-stain resistance of tinplate, and sulfide-stain resistance of La-passivated tinplate is slightly higher than that of Cr-passivated tinplate. La-passivation treatment also significantly improves corrosion protection property of tinplate. In contact with 3.5% NaCl solution, corrosion resistance of La-passivated tinplate is close to that of Cr-passivated tinplate, and in contact with 0.1 M citric-citrate buffer solution, corrosion resistance of La-passivated tinplate is higher than that of Cr-passivated tinplate. Lanthanum film is composed of spherical particles about 50-1000 nm in diameter, while most part of tinplate's surface is covered with the small particles about 50-200 nm. The film mainly consists of lanthanum and oxygen, which mainly exist as La 2 O 3 and its hydrates such as La(OH) 3 and LaOOH. The amount of lanthanum in the film is about 0.0409 g/m 2

Lanthanum Nitrate As Electrolyte Additive To Stabilize the Surface Morphology of Lithium Anode for Lithium-Sulfur Battery.

Science.gov (United States)

Liu, Sheng; Li, Guo-Ran; Gao, Xue-Ping

2016-03-01

Lithium-sulfur (Li-S) battery is regarded as one of the most promising candidates beyond conventional lithium ion batteries. However, the instability of the metallic lithium anode during lithium electrochemical dissolution/deposition is still a major barrier for the practical application of Li-S battery. In this work, lanthanum nitrate, as electrolyte additive, is introduced into Li-S battery to stabilize the surface of lithium anode. By introducing lanthanum nitrate into electrolyte, a composite passivation film of lanthanum/lithium sulfides can be formed on metallic lithium anode, which is beneficial to decrease the reducibility of metallic lithium and slow down the electrochemical dissolution/deposition reaction on lithium anode for stabilizing the surface morphology of metallic Li anode in lithium-sulfur battery. Meanwhile, the cycle stability of the fabricated Li-S cell is improved by introducing lanthanum nitrate into electrolyte. Apparently, lanthanum nitrate is an effective additive for the protection of lithium anode and the cycling stability of Li-S battery.

Synthesis and characterization of lanthanum complex (5-choloro-8-hydroxy quinoline) bis (2-2'bipyridine) lanthanum La(Bpy)2(5-Clq)

Science.gov (United States)

Kumar, Rahul; Soam, Ankur; Bhargava, Parag

2017-05-01

Lanthanum complex, (5-choloro 8-hydroxy quinoline) bis (2-2'bipyridine) has been synthesized and characterized by different techniques. Lanthanum complex, La(Bpy)2(5-Clq) was characterized for structural, thermal and photoluminescence analysis. Structural analysis of this material was done by Fourier transformed infrared spectroscopy (FTIR) and mass spectroscopy. Thermal analysis of this material was done by thermal gravimetric analysis (TGA) and material shows the thermal stability up to 400°C. Absorption and emission spectra of the material was measured by UV-visible spectroscopy and photoluminescence spectroscopy. Solution of this material La(Bpy)2(5-Clq) in ethanol showed absorption peak at 332 nm, which may be attributed due to (π - π*) transitions. The photoluminescence spectra of La(Bpy)2(5-Clq) in ethanol solution showed intense peak at 505 nm.

Plasma spheroidization and high temperature stability of lanthanum phosphate and its compatibility with molten uranium

International Nuclear Information System (INIS)

Ananthapadmanabhan, P.V.; Sreekumar, K.P.; Thiyagarajan, T.K.; Satpute, R.U.; Krishnan, K.; Kulkarni, N.K.; Kutty, T.R.G.

2009-01-01

Lanthanum phosphate has excellent thermal stability and corrosion resistance against many molten metals and other chemically corrosive environments. Lanthanum phosphate (LaPO 4 ) was synthesized from lanthanum oxalate by thermal dissociation of the oxalate to the oxide, followed by conversion to hydrated lanthanum phosphate (LaPO 4 .0.5H 2 O). Thermal treatment of LaPO 4 .0.5H 2 O above 773 K resulted in the irreversible transformation of the hydrated phase to the stable monazite phase. Thermal and chemical stability of monazite was studied by plasma spheroidization experiments using a DC thermal plasma reactor set up. Compatibility of monazite with molten uranium was studied by thermal analysis. Results showed that monazite is thermally stable up to its melting point and also is resistant towards attack by molten uranium. Adherent coatings of LaPO 4 could be deposited onto various substrates by atmospheric plasma spray technique

First-principles calculation on oxygen ion migration in alkaline-earth doped La2GeO5

International Nuclear Information System (INIS)

Thuy Linh, Tran Phan; Sakaue, Mamoru; Aspera, Susan Meñez; Alaydrus, Musa; Wungu, Triati Dewi Kencana; Hoang Linh, Nguyen; Kasai, Hideaki; Mohri, Takahiro; Ishihara, Tatsumi

2014-01-01

By using first-principles calculations based on the density functional theory, we investigated the doping effects of alkaline-earth metals (Ba, Sr and Ca) in monoclinic lanthanum germanate La 2 GeO 5 on its oxygen ion conduction. Although the lattice parameters of the doped systems changed due to the ionic radii mismatch, the crystal structures remained monoclinic. The contribution of each atomic orbital to electronic densities of states was evaluated from the partial densities of states and partial charge densities. It was confirmed that the materials behaved as ionic crystals comprising of cations of La and dopants and anions of oxygen and covalently formed GeO 4 . The doping effect on the activation barrier for oxygen hopping to the most stable oxygen vacancy site was investigated by the climbing-image nudged elastic band method. By tracing the charge density change during the hopping, it was confirmed that the oxygen motion is governed by covalent interactions. The obtained activation barriers showed excellent quantitative agreements with an experiment for the Ca- and Sr-doped systems in low temperatures as well as the qualitative trend, including the Ba-doped system. (paper)

Transdermal solid delivery of epigallocatechin-3-gallate using self-double-emulsifying drug delivery system as vehicle: Formulation, evaluation and vesicle-skin interaction.

Science.gov (United States)

Hu, Caibiao; Gu, Chengyu; Fang, Qiao; Wang, Qiang; Xia, Qiang

2016-02-01

The present study investigated a self-double-emulsifying drug delivery system loaded with epigallocatechin-3-gallate to improve epigallocatechin-3-gallate skin retention. The long chain solid lipids (cetostearyl alcohol) and macadamia oil were utilized as a carrier to deliver the bioactive ingredient. Response surface methodology was used to optimize the formulation, and the solid lipid to total lipid weight ratio, concentration of epigallocatechin-3-gallate and hydrophilic surfactant on skin retention were found to be the principal factors. The optimum formulation with high encapsulation efficiency (95.75%), self-double-emulsification performance (99.58%) and skin retention (87.24%) were derived from the fitted models and experimentally examined, demonstrating a reasonable agreement between experimental and predicted values. Epigallocatechin-3-gallate-self-double-emulsifying drug delivery system was found to be stable for 3 months. Transdermal studies could explain a higher skin diffusion of epigallocatechin-3-gallate from the self-double-emulsifying drug delivery system compared with EGCG aqueous solution. In vitro cytotoxicity showed that epigallocatechin-3-gallate-self-double-emulsifying drug delivery system did not exert hazardous effect on L929 cells up to 1:10. © The Author(s) 2015.

Nanoscale photoelectron ionisation detector based on lanthanum hexaboride

International Nuclear Information System (INIS)

Zimmer, C.M.; Kunze, U.; Schubert, J.; Hamann, S.; Doll, T.

2011-01-01

A nanoscale ioniser is presented exceeding the limitation of conventional photoionisation detectors. It employs accelerated photoelectrons that allow obtaining molecule specificity by the tuning of ionisation energies. The material lanthanum hexaboride (LaB 6 ) is used as air stable photo cathode. Thin films of that material deposited by pulsed laser deposition (PLD) show quantum efficiency (QE) in the range of 10 -5 which is comparable to laser photo stimulation results. A careful treatment of the material yields reasonable low work functions even after surface reoxidation which opens up the possibility of using ultraviolet light emitting diodes (UV LEDs) in replacement of discharge lamps. Schematic diagram of a photoelectron ionisation detector (PeID) operating by an electron emitter based on the photoelectric effect of lanthanum hexaboride. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Spin injection and detection in lanthanum- and niobium-doped SrTiO3 using the Hanle technique

KAUST Repository

Han, Wei

2013-07-08

There has been much interest in the injection and detection of spin-polarized carriers in semiconductors for the purposes of developing novel spintronic devices. Here we report the electrical injection and detection of spin-polarized carriers into Nb-doped strontium titanate single crystals and La-doped strontium titanate epitaxial thin films using MgO tunnel barriers and the three-terminal Hanle technique. Spin lifetimes of up to ∼100 ps are measured at room temperature and vary little as the temperature is decreased to low temperatures. However, the mobility of the strontium titanate has a strong temperature dependence. This behaviour and the carrier doping dependence of the spin lifetime suggest that the spin lifetime is limited by spin-dependent scattering at the MgO/strontium titanate interfaces, perhaps related to the formation of doping induced Ti 3+. Our results reveal a severe limitation of the three-terminal Hanle technique for measuring spin lifetimes within the interior of the subject material. © 2013 Macmillan Publishers Limited. All rights reserved.

The study of interaction of lanthanum-, cerium- and neodymium chlorides with sodium borohydride in pyridine- and tetrahydrofuran medium

International Nuclear Information System (INIS)

Mirsaidov, U.; Rotenberg, T.G.; Dymova, T.N.

1976-01-01

Bis-tetrahydrofurans of lanthanum and neodymium borohydrides and bis-pyridinates of lanthanum, cerium and neodymium borohydrides were obtained by interacting sodium borohydride with lanthanum-, cerium and neodymium chlorides in pyridine and tetrahydrofuran media. All operations involving reagent combination, sampling and phase separation are performed in inert atmosphere using argonvacuum equipment. The reaction in pyridine was virtually instantaneous and accompanied by flocculanet precipitation. The interaction of lanthanum chloride and neodymium chloride with sodium borohydride in tetrahydrofuran (THF) was a slow (23-30 hr) heterophase process. The interaction rate was affected by size reduction of the intial substances, temperature, reagent proportion and mixing rate. The reaction time was twice reduced with boiling tetrahydrofuran

Grain growth kinetics and electrical properties of lanthanum modified lead zirconate titanate (9/65/35) based ferroelectric ceramics

International Nuclear Information System (INIS)

Roca, R. Alvarez; Guerrero, F.; Botero, E. R.; Garcia, D.; Eiras, J. A.; Guerra, J. D. S.

2009-01-01

The influence of the microstructural characteristics on the dielectric and electrical properties has been investigated for Nd 3+ doped lanthanum modified lead zirconate titanate ferroelectric ceramics, obtained by the conventional solid-state reaction method, by taking into account different sintering conditions. The grain growth mechanism has been investigated and a cubic-type grain growth law was observed for samples with grain size varying from 1.00 up to 2.35 μm. The porosity and grain size dependences of the phase transition parameters, such as the maximum dielectric permittivity and its corresponding temperature (ε m and T m , respectively) were also investigated. The ac conductivity analyses followed the universal Jonscher law. The behavior of the frequency exponent (s) was analyzed through the correlated barrier hopping model. Both ac and dc conductivity results have been correlated with the observed microstructural features

Plasma spheroidization and high temperature stability of lanthanum phosphate and its compatibility with molten uranium

Energy Technology Data Exchange (ETDEWEB)

Ananthapadmanabhan, P.V. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)], E-mail: pvananth@barc.gov.in; Sreekumar, K.P.; Thiyagarajan, T.K.; Satpute, R.U. [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Krishnan, K.; Kulkarni, N.K. [Fuel Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Kutty, T.R.G. [Radiometallurgy Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2009-01-15

Lanthanum phosphate has excellent thermal stability and corrosion resistance against many molten metals and other chemically corrosive environments. Lanthanum phosphate (LaPO{sub 4}) was synthesized from lanthanum oxalate by thermal dissociation of the oxalate to the oxide, followed by conversion to hydrated lanthanum phosphate (LaPO{sub 4}.0.5H{sub 2}O). Thermal treatment of LaPO{sub 4}.0.5H{sub 2}O above 773 K resulted in the irreversible transformation of the hydrated phase to the stable monazite phase. Thermal and chemical stability of monazite was studied by plasma spheroidization experiments using a DC thermal plasma reactor set up. Compatibility of monazite with molten uranium was studied by thermal analysis. Results showed that monazite is thermally stable up to its melting point and also is resistant towards attack by molten uranium. Adherent coatings of LaPO{sub 4} could be deposited onto various substrates by atmospheric plasma spray technique.

NMR studies of the structure of glasses

International Nuclear Information System (INIS)

Bray, P.J.; Gravina, S.J.; Stallworth, P.E.; Szu, S.P.; Jianhui Zhong

1988-01-01

Earlier continuous wave (CW) NMR studies of chemical bonding and structure in glasses are summarized. Examples are given of this use of the quadrupolar interaction and chemical shift to obtain structural information. New NMR data and analyses are presented for alkali borate and gallate glasses. Extensions to other elements (e.g. molybdenum, lanthanum) are suggested. 44 refs. (author)

Growth and Evaluation of Nonlinear Optical Crystals for Laser Applications: Lithium Borate, Barium Borate and Silver Gallium Selenide.

Science.gov (United States)

1994-12-08

communication 2. S. A. Kutovi, V. V. Laptev and S. Yu. Matsnev, " Lanthanum scandoborate as a new highly efficient active medium of solid state lasers," Sov. J...34Noncritical detection of tunable C02 laser radiation into green by upconversion in silver thio- gallate ," Applied Physics B53, 19 (1991). 3. N.-H

Preparation and microstructure of ZrO2- and LaGaO3-based high-porosity ceramics

International Nuclear Information System (INIS)

Kaleva, G.M.; Golubko, N.V.; Suvorkin, S.V.; Kosarev, G.V.; Sukhareva, I.P.; Avetisov, A.K.; Politova, E.D.

2006-01-01

The morphology and concentration of pore formers are studied for their effect on the microstructure and gas permeability of porous zirconia- and lanthanum-gallate-based oxygen-ion-conducting ceramics. The results have been used to optimize the preparation conditions and composition of the ceramics. The resultant dense, fine-grained materials have porosities of up to ∼56% [ru

Characterization of Materials by Raman Scattering

Science.gov (United States)

Kozielski, M.

2007-03-01

The paper reports on the use of phonon spectra obtained with the Raman spectroscopy for characterization of different materials. The Raman scattering spectra obtained for zinc selenide crystals, mixed crystals zinc selenide admixtured with magnesium or beryllium, oxide crystals including strontium lanthanum gallate, molecular crystals of triammonium hydrogen diseleniate and a homologous series of polyoxyethylene glycols are analysed.

Increased cellular uptake of lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles due to surface modification with folic acid.

Science.gov (United States)

Feuser, Paulo Emilio; Arévalo, Juan Marcelo Carpio; Junior, Enio Lima; Rossi, Gustavo Rodrigues; da Silva Trindade, Edvaldo; Rocha, Maria Eliane Merlin; Jacques, Amanda Virtuoso; Ricci-Júnior, Eduardo; Santos-Silva, Maria Claudia; Sayer, Claudia; de Araújo, Pedro H Hermes

2016-12-01

Lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles surface modified with folic acid were synthesized by miniemulsion polymerization in just one step. In vitro biocompatibility and cytotoxicity assays on L929 (murine fibroblast), human red blood, and HeLa (uterine colon cancer) cells were performed. The effect of folic acid at the nanoparticles surface was evaluated through cellular uptake assays in HeLa cells. Results showed that the presence of folic acid did not affect substantially the polymer particle size (~120 nm), the superparamagnetic behavior, the encapsulation efficiency of lauryl gallate (~87 %), the Zeta potential (~38 mV) of the polymeric nanoparticles or the release profile of lauryl gallate. The release profile of lauryl gallate from superparamagnetic poly(methyl methacrylate) nanoparticles presented an initial burst effect (0-1 h) followed by a slow and sustained release, indicating a biphasic release system. Lauryl gallate loaded in superparamagnetic poly(methyl methacrylate) nanoparticles with folic acid did not present cytotoxicity effects on L929 and human red blood cells. However, free lauryl gallate presented significant cytotoxic effects on L929 and human red blood cells at all tested concentrations. The presence of folic acid increased the cytotoxicity of lauryl gallate loaded in nanoparticles on HeLa cells due to a higher cellular uptake when HeLa cells were incubated at 37 °C. On the other hand, when the nanoparticles were incubated at low temperature (4 °C) cellular uptake was not observed, suggesting that the uptake occurred by folate receptor mediated energy-dependent endocytosis. Based on presented results our work suggests that this carrier system can be an excellent alternative in targeted drug delivery by folate receptor.

Epigallocatechin-3-Gallate Protects Erythrocyte Ca2+-ATPase and Na+/K+-ATPase Against Oxidative Induced Damage During Aging in Humans

Directory of Open Access Journals (Sweden)

Prabhanshu Kumar

2014-10-01

Full Text Available Purpose: The main purpose of this study was to investigate the protective role of epigallocatechin-3-gallate on tertiary butyl hydroperoxide induced oxidative damage in erythrocyte during aging in humans. Methods: Human erythrocyte membrane bound Ca2+-ATPase and Na+/K+-ATPase activities were determined as a function of human age. Protective role of epigallocatechin-3-gallate was evaluated by in vitro experiments by adding epigallocatechin-3-gallate in concentration dependent manner (final concentration range 10-7M to 10-4M to the enzyme assay medium. Oxidative stress was induced in vitro by incubating washed erythrocyte ghosts with tertiary butyl hydroperoxide (10-5 M final concentration. Results: We have reported concentration dependent effect of epigallocatechin-3-gallate on tertiary butyl hydroperoxide induced damage on activities of Ca2+-ATPase and Na+/K+-ATPase during aging in humans. We have detected a significant (p < 0.001 decreased activity of Ca2+-ATPase and Na+/K+ -ATPase as a function of human age. Epigallocatechin-3-gallate protected ATPases against tertiary butyl hydroperoxide induced damage in concentration dependent manner during aging in humans. Conclusion: Epigallocatechin-3-gallate is a powerful antioxidant that is capable of protecting erythrocyte Ca2+-ATPase and Na+/K+ -ATPase against oxidative stress during aging in humans. We may propose hypothesis that a high intake of catechin rich diet may provide some protection against development of aging and age related diseases.

Exchange, x-ray and IR spectral behaviour of lanthanum and praseodymium exchanged zeolite X

International Nuclear Information System (INIS)

Das, D.; Upreti, M.C.

1995-01-01

Exchange behaviour of lanthanum and praseodymium ions in zeolite X involves three steps: preferential exchange, intrazeolitic exchange and irreversible exchange. At room temperature , higher exchange has been observed with La(III) than with Pr(III) which is attributed to the smaller hydrosphere of lanthanum than praseodymium. IR spectra of these zeolites in KBr pellets show a shift in the major Si-O stretching vibration of 972 cm -1 to higher frequencies. Their x-ray diffraction patterns remain unchanged except a large decrease of the line intensities caused by the absorption of x-rays by heavy La(III) and Pr(III) ions. The present study reports the preparation and physicochemical properties of lanthanum and praseodymium exchanged zeolite X. (author). 12 refs., 3 figs., 3 tabs

Combustion synthesis and photoluminescence properties of LaAlO{sub 3} nanophosphors doped with Yb{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Dhahri, A. [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National des Recherches en Sciences des Matériaux, Technopole de Borj Cedria, B.P. 73, Soliman 8027 (Tunisia); Horchani-Naifer, K., E-mail: karima_horchani@yahoo.com [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National des Recherches en Sciences des Matériaux, Technopole de Borj Cedria, B.P. 73, Soliman 8027 (Tunisia); Benedetti, A. [Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca’ Foscari Venezia, Dorsoduro 2137, 30123 Venezia (Italy); Enrichi, F. [CIVEN – Coordinamento Interuniversitario Veneto per le Nanotecnologie, Via Delle Industrie 5, Marghera, Venice 30175 (Italy); Ferid, M. [Laboratoire de Physico-chimie des Matériaux Minéraux et leurs Applications, Centre National des Recherches en Sciences des Matériaux, Technopole de Borj Cedria, B.P. 73, Soliman 8027 (Tunisia)

2014-09-15

Ytterbium doped lanthanum aluminate (LaAlO{sub 3}) nanophosphors have been prepared by a combustion process with glycine as a fuel. The structures of the powders were determined by X-ray diffraction (XRD), the morphology of the annealed materials was observed using scanning electron microscopy (SEM), the average crystalline grain sizes have been determined by transmission electron microscopy (TEM) and photoluminescence properties using fluorescence spectroscopy. Pure LaAlO{sub 3} phase was obtained at 800 °C heated for 4 h, with an average crystal size, as determined by TEM, of 60 nm. Emission spectra and decay times of main luminescence transitions were measured at room temperature. A strong emission is reported at 986 nm from the ({sup 2}F{sub 5/2}→{sup 2}F{sub 7/2}) transition, whose intensity depends on Yb concentration. - Highlights: • Ytterbium doped lanthanum aluminate (LaAlO{sub 3}) nanophosphors have been prepared by a combustion process with glycine as a fuel. • Powders were characterized by DRX, FTIR, TEM and fluorescence spectroscopy. • Pure LaAlO{sub 3} phase was obtained at 800 °C heated for 4 h, with an average crystal size of 60 nm. • A strong emission is reported at 986 nm from the ({sup 2}F{sub 5/2}→{sup 2}F{sub 7/2}) transition, whose intensity depends on Yb concentration.

Structure and Dynamics Investigations of Sr/Ca-Doped LaPO₄ Proton Conductors

Energy Technology Data Exchange (ETDEWEB)

al-Wahish, Amal [Univ. of Missouri, Columbia, MO (United States). Research Reactor; al-Binni, U. [Univ. of Washington, Seattle, WA (United States). Dept. of Physics and Astronomy; Tetard, L. [Univ. of Central Florida, Orlando, FL (United States). NanoScience Technology Center; Bridges, Craig A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division; Kharel, Krishna [Lamar Univ., Beaumont, TX (United States). Dept. of Chemistry and Biochemistry; Günaydın-Şen, Özge [Lamar Univ., Beaumont, TX (United States). Dept. of Chemistry and Biochemistry; Huq, A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical and Engineering Materials Division; Musfeldt, J. L. [Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemistry; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Paranthaman, M. P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Chemical Sciences Division; Mandrus, D. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science & Technology Division; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Univ. of Tennessee, Knoxville, TN (United States). Dept. of Materials Science and Engineering

2017-05-15

Proton conductors loom out of the pool of candidate materials with great potential to boost hydrogen alternatives to fossil-based resources for energy. Acceptor doped lanthanum orthophosphates are considered for solid oxide fuel cells (SOFCs) for their potential stability and conductivity at high temperature. By exploring the crystal and defect structure of x% Sr/Ca-doped LaPO₄ with different nominal Sr/Ca concentrations (x = 0 – 10) with Neutron powder diffraction (NPD) and X-ray powder diffraction (XRD), we confirm that Sr/Ca-doped LaPO₄ can exist as self-supported structures at high temperatures during solid oxide fuel cell operation. Thermal stability, surface topography, size distribution are also studied to better understand the proton conductivity for dry and wet compounds obtained at sintering temperatures ranging from 1200 to 1400 °C using a combination of scanning electron microscopy (SEM), Atomic Force Microscopy (AFM), Fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectroscopy (EIS). In conclusion, the results suggest that Sr doped samples exhibit the highest proton conductivity of our samples and illustrate the impact of material design and versatile characterization schemes on the development of proton conductors with superior functionality.

Ni-SDC cermet anode for medium-temperature solid oxide fuel cell with lanthanum gallate electrolyte

Energy Technology Data Exchange (ETDEWEB)

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

1999-10-01

The polarization properties and microstructure of Ni-SDC (samaria-doped ceria) cermet anodes prepared from spray pyrolysis (SP) composite powder, and element interface diffusion between the anode and a La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM) electrolyte are investigated as a function of anode sintering temperature. The anode sintered at 1250 C displays minimum anode polarization (with anode ohmic loss), while the anode prepared at 1300 C has the best electrochemical overpotential, viz., 27 mV at 300 mA cm{sup -2} operating at 800 C. The anode ohmic loss gradually increases with increase in the sintering temperature at levels below 1300 C, and sharply increases at 1350 C. Electron micrographs show a clear grain growth at sintering temperatures higher than 1300 C. The anode microstructure appears to be optimized at 1300 C, in which nickel particles form a network with well-connected SDC particles finely distributed over the surfaces of the nickel particles. The anode sintered at 1350 C has severe grain growth and an apparent interface diffusion of nickel from the anode to the electrolyte. The nickel interface diffusion is assumed to be the main reason for the increment in ohmic loss, and the resulting loss in anode performance. The findings suggest that sintering Ni-SDC composite powder near 1250 C is the best method to prepare the anode on a LSGM electrolyte. (orig.)

Ni-SDC cermet anode for medium-temperature solid oxide fuel cell with lanthanum gallate electrolyte

Science.gov (United States)

Zhang, Xinge; Ohara, Satoshi; Maric, Radenka; Mukai, Kazuo; Fukui, Takehisa; Yoshida, Hiroyuki; Nishimura, Masayoshi; Inagaki, Toru; Miura, Kazuhiro

The polarization properties and microstructure of Ni-SDC (samaria-doped ceria) cermet anodes prepared from spray pyrolysis (SP) composite powder, and element interface diffusion between the anode and a La 0.9Sr 0.1Ga 0.8Mg 0.2O 3- δ (LSGM) electrolyte are investigated as a function of anode sintering temperature. The anode sintered at 1250°C displays minimum anode polarization (with anode ohmic loss), while the anode prepared at 1300°C has the best electrochemical overpotential, viz., 27 mV at 300 mA cm -2 operating at 800°C. The anode ohmic loss gradually increases with increase in the sintering temperature at levels below 1300°C, and sharply increases at 1350°C. Electron micrographs show a clear grain growth at sintering temperatures higher than 1300°C. The anode microstructure appears to be optimized at 1300°C, in which nickel particles form a network with well-connected SDC particles finely distributed over the surfaces of the nickel particles. The anode sintered at 1350°C has severe grain growth and an apparent interface diffusion of nickel from the anode to the electrolyte. The nickel interface diffusion is assumed to be the main reason for the increment in ohmic loss, and the resulting loss in anode performance. The findings suggest that sintering Ni-SDC composite powder near 1250°C is the best method to prepare the anode on a LSGM electrolyte.

Electrical conductivity of cobalt doped La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ

Science.gov (United States)

Wang, Shizhong; Wu, Lingli; Liang, Ying

La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10 -5 atm) and low oxygen partial pressure regions (lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number.

Lake responses following lanthanum-modified bentonite clay (Phoslock) application: an analysis of water column lanthanum data from 16 case study lakes

NARCIS (Netherlands)

Spears, B.M.; Lürling, M.F.L.L.W.; Yasseri, S.; Castro-Castellon, A.T.; Gibbs, M.; Meis, S.; McDonald, C.; McIntosh, J.; Sleep, D.; Oosterhout, van F.

2013-01-01

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

On dependence of stability of lanthanum complexes with aminopolycarboxylic acids on the complex structure

International Nuclear Information System (INIS)

Poluehktov, N.S.; Meshkova, S.B.; Danilkovich, M.M.; Topilova, Z.M.

1985-01-01

Regularities in changes of stability constants of lanthanum complexes with aminopolycarboxylic acids (APA) versus their structure are studied, The stability of lathanum-APA complexes depends mainly on the number of carboxyl groups in a ligand molecule. At that, the highest stability constant is characteristic of a complex with a ligand, containing 3 nitrogen atoms and 5 carboxyl groups, in the presenoe of which the lanthanum ion coordination sphere gets satupated. The oxyethy group introduction into a ligand molecule also improves the lanthanum complex stability but to a lesser degree than during the introduction of a carboxyl group. The number of nitrogen atoms in a ligand polecule affects insignificantly the complex stability constant value, and the elongation of a chain of CH 2 groups, separating nitrogen atoms, reduces the constant to a -0.6 power

Textile Dye Removal from Aqueous Solution using Modified Graphite Waste/Lanthanum/Chitosan Composite

Science.gov (United States)

Kusrini, E.; Wicaksono, B.; Yulizar, Y.; Prasetyanto, EA; Gunawan, C.

2018-03-01

We investigated various pre-treatment processes of graphite waste using thermal, mechanical and chemical methods. The aim of this work is to study the performance of modified graphite waste/lanthanum/chitosan composite (MG) as adsorbent for textile dye removal from aqueous solution. Effect of graphite waste resources, adsorbent size and lanthanum concentration on the dye removal were studied in batch experiments. Selectivity of MG was also investigated. Pre-heated graphite waste (NMG) was conducted at 80°C for 1 h, followed by mechanical crushing of the resultant graphite to 75 μm particle size, giving adsorption performance of ˜58%, ˜67%, ˜93% and ˜98% of the model dye rhodamine B (concentration determined by UV-vis spectroscopy at 554 nm), methyl orange (464 nm), methylene blue (664 nm) and methyl violet (580 nm), respectively from aqueous solution. For this process, the system required less than ˜5 min for adsorbent material to be completely saturated with the adsorbate. Further chemical modification of the pre-treated graphite waste (MG) with lanthanum (0.01 – V 0.03 M) and chitosan (0.5% w/w) did not improve the performance of dye adsorption. Under comparable experimental conditions, as those of the ‘thermal-mechanical-pre-treated-only’ (NMG), modification of graphite waste (MG) with 0.03 M lanthanum and 0.5% w/w chitosan resulted in ˜14%, ˜47%, ˜72% and ˜85% adsorption of rhodamine B, methyl orange, methylene blue and methyl violet, respectively. Selective adsorption of methylene blue at most to ˜79%, followed by methyl orange, methyl violet and rhodamine B with adsorption efficiency ˜67, ˜38, and ˜9% sequentially using MG with 0.03 M lanthanum and 0.5% w/w chitosan.

XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referencing and peak fitting procedures

International Nuclear Information System (INIS)

Sunding, M.F.; Hadidi, K.; Diplas, S.; Lovvik, O.M.; Norby, T.E.; Gunnaes, A.E.

2011-01-01

Highlights: → Gold particles deposited in vacuum as energy reference for insulating samples in XPS. → Separation of La 3d and MNN peaks in XP spectra acquired with Al Kα radiation. → We describe the spectral differences between lanthanum oxide and lanthanum hydroxide. → A doublet in O 1s of La 2 O 3 is ascribed to two distinct oxygen sites in the crystal. - Abstract: A technique is described for deposition of gold nanoparticles under vacuum, enabling consistent energy referencing of X-ray photoelectron spectra obtained from lanthanum hydroxide La(OH) 3 and in situ treated lanthanum oxide La 2 O 3 powders. A method is also presented for the separation of the overlapping lanthanum 3d and MNN peaks in X-ray photoelectron spectra acquired with Al Kα radiation. The lower satellite intensity in La(OH) 3 compared to La 2 O 3 is related to the higher ionicity of the La-O bond in the former compared to the latter compound. The presence of an additional peak in the valence band spectrum of the hydroxide compared to the oxide is attributed to the O-H bond as indicated by density functional theory based calculations. A doublet in the O 1s peak of lanthanum oxide is associated to the presence of two distinct oxygen sites in the crystal structure of this compound.

In Situ Neutron Diffraction of Rare-Earth Phosphate Proton Conductors Sr/Ca-doped LaPO4 at Elevated Temperatures

Science.gov (United States)

Al-Wahish, Amal; Al-Binni, Usama; Bridges, C. A.; Huq, A.; Bi, Z.; Paranthaman, M. P.; Tang, S.; Kaiser, H.; Mandrus, D.

Acceptor-doped lanthanum orthophosphates are potential candidate electrolytes for proton ceramic fuel cells. We combined neutron powder diffraction (NPD) at elevated temperatures up to 800° C , X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) to investigate the crystal structure, defect structure, thermal stability and surface topography. NPD shows an average bond length distortion in the hydrated samples. We employed Quasi-Elastic Neutron Scattering (QENS) and electrochemical impedance spectroscopy (EIS) to study the proton dynamics of the rare-earth phosphate proton conductors 4.2% Sr/Ca-doped LaPO4. We determined the bulk diffusion and the self-diffusion coefficients. Our results show that QENS and EIS are probing fundamentally different proton diffusion processes. Supported by the U.S. Department of Energy.

Growth of langasite via Bridgman technique along [ 0 0 0 1], [ 2 1¯ 1¯ 0] and [ 0 1 1¯ 1] for piezoelectric applications

Science.gov (United States)

Uda, Satoshi; Inaba, Hitoshi; Harada, Jiro; Hoshikawa, Keigo

2004-10-01

2-inch langasite (La 3Ga 5SiO 14) single crystals were grown for the first time via a vertical Bridgman method, assisted by the accelerated crucible rotation technique (ACRT) along [ 0 0 0 1] ( Z-axis), [ 2 1¯ 1¯ 0] ( X-axis) and [ 0 1 1¯ 1] (54°-rotated Y-axis) for piezoelectric applications. Because of the possible liquid immiscibility, incongruency and segregation, secondary phases other than langasite are formed during growth. The mode of occurrence of these phases was closely related to the interface instability that was specific to the growth direction. The formation of inclusions consisting of lanthanum gallate (LaGaO 3), aligned parallel to ( 0 1 1¯ 0), was associated with the constitutional supercooling. The residual products during the terminal transient were the mixture of gallium oxide (Ga 2O 3) and lanthanum gallate (LaGaO 3) or the mixture of gallium oxide and lanthanum silicate (La 2Si 2O 7) reflecting the position of the initial melt, relative to the tie line connecting the langasite solid solution with gallium oxide in the system of La 2O 3-Ga 2O 3-SiO 2. The homogeneity of the grown crystal was evaluated by the distribution of SAW velocities of the devices fabricated on the ( 0 1 1¯ 0) wafer, as well as by the uniformity of d-spacing of 0 5 5¯ 5.

XPS characterisation of in situ treated lanthanum oxide and hydroxide using tailored charge referencing and peak fitting procedures

Energy Technology Data Exchange (ETDEWEB)

Sunding, M.F., E-mail: m.f.sunding@fys.uio.no [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Hadidi, K. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Diplas, S. [Department of Chemistry and Centre for Material Science and Nanotechnology (SMN), University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo (Norway); SINTEF Materials and Chemistry, P.O. Box 124 Blindern, NO-0314 Oslo (Norway); Lovvik, O.M. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); SINTEF Materials and Chemistry, P.O. Box 124 Blindern, NO-0314 Oslo (Norway); Norby, T.E. [Department of Chemistry and Centre for Material Science and Nanotechnology (SMN), University of Oslo, P.O. Box 1033 Blindern, NO-0315 Oslo (Norway); Gunnaes, A.E. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway)

2011-07-15

Highlights: {yields} Gold particles deposited in vacuum as energy reference for insulating samples in XPS. {yields} Separation of La 3d and MNN peaks in XP spectra acquired with Al K{alpha} radiation. {yields} We describe the spectral differences between lanthanum oxide and lanthanum hydroxide. {yields} A doublet in O 1s of La{sub 2}O{sub 3} is ascribed to two distinct oxygen sites in the crystal. - Abstract: A technique is described for deposition of gold nanoparticles under vacuum, enabling consistent energy referencing of X-ray photoelectron spectra obtained from lanthanum hydroxide La(OH){sub 3} and in situ treated lanthanum oxide La{sub 2}O{sub 3} powders. A method is also presented for the separation of the overlapping lanthanum 3d and MNN peaks in X-ray photoelectron spectra acquired with Al K{alpha} radiation. The lower satellite intensity in La(OH){sub 3} compared to La{sub 2}O{sub 3} is related to the higher ionicity of the La-O bond in the former compared to the latter compound. The presence of an additional peak in the valence band spectrum of the hydroxide compared to the oxide is attributed to the O-H bond as indicated by density functional theory based calculations. A doublet in the O 1s peak of lanthanum oxide is associated to the presence of two distinct oxygen sites in the crystal structure of this compound.

Lanthanum Deposition in the Stomach in the Absence of Helicobacter pylori Infection.

Science.gov (United States)

Iwamuro, Masaya; Urata, Haruo; Tanaka, Takehiro; Kawano, Seiji; Kawahara, Yoshiro; Kimoto, Katsuhiko; Okada, Hiroyuki

2018-03-15

In this case report, we describe two patients who showed a diffusely whitish mucosa in the posterior wall and the lesser curvature of the gastric body. The patients were serologically- and histopathologically-negative for Helicobacter pylori. Random biopsy specimens from the stomach revealed no regenerative changes, intestinal metaplasia, and/or foveolar hyperplasia in either of the patients. Although lanthanum deposition in the gastric mucosa has been reported to occur in close association with H. pylori-associated gastritis, our patients tested negative for H. pylori. These cases suggest that lanthanum deposition presents as whitish lesions in the gastric body in H. pylori-negative patients.

Crystal structure and ionic conduction path of solid electrolytic materials by high temperature neutron diffraction method

International Nuclear Information System (INIS)

Yashima, Masatomo; Nomura, Katsuhiro

2005-01-01

Research of the distribution of oxide ions and the ionic conduction path of bismuth oxide (Bi 2 O 3 ), cerium oxide (CeO 2 ) and lanthanum gallate ((La 0.8 Sr 0.2 )(Ga 0.8 Mg 0.15 Co 0.05 )O 3-δ ) is stated. The high temperature neutron diffraction method, analytical method such as Rietveld method, crystal structure analysis of ionic conductor and MEM (Maximum- Entropy Method) are explained. The nuclear density distribution of oxide ions in bismuth oxide showed so larger distribution in the direction of and than Bi ions that the oxide ions conducted these direction in the crystal. The nuclear density distribution of oxide ions of cerium oxide indicated larger distribution in the direction of than Ce ions and its tendency was remarkable at high temperature. Accordingly, the oxide ions conducted in the direction of and . The oxide ions distribution in lanthanum gallate compound was larger and complicated than positive ions. The oxide ions conducted to by describing an arc between the two stable positions. The nuclear density on the conduction path increased with increasing temperature. This above result corresponded to increase of oxide ion conductivity in the area. (S.Y.)

Properties of lanthanum hexaboride a compilation

CERN Document Server

Fisher, D J

2013-01-01

Lanthanum hexaboride is useful because it possesses a high melting point (2210C), a low work function, one of the highest known electron emissivities, and is stable in vacuum. This volume summarises the extant data on the properties of this material, including the: bulk modulus, conductivity, crystal structure, Debye temperature, defect structure, elastic constants, electronic structure, emissivity, Fermi surface, hardness, heat capacity, magnetoresistance, reflectivity, resistivity, specific heat, surface structure, thermal conductivity, thermoelectric power, toughness and work function. The

Lake responses following lanthanum-modified bentonite clay (Phoslock®) application: an analysis of water column lanthanum data from 16 case study lakes.

Science.gov (United States)

Spears, Bryan M; Lürling, 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 0.8 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. Copyright © 2013 Elsevier Ltd. All rights reserved.

Antioxidant activity of gallic acid and methyl gallate in triacylglycerols of Kilka fish oil and its oil-in-water emulsion.

Science.gov (United States)

Asnaashari, Maryam; Farhoosh, Reza; Sharif, Ali

2014-09-15

The anti-DPPH radical effect as well as anti-peroxide activity of gallic acid, methyl gallate, and α-tocopherol in a bulk Kilka fish oil and its oil-in-water emulsion stabilized by soy protein isolate at 55°C were investigated. Gallic acid with the lowest hydrophobicity (log P=-0.28) was found to be the most active antiradical agent (IC50=29.5 μM), followed by methyl gallate (IC50=38.0 μM, log P=-0.23) and α-tocopherol (IC50=105.3 μM, log P=0.70). The anti-peroxide activity in the bulk oil system decreased in the order of methyl gallate>gallic acid>α-tocopherol. In the emulsion system, methyl gallate still behaved better than gallic acid, but the highest activity belonged to α-tocopherol. Based on the calculation of a number of kinetic parameters, the antioxidants, in general, showed better performances in the bulk oil system than in the emulsion system. Copyright © 2014 Elsevier Ltd. All rights reserved.

Chemical compatibility and properties of suspension plasma-sprayed SrTiO3-based anodes for intermediate-temperature solid oxide fuel cells

Science.gov (United States)

Zhang, Shan-Lin; Li, Cheng-Xin; Li, Chang-Jiu

2014-10-01

La-doped strontium titanate (LST) is a promising, redox-stable perovskite material for direct hydrocarbon oxidation anodes in intermediate-temperature solid oxide fuel cells (IT-SOFCs). In this study, nano-sized LST and Sm-doped ceria (SDC) powders are produced by the sol-gel and glycine-nitrate processes, respectively. The chemical compatibility between LST and electrolyte materials is studied. A LST-SDC composite anode is prepared by suspension plasma spraying (SPS). The effects of annealing conditions on the phase structure, microstructure, and chemical stability of the LST-SDC composite anode are investigated. The results indicate that the suspension plasma-sprayed LST-SDC anode has the same phase structure as the original powders. LST exhibits a good chemical compatibility with SDC and Mg/Sr-doped lanthanum gallate (LSGM). The anode has a porosity of ∼40% with a finely porous structure that provides high gas permeability and a long three-phase boundary for the anode reaction. Single cells assembled with the LST-SDC anode, La0.8Sr0.2Ga0.8Mg0.2O3 electrolyte, and La0.8Sr0.2CoO3-SDC cathode show a good performance at 650-800 °C. The annealing reduces the impedances due to the enhancement in the bonding between the particles in the anode and interface of anode and LSGM electrolyte, thus improving the output performance of the cell.

Plasma sprayed metal supported YSZ/Ni-LSGM-LSCF ITSOFC with nanostructured anode

Science.gov (United States)

Hwang, Changsing; Tsai, Chun-Huang; Lo, Chih-Hung; Sun, Cha-Hong

Intermediate temperature solid oxide fuel cells (ITSOFCs) supported by a porous Ni-substrate and based on Sr and Mg doped lanthanum gallate (LSGM) electrolyte, lanthanum strontium cobalt ferrite (LSCF) cathode and nanostructured yttria stabilized zirconia-nickel (YSZ/Ni) cermet anode have been fabricated successfully by atmospheric plasma spraying (APS). From ac impedance analysis, the sprayed YSZ/Ni cermet anode with a novel nanostructure and advantageous triple phase boundaries after hydrogen reduction has a low resistance. It shows a good electrocatalytic activity for hydrogen oxidation reactions. The sprayed LSGM electrolyte with ∼60 μm in thickness and ∼0.054 S cm -1 conductivity at 800 °C shows a good gas tightness and gives an open circuit voltage (OCV) larger than 1 V. The sprayed LSCF cathode with ∼30 μm in thickness and ∼30% porosity has a minimum resistance after being heated at 1000 °C for 2 h. This cathode keeps right phase structure and good porous network microstructure for conducting electrons and negative oxygen ions. The APS sprayed cell after being heated at 1000 °C for 2 h has a minimum inherent resistance and achieves output power densities of ∼440 mW cm -2 at 800 °C, ∼275 mW cm -2 at 750 °C and ∼170 mW cm -2 at 700 °C. Results from SEM, XRD, ac impedance analysis and I- V- P measurements are presented here.

The effect of point defects on ferroelastic phase transition of lanthanum-doped calcium titanate ceramics

International Nuclear Information System (INIS)

Ni, Yan; Zhang, Zhen; Wang, Dong; Wang, Yu; Ren, Xiaobing

2013-01-01

Highlights: ► The effect of point defects on phase transitions in Ca (1−x) La 2x/3 TiO 3 was studied. ► When x = 0.45, normal ferroelastic phase transition happens. ► When x = 0.7, a “glassy-like” frozen process appears. ► Point defects weaken the thermodynamic stability of ferroelastic phase. ► Point defects induce a “glassy-like” frozen process. -- Abstract: In the present paper, La-doped CaTiO 3 is studied to investigate the effect of point defects on ferroelastic phase transition of the ceramics. The dynamic mechanical measurements show that the transition temperature of the orthorhombic to tetragonal phase transition of Ca (1−x) La 2x/3 TiO 3 decreases with increasing dopant (La) concentration x. The samples with the dopant content of x = 0.45 and 0.7 exhibit different structure evolution features during their transition processes as revealed by in situ powder X-ray diffraction (XRD) measurement. Moreover, when x = 0.7, the storage modulus shows a frequency-dependent minimum at T g , which can be well fitted with the Vogel–Fulcher relation, and the corresponding internal friction also exhibits a frequency-dependent peak within the same temperature regime. These results thus indicate that doping La suppresses ferroelastic phase transition in CaTiO 3 and induces a “glassy-like” behavior in Ca (1−x) La 2x/3 TiO 3 , which is similar to “strain glass” in Ni-doped Ti 50−x Ni 50+x

Conductometric study of lanthanum chloride interaction with potash soaps of higher fatty acids

International Nuclear Information System (INIS)

Skrylev, L.D.; Sazonova, V.F.; Kornelli, M.Eh.; Shumilina, N.A.

1978-01-01

Interaction of lanthanum chloride with potassium salts of higher aliphatic acids, containing from 10 to 16 carbon atoms, at room temperature in weakly acid media (pH=5.5) gives rise to neutral soaps of the La[CHsub(3)(CHsub(2))sub(n)COO]sub(3) composition, while in alkaline media (pH=8.0) base soaps of the LaOH[CHsub(3)(CHsub(2))sub(n)COO]sub(2) composition are formed. In acid solutions (pH=2.0) no interaction of lanthanum chloride with potassium soaps of the above carboxylic acids is observed

Real structure of LaGaO3 monocrystals grown by Czochralski method

International Nuclear Information System (INIS)

Morozov, A.N.; Morozova, O.Yu.; Ponomarev, N.M.

1993-01-01

A complex X-ray diffraction study of lanthanum (ortho)gallate crystal structure and structural defects in LaGaO 3 crystals grown by the Czochralski method is carried out. Coordinates of atoms in LaGaO 3 unit cell are determined. X-Ray topographic studies of oriented LaGaO 3 sublayers for high-tc superconductor film growth are optimized. The substructure of monocrystals is studied

Room temperature synthesis of high temperature stable lanthanum phosphate–yttria nano composite

International Nuclear Information System (INIS)

Sankar, Sasidharan; Raj, Athira N.; Jyothi, C.K.; Warrier, K.G.K.; Padmanabhan, P.V.A.

2012-01-01

Graphical abstract: A facile aqueous sol–gel route involving precipitation–peptization mechanism followed by electrostatic stabilization is used for synthesizing nanocrystalline composite containing lanthanum phosphate and yttria. Highlights: ► A novel lanthanum phosphate–Y 2 O 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 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 sol–gel route involving precipitation–peptization 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 4 –20%Y 2 O 3 ), has an average particle size of ∼70 nm after heat treatment of precursor at 600 °C. TG–DTA 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 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.

Superconducting microwave electronics at Lewis Research Center

Science.gov (United States)

Warner, Joseph D.; Bhasin, Kul B.; Leonard, Regis F.

Over the last three years, NASA Lewis Research Center has investigated the application of newly discovered high temperature superconductors to microwave electronics. Using thin films of YBa2Cu3O7-delta and Tl2Ca2Ba2Cu3Ox deposited on a variety of substrates, including strontium titanate, lanthanum gallate, lanthanum aluminate and magnesium oxide, a number of microwave circuits have been fabricated and evaluated. These include a cavity resonator at 60 GHz, microstrip resonators at 35 GHz, a superconducting antenna array at 35 GHz, a dielectric resonator at 9 GHz, and a microstrip filter at 5 GHz. Performance of some of these circuits as well as suggestions for other applications are reported.

Superconducting Microwave Electronics at Lewis Research Center

Science.gov (United States)

Warner, Joseph D.; Bhasin, Kul B.; Leonard, Regis F.

1991-01-01

Over the last three years, NASA Lewis Research Center has investigated the application of newly discovered high temperature superconductors to microwave electronics. Using thin films of YBa2Cu3O7-delta and Tl2Ca2Ba2Cu3Ox deposited on a variety of substrates, including strontium titanate, lanthanum gallate, lanthanum aluminate and magnesium oxide, a number of microwave circuits have been fabricated and evaluated. These include a cavity resonator at 60 GHz, microstrip resonators at 35 GHz, a superconducting antenna array at 35 GHz, a dielectric resonator at 9 GHz, and a microstrip filter at 5 GHz. Performance of some of these circuits as well as suggestions for other applications are reported.

Structural consideration with respect to the thermal stability of a new platinum supported lanthanum-alumina catalyst

International Nuclear Information System (INIS)

Oudet, F.; Bordes, E.; Courtine, P.; Maxant, G.; Lambert, C.; Guerlet, J.P.

1987-01-01

The influence of lanthanum aluminate, LaAlO 3 , on the thermal stability of both alumina and platinum supported alumina catalysts is investigated. In the case of alumina, the stabilization is interpreted in terms of structural coherence between δ-Al 2 O 3 and a three-fold superstructure of LaAlO 3 . The addition of LaAlO 3 , is shown to increase both the dispersion and the resistance to sintering of the platinum supported alumina catalyst. Moreover, lanthanum hexa-aluminate (La-β-Al 2 O 3 ) is present in the platinum catalyst fired at 1150 0 C. These observations are assumed to result for the epitaxial relations between platinum and the lanthanum-alumina support. 23 refs.; 8 figs.; 2 tabs

Investigation of paramagnetic saturation in lanthanum manganese nitrate

NARCIS (Netherlands)

Flokstra, Jakob; Meijer, H.C.; Bots, G.J.C.; Verheij, W.A.; van der Marel, L.C.

1973-01-01

Paramagnetic saturation of lanthanum manganese nitrate, La2Mn3(NO3)12·24H2O, has been investigated at liquid He temperatures in a static as well as a dynamical way. With the aid of the molecular-field theory the Casimir and Du Pré dispersion and absorption curves are adapted explicitly to the

Eucalyptus tolerance mechanisms to lanthanum and cerium: subcellular distribution, antioxidant system and thiol pools.

Science.gov (United States)

Shen, Yichang; Zhang, Shirong; Li, Sen; Xu, Xiaoxun; Jia, Yongxia; Gong, Guoshu

2014-12-01

Guanglin 9 (Eucalyptus grandis × Eucalyptus urophlla) and Eucalyptus grandis 5 are two eucalyptus species which have been found to grow normally in soils contaminated with lanthanum and cerium, but the tolerance mechanisms are not clear yet. In this study, a pot experiment was conducted to investigate the tolerance mechanisms of the eucalyptus to lanthanum and cerium. Cell walls stored 45.40-63.44% of the metals under lanthanum or cerium stress. Peroxidase and catalase activities enhanced with increasing soil La or Ce concentrations up to 200 mg kg(-1), while there were no obvious changes in glutathione and ascorbate concentrations. Non-protein thiols concentrations increased with increasing treatment levels up to 200 mg kg(-1), and then decreased. Phytochelatins concentrations continued to increase under La or Ce stress. Therefore, the two eucalyptus species are La and Ce tolerant plants, and the tolerance mechanisms include cell wall deposition, antioxidant system response, and thiol compound synthesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fabrication of Polycrystalline Lanthanum Manganite (La0.99 Mn0.01 O3) Powder and Fibres by Electrospinning Method

International Nuclear Information System (INIS)

Yin Yin Win; That Htar Lwin; Than Than Win; Yin Maung Maung; Ko Ko Kyaw Soe

2011-12-01

Lanthanum manganite (La0.99 Mn0.01 O3) powder have been prepared by using pyrolysis methods. Lanthanum manganite fibres were successfully fabricated by electro-spinning utilizing precursors. Polycrystalline perovskite structure lanthanum manganite powder and fibres showed that the grain size and crystal grain increased significantly with the increase in calcination temperature. A variety of techniques (SEM, FT-IR and TG-DTA) were employed to study the morphology and fibre quality, crystal structure, and thermal analysis of La0.99 Mn0.01 O3 specimen respectively.

The Catalytic Activity of Modified Zeolite Lanthanum on the Catalytic Cracking of Al-Duara Atmospheric Distillation Residue

Directory of Open Access Journals (Sweden)

Karim Khalifa Esgair

2016-03-01

Full Text Available Atmospheric residue fluid catalytic cracking was selected as a probe reaction to test the catalytic performance of modified NaY zeolites and prepared NaY zeolites. Modified NaY zeolites have been synthesized by simple ion exchange methods. Three samples of modified zeolite Y have been obtained by replacing the sodium ions in the original sample with lanthanum and the weight percent added are 0.28, 0.53, and 1.02 respectively. The effects of addition of lanthanum to zeolite Y in different weight percent on the cracking catalysts were investigated using an experimental laboratory plant scale of fluidized bed reactor. The experiments have been performed with weight hourly space velocity (WHSV range of 6 to 24 h-1, and the range of temperature from 450 to 510 oC. The activity of the catalyst with 1.02 wt% lanthanum has been shown to be much greater than that of the sample parent NaY. Also it was observed that the addition of the lanthanum causes an increase in the thermal stability of the zeolite.

Interactions of a La{sub O.9}Sr{sub O.1}Ga{sub O.8}Mg{sub O.2}O{sub 3-{delta}} electrolyte with Fe{sub 2}O{sub 3}, Co{sub 2}O{sub 3} and NiO anode materials

Energy Technology Data Exchange (ETDEWEB)

Zhang, X.; Ohara, S.; Okawa, H.; Maric, R.; Fukui, T. [Japan Fine Ceramics Center, 2-4-1 Mutsuo, Atsuta-ku, 456-8587 Nagoya (Japan)

2001-01-02

In this study, the interactions of a Sr- and Mg-doped lanthanum gallate (LSGM with composition La{sub O.9}Sr{sub O.1}Ga{sub O.8}Mg{sub O.2}O{sub 3-{delta}}) electrolyte with Fe{sub 2}O{sub 3}, Co{sub 2}O{sub 3} and NiO as the anode starting materials were investigated. It was found that the order of reactivity of the LSGM with the three oxides was Co{sub 2}O{sub 3}>NiO>Fe{sub 2}O{sub 3}, and La-containing oxides were detected in these binary powder mixtures after firing. The anode performance was greatly influenced by the interaction. The Fe{sub 2}O{sub 3}-LSGM anode, mixed with 40 vol.% LSGM powder and sintered at 1150C, exhibited the highest initial performance in comparison with NiO-LSGM and Co{sub 2}O{sub 3}-LSGM anodes. It seems that Fe{sub 2}O{sub 3} is a possible anode starting material for a LSGM-based solid oxide fuel cell.

Stability constant of the lanthanum complex with humic acid

International Nuclear Information System (INIS)

Jimenez R, M.; Solache R, M. J.

2008-01-01

The work described here is a study on the formation of trivalent lanthanum complex with humic acid. Commercial humic acid was purified and then characterized by various analytical techniques. The stability constant determined by a radiochemical method has a worth of log β La , AHA = 13.6. (Author)

Sintering and Electrical Characterization of La and Nb Co‐doped SrTiO3 Electrode Materials for Solid Oxide Cell Applications

DEFF Research Database (Denmark)

Sudireddy, Bhaskar Reddy; Agersted, Karsten

2014-01-01

Single‐phase lanthanum and niobium co‐doped strontium titanate (Sr1–3x/2LaxTi0.9Nb0.1O3; x = 0–0.02) ceramics were prepared. Dilatometry in reducing atmosphere showed an increase in the sintering rate and sintered density with an increase in La amount. Microscopy of fractured surfaces of sintered...... samples showed that the average grain size increased drastically in reducing conditions with increasing La content (and associated A‐site vacancies). By incorporating 2 mol.% La, the electronic conductivity significantly improved from 80 to 135 S cm−1 at 1,000 °C, and even larger improvements were...... observed at lower temperatures. These observations demonstrate the flexibility in tailoring the microstructure and electronic transport properties by doping small amounts of La into the Nb‐doped SrTiO3 and show that Sr1–3x/2LaxTi0.9Nb0.1O3 is a potential electrode material for solid oxide cells....

Revised energy levels of singly ionized lanthanum

Science.gov (United States)

Güzelçimen, Feyza; Tonka, Mehdi; Uddin, Zaheer; Bhatti, Naveed Anjum; Windholz, Laurentius; Kröger, Sophie; Başar, Gönül

2018-05-01

Based on the experimental wavenumbers of 344 spectral lines from calibrated Fourier transform (FT) spectra as well as wavenumbers of 81 lines from the wavelength tables from literature, the energy of 115 fine structure levels of singly ionized lanthanum has been revised by weighted global fits. The classifications of the lines are provided by numerous previous investigations of lanthanum by different spectroscopic methods and authors. For the high accurate determination of the center of gravity wavenumbers from the experimental spectrum, the hyperfine constants of the involved levels have been taken into account, if possible. For the 94 levels with known hyperfine constants the accuracy of energy values is better than 0.01 cm-1. For 34 levels the magnetic dipole hyperfine constants A have been determined from FT spectra as part of this work. For four of these 34 levels even electric quadrupole hyperfine constants B could be estimated. For levels, which have experimentally unknown hyperfine constants and which are connected only by lines not found in the FT spectra but taken from literature, the uncertainties of energy values are about a factor of 10 higher. A list of all revised level energies together with a compilation of hyperfine structure data is given as well as a list of all lines used.

A solid oxide fuel cell with a gadolinia-doped ceria anode: Preparation and performance

DEFF Research Database (Denmark)

Marina, O.A.; Bagger, C.; Primdahl, S.

1999-01-01

) electrolyte without detrimental reaction. Single SOFCs comprising the CG4 anode, a composite strontium-doped lanthanum manganite-based cathode and the YSZ electrolyte were manufactured and tested in H-2/H2O and CH4/H2O atmospheres vs. air in the temperature range of 800-1015 degrees C, An area specific....../N-2 = 33/3/64. No carbon deposition was found on CG4 after cell operation at a steam-to-carbon ratio of 0.3 for 1000 h. Cells sustained several rapid thermal cycles in the temperature interval 200-1000 degrees C and a full redox cycle without degradation. (C) 1999 Elsevier Science B.V. All rights...

Controlling the reaction between boron-containing sealing glass and a lanthanum-containing cathode by adding Nb2O5

Science.gov (United States)

Zhao, Dandan; Fang, Lihua; Tang, Dian; Zhang, Teng

2016-09-01

In solid oxide fuel cell (SOFC) stacks, the volatile boron species present in the sealing glass often react with the lanthanum-containing cathode, degrading the activity of the cathode (this phenomenon is known as boron poisoning). In this work, we report that this detrimental reaction can be effectively reduced by doping bismuth-containing borosilicate sealing glass-ceramic with a niobium dopant. The addition of Nb2O5 not only condenses the [SiO4] structural units in the glass network, but also promotes the conversion of [BO3] to [BO4]. Moreover, the Nb2O5 dopant enhances the formation of boron-containing phases (Ca3B2O6 and CaB2Si2O8), which significantly reduces the volatility of boron compounds in the sealing glass, suppressing the formation of LaBO3 in the reaction couple between the glass and the cathode. The reported results provide a new approach to solve the problem of boron poisoning.

Effects of intravenously injected lanthanum chloride on the femur of rats

International Nuclear Information System (INIS)

Miyagawa, Makoto; Daimon, Tateo

2010-01-01

Lanthanum (La) is widely used in industry and medicine. Because of lanthanum's physicochemical resemblance to calcium, the possible effects of it on bone have to be considered. The aim of this study was to examine the effects of La on bone toxicity. Rats were intravenously administrated with lanthanum chloride at 5 mg La/kg per week for five weeks. Histomorphometric analysis of femurs were performed using micro-CT scan. Compared with normal controls, the total bone area of the femur did not show any change in La-administrated rats, whereas the trabecular area slightly decreased. The trabecular bone mineral density in the experimented rats was higher than that in the normal controls, although the mineral density of the cortical bone and cancerou one was unchanged after the administration of La. La did not alter mechanical barometers of the femur such as mean cross-sectional moment of inertia, minimum cross-sectional moment of inertia and polar moment of inertia. Additionally, light microscopic analysis of the femurs revealed that histological features of osteoid, calcification front and bone matrix were normal after the administration of La. La was detected in the macrophages in the bone marrow, but not in the bone matrix by histological stain for La and X-ray fluorescence microanalysis. Thus, these micro-CT imaging and microscopy of the femurs did not reveal toxic changes due to La. (author)

Microstructured fibers with high lanthanum oxide glass core for nonlinear applications

Science.gov (United States)

Kobelke, J.; Schuster, K.; Litzkendorf, D.; Schwuchow, A.; Kirchhof, J.; Bartelt, H.; Tombelaine, V.; Leproux, P.; Couderc, V.; Labruyere, A.

2009-05-01

We demonstrate a low loss microstructured fiber (MOF) with a high nonlinear glass core and silica holey cladding. The substitution of mostly used silica as core material of microstructured fibers by lanthanum oxide glass promises a high nonlinear conversion efficiency for supercontinuum (SC) generation. The glass composition is optimized in terms of thermochemical and optical requirements. The glass for the MOF core has a high lanthanum oxide concentration (10 mol% La2O3) and a good compatibility with the silica cladding. This is performed by adding a suitable alumina concentration up to 20 mol%. The lanthanum oxide glass preform rods were manufactured by melting technique. Besides purity issues the material homogeneity plays an important role to achieve low optical loss. The addition of fluorides allows the better homogenization of the glass composition in the preform volume by refining. The minimum attenuation of an unstructured fiber drawn from this glass is about 0.6 dB/m. It is mostly caused by decreasing of scattering effects. The microstructured silica cladding allows the considerable shifting of dispersive behavior of the MOF for an optimal pump light conversion. The MOF shows zero dispersion wavelengths (ZDW) of 1140 nm (LP01 mode) and 970 nm (LP11 mode). The supercontinuum generation was investigated with a 1064 nm pump laser (650 ps). It shows a broad band emission between 500 nm and 2200 nm.

Preparation, characterization and optical properties of Lanthanum-(nanometer MCM-41) composite materials

International Nuclear Information System (INIS)

Zhai, Q. Z.; Wang, P.

2008-01-01

Nanometer MCM-41 molecular sieve was prepared under a base condition by using cetyltrimethylammonium bromide as template and tetraethyl orthosilicate as silica source by means of hydrothermal method. Lanthanum(III) was incorporated into the nanometer MCM-41 by a liquid phase grafting method. The prepared nano composite materials were characterized by means of powder X-ray diffraction, spectrophotometric analysis, Fourier transform infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid diffuse reflectance absorption spectra and luminescence. The powder X-ray diffraction studies show that the nanometer MCM-41 molecular sieve is successfully prepared. The highly ordered meso porous two-dimensional hexagonal channel structure and framework of the support MCM-41 is retained intact in the prepared composite material La-(nanometer MCM-41). The spectrophotometric analysis indicates that lanthanum exists in the prepared nano composite materials. The Fourier transform infrared spectra indicate that the framework of the MCM-41 molecular sieve still remains in the prepared nano composite materials and some framework vibration peaks show blue shifts relative to those of the MCM-41 molecular sieve. The low temperature nitrogen adsorption-desorption indicates that the guest locales in the channel of the molecular sieve. Compared with bulk lanthanum oxide, the guest in the channel of the molecular sieve has smaller particle size and shows a significant blue shift of optical absorption band in solid diffuse reflectance absorption spectra. The observed blue shift in the solid state diffuse reflectance absorption spectra of the lanthanum-(nanometer MCM-41) sample show the obvious stereoscopic confinement effect of the channel of the host on the guest, which further indicates the successful encapsulation of the guest in the host. The La-(nanometer MCM-41) sample shows luminescence

Energetically benign synthesis of lanthanum silicate through “silica garden” route and its characterization

Energy Technology Data Exchange (ETDEWEB)

Parmar, Kavita [Central University of Jharkhand, Ranchi (India); Bhattacharjee, Santanu, E-mail: santanu@nmlindia.org [CSIR-National Metallurgical Laboratory, Jamshedpur (India)

2017-06-15

Lanthanum silicate synthesis through “silica garden” route has been reported as an alternative to energy intensive milling procedure. Under optimum conditions lanthanum chloride crystals react with water glass (sodium silicate) to produce self generating hollow lanthanum silicate precipitation tube(s) (LaSPT). The micro tubes are irregular, thick, white coloured and amorphous but are hierarchically built from smaller tubules of 10–20 nm diameters. They retain their amorphous nature on being heated up to 600 °C beyond which crystallization starts. The major phase in the LaSPT heated at 900 °C is La{sub 2}Si{sub 2}O{sub 7}. “As synthesized” LaSPT is heterogeneous and comprises non stoichiometric phases. The exterior and interior surfaces of these tubes are remarkably different in their morphology and chemical composition. LaSPT sintered at 1200 and 1300 °C show fair amount of ionic conductivity. - Graphical abstract: Lanthanum silicate precipitation tube (LaSPT) produced through ‘silica garden’ route offers a green alternative to energy intensive milling procedure. - Highlights: • La-silicate precipitation tube (LaSPT) synthesized via silica garden route. • The microtubes are irregular, thick, white coloured and amorphous. • They are hierarchically built from smaller tubules of 10–20 nm diameters. • The major phase in the LaSPT heated at 900 °C is La{sub 2}Si{sub 2}O{sub 7}. • LaSPT sintered at 1200 °C is fairly conducting.

Energetically benign synthesis of lanthanum silicate through “silica garden” route and its characterization

International Nuclear Information System (INIS)

Parmar, Kavita; Bhattacharjee, Santanu

2017-01-01

Lanthanum silicate synthesis through “silica garden” route has been reported as an alternative to energy intensive milling procedure. Under optimum conditions lanthanum chloride crystals react with water glass (sodium silicate) to produce self generating hollow lanthanum silicate precipitation tube(s) (LaSPT). The micro tubes are irregular, thick, white coloured and amorphous but are hierarchically built from smaller tubules of 10–20 nm diameters. They retain their amorphous nature on being heated up to 600 °C beyond which crystallization starts. The major phase in the LaSPT heated at 900 °C is La_2Si_2O_7. “As synthesized” LaSPT is heterogeneous and comprises non stoichiometric phases. The exterior and interior surfaces of these tubes are remarkably different in their morphology and chemical composition. LaSPT sintered at 1200 and 1300 °C show fair amount of ionic conductivity. - Graphical abstract: Lanthanum silicate precipitation tube (LaSPT) produced through ‘silica garden’ route offers a green alternative to energy intensive milling procedure. - Highlights: • La-silicate precipitation tube (LaSPT) synthesized via silica garden route. • The microtubes are irregular, thick, white coloured and amorphous. • They are hierarchically built from smaller tubules of 10–20 nm diameters. • The major phase in the LaSPT heated at 900 °C is La_2Si_2O_7. • LaSPT sintered at 1200 °C is fairly conducting.

Effects of lanthanum exposure on elemental distribution in rat brains measured by synchrotron radiation XRF

International Nuclear Information System (INIS)

Feng Liuxing; Xiao Haiqing; He Xiao; Liu Nianqing; Zhao Yuliang; Chai Zhifang; Zhang Zhiyong

2005-01-01

Rare earth elements (REEs) comprise a coherent series of 15 elements from lanthanum to lutetium and possessing very similar chemical properties. In recent decades, with the rapid increase of the exploitation of REE resources and their applications to modern industry and daily life, particularly to agriculture as fertilizer additives in China, more and more REEs are coming into environmental system as well as food chain through various ways. It has become increasingly important to obtain more information on the physiological function of REEs and their long-term biological effects on body of living beings. Epidemiological investigations found that the intelligence quotients (IQ) of children from the REE-high background regions are obviously different from that of the normal region. This indicated that REEs probably affect the function of brain. However, the mechanism is totally unknown. The contents and distributions of major and trace elements are sometimes good indicators of the physiological and pathological conditions of human and animal brains In this study, the effects of subchronic lanthanum exposure on the elemental distribution in the rat brains were studied. Wistar rats were exposed to lanthanum chloride through oral administration at O, 0.1, 2, and 40-mg/kg doses for 6 months. The elements such as Cl, K, Ca, Fe, Cu, and Zn in brain slices were identified by synchrotron radiation X-ray fluorescence analysis. Differences in two-dimensional maps of elemental distribution were noticed. Cl, Ca, and Zn were primarily concentrated in hippocampus of the controls. With the increase of the lanthanum dosage, the Ca and Zn levels were significantly decreased, while the Cu levels were significantly elevated in cortex, hippocampus and thalamus. Our results suggest that subchronic lanthanum exposure in rats appears to change elemental distribution in brain. The impact of lanthanides on brain function is not negligible.

The rare earth element (REE) lanthanum (La) induces hormesis in plants.

Science.gov (United States)

Agathokleous, Evgenios; Kitao, Mitsutoshi; Calabrese, Edward J

2018-07-01

Lanthanum is a rare earth element (REE) which has been extensively studied due to its wide application in numerous fields with a potential accumulation in the environment. It has long been known for its potential to stimulate plant growth within a hormetic-biphasic dose response framework. This article provides evidence from a series of high resolution studies published within the last two decades demonstrating a substantial and significant occurrence of lanthanum-induced hormesis in plants. These findings suggest that hormetic responses should be built into the study design of hazard assessment study protocols and included in the risk assessment process. Hormesis also offers the opportunity to substantially improve cost benefit estimates for environmental contaminants, which have the potential to induce beneficial/desirable effects at low doses. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electric properties and phase transition behavior in lead lanthanum zirconate stannate titanate ceramics with low zirconate content

Science.gov (United States)

Zeng, Tao; Lou, Qi-Wei; Chen, Xue-Feng; Zhang, Hong-Ling; Dong, Xian-Lin; Wang, Gen-Shui

2015-11-01

The phase transitions, dielectric properties, and polarization versus electric field (P-E) hysteresis loops of Pb0.97La0.02(Zr0.42Sn0.58-xTix)O3 (0.13≤ x ≤0.18) (PLZST) bulk ceramics were systematically investigated. This study exhibited a sequence of phase transitions by analyzing the change of the P-E hysteresis loops with increasing temperature. The antiferroelectric (AFE) to ferroelectric (FE) phase boundary of PLZST with the Zr content of 0.42 was found to locate at the Ti content between 0.14 and 0.15. This work is aimed to improve the ternary phase diagram of lanthanum-doped PZST with the Zr content of 0.42 and will be a good reference for seeking high energy storage density in the PLZST system with low-Zr content. Project supported by the National Natural Science Foundation of China (Grant Nos. 51202273, 11204304, and 11304334) and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 14DZ2261000).

Optical basicity and electronic polarizability of zinc borotellurite glass doped La3+ ions

Directory of Open Access Journals (Sweden)

M.K. Halimah

Full Text Available Zinc borotellurite glasses doped with lanthanum oxide were successfully prepared through melt-quenching technique. The amorphous nature of the glass system was validated by the presence of a broad hump in the XRD result. The refractive index of the prepared glass samples was calculated by using the equation proposed by Dimitrov and Sakka. The theoretical value of molar refraction, electronic polarizability, oxide ion polarizability and metallization criterion were calculated by using Lorentz-Lorenz equation. Meanwhile, expression proposed by Duffy and Ingram for the theoretical value of optical basicity of multi-component glasses were applied to obtain energy band gap based optical basicity and refractive index based optical basicity. The optical basicity of prepared glasses decreased with the increasing concentration of lanthanum oxide. Metallization criterion on the basis of refractive index showed an increasing trend while energy band gap based metallization criterion showed a decreasing trend. The small metallization criterion values of the glass samples represent that the width of the conduction band becomes larger which increase the tendency for metallization of the glasses. The results obtained indicates that the fabricated glasses have high potential to be applied on optical limiting devices in photonic field. Keywords: Borotellurite glasses, Refractive index, Electronic polarizability, Oxide ion polarizability, Optical basicity, Metallization criterion

Responses in sediment phosphorus and lanthanum concentrations and composition across 10 lakes following applications of lanthanum modified bentonite

DEFF Research Database (Denmark)

Dithmer, Line; Nielsen, Ulla Gro; Lürling, Miquel

2016-01-01

and binding forms, P adsorption capacity of discrete sediment layers, and pore water P concentrations. Lanthanum phosphate mineral phases were confirmed by solid state (31)P MAS NMR and LIII EXAFS spectroscopy. Rhabdophane (LaPO4 · nH2O) was the major phase although indications of monazite (LaPO4) formation...... conditions of P retention (with the exception of two lakes) by sediments, indicating effective control of sediment P release, i.e. between two and nine years after treatment....

Yttrium and lanthanum recovery from low cerium carbonate, yttrium carbonate and yttrium concentrate

International Nuclear Information System (INIS)

Vasconcelos, Mari Estela de

2006-01-01

In this work, separation, enrichment and purification of lanthanum and yttrium were performed using as raw material a commercial low cerium rare earth concentrate named LCC (low cerium carbonate), an yttrium concentrate named 'yttrium carbonate', and a third concentrated known as 'yttrium earths oxide. The first two were industrially produced by the late NUCLEMON - NUCLEBRAS de Monazita e Associados Ltda, using Brazilian monazite. The 'yttrium earths oxide' come from a process for preparation of lanthanum during the course of the experimental work for the present thesis. The following techniques were used: fractional precipitation with urea; fractional leaching of the LCC using ammonium carbonate; precipitation of rare earth peroxycarbonates starting from the rare earth complex carbonates. Once prepared the enriched rare earth fractions the same were refined using the ion exchange chromatography with strong cationic resin without the use of retention ion and elution using the ammonium salt of ethylenediaminetetraacetic acid. With the association of the above mentioned techniques were obtained pure oxides of yttrium (>97,7%), lanthanum (99,9%), gadolinium (96,6%) and samarium (99,9%). The process here developed has technical and economic viability for the installation of a large scale unity. (author)

Selective isotope determination of lanthanum by diode-laser-initiated resonance-ionization mass spectrometry

International Nuclear Information System (INIS)

Young, J.P.; Shaw, R.W.

1995-01-01

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 10 3 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 4 D 5/2 state of lanthanum at 30 354 cm --1 . The general utility of this spectral approach is discussed

Oriented growing and anisotropy of emission properties of lanthanum hexaboride single crystals

International Nuclear Information System (INIS)

Lazorenko, V.I.; Lotsko, D.V.; Platonov, V.F.; Kovalev, A.V.; Galasun, A.P.; Matvienko, A.A.; Klinkov, A.E.

1987-01-01

Single crystals of lanthanum hexaboride with preset crystallographic orientation are grown by the method of crucible-free zone melting. It is shown that oriented growing of single crystals of the given compound is possible only when using seed crystals of the required orientation because no predominant orientation of the LaB 6 growth is found in case of spontaneous crystallization. Orientation of spontaneously growing LaB 6 crystals does not depend on their growth rate, degree of the melt diffusion annealing, purity of the inital powder. Anisotropy of the electronic work function for single crystal lanthanum hexaboride is confirmed. Its value grows as (100)<(110)<(111). Conditions of the preliminary thermovacuum purification of the surface are shown to affect the measured work function

A case of lanthanum carbonate ingestion thought to be phlebosclerotic colitis on CT imaging and abdominal radiograph

International Nuclear Information System (INIS)

Harris, K.; Balcam, S.

2017-01-01

A male admitted in the early hours of the morning, complained of a four week, right sided, non-radiating, dull and intermittent abdominal pain. Imaging suggested a diagnosis of phlebosclerotic colitis which was later discounted when the patients' history of lanthanum carbonate ingestion was examined. Phlebosclerotic colitis mostly affects the Asian population, and its cause is still not known, but can be associated with specific radiographic features. Collections of lanthanum may confuse a diagnosis of phlebosclerotic colitis as well as other factors such as voxel errors, photon starvation and movement. - Highlights: • PC can be non-specific, its cause unknown, diagnosis is often delayed. • PC depends on specific radiographic features. • Lanthanum Carbonate can collect within the lumen and confuses diagnosis. • Voxel errors, photon starvation and patient movement can displace densities.

Self-assembly in lanthanum(III) and calcium(II) complexes of salicylaldimines derived from putrescine

International Nuclear Information System (INIS)

Pospieszna-Markiewicz, Izabela; Kaczmarek, Malgorzata T.; Kubicki, Maciej; Radecka-Paryzek, Wanda

2008-01-01

The one-step template reaction of salicylaldehyde with putrescine, a biogenic diamine, in the presence of lanthanum(III) or calcium(II) ions produces salicylaldimine complexes containing the N,N'-bis(salicylidene)-1,4-butanediamine ligand L as a result of the [2 + 1] Schiff base condensation. The X-ray diffraction studies of the lanthanum complex reveals an infinite [La 2 L 4 (NO 3 ) 6 ] ∞ polymeric structure based on networks of 10-coordinated La(III) nodes linked by bridging unionized ligands that use exclusively the oxygens as donor atoms with the nitrogen atoms not being involved in coordination

Optical characteristics of novel bulk and nanoengineered laser host materials

Science.gov (United States)

Prasad, Narasimha S.; Sova, Stacey; Kelly, Lisa; Bevan, Talon; Arnold, Bradley; Cooper, Christopher; Choa, Fow-Sen; Singh, N. B.

2018-02-01

The hexagonal apatite single crystals have been investigated for their applications as laser host materials. Czochralksi and flux growth methods have been utilized to obtain single crystals. For low temperature processing (useful properties as laser hosts and bone materials. Calcium lanthanum silicate (Nd-doped) and lanthanum aluminate material systems were studied in detail. Nanoengineered calcium and lanthanum based silicates were synthesized by a solution method and their optical and morphological characteristics were compared with Czochralski grown bulk hydroxyapatite single crystals. Materials were evaluated by absorbance, fluorescence and Raman characteristics. Neodymium, iron and chromium doped crystals grown by a solution method showed weak but similar optical properties to that of Czochralski grown single crystals.

Production of the Lax Ca1-x Cry Al1-y O3 compound through hydroxide precipitation

International Nuclear Information System (INIS)

Martins, L.C.; Machado, A.J.S.

1996-01-01

Purposing to reduce the cost of preparation of the lanthanum chromite doped with calcium and aluminum, it was made a study of the condition of hydroxide precipitation, using calcium, chromium and aluminum nitrates and lanthanum oxide, as precursors and as precipitate agent was used potassium hydroxide. In this study are showed results about the reaction kinetic, x-ray diffraction and yield as function of the pH. These results suggest a high yield for also elements studied. The phase of stoichiometry, La 0.8 Ca 0.2 Cr 0.75 Al 0.25 O 3 was obtained in low temperature. In fact, this process is viable to produce of lanthanum chromite doped with calcium and aluminum. (author)

Investigation of new materials for SOFC applications; Untersuchungen zum Einsatz neuer Werkstoffe fuer SOFC-Anwendungen

Energy Technology Data Exchange (ETDEWEB)

Wackerl, J.

2007-05-04

Fuel cells based on solid oxides ('SOFC') are excellent alternative devices for power generation, when they are operated at high temperature, e.g. above 600 C. Having only fixed parts for the power generating part of the device is only one advantage of the fuel cell. Due to their unique design, these devices offer a maximum of efficiency for energy conversion compared to conventional power generating systems, which are mainly based on turbines. One aim of this thesis is the examination of alternative electrolyte and cathode materials for the SOFC applications at reduced temperatures, which means in the temperature range between 600 C and 750 C. For the first main task, several materials from the oxygen ion conducting electrolytes were selected. Different strontium and magnesium doped lanthanum gallate (LSGM) materials with additional transition metal doping were selected and prepared via two different preparation methods. The optimum calcining conditions were determined using thermal analysis methods. The results of the structural analysis of the sintered electrolyte materials were used to select the most suitable electrolyte materials. As a result, LSGM and iron doped LSGM (LSGMF) were the most promising materials. Further investigations were carried out on LSGMF materials with different strontium content. The influence of chemical cation non-stoichiometry on the perovskite material was investigated. Therefore, measurements to gather information about the crystallographic structure, morphology, electrochemistry and electrical conductivity were carried out. For a selected sample, the correlations between single effects, such as the crystallographic structure, and the electrical properties are shown by combining the different analysis methods. It could be shown that both the electrochemistry and the crystallographic structure have a significant influence on the electrical conductivity of the LSGMF materials. The second aim of the thesis was the selection

Defect disorder of undoped and Sr-doped LaCoO3-δ

International Nuclear Information System (INIS)

Nowotny, J.; Rekas, M.

2002-01-01

The paper considers defect disorder models of undoped lanthanum cobaltate LaCoO 3-δ , and Sr-doped LaCoO 3-δ , La 1-x Sr x Co) 3-δ (LSC), involving both random defect model and cluster defect model. The models are derived using the nonstoichiometry data reported in the literature. Doubly ionized oxygen vacancies are assumed to be the predominate ionic defects within the entire range of compositions. The effect of Sr content on defect disorder of LSC is discussed in terms of both defect models. Impact of segregation on surface composition of ionic solids in general and LSC materials in particular is briefly outlined. The effect of the interface layer on functional properties of LSC as electrode material is briefly discussed. (author)

Persistent luminescence of transition metal (Co, Ni...)-doped ZnGa2O4 phosphors for applications in the near-infrared range

Science.gov (United States)

Pellerin, Morgane; Castaing, Victor; Gourier, Didier; Chanéac, Corinne; Viana, Bruno

2018-02-01

Persistent luminescence materials present many applications including security lighting and bio-imaging. Many progresses have been made in the elaboration of persistent luminescent nanoparticles suitable for the first NIR partial transparency window (650 - 950 nm). Moving to the second and third near-infrared partial transparency windows (1000 nm - 1800 nm) allows further reducing of scattering, absorption and tissue autofluorescence effects. In this work, we present the synthesis of Co2+ and Ni2+ doped zinc-gallate nanoparticles with broad emission covering the NIR-II range. Site occupancy, energy levels, optical features and persistent phenomena are presented.

Effect of voltage on the characteristics of magnesium-lanthanum deposits synthesized by an electrodeposition process

Energy Technology Data Exchange (ETDEWEB)

Sahli, M. [Laboratoire de Physique Energétique, Université de Constantine 1 (Algeria); Chetehouna, K.; Gascoin, N. [INSA-CVL, Univ. Orléans, PRISME, EA 4229, F-18020, Bourges (France); Bellel, N. [Laboratoire de Physique Energétique, Université de Constantine 1 (Algeria); Tadini, P., E-mail: tadini.pietro@gmail.com [INSA-CVL, Univ. Orléans, PRISME, EA 4229, F-18020, Bourges (France)

2017-04-15

This work deals with the characterization of magnesium-lanthanum powders deposits produced with an electrodeposition technique using an aqueous solution based on magnesium chloride and lanthanum(III) nitrate. In recent years, the interest for magnesium-based alloys is growing due to their potential use as solid state systems for hydrogen storage. This work is a preliminary study on the synthesis of magnesium-lanthanum powders oriented to their later evaluation in systems for hydrogen storage. Magnesium and Lanthanum are deposited on a copper plate used as a cathode. Chemical composition, structure and morphology are investigated by EDS, XRD, FTIR and SEM. The effect of voltage on powders characteristics is studied considering three values (3, 3.5 and 4 V). EDS analysis shows the presence of three major elements (Mg, La and O) with a little amount of Cl. The weight percentages of Mg and O increase whereas the one of La decreases with the growth of voltage. Morphological characterization reveals that heterogeneous chemical structures are formed on the surface of the electrode and the size of aggregates decreases with the increase of voltage. From the results of X-ray analysis the deposits reveal the significant presence of two phases: Mg(OH){sub 2} and La(OH){sub 3}. The peaks originating from the Mg(OH){sub 2} phase has a non-monotonic behavior and those of La(OH){sub 3} phase increase with the increase of voltage. FTIR analysis confirms the presence of the two phases identified in XRD diffractograms and exhibits that their corresponding transmittance values increase for higher voltage values. - Highlights: • Synthesis of magnesium-lanthanum deposits by an electrodeposition process. • Voltage effect is investigated using different physicochemical analysis techniques (EDS, XRD, FTIR and SEM). • The EDS analysis shows the presence of three major elements (Mg, La and O) and a little amount of Cl. • Two phases, namely Mg(OH){sub 2} and La(OH){sub 3} are

Influence of lanthanum on the optomagnetic properties of zinc ferrite prepared by combustion method

International Nuclear Information System (INIS)

Tholkappiyan, R.; Vishista, K.

2014-01-01

Pure and lanthanum doped zinc ferrite nanoparticles were synthesized by a combustion method using glycine as fuel. The mechanism of formation of these nanoferrites is discussed briefly. The prepared nanoparticles characterized using powder X-ray diffraction analysis (XRD) revealed the formation of cubic spinel phase with high crystallinity. Average crystallite size, X-ray density and bulk density were found to decrease with an increase in La 3+ concentration. The chemical elements and states on the surface of these ferrites were determined using X-ray photoelectron spectroscopy (XPS). The detailed core level spectra of the photoelectron peaks of Zn 2p, Fe 2p, La 3d and O 1s were analyzed. The magnetic behavior of these nanoparticles was studied using a vibrating sample magnetometer (VSM) and corresponding changes in the saturation magnetization (Ms), coercivity (Hc) and remanent magnetization (Mr) were analyzed. The optical behavior of these ferrite nanoparticles was characterized by UV–Diffuse reflectance studies (UV–DRS). From the UV–DRS studies, the optical band gap was found to be in the range of 1.87–1.97 eV. The combustion method significantly produces large amount of products within a short time. Therefore, this method is potentially suitable for manufacturing industries for preparing the magnetic nanoparticles

Correlation of the radioprotective effect of the methyl gallate on the ruptures induction in DNA and it effect in the capture of free radicals

International Nuclear Information System (INIS)

Morales R, P.; Cabral P, A.; Cruz V, V.L.; Gonzalez B, F.; Zarco M, A.

2007-01-01

It is shown in alive, the capacity of the methyl gallate to reduce the induced ruptures in the DNA for γ radiation. As well as to capture free radicals in a system in vitro. This suggests that the methyl gallate can be a radioprotector that acts capturing free radicals. (Author)

Impact of Annealing Temperature on the Physical Properties of the Lanthanum Deficiency Manganites

Directory of Open Access Journals (Sweden)

Skini Ridha

2017-10-01

Full Text Available The lanthanum deficiency manganites La0.8-x□xCa0.2MnO3 (x = 0, 0.1 and 0.2, where □ is a lanthanum vacancy, were prepared using the classic ceramic methods with different thermal treatments (1373 K and 973 K. The structural, magnetic, and magnetocaloric properties of these compounds were studied as a function of annealing temperature. It was noted that the annealing temperature did not affect the crystal structure of our samples (orthorhombic structure with Pnma space group. Nevertheless, a change in the variation of the unit cell volume V, the average bond length dMn–O, and the average bond angles θMn–O–Mn were observed. Magnetization versus temperature study has shown that all samples exhibited a magnetic transition from ferromagnetic (FM to paramagnetic (PM phase with increasing temperature. However, it can be clearly seen that the annealing at 973 K induced an increase of the magnetization. In addition, the magnetocaloric effect (MCE as well as the relative cooling power (RCP were estimated. As an important result, the values of MCE and RCP in our Lanthanum-deficiency manganites are reported to be near to those found in gadolinium, considered as magnetocaloric reference material.

Plasma sprayed metal supported YSZ/Ni-LSGM-LSCF ITSOFC with nanostructured anode

Energy Technology Data Exchange (ETDEWEB)

Hwang, Changsing; Tsai, Chun-Huang; Lo, Chih-Hung; Sun, Cha-Hong [Physics Division, Institute of Nuclear Energy Research, Lungtan, Taoyuan 32546 (China)

2008-05-15

Intermediate temperature solid oxide fuel cells (ITSOFCs) supported by a porous Ni-substrate and based on Sr and Mg doped lanthanum gallate (LSGM) electrolyte, lanthanum strontium cobalt ferrite (LSCF) cathode and nanostructured yttria stabilized zirconia-nickel (YSZ/Ni) cermet anode have been fabricated successfully by atmospheric plasma spraying (APS). From ac impedance analysis, the sprayed YSZ/Ni cermet anode with a novel nanostructure and advantageous triple phase boundaries after hydrogen reduction has a low resistance. It shows a good electrocatalytic activity for hydrogen oxidation reactions. The sprayed LSGM electrolyte with {proportional_to}60 {mu}m in thickness and {proportional_to}0.054 S cm{sup -1} conductivity at 800 C shows a good gas tightness and gives an open circuit voltage (OCV) larger than 1 V. The sprayed LSCF cathode with {proportional_to}30 {mu}m in thickness and {proportional_to}30% porosity has a minimum resistance after being heated at 1000 C for 2 h. This cathode keeps right phase structure and good porous network microstructure for conducting electrons and negative oxygen ions. The APS sprayed cell after being heated at 1000 C for 2 h has a minimum inherent resistance and achieves output power densities of {proportional_to}440 mW cm{sup -2} at 800 C, {proportional_to}275 mW cm{sup -2} at 750 C and {proportional_to}170 mW cm{sup -2} at 700 C. Results from SEM, XRD, ac impedance analysis and I-V-P measurements are presented here. (author)

Determination of catechins and catechin gallates in tissues by liquid chromatography with coulometric array detection and selective solid phase extraction.

Science.gov (United States)

Chu, Kai On; Wang, Chi Chiu; Chu, Ching Yan; Rogers, Michael Scott; Choy, Kwong Wai; Pang, Chi Pui

2004-10-25

Catechins levels in organ tissues, particularly liver, determined by published methods are unexpectedly low, probably due to the release of oxidative enzymes, metal ions and reactive metabolites from tissue cells during homogenization and to the pro-oxidant effects of ascorbic acid during sample processing in the presence of metal ions. We describe a new method for simultaneous analysis of eight catechins in tissue: (+)-catechin (C), (-)-epicatechin (EC), (-)-gallocatechin (GC), (-)-epigallocatechin (EGC), (-)-catechin gallate (CG), (-)-epicatechin gallate (ECG), (-)-gallocatechin gallate (GCG) and (-)-epigallocatechin gallate (EGCG) (Fig. 1). The new extraction procedure utilized a methanol/ethylacetate/dithionite (2:1:3) mixture during homogenization for simultaneous enzyme precipitation and antioxidant protection. Selective solid phase extraction was used to remove most interfering bio-matrices. Reversed phase HPLC with CoulArray detection was used to determine the eight catechins simultaneously within 25 min. Good linearity (>0.9922) was obtained in the range 20-4000 ng/g. The coefficients of variance (CV) were less than 5%. Absolute recovery ranged from 62 to 96%, accuracy 92.5 +/- 4.5 to 104.9 +/- 6%. The detection limit was 5 ng/g. This method is capable for determining catechins in rat tissues of liver, brain, spleen, and kidney. The method is robust, reproducible, with high recovery, and has been validated for both in vitro and in vivo sample analysis.

Molecular absorption spectra of beryllium, cerium, lanthanum, iron, and platinum salts

International Nuclear Information System (INIS)

Daidoji, Hidehiro

1980-01-01

The absorption spectra of some salts of beryllium, cerium, lanthanum, iron and platinum in air-acetylene flame were measured in the wavelength range from 200 to 400 nm. A Hitachi 207 type atomic absorption spectrophotometer was used. A deuterium lamp, a home-made continuous radiation lamp and some hollow cathode lamps were used as light sources. The new molecular absorption spectra of cerium, lanthanum and platinum and the absorption spectra due to Be(OH) 2 , LaO, PtH, FeO and FeCl in 200-400 nm region were obtained. Emission spectra of CeO, LaO and FeOH were also obtained. These molecular absorption bands were estimated as absorption errors of maximum 15 times to the sensitivity of each elements in atomic absorption spectrometry. In addition, spectral line interferences of iron were observed in atomic absorption spectrometry of Zn, Cd, Ni, Cu and Cr. (author)

Sol-gel synthesis of lanthanum-gallate-based ceramic coatings

International Nuclear Information System (INIS)

Golubko, N.V.; Kaleva, G.M.; Roginskaya, Yu.E.; Politova, E.D.

2007-01-01

Phase-pure (La 0.9 Sr 0.1 )(Ga 0.7 Fe 0.3 )O 3-y and (Sr 1.8 La 0.2 )(GaFe)O 5.1 solid solutions with the perovskite and brownmillerite structures have been prepared from salt solutions by sol-gel processing at temperatures from 570 to 870 K. Ceramic coatings up to 100 μm in thickness have been produced by applying suspensions of the sol-gel powders to various substrates. The structure and microstructure of the ceramic coatings have been studied by X-ray diffraction and scanning electron microscopy [ru

The combination of lanthanum chloride and the calcimimetic calindol delays the progression of vascular smooth muscle cells calcification

Energy Technology Data Exchange (ETDEWEB)

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); Borghi, Elisa [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); 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)

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.

Effects of adding lanthanum to Ni/ZrO2 catalysts on ethanol steam reforming

International Nuclear Information System (INIS)

Profeti, Luciene Paula Roberto; Habitzheuter, Filipe; Assaf, Elisabete Moreira

2012-01-01

The catalytic performance of Ni/ZrO 2 catalysts loaded with different lanthanum content for steam reforming of ethanol was investigated. Catalysts were characterized by BET surface area, X-ray diffraction, UV-vis spectroscopy, temperature programmed reduction, and X-ray absorption fine structure techniques. Results showed that lanthanum addition led to an increase in the degree of reduction of both NiO and nickel surface species interacting with the support, due to the higher dispersion effect. The best catalytic performance at 450 deg C was found for the Ni/12LZ catalyst, which exhibited an effluent gaseous mixture with the highest H 2 yield. (author)

Structural characteristics and UV-light enhanced gas sensitivity of La-doped ZnO nanoparticles

International Nuclear Information System (INIS)

Ge Chunqiao; Xie Changsheng; Hu Mulin; Gui Yanghai; Bai Zikui; Zeng Dawen

2007-01-01

La-doped ZnO nanoparticles were synthesized by sol-gel method starting from zinc acetate dihydrate, lanthanum sesquioxide, alcohol and nitric acid. The crystal structure and morphology of the nanoparticles were characterized by XRD, FESEM, respectively. The thermal decomposition behavior of the the ZnO-based xerogel was detected by TG-DSC. The results show that as-prepared nanoparticles with the hexagonal wurtzite contain the adsorbed water and some organic compounds below 300 o C, which is the key to the calcinations of the ZnO-based xerogel. Pure ZnO and La-doped ZnO thick film sensors were prepared and tested for specific sensitivity to alcohol and benzene with (and without) UV-light excitation. Among all, 10 at.%La-ZnO-based sensors are significantly sensitive to 100 ppm alcohol and 100 ppm benzene. There is an obvious enhancement of the gas-sensing performances with UV-light excitation. That is, the sensitivity to 100 ppm benzene rises twice. The observed sensitivity to alcohol and benzene could be explained with the surface adsorption theory and the conduction-band theory

Growth and physico chemical characterization of lanthanum neodymium oxalate single crystals

International Nuclear Information System (INIS)

Raju, K.S.; John, Varughese; Ittyachen, M.A.

1998-01-01

Single crystals of lanthanum neodymium oxalate (LNO) are grown in sodium meta silicate gels, by the diffusion of a mixture of aqueous solutions of lanthanum nitrate and neodymium nitrate into the test tube having the set gel containing oxalic acid. The bluish pink coloured tabular crystals of LNO having well defined hexagonal basal planes appear either as foggy or clear, the latter at the greater depths inside the gel. The coloration of LNO visually observed is evidenced in UV-visible spectrum, by the revelation of well pronounced characteristic peaks in the visible region (500-900 nm). X-ray diffraction (XRD) of powdered LNO is ordered, meaning crystalline in nature, besides its isostructurality with similarly grown lanthanum samarium oxalate crystals. The single crystallinity of LNO is established by its oscillation XRD pattern. Thermogravimetric analysis (TGA) and differential scanning colorimetry (DSC) support that LNO loses water of crystallization around 120 degC and CO and CO 2 around 350-450 degC, while the infrared absorption (IR) spectrum of LNO establishes the presence of oxalate (C 2 O 4 ) 2- ions. Energy dispersive x-ray analysis (EDAX) confirms the presence of La and Nd in the sample. X-ray photoelectron spectroscopic (XPS) studies of LNO establish the presence of La and Nd in their respective oxide states. An empirical structure for LNO has been proposed on the basis of these findings. The smokiness in the foggy LNO crystal has been attributed due to the gel inclusion during the growth process. (author)

Thermochemistry of rare earth doped uranium oxides LnxU1-xO2-0.5x+y (Ln = La, Y, Nd)

Science.gov (United States)

Zhang, Lei; Navrotsky, Alexandra

2015-10-01

Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10-50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO1.5, UO2 and UO3 in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of LnxU1-xO2-0.5x+y is similar to that of UO2 to UO3 for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U5+, U6+, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements.

Synthesis and Characterization of Lanthanum Complexes with Amino Acid Schiff Base

Institute of Scientific and Technical Information of China (English)

张秀英; 张有娟; 杨林

2001-01-01

Six new complexes of lanthanum with amino acid Schiff base ligands, A-F, were prepared in methanol-aqueous solution. The composition and properties of the title complexes were characterized by elemental analysis, molar conductance, infrared, electronic spectra, 1H NMR, thermogravimetric and differential thermal analysis.

Effect of long-term intake of lanthanum chloride on the concentrations of some macro- and trace elements in rat brains using NAA

International Nuclear Information System (INIS)

Yu Tong; Li Yaming; Ren Yan; Wang Enbo; Xu Hongying; Wang Wenzhong

2005-01-01

Effects of long-term intake of lanthanum in drinking water on the concentrations of twelve kinds of macro- and trace elements in rat brains were primarily studied by neutron activation analysis. The results show that, along with the elevation of the dose of lanthanum, more and more elements were affected in the rat brain tissues. Compared with control group, the concentrations of five elements were changed in the 1000 mg/L group. These elements have close relations with brain function. Accordingly, intake of lanthanum may have negative effects on brain function. (authors)

Solid state electrolyte systems

Energy Technology Data Exchange (ETDEWEB)

Pederson, L.R.; Armstrong, B.L.; Armstrong, T.R. [Pacific Northwest Lab., Richland, WA (United States)] [and others

1997-12-01

Lanthanum gallates are a new family of solid electrolytes that exhibit high ionic conductivity and are stable to high temperatures. Compositions have been developed that are as much as a factor of two more conductive than yttria-stabilized zirconia at a given temperature, through partial replacement of lanthanum by calcium, strontium, and/or barium and through partial replacement of gallium by magnesium. Oxide powders were prepared using combustion synthesis techniques developed in this laboratory; these were sintered to >95% of theoretical density and consisted of a single crystalline phase. Electrical conductivities, electron and ion transference numbers, thermal expansion, and phase behavior were evaluated as a function of temperature and oxygen partial pressure. A key advantage of the use of lanthanum gallate electrolytes in solid oxide fuel cells is that the temperature of operation may be lowered to perhaps 800 C, yet provide approximately the same power density as zirconia-based cells operating at 1000 C. Ceramic electrolytes that conduct both oxygen ions and electrons are potentially useful to passively separate pure oxygen from an air source at low cost. In such materials, an oxygen ion flux in one direction is charge-compensated by an opposing electron flux. The authors have examined a wide range of mixed ion and electron conducting perovskite ceramics in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, where M = Sr, Ca, and Ba, and N = Pr, Mn, Ni, Cu, Ti, and Al, as well as mixed conducting brownmillerite ceramics, and have characterized oxygen permeation behavior, defect chemistry, structural and phase stability, and performance as cathodes.

Spin injection and detection in lanthanum- and niobium-doped SrTiO3 using the Hanle technique

KAUST Repository

Han, Wei; Jiang, Xin; Kajdos, Adam; Yang, See-Hun; Stemmer, Susanne; Parkin, Stuart S. P.

2013-01-01

as the temperature is decreased to low temperatures. However, the mobility of the strontium titanate has a strong temperature dependence. This behaviour and the carrier doping dependence of the spin lifetime suggest that the spin lifetime is limited by spin

Separation of lanthanum from samarium on solid aluminum electrode in LiCl-KCl eutectic melts

International Nuclear Information System (INIS)

De-Bin Ji; Mi-Lin Zhang; Xing Li; Xiao-Yan Jing; Wei Han; Yong-De Yan; Yun Xue; Zhi-Jian Zhang; Harbin Engineering University, Harbin

2015-01-01

This paper presents an electrochemical study on the separation of lanthanum from samarium on aluminum electrode at 773 K. The results from different electrochemical methods showed that Sm(III) and La(III) formed Al-Sm and Al-La intermetallic compounds on an aluminum electrode at electrode potential around -1.67 and -1.46 V, respectively. The electrochemical separation of lanthanum was carried out in LiCl-KCl-LaCl 3 -SmCl 3 melts on solid aluminum electrodes at 773 K by potentiostatic electrolysis at -1.45 V for 40 h and the separation efficiency was 99.1 %. (author)

Effect of lanthanum substitution on dielectric relaxation, impedance response, conducting and magnetic properties of strontium hexaferrite

Energy Technology Data Exchange (ETDEWEB)

Want, Basharat, E-mail: bawant@kashmiruniversity.ac.in; Bhat, Bilal Hamid; Ahmad, Bhat Zahoor

2015-04-05

Highlights: • The substitution of La affects the dielectric and magnetic properties of strontium hexaferrite. • The electric behaviour of the compound follows the Koop’s phenomenological theory. • The impedance study shows the role of grain boundaries to the electric properties of the compound. • The substitution of La to strontium hexaferrite reduces the resistive nature of grain boundaries. - Abstract: Lanthanum strontium hexaferrite Sr{sub 1−x}La{sub x}Fe{sub 12}O{sub 19} (x = 0, 0.08, 0.13 , 0.18) has been successfully synthesized by using citrate-precursor method and characterized by different techniques. The X-ray diffraction results revealed that the sample is crystalline in nature and is of single phase with the space group P63/mmc. The dielectric, conducting and impedance related studies have been carried out as a function of frequency and concentration of lanthanum in the frequency ranges of 20 Hz–3 MHz. Impedance studies were performed in the frequency domain to distinguish between bulk and grain boundary contributions of the material to the overall dielectric response. The electric response of the material was also modeled by an equivalent circuit and different circuit parameters were calculated. Magnetic characterization of the material was also performed and the effect of lanthanum concentration was studied. The hysteresis loop obtained from the magnetometer showed that with the increase of lanthanum concentration, the saturation magnetisation decreases while as coercivity increases.

Fabrication of large-volume, low-cost ceramic lanthanum halide scintillators for gamma ray detection : final report for DHS/DNDO/TRDD project TA-01-SL01.

Energy Technology Data Exchange (ETDEWEB)

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

Studies on the lanthanum arsenate ion-exchanger: preparation, physicochemical properties and applications

International Nuclear Information System (INIS)

Mukherjee, A.K.; Mandal, S.K.

1984-01-01

The cation-exchange behaviour of lanthanum arsenate has been studied. This paper reports the preparation and physicochemical properties of the exchanger. Its analytical utility is compared with that of other arsenate exchangers. Some practical analytical applications are described. (author)

Magnetic study of interatomic interactions, synthesis, structural and mass spectroscopy investigations of lanthanum gallate doped with cobalt and magnesium

International Nuclear Information System (INIS)

Korolev, D.A.; Chezhina, N.V.; Lopatin, S.I.

2015-01-01

Highlights: • Single phase LaCo x Ga 1−1.2x Mg 0.2x O 3 and LaCo x Ga 1−1.5x Mg 0.5x O 3 solutions were obtained. • Two crystalline modifications of solid solutions were found by Rietveld method. • Ferromagnetic clusters including Co, Mg and accompanying oxygen vacancies are found. • Magnetic behavior of clusters is of superparamagnetic type. - Abstract: For the first time by X-ray method two phases of the solid solutions LaCo x Ga 1−1.2x Mg 0.2x O 3−δ and LaCo x Ga 1−1.5x Mg 0.5x O 3−δ (x = 0.01–0.10) with different structure were found – rhombohedral and orthorhombic phases. On the basis of the data on evaporation of the components a synthetic procedure was advanced allowing the losses of cobalt to be minimized. The study of magnetic characteristics of obtained solid solutions showed the formation of high nuclearity clusters containing cobalt atoms, and also magnesium and associated vacancies even in diluted solid solutions. Clusters are characterized by a competition between ferro- and antiferromagnetic exchange interactions, whereas the long order exchange is antiferromagnetic

Magnetic study of interatomic interactions, synthesis, structural and mass spectroscopy investigations of lanthanum gallate doped with cobalt and magnesium

Energy Technology Data Exchange (ETDEWEB)

Korolev, D.A., E-mail: chemdim@mail.ru; Chezhina, N.V.; Lopatin, S.I.

2015-03-05

Highlights: • Single phase LaCo{sub x}Ga{sub 1−1.2x}Mg{sub 0.2x}O{sub 3} and LaCo{sub x}Ga{sub 1−1.5x}Mg{sub 0.5x}O{sub 3} solutions were obtained. • Two crystalline modifications of solid solutions were found by Rietveld method. • Ferromagnetic clusters including Co, Mg and accompanying oxygen vacancies are found. • Magnetic behavior of clusters is of superparamagnetic type. - Abstract: For the first time by X-ray method two phases of the solid solutions LaCo{sub x}Ga{sub 1−1.2x}Mg{sub 0.2x}O{sub 3−δ} and LaCo{sub x}Ga{sub 1−1.5x}Mg{sub 0.5x}O{sub 3−δ} (x = 0.01–0.10) with different structure were found – rhombohedral and orthorhombic phases. On the basis of the data on evaporation of the components a synthetic procedure was advanced allowing the losses of cobalt to be minimized. The study of magnetic characteristics of obtained solid solutions showed the formation of high nuclearity clusters containing cobalt atoms, and also magnesium and associated vacancies even in diluted solid solutions. Clusters are characterized by a competition between ferro- and antiferromagnetic exchange interactions, whereas the long order exchange is antiferromagnetic.

Lanthanum (samarium) nitrate-4-aminoantipyrine nitrate-water systems

International Nuclear Information System (INIS)

Starikova, L.I.; Zhuravlev, E.F.

1985-01-01

Using the isothermal method of cross-sections at 50 deg C systems lanthanum nitrate-4-aminoantipyrine nitrate-water (1), samarium nitrate-4-aminoantipyrine nitrate-water (2), are studied. Isotherms of system 1 consist of two crystallization branches of initial salt components. In system 2 formation of congruently soluble compounds of the composition Sm(No) 3 ) 3 xC 11 H 13 ON 3 xHNO 3 is established. Analytical, X-ray phase and thermogravimetric analysis of the isolated binary salt are carried out

Apparent molar volumes and compressibilities of lanthanum, gadolinium and lutetium trifluoromethanesulfonates in dimethylsulfoxide

International Nuclear Information System (INIS)

Warmińska, Dorota; Wawer, Jarosław

2012-01-01

Highlights: ► Sequence of volumes and compressibilities of Ln 3+ ions in DMSO is: La 3+ > Gd 3+ 3+ . ► Sequence of the partial molar volumes do not change with temperature. ► These results are the consequence of nature of the ion–solvent bonding. - Abstract: Temperature dependencies of the densities of dimethylsulfoxide solutions of lanthanum, gadolinium and lutetium trifluoromethanesulfonates have been determined over a wide range of concentrations. The apparent molar volumes and partial molar volumes of the salts at infinite dilution, as well as the expansibilities of the salts, have been calculated from density data. Additionally, the apparent molar isentropic compressibilities of lanthanum, gadolinium and lutetium trifluoromethanesulfonates have been calculated from sound velocity data at 298.15 K. The data obtained have been interpreted in terms of ion−solvent interactions.

Effect of various lanthanum sol-gel coatings on the 330Cb (Fe-35Ni-18Cr-1Nb-2Si) oxidation at 900 deg. C

Energy Technology Data Exchange (ETDEWEB)

Buscail, H., E-mail: buscail@iut.u-clermont1.fr [Clermont Universite- LVEEM, 8 rue J.B. Fabre, BP 219, 43006 Le Puy en Velay (France); Issartel, C.; Riffard, F.; Rolland, R.; Perrier, S. [Clermont Universite- LVEEM, 8 rue J.B. Fabre, BP 219, 43006 Le Puy en Velay (France); Fleurentin, A. [CETIM, 52 av Felix Louat, BP 80067, 60304 Senlis (France); Josse, C. [L' ICB UMR5209 CNRS, BP 47870, 21078 Dijon (France)

2011-11-01

The influence of a lanthanum sol-gel coating on the oxide scale adherence has been studied during the 330Cb (Fe-35Ni-18Cr-1Nb-2Si) oxidation at 900 deg. C, in air. The alloy oxidation is performed in order to generate a protective chromia scale acting as a good barrier against carburization. Argon annealing of lanthanum sol-gel coatings have been performed at various temperatures in order to find the best conditions to insure the scale adherence. Kinetic results show that lanthanum sol-gel coatings lead to a lower oxidation rate compared to blank specimens. Thermal cycling tests on lanthanum the sol-gel coated specimen show that the oxide scale formed at 900 deg. C, in air, is adherent.

Solid oxide fuel cell (SOFC) materials

CERN Document Server

Saravanan, R

2018-01-01

Developing materials for SOFC applications is one of the key topics in energy research. The book focuses on manganite structured materials, such as doped lanthanum chromites and lanthanum manganites, which have interesting properties: thermal and chemical stability, mixed ionic and electrical conductivity, electrocatalytic activity, magnetocaloric property and colossal magnetoresistance (CMR).

Optical and Physical Investigations of Lanthanum Bismuth Borate glasses doped with Ho2O3

Science.gov (United States)

Ramesh, P.; Jagannath, G.; Eraiah, B.; Kokila, M. K.

2018-02-01

Holmium doped 10La2O3-15Bi2O3-(75-x) B2O3 (Ho3+: LBB) glasses have been prepared by melt quench technique and the impact of holmium ions concentration on optical and physical properties of present glasses have been examined. Ho3+ dependent density, molar volume, refractive index, rare earth ion concentration, polaron radius, inter ionic distance, field strength and energy band gap are calculated and tabulated. Amorphous nature of the all glasses has been confirmed by XRD patterns. The room temperature (RT) Uv-Vis absorption spectrum doped with 1 mol% of Ho2O3 exhibit eight prominent bands centred at 895, 641, 537, 486, 472, 467, 451 and 416 due to transition between ground state to various excited states. The results show that, the density is increases and molar volume of the glasses is decreases with an increase in Ho2O3 concentration and consequently generate more non-bridging oxygen (NBOs) in the glass matrix. The Urbach energy is increases with holmium concentration which exemplifies the degree of disorder present in the LBB glasses. The considerable increase in field strength observed in present glasses is attributed to occurrence of strong bridge between Ho3+ and B- ions and this strong bridge is possibly due to the displacement between Ho3+ and oxygen atoms which are generated from the conversion BO3-BO4 units.

Hydrocarbon conversion with cracking catalyst having co-combustion promoters lanthanum and iron

International Nuclear Information System (INIS)

Csicsery, S.M.

1979-01-01

A composition useful in hydrocarbon conversion processes such as catalytic cracking comprises 0.05 to 10 weight percent lanthanum associated with a refractory support. The composition may also include 0.02 to 10 weight percent iron. The refractory support is a zeolitic crystalline aluminosilicate

Adsorbtion of oxygen and cesium on lanthanum hexaboride

International Nuclear Information System (INIS)

Gorodetskij, D.A.; Tskhakaya, V.K.; Shchudlo, Yu.G.; Yarygin, V.I.; Yas'ko, A.A.

1982-01-01

Oxygen and cesium adsorption on lanthanum hexaboride was investigated. Especial attention was paid to structural investigations of the LaB 6 (100)-O system. Diffraction pictures and curves of changes in work function in the process of oxygen disorption have been obtained. At oxygen adsorption on a crystal heated up to different temperatures in the range of 900-1400 K the same diffraction pictures as at corresponding annealing temperatures observed were. It is noted that adsorption heat changes slightly in the LaB 6 -O-Cs system

High performance Ni-Sm{sub 0.15}Ce{sub 0.85}O{sub 2-{delta}} cermet anodes for intermediate temperature solid oxide fuel cells using LaGaO{sub 3} based oxide electrolytes

Energy Technology Data Exchange (ETDEWEB)

Wang, Shizhong; Takita, Yusaku [Department of Applied Chemistry, Faculty of Engineering, Oita University, Dannoharu 700, Oita 870-1192 (Japan); Ando, Masaki [Materials Production Course, Graduate School of Engineering, Oita University, Dannoharu 700, Oita 870-1192 (Japan); Ishihara, Tatsumi [Department of Applied Chemistry, Faculty of Engineering, Kyushu University, Hakozaki 6-10-1, Higashi-ku, Fukuoka 812-8581 (Japan)

2004-10-29

Effect of the composition and synthesizing approaches on the performance of Ni-15 mol% Sm{sup 3+} doped CeO{sub 2} (Sm{sub 0.15}Ce{sub 0.85}O{sub 2-{delta}}, SDC) composite anodes were studied. The results showed that the addition of SDC into Ni significantly improved the performance of Ni anode mainly by reducing the ohmic resistance of the cell and the overpotential at anode/electrolyte interface. The introduction of SDC into Ni created more active sites for H{sub 2} oxidation; however, it also increased the activation energy of the process at the same time. Therefore, the anodic overpotential of Ni-SDC composite electrode was higher than pure Ni at low reaction temperatures (873 K), while lower than that of pure Ni at 1073 K. Further experiments showed that the activities of Ni-SDC composite electrodes showed strong dependency on the synthesizing approaches. The electrodes prepared with impregnation methods exhibited a much higher activity compared with the electrodes prepared with solid-state reaction due to the reduced ohmic resistance. The low ohmic resistance of the cells using Ni-SDC anodes prepared with impregnation method is due to the improved distribution of Ni and SDC in the green powder of anode. An equal distribution of Ni and SDC is essential to minimize the reaction between Ni and strontium and magnesium doped lanthanum gallate (LSGM), and decrease the ohmic resistance.

Lanthanum carbonate versus placebo for management of hyperphosphatemia in patients undergoing peritoneal dialysis: a subgroup analysis of a phase 2 randomized controlled study of dialysis patients

Directory of Open Access Journals (Sweden)

Hutchison Alastair J

2013-02-01

Full Text Available Abstract Background This short-term study assessed the efficacy and safety of lanthanum carbonate in the treatment of hyperphosphatemia in dialysis patients; here, we report a prespecified subgroup analysis of patients undergoing peritoneal dialysis. Methods Men and women (n = 39 who had received continuous ambulatory peritoneal dialysis for chronic kidney disease for 6 months or more were enrolled in eight renal medicine departments in the United Kingdom. A 2-week washout period was followed by a 4-week dose-titration phase during which patients received lanthanum carbonate titrated up to 2250 mg/day. This was followed by a 4-week, randomized, placebo-controlled, parallel-group phase during which patients continued to receive either lanthanum carbonate at the titrated dose, or a matched dose of placebo. The main outcome measure was control of serum phosphate levels (1.3-1.8 mmol/l at the end of the parallel-group phase. Results Serum phosphate was controlled in 3/39 (8% patients at the beginning of the dose-titration phase (after washout and in 18/31 (58% patients treated with lanthanum carbonate at its end. After the parallel-group phase, 60% of lanthanum carbonate-treated patients and 10% of those receiving placebo had controlled serum phosphate. There was no difference in mean (95% confidence interval serum phosphate levels between groups at randomization: lanthanum carbonate, 1.57 (1.34-1.81 mmol/l; placebo, 1.58 (1.40-1.76 mmol/l (p = 0.96. However, a difference was seen at the end of the parallel-group phase: lanthanum carbonate, 1.56 (1.33-1.79 mmol/l; placebo, 2.25 (1.81-2.68 mmol/l (p = 0.0015. There were no clinically important changes in nutritional parameters and no serious treatment-related adverse events were recorded. Conclusions At doses up to 2250 mg/day, lanthanum carbonate is well tolerated and controls hyperphosphatemia effectively. Treatment with higher doses of lanthanum carbonate may allow patients undergoing

Microstructural characterization of composite cobaltite and lanthanum-based ceria for use as fuel cell cathodes; Caracterizacao microestrutural de compositos a base de cobaltita de lantanio e ceria para aplicacao como catodos de celulas a combustivel

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, E.R.T.; Nascimento, R.M.; Miranda, A.C. de; Lima, A.M. de, E-mail: erickssonrtr@gmail.com [Universidade Federal do Rio Grande do Norte (UFRN), RN (Brazil); Macedo, D.A. [Universidade Federal da Paraiba (UFPB), PB (brazil)

2016-07-01

Fuel cells are devices that convert chemical energy into electricity via redox reactions. In this work, the lanthanum cobaltite doped with strontium and iron (La{sub 0,6}Sr{sub 0,4}Co{sub 0,2}Fe{sub 0,8}O{sub 3} - LSCF) a traditional cathodes material of the fuel cell was mixed with an electrolyte material (composite) to the base ceria doped with gadolinia and a eutectic mixture of lithium carbonates and sodium (CGO-NLC). The powders of LSCF and CGO-NLC were obtained by the citrate method and mixed to obtain a composite cathode. Samples obtained by uniaxial pressure between 5 and 10 MPa were sintered at 1100°C and investigated by X-ray diffraction, scanning electron microscopy and micro hardness test. A symmetric cell cathode / electrolyte / cathode, obtained by co-pressing and co-sintering was investigated by electron microscopy. The results indicated that the composite is chemically stable up to the sintering temperature used. The hardness ranged between 51 and 227 HV. (author)

Electrical conductivity of cobalt doped La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}}

Energy Technology Data Exchange (ETDEWEB)

Wang, Shizhong; Wu, Lingli; Liang, Ying [Department of Chemistry, Xiamen University, Xiamen 361005, Fujian (China)

2007-03-30

La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.2}O{sub 3-{delta}} (LSGM8282), La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.15}Co{sub 0.05}O{sub 3-{delta}} (LSGMC5) and La{sub 0.8}Sr{sub 0.2}Ga{sub 0.8}Mg{sub 0.115}Co{sub 0.085}O{sub 3-{delta}} (LSGMC8.5) were prepared using a conventional solid-state reaction. Electrical conductivities and electronic conductivities of the samples were measured using four-probe impedance spectrometry, four-probe dc polarization and Hebb-Wagner polarization within the temperature range of 973-1173 K. The electrical conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high (>10{sup -5} atm) and low oxygen partial pressure regions (<10{sup -15} atm). However, the electrical conductivity in LSGM8282 had no dependency on the oxygen partial pressure. At temperatures higher than 1073 K, P{sub O{sub 2}} dependencies of the free electron conductivities in LSGM8282, LSGMC5 and LSGMC8.5 were about -1/4, and P{sub O{sub 2}} dependencies of the electron hole conductivities were about 0.25, 0.12 and 0.07, respectively. Oxygen ion conductivities in LSGMC5 and LSGMC8.5 increased with decreasing oxygen partial pressures especially in the high and low oxygen partial pressure regions, which was due to the increase in the concentration of oxygen vacancies. The change in the concentration of oxygen vacancies and the valence of cobalt with oxygen partial pressure were determined using a thermo-gravimetric technique. Both the electronic conductivity and oxygen ion conductivity in cobalt doped lanthanum gallate samples increased with increasing concentration of cobalt, suggesting that the concentration of cobalt should be optimized carefully to maintain a high electrical conductivity and close to 1 oxygen ion transference number. (author)

Electrochemical evaluation of La{sub 0.6}Sr{sub 0.4}CoO{sub 3}-La{sub 0.45}Ce{sub 0.55}O{sub 2} composite cathodes for anode-supported La{sub 0.45}Ce{sub 0.55}O{sub 2}-La{sub 0.9}Sr{sub 0.1}Ga{sub 0.8}Mg{sub 0.2}O{sub 2.85} bilayer electrolyte solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Bi, Zhonghe; Cheng, Mojie; Dong, Yonglai; Wu, Hejin; She, Yunchuan; Yi, Baolian [Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

2005-02-28

The electrochemical properties of porous composite cathodes of La{sub 0.6}Sr{sub 0.4}CoO{sub 3} (LSC) and La{sub 0.45}Ce{sub 0.55}O{sub 2} (LDC) in anode supported lanthanum-doped ceria (LDC)/lanthanum gallate (LSGM) bilayer electrolyte single cells have been investigated. The composite cathodes with different LDC and LSC contents were in contact with the LSGM layer in the single cells. Comparing with the pure LSC cathode, the interfacial resistance decreased upon the addition of LDC and the optimum content of LDC was 50 wt.%. The variation in ohmic resistance suggests that the composite cathode can suppress Co diffusion from the cathode into the LSGM electrolyte during the firing of the composite cathode onto the electrolyte. The composite cathode with 50 wt.% LDC showed an ohmic resistance near to the calculated resistance of an electrolyte film. For the pure LSC cathode, the optimum firing temperature was about 1150 {sup o}C, at which both the electrolyte resistance and interface resistance were the smallest. The cathodic interfacial resistance was effectively reduced for the composite cathodes, especially for the cathode with 50 wt.% LDC, which might be due to the suppressing of sintering and the growth of LSC particles from LDC particles during the firing onto the electrolyte. The complicated effects of the composite cathode on the interfacial resistance and ohmic resistance resulted in the best single cell performance at 650 {sup o}C with a 50 wt.% LDC composite cathode, and the best cell performance above 700 {sup o}C on the single cell with pure LSC cathode.

Effects of combined flocculant – Lanthanum modified bentonite treatment on aquatic macroinvertebrate fauna

NARCIS (Netherlands)

Waajen, G.; Pauwels, M.; Lürling, M.

2017-01-01

A low dose flocculant (FeCl3), combined with lanthanum modified bentonite (LMB) as phosphate-binding agent, has been applied for eutrophication management in Lake De Kuil (The Netherlands). After the treatment, the state of the lake shifted from hypertrophic to mesotrophic. Although

Effect of pressure on the magnetic properties of lanthanum manganite

International Nuclear Information System (INIS)

Gonchar', L. E.; Leskova, Yu. V.; Nikiforov, A. E.; Kozlenko, D. P.

2010-01-01

The crystalline structure of pure lanthanum manganite under external hydrostatic pressure has been studied. The behavior of magnetic properties and nuclear magnetic resonance (NMR) spectra under these conditions is theoretically predicted. It is shown that an increase in the Neel temperature with pressure is not only caused by the general contraction of the crystal, but is also related to certain peculiarities in the baric behavior of the orbital structure.

Uranyl(VI) and lanthanum(III) complexes with functionalized macrocyclic and macroacyclic Schiff bases

International Nuclear Information System (INIS)

Aguiari, A.; Brianese, N.; Tamburini, S.; Vigato, P.A.

1995-01-01

Acyclic Schiff bases have been prepared by [2 + 1] condensation of 2,6-diformyl-4-chlorophenol and H 2 NCH 2 [CH 2 XCH 2 ] n CH 2 NH 2 (n =3D 0 H 2 -I; X =3D NH, S, O n =3D 1 H 2 -II...H 2 -IV; X =3D 0 n =3D 2 H 2 -V; X =3D 0 n =3D 3 H 2 -VI). The related uranlyl(VI) and lanthanum (III) complexes have bee synthesized by reaction by reaction of the preformed ligands with the appropriate salt or by the template procedure, in the presence of base. No base was employed in the preparation of lanthanum (III) complexes, La(H 2 -II)(NO 3 ) 3 , La(H 2 -IV)(NO 3 ) 3 where the Schiff bases coordinate as neutral chelate ligands. These acyclic complexes have been used for further condensation, and symmetric and asymmetric cyclic complexes have been obtained by their reaction with the polyamines H 2 NCH 2 [CH 2 XCH 2 ]nCH 2 NH 2 or with 4,4'-diaminodibenzo -18-crown-6. By reaction with 4-aminobenzo-15-crown-5 or 2-amino-methyl-15-crown-5, the same acyclic complexes give rise to functionalized complexes bearing crown-ether moieties. Analogously, the acyclic ligand H 3 -IXX, prepared by condensation of 2,6 diformyl-4-chlorophenol and tris(aminoethyl)amine, forms mono and homodinuclear lanthanum (III) complexes, which may undergo further condensation when reacted with primary functionalized amines. (authors). 42 refs., 2 figs., 2 schemes, 1 tab

Near fifty percent sodium substituted lanthanum manganites—A potential magnetic refrigerant for room temperature applications

Energy Technology Data Exchange (ETDEWEB)

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 J·kg{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.

Stabilization of antioxidant gallate in layered double hydroxide by exfoliation and reassembling reaction

Science.gov (United States)

Ansy, Kanakappan Mickel; Lee, Ji-Hee; Piao, Huiyan; Choi, Goeun; Choy, Jin-Ho

2018-06-01

As for the stabilization of chemically sensitive bioactive molecule in this study, gallic acid (GA) with antioxidant property was intercalated into interlayer space of layered double hydroxide (LDH), which was realized by exfoliation and reassembling reaction. At first, the pristine nitrate-type Zn2Al-LDH in solid state was synthesized via co-precipitation followed by the hydrothermal treatment at 80 °C for 6 h, and then exfoliated in formamide to form a colloidal solution of exfoliated LDH nanosheets, and finally reassembled in the presence of GA to prepare GA intercalated LDH (GA-LDH) desired, where the pH was adjusted to 8.0 in order to deprotonate GA to form gallate anion. According to the XRD analysis, GA-LDH showed well-developed (00l) diffraction peaks with a basal spacing of 1.15 nm, which was estimated to be larger than that of the pristine LDH (0.88 nm), indicating that gallate molecules were incorporated into LDH layers with perpendicular orientation. From the FT-IR spectra it was found that gallic acid was completely deprotonated into gallate, and stabilized in between LDH lattices via electrostatic interaction. The content of GA in GA-LDH was determined to be around 23 wt% by UV-vis spectroscopic study, which was also confirmed by HPLC analysis. According to the in-vitro release of GA out of GA-LDH in PBS solution (pH 7.4) at 4 °C, GA was sustainably released from GA-LDH nanohybrid up to 86% within 72 h. The antioxidant property of GA-LDH was almost the same with that of intact GA which was examined by DPPH. The photostability of GA-LDH under UV light irradiation was immensely enhanced compared to intact GA. It is, therefore, concluded that the present GA-LDH nanohybrid can be considered as an excellent antioxidant material with high chemical- and photo-stabilities, and controlled release property.

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

International Nuclear Information System (INIS)

Michael E. McIlwain; Da Gao; Nick Thompson

2007-01-01

Considerable interest is given to the excellent scintillation properties of cerium doped lanthanum chloride (LaCl3) and lanthanum bromide (LaBr3). The scintillation efficiencies are much greater than other materials, even those containing cerium. This high efficiency is attributed to the high mobility of electrons and holes, unique placement of the cerium 5d states within the band gap, and energy of the band gap. To better understand the scintillation process and better define the nature of the Self Trapped Exciton (STE) within these unique scintillation materials, density functional theory (DFT), and Ab-initio (HF-MP2) calculations are reported. DFT calculations have yielded a qualitative description of the orbital composition and energy distribution of the band structure in the crystalline material. MP2 and single configuration interaction calculations have provided quantitative values for the band gap and provided energies for the possible range of excited states created following hole and electron creation. Based on this theoretical treatment, one possible description of the STE is the combination of Vk center (Br2-1) and LaBr+1 species that recombine to form a distorted geometry LaBr3* (triplet state). Depending on the distance between the LaBr and Br2, the STE emission band can be reproduced

Magnetic, electric and electron magnetic resonance properties of orthorhombic self-doped La1-xMnO3 single crystals

International Nuclear Information System (INIS)

Markovich, V; Fita, I; Shames, A I; Puzniak, R; Rozenberg, E; Yuzhelevski, Ya; Mogilyansky, D; Wisniewski, A; Mukovskii, Ya M; Gorodetsky, G

2003-01-01

The effect of lanthanum deficiency on structural, magnetic, transport, and electron magnetic resonance (EMR) properties has been studied in a series of La 1-x MnO 3 (x = 0.01, 0.05, 0.11, 0.13) single crystals. The x-ray diffraction study results for the crystals were found to be compatible with a single phase of orthorhombic symmetry. The magnetization curves exhibit weak ferromagnetism for all samples below 138 K. It was found that both the spontaneous magnetization and the coercive field increase linearly with x. The pressure coefficient dT N /dP decreases linearly with self-doping, from a value of 0.68 K kbar -1 for La 0.99 MnO 3 to 0.33 K kbar -1 for La 0.87 MnO 3 . The resistivity of low-doped La 0.99 MnO 3 crystal is of semiconducting character, while that of La 0.87 MnO 3 depends weakly on temperature between 180 and 210 K. It was found that the magnetic and transport properties of the self-doped compounds may be attributed to a phase separation involving an antiferromagnetic matrix and ferromagnetic clusters. The latter phases as well as their paramagnetic precursors have been directly observed by means of EMR

Influence of the sintering temperature on the structural and electronic properties of LaCrO3 doped with barium

International Nuclear Information System (INIS)

Silva, A.L.A. da; Souza, M.V.M.M.; Rocco, A.M.

2010-01-01

Ba-doped lanthanum chromites were synthesized by combustion method, utilizing urea and glycine as fuel agents. The powders were calcined (800 deg C/6 h), pelletized, sintered in various temperatures and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), density/porosity and electrical conductivity. The diffractograms of the sintered samples presented a well-defined structure, with presence of secondary phases which increase with the sintering temperature. The samples presented low densities and a high porosities (40 - 50%), which was also observed in SEM analysis. The urea-synthesized sample presented a higher conductivity (10.4 S/cm at 1000 deg C), which is related to the influence of the fuel agent in the material properties. (author)

The structure of new germanates, gallates, borates and silicates with laser, piezo, ferroelectric and ion conducting properties

International Nuclear Information System (INIS)

Belokonev, E.L.

1994-01-01

The results of structure investigation of more than 50 new crystalline germanates, gallates, borogermanates, borates, and silicates with laser, piezo, ferroelectric, and ion-conducting properties are described. The structure - properties relationship is examined. 71 refs.; 24 figs.; 10 tabs

Method of producing a solution of radioactive lanthanum-140 from radioactive barium-140 in an isotope generator and installation to carry out the method

International Nuclear Information System (INIS)

Akerman, K.; Jacobs, G.; Sauerwein, K.

1979-01-01

A method of separating radioactive lanthanum-140 from radioactive Ba-140 is proposed. The lanthanum-140 will be washed out of a sulphate precipitate and separated from Ba-140-sulphate by a granular filter mass of CaSO 4 and BaSO 4 . Details of the process are given. (UWI) [de

Dielectric properties of lanthanum gallate (LaGaO3) crystal

Science.gov (United States)

Dube, D. C.; Scheel, H. J.; Reaney, I.; Daglish, M.; Setter, N.

1994-04-01

Dielectric properties of single crystals of LaGaO3 have been measured at low frequencies as well as in the microwave region over a wide temperature range. Measurements performed on two crystal orientations, viz. (001) and (110), show dielectric anomalies at a transition near 145 °C. Dielectric anisotropy below, but not above, 145 °C confirm the previously reported orthorhombic symmetry at room temperature and rhombohedral symmetry above 145 °C. Domain wall motion which arises as a result of a phase transition has been observed around 145 °C.

High-temperature electromass transfer in the perovskite La-Sr-Ga-Fe-Mg-O ceramics

International Nuclear Information System (INIS)

Aleksandrovskij, V.V.; Kaleva, G.M.; Mosunov, A.V.; Politova, E.D.; Stefanovich, S.Yu.; Avetistov, A.K.; Venskovskij, N.U.

2001-01-01

Physicochemical mechanism of oxygen-ion transfer in perovskite-like solid solutions within La-Sr-Ga-Fe-Mg-O system was studied using kinetic dependences of oxygen deficit at variation of gas medium composition. One discusses relation between the phenomenon of mass loss, linear deformation and conducting features of a ceramic material. Oxygen-ion transfer was determined to proceed by vacancy jumping mechanism. On the basis of data on dielectric relaxation in lanthanum gallate base solid solutions one obtained new evidences of vacancy correlation under high temperature [ru

Q factor of megahertz LC circuits based on thin films of YBaCuO high-temperature superconductor

Science.gov (United States)

Masterov, D. V.; Pavlov, S. A.; Parafin, A. E.

2008-05-01

High-frequency properties of resonant structures based on thin films of YBa2Cu3O7 δ high-temperature superconductor are studied experimentally in the frequency range 30 100 MHz. The structures planar induction coils with a self-capacitance fabricated on neodymium gallate and lanthanum aluminate substrates. The unloaded Q factor of the circuits exceeds 2 × 105 at 77 K and 40 MHz. Possible loss mechanisms that determine the Q factor of the superconducting resonant structures in the megahertz range are considered.

Effect of thickness on microwave absorptive behavior of La-Na doped Co-Zr barium hexaferrites in 18.0–26.5 GHz band

Energy Technology Data Exchange (ETDEWEB)

Arora, Amit [D.A.V. Institute of Engineering and Technology, Jalandhar (India); Narang, Sukhleen Bindra, E-mail: sukhleen2@yahoo.com [Department of Electronics Technology, Guru Nanak Dev University, Amritsar (India); Pubby, Kunal [Department of Electronics Technology, Guru Nanak Dev University, Amritsar (India)

2017-02-01

In this research, the microwave properties of Lanthanum-Sodium doped Cobalt-Zirconium barium hexaferrites, intended as microwave absorbers, are analyzed on Vector Network Analyzer in K-band. The results indicate that the doping has resulted in lowering of real permittivity and enhancement of dielectric losses. Real permeability has shown increase while magnetic losses have shown decrease in value with doping. All these four properties have shown very small variation with frequency in the scanned frequency range which indicates the relaxation type of behavior. Microwave absorption characteristics of these compositions are analyzed with change in sample thickness. The results demonstrate that the matching frequency of the microwave absorber shifts towards lower side of frequency band with increase in thickness. The complete analysis of the prepared microwave absorbers shows a striking achievement with very low reflection loss and wide absorption bandwidth for all the six compositions in 18–26.5 GHz frequency band. - Highlights: • Electromagnetic Characterization of M-hexaferrites in K-band (18–26.5 GHz) • Variation of absorption properties with thickness of sample. • Satisfaction of quarter-wavelength condition for absorption properties • Results of double-layer absorbers (not reports till day by anyone).

Investigation of lanthanum- and neodymium ion interaction with potassium polyphosphate in aqueous solution

International Nuclear Information System (INIS)

Ezhova, Zh.A.; Tananaev, I.V.; Koval', E.M.

1983-01-01

A study was made on the interaction in the LaCl 3 -KPO 3 -H 2 O and NdCl 3 -KPO 3 -H 2 O systems at 0 deg C by methods of solubility of residual concentrations and measurement of the pH value. The formation of binary KLa 2 (PO 3 ) 7 x10H 2 O and KLa(PO 3 ) 4 X5H 2 O lanthanum- and potassium polyphosphates, as well as KNd 2 (PO 3 ) 7 X10H 2 O and KNd(PO 3 ) 4 X5H 2 O neodymium- apd potassiUm polyphasphates was established. Chemical, paper-chromatographic, infrared spectroscopic, X-ray diffraction and differential thermal analyses of the prepared compoUnds were conducted. Anhydrous binary lanthanum- and neodymium polyphosphates with potassium-=Kla(PO 3 ) 4 , KNd(PO 3 ) 4 , KLa 2 (PO 3 ) 7 and KNd 2 x(PO 3 ) 7 - eere prepared

Lanthanum-modified bentonite: potential for efficient removal of phosphates from fishpond effluents.

Science.gov (United States)

Kurzbaum, Eyal; Raizner, Yasmin; Cohen, Oded; Rubinstein, Guy; Bar Shalom, Oded

2017-06-01

Adsorption has been suggested as an effective method for removing phosphates from agricultural wastewater effluents that contain relatively high phosphate concentrations. The present study focused on the use of a bentonite-lanthanum clay (Phoslock ® ) for reducing the dissolved phosphate concentration in fishpond effluents. Batch experiments with synthetic phosphate-spiked solutions and with fishpond effluents were performed in order to determine adsorption equilibrium isotherms and kinetics as well as to determine the efficiency of Phoslock ® in removing phosphate from these solutions. In the synthetic phosphate-spiked solution, the mean maximum phosphate adsorption capacity was 92 mg Phoslock ® /mg phosphate removal. A ratio of 50, 100, and 200 mg Phoslock ® /mg phosphate removal was found for complete phosphate removal from the fishpond effluents, where higher doses of Phoslock ® led to a faster removal rate (94% removal within the first 150 min). These results show that bentonite-lanthanum clay can be employed for designing a treatment process for efficient phosphate removal from fishpond effluents.

Chemically produced nanostructured ODS-lanthanum oxide-tungsten composites sintered by spark plasma

International Nuclear Information System (INIS)

Yar, Mazher Ahmed; Wahlberg, Sverker; Bergqvist, Hans; Salem, Hanadi G.; Johnsson, Mats; Muhammed, Mamoun

2011-01-01

High purity W and W-0.9La 2 O 3 (wt.%) nanopowders were produced by a wet chemical route. The precursor was prepared by the reaction of ammonium paratungstate (APT) with lanthanum salt in aqueous solutions. High resolution electron microscopy investigations revealed that the tungstate particles were coated with oxide precipitates. The precursor powder was reduced to tungsten metal with dispersed lanthanum oxide. Powders were consolidated by spark plasma sintering (SPS) at 1300 and 1400 o C to suppress grain growth during sintering. The final grain size relates to the SPS conditions, i.e. temperature and heating rate, regardless of the starting powder particle size. Scanning electron microscopy revealed that oxide phases were mainly accumulated at grain boundaries while the tungsten matrix constituted of nanosized sub-grains. The transmission electron microscopy revealed that the tungsten grains consist of micron-scale grains and finer sub-grains. EDX analysis confirmed the presence of W in dispersed oxide phases with varying chemical composition, which evidenced the presence of complex oxide phases (W-O-La) in the sintered metals.

Simultaneous determination of dopamine, uric acid and nitrite using carboxylated graphene oxide/lanthanum modified electrode

International Nuclear Information System (INIS)

Ye, Fengying; Feng, Chenqi; Jiang, Jibo; Han, Sheng

2015-01-01

Highlights: • The carboxylated graphene oxide/lanthanum-modified glassy carbon electrode (GO-COOLa/GCE) was successfully utilized for the simultaneous detection and quantification of DA, UA and NO 2 − . • Combining the benefits of carboxylated graphene oxide and lanthanum, the modified sensor displayed large peak separations, long linear ranges and low detection limits for simultaneously detecting DA, UA and NO 2 − . • The GO-COOLa/GCE electrode showed well stability, good repeatability, rapid response, and high catalytic performance toward the oxidations of DA, UA and NO 2 − . - Abstract: A bare glassy carbon electrode (GCE) was reformed by carboxylated graphene oxide/lanthanum, and the modified electrode, called GO-COOLa/GCE, was fabricated for simultaneously detecting dopamine (DA), uric acid (UA) and nitrite (NO 2 − ) by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and amperometry. Several factors which affected the electrocatalytic activity of the GO-COOLa/GCE electrode, such as the effect of pH, scan rate and concentration were studied. Due to the combination of carboxylated graphene oxide and lanthanum ions, the GO-COOLa/GCE sensor showed rapid response, excellent selectivity and high catalytic performance toward the electrooxidation of DA, UA and NO 2 − . In optimized conditions, two linear response ranges for determining DA were obtained over ranges of 0.01-1.96×10 2 μM and 1.96×10 2 -1.23×10 3 μM with detection limit of 0.018 μM (S/N = 3). And the responses of the GO-COOLa/GCE electrode for UA and NO 2 − were linear in the region of 1-1.53×10 3 μM and 1-2.75×10 3 μM with detection limits of 0.058 μM and 0.070 μM, respectively. Furthermore, this reformed electrode was successfully used to the detection of DA, UA and NO 2 − in real urine and serum samples, showing its promising application in the electroanalysis of real samples.

Antiapoptotic Actions of Methyl Gallate on Neonatal Rat Cardiac Myocytes Exposed to H2O2

Directory of Open Access Journals (Sweden)

Sandhya Khurana

2014-01-01

Full Text Available Reactive oxygen species trigger cardiomyocyte cell death via increased oxidative stress and have been implicated in the pathogenesis of cardiovascular diseases. The prevention of cardiomyocyte apoptosis is a putative therapeutic target in cardioprotection. Polyphenol intake has been associated with reduced incidences of cardiovascular disease and better overall health. Polyphenols like epigallocatechin gallate (EGCG can reduce apoptosis of cardiomyocytes, resulting in better health outcomes in animal models of cardiac disorders. Here, we analyzed whether the antioxidant N-acetyl cysteine (NAC or polyphenols EGCG, gallic acid (GA or methyl gallate (MG can protect cardiomyocytes from cobalt or H2O2-induced stress. We demonstrate that MG can uphold viability of neonatal rat cardiomyocytes exposed to H2O2 by diminishing intracellular ROS, maintaining mitochondrial membrane potential, augmenting endogenous glutathione, and reducing apoptosis as evidenced by impaired Annexin V/PI staining, prevention of DNA fragmentation, and cleaved caspase-9 accumulation. These findings suggest a therapeutic value for MG in cardioprotection.

Determination of Aluminum in Dialysis Concentrates by Atomic Absorption Spectrometry after Coprecipitation with Lanthanum Phosphate.

Science.gov (United States)

Selvi, Emine Kılıçkaya; Şahin, Uğur; Şahan, Serkan

2017-01-01

This method was developed for the determination of trace amounts of aluminum(III) in dialysis concentrates using atomic absorption spectrometry after coprecipitation with lanthanum phosphate. The analytical parameters that influenced the quantitative coprecipitation of analyte including amount of lanthanum, amount of phosfate, pH and duration time were optimized. The % recoveries of the analyte ion were in the range of 95-105 % with limit of detection (3s) of 0.5 µg l -1 . Preconcentration factor was found as 1000 and Relative Standard Deviation (RSD) % value obtained from model solutions was 2.5% for 0.02 mg L -1 . The accuracy of the method was evaluated with standard reference material (CWW-TMD Waste Water). The method was also applied to most concentrated acidic and basic dialysis concentrates with satisfactory results.

Antifungal Activity of Decyl Gallate against Several Species of Pathogenic Fungi

Directory of Open Access Journals (Sweden)

Ana Carolina Alves de Paula e Silva

2014-01-01

Full Text Available This work aims to demonstrate that the gallic acid structure modification to the decyl gallate (G14 compound contributed to increase the antifungal activity against several species of pathogenic fungi, mainly, Candida spp., Cryptococcus spp., Paracoccidioides spp., and Histoplasma capsulatum, according to standardized microdilution method described by Clinical Laboratory Standard Institute (CLSI documents. Moreover this compound has a particularly good selectivity index value, which makes it an excellent candidate for broad-spectrum antifungal prototype and encourages the continuation of subsequent studies for the discovery of its mechanism of action.

Radical chemistry of epigallocatechin gallate and its relevance to protein damage

DEFF Research Database (Denmark)

Hagerman, Ann E; Dean, Roger T; Davies, Michael Jonathan

2003-01-01

The radical chemistry of the plant polyphenolics epigallocatechin gallate (EGCG) and epigallocatechin (EGC) were investigated using electron paramagnetic resonance spectroscopy. Radical species formed spontaneously in aqueous solutions at low pH without external oxidant and were spin stabilized...... redox potentials of EGCG and EGC varied from 1000 mV at pH 3 to 400 mV at pH 8. The polyphenolics did not produce hydroxyl radicals unless reduced metal ions such as iron(II) were added to the system. Zinc(II)-stabilized EGCG radicals were more effective protein-precipitating agents than unoxidized EGCG...

In situ synthesis and characterization of fine-patterned La and Mn co-doped BiFeO{sub 3} film

Energy Technology Data Exchange (ETDEWEB)

Yan, Fuxue, E-mail: yanfuxue@126.com; Zhao, Gaoyang, E-mail: zhaogy@xaut.edu.cn; Song, Na; Zhao, Nana; Chen, Yuanqing

2013-09-05

Highlights: •La and Mn co-doped BiFeO{sub 3} film was prepared by a photosensitive sol–gel method. •XRD and Raman spectra confirmed single-phase rhombohedral structure with space group R3c. •Fine-patterned BLFMO film was obtained by a direct-patterning technique. •The saturation magnetization and Pr were enhanced in the fine-patterned BLFMO film. -- Abstract: La and Mn co-doped BiFeO{sub 3} (BLFMO) film was prepared by a photosensitive sol–gel method utilizing bismuth nitrate, lanthanum nitrate, manganese nitrate and ferric nitrate as starting materials. After a chelating reaction between benzoylacetone (BzAcH) and metallic ions, the precursor solution presented photosensitivity. Through a direct patterning process, a fine-patterned BLFMO film was obtained. The phase constituents, morphology, electric and magnetic properties of the as-prepared BLFMO film were characterized by X-ray diffractometer (XRD), Raman spectroscopy, scanning electron microscopy (SEM), ferroelectric testing unit, LCR Meter and vibrating sample magnetometer (VSM). The Mn dopant enhanced the saturation magnetization and remnant polarization of the BLFMO film.

PROCESS USING POTASSIUM LANTHANUM SULFATE FOR FORMING A CARRIER PRECIPITATE FOR PLUTONIUM VALUES

Science.gov (United States)

Angerman, A.A.

1958-10-21

A process is presented for recovering plutonium values in an oxidation state not greater than +4 from fluoride-soluble fission products. The process consists of adding to an aqueous acidic solution of such plutonium values a crystalline potassium lanthanum sulfate precipitate which carries the plutonium values from the solution.

Studies on the Food Additive Propyl Gallate: Synthesis, Structural Characterization, and Evaluation of the Antioxidant Activity

Science.gov (United States)

Garrido, Jorge; Garrido, E. Manuela; Borges, Fernanda

2012-01-01

Antioxidants are additives largely used in industry for delaying, retarding, or preventing the development of oxidative deterioration. Propyl gallate (E310) is a phenolic antioxidant extensively used in the food, cosmetics, and pharmaceutical industries. A series of lab experiments have been developed to teach students about the importance and…

海藻酸镧颗粒除氟研究：吸附剂物性和吸附机理%Fluoride Removal by Lanthanum Alginate Bead:Adsorbent Characterization and Adsorption Mechanism

Institute of Scientific and Technical Information of China (English)

霍亚坤; 丁文明; 黄霞; 徐静年; 赵梦华

2011-01-01

Lanthanum alginate bead is a new, highly active adsorbent. In the present study, we investigated its adsorption performance and its adsorption mechanism. The adsorption isotherm for fluoride onto lanthanum alginate bead fits the Langmuir model well, and the maximum adsorption capacity is 197.2 mg·g-1. X-ray diffraction shows the amorphous nature of lanthanum alginate bead, which allows for better accessibility to fluoride and thus better activity. Infrared spectra of lanthanum alginate bead before and after adsorption confirm its stable skeletal structure.Scanning electron microscopy shows that the dense surface structure of the adsorbent appear cracks after adsorption.The adsorption mechanism of lanthanum alginate bead is considered as an ion exchange between F- and Cl- or OH-,as verified from the adsorbent and the solution by pH effect, energy dispersive X-ray, and ion chromatography.

Inductively coupled plasma optical emission spectrometry analysis of lanthanum, samarium and gadolinium oxides for rare earths impurities

International Nuclear Information System (INIS)

Reino, L.C.P.; Lordello, A.R.

1990-09-01

An inductively coupled plasma optical emission spectrometry method is described for the determination of Sm, Eu, La, Gd, Dy, Pr, Ho, Nd, Tb and Y in purified oxides of lanthanum, samarium and gadolinium. The method enables a simple, precise and readily available determination. Dissolution of the samples is achieved with diluted hydrochloric acid (1:1). The solutions are diluted to volume for a concentration of 1mg/ml. The lowest determination limit is 0,01% for most elements and 0,05 or 0,1% for a few rare earths in samarium and gadolinium matrices. Lanthanum, Samarium and Gadolinium concentrates with purity grade of 99,9%, 99,6% and 99,8%, respectively, can be analysed by this procedure. (author)

Metabolic interactions between cysteamine and epigallocatechin gallate.

Science.gov (United States)

Izzo, Valentina; Pietrocola, Federico; Sica, Valentina; Durand, Sylvère; Lachkar, Sylvie; Enot, David; Bravo-San Pedro, José Manuel; Chery, Alexis; Esposito, Speranza; Raia, Valeria; Maiuri, Luigi; Maiuri, Maria Chiara; Kroemer, Guido

2017-02-01

Phase II clinical trials indicate that the combination of cysteamine plus epigallocatechin gallate (EGCG) is effective against cystic fibrosis in patients bearing the most frequent etiological mutation (CFTRΔF508). Here, we investigated the interaction between both agents on cultured respiratory epithelia cells from normal and CFTRΔF508-mutated donors. We observed that the combination of both agents affected metabolic circuits (and in particular the tricarboxylic acid cycle) in a unique way and that cysteamine plus EGCG reduced cytoplasmic protein acetylation more than each of the 2 components alone. In a cell-free system, protein cross-linking activity of EGCG was suppressed by cysteamine. Finally, EGCG was able to enhance the conversion of cysteamine into taurine in metabolic flux experiments. Altogether, these results indicate that multiple pharmacological interactions occur between cysteamine and EGCG, suggesting that they contribute to the unique synergy of both agents in restoring the function of mutated CFTRΔF508.

High Q-factor tunable superconducting HF circuit

CERN Document Server

Vopilkin, E A; Pavlov, S A; Ponomarev, L I; Ganitsev, A Y; Zhukov, A S; Vladimirov, V V; Letyago, A G; Parshikov, V V

2001-01-01

Feasibility of constructing a high Q-factor (Q approx 10 sup 5) mechanically tunable in a wide range of frequencies (12-63 MHz) vibration circuit of HF range was considered. The tunable circuit integrates two single circuits made using YBaCuO films. The circuit frequency is tuned by changing distance X (capacity) between substrates. Potentiality of using substrates of lanthanum aluminate, neodymium gallate and strontium titanate for manufacture of single circuits was considered. Q-factor of the circuit amounted to 68000 at resonance frequency of 6.88 MHz

High Q-factor tunable superconducting HF circuit

International Nuclear Information System (INIS)

Vopilkin, E.A.; Parafin, A.E.; Pavlov, S.A.; Ponomarev, L.I.; Ganitsev, A.Yu.; Zhukov, A.S.; Vladimirov, V.V.; Letyago, A.G.; Parshikov, V.V.

2001-01-01

Feasibility of constructing a high Q-factor (Q ∼ 10 5 ) mechanically tunable in a wide range of frequencies (12-63 MHz) vibration circuit of HF range was considered. The tunable circuit integrates two single circuits made using YBaCuO films. The circuit frequency is tuned by changing distance X (capacity) between substrates. Potentiality of using substrates of lanthanum aluminate, neodymium gallate and strontium titanate for manufacture of single circuits was considered. Q-factor of the circuit amounted to 68000 at resonance frequency of 6.88 MHz [ru

Electronic and atomic structure at metal-oxide heterointerfaces

International Nuclear Information System (INIS)

Schlueter, Christoph Friedrich

2013-01-01

The results of a series of investigations on modern oxide materials using hard X-ray photoelectron spectroscopy (HAXPES) combined with the X-ray standing wave (XSW) method are described in this thesis. The combination of hard X-ray photoelectron spectroscopy and X-ray standing waves enables the electronic structure to be measured with a spatial resolution in the picometer range. Under suitable preparation conditions, a quasi two-dimensional electron gas (2DEG) is formed at the heterointerfaces of strontium titanate (SrTiO 3 ) with polar oxides, such as lanthanum aluminate (LaAlO 3 ) or lanthanum gallate (LaGaO 3 ). Samples were grown at the ESRF and in Naples and surface X-ray diffraction confirmed the excellent epitaxial quality of the films. The XSW-method was used to reconstruct images of the structure of LaAlO 3 layers in real space. These images give evidence of distortions in the LaAlO 3 structure which facilitate the compensation of the potential differences. Furthermore, XSW/HAXPES measurements permit the Ti and Sr,O contributions to the 2DEG close to the Fermi level to be identified unambiguously. The analysis shows that the 3d band crosses the Fermi level and that some density of states is associated with oxygen vacancies. Superlattices of SrTiO 3 with polar calcium cuprate (CaCuO 2 ) were investigated by HAXPES. Similar to the case of SrTiO 3 /LaAlO 3 , the polarity of CaCuO 2 should lead to a diverging surface potential. The core level spectra from Ca, Sr, and Ti show that there is a redistribution mechanism for oxygen which compensates the potential differences. When the oxygen concentration is enhanced these superstructures become superconducting (T C = 40 K). The increased oxidation of the superconducting material is revealed by the additional components in the core level spectra of the metal atoms and in the appearance of a new screening channel in Cu 2p core level spectra, which signals the hole doping of the CaCuO 2 blocks. Magnetoresistive

Thermal stability and microstructure of catalytic alumina composite support with lanthanum species

Science.gov (United States)

Ozawa, Masakuni; Nishio, Yoshitoyo

2016-09-01

Lanthanum (La) modified γ-alumina composite was examined for application toward thermostable catalytic support at elevated temperature. La added alumina was prepared through an aqueous process using lanthanum (III) nitrate and then characterized by surface area measurement, X-ray powder diffraction (XRD), differential thermal analysis (DTA), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoemission spectroscopy (XPS) and surface desorption of CO2. It was found that the properties depended on the La content and heat treatment temperatures. The characterization of the surface, structural and chemical properties of La-Al2O3 showed the existence of a strong interaction between the La species and alumina via formation of new phase and modified surface in Al2O3 samples. LaAlO3 nanoparticle formed among alumina particles by the solid phase reaction of Al2O3 and La2O3. The increase of the surface basicity of La modified alumina was demonstrated using CO2 temperature programmed desorption experiments. The controlled surface interaction between La oxide and alumina provide the unique surface and structural properties of the resulting mixed oxides as catalysts and catalytic supports.

Modeling and experimental performance of an intermediate temperature reversible solid oxide cell for high-efficiency, distributed-scale electrical energy storage

Science.gov (United States)

Wendel, Christopher H.; Gao, Zhan; Barnett, Scott A.; Braun, Robert J.

2015-06-01

Electrical energy storage is expected to be a critical component of the future world energy system, performing load-leveling operations to enable increased penetration of renewable and distributed generation. Reversible solid oxide cells, operating sequentially between power-producing fuel cell mode and fuel-producing electrolysis mode, have the capability to provide highly efficient, scalable electricity storage. However, challenges ranging from cell performance and durability to system integration must be addressed before widespread adoption. One central challenge of the system design is establishing effective thermal management in the two distinct operating modes. This work leverages an operating strategy to use carbonaceous reactant species and operate at intermediate stack temperature (650 °C) to promote exothermic fuel-synthesis reactions that thermally self-sustain the electrolysis process. We present performance of a doped lanthanum-gallate (LSGM) electrolyte solid oxide cell that shows high efficiency in both operating modes at 650 °C. A physically based electrochemical model is calibrated to represent the cell performance and used to simulate roundtrip operation for conditions unique to these reversible systems. Design decisions related to system operation are evaluated using the cell model including current density, fuel and oxidant reactant compositions, and flow configuration. The analysis reveals tradeoffs between electrical efficiency, thermal management, energy density, and durability.

Defect formation in LaGa(Mg,Ni)O3-δ : A statistical thermodynamic analysis validated by mixed conductivity and magnetic susceptibility measurements

Science.gov (United States)

Naumovich, E. N.; Kharton, V. V.; Yaremchenko, A. A.; Patrakeev, M. V.; Kellerman, D. G.; Logvinovich, D. I.; Kozhevnikov, V. L.

2006-08-01

A statistical thermodynamic approach to analyze defect thermodynamics in strongly nonideal solid solutions was proposed and validated by a case study focused on the oxygen intercalation processes in mixed-conducting LaGa0.65Mg0.15Ni0.20O3-δ perovskite. The oxygen nonstoichiometry of Ni-doped lanthanum gallate, measured by coulometric titration and thermogravimetric analysis at 923-1223K in the oxygen partial pressure range 5×10-5to0.9atm , indicates the coexistence of Ni2+ , Ni3+ , and Ni4+ oxidation states. The formation of tetravalent nickel was also confirmed by the magnetic susceptibility data at 77-600K , and by the analysis of p -type electronic conductivity and Seebeck coefficient as function of the oxygen pressure at 1023-1223K . The oxygen thermodynamics and the partial ionic and hole conductivities are strongly affected by the point-defect interactions, primarily the Coulombic repulsion between oxygen vacancies and/or electron holes and the vacancy association with Mg2+ cations. These factors can be analyzed by introducing the defect interaction energy in the concentration-dependent part of defect chemical potentials expressed by the discrete Fermi-Dirac distribution, and taking into account the probabilities of local configurations calculated via binomial distributions.

Surface damages of polycrystalline W and La2O3-doped W induced by high-flux He plasma irradiation

Science.gov (United States)

Liu, Lu; Li, Shouzhe; Liu, Dongping; Benstetter, Günther; Zhang, Yang; Hong, Yi; Fan, Hongyu; Ni, Weiyuan; Yang, Qi; Wu, Yunfeng; Bi, Zhenhua

2018-04-01

In this study, polycrystalline tungsten (W) and three oxide dispersed strengthened W with 0.1 vol %, 1.0 vol % and 5.0 vol % lanthanum trioxide (La2O3) were irradiated with low-energy (200 eV) and high-flux (5.8 × 1021 or 1.4 × 1022 ions/m2ṡs) He+ ions at elevated temperature. After He+ irradiation at a fluence of 3.0 × 1025/m2, their surface damages were observed by scanning electron microscopy, energy dispersive spectroscopy, scanning electron microscopy-electron backscatter diffraction, and conductive atomic force microscopy. Micron-sized holes were formed on the surface of W alloys after He+ irradiation at 1100 K. Analysis shows that the La2O3 grains doped in W were sputtered preferentially by the high-flux He+ ions when compared with the W grains. For irradiation at 1550 K, W nano-fuzz was formed at the surfaces of both polycrystalline W and La2O3-doped W. The thickness of the fuzz layers formed at the surface of La2O3-doped W is 40% lower than the one of polycrystalline W. The presence of La2O3 could suppress the diffusion and coalescence of He atoms inside W, which plays an important role in the growth of nanostructures fuzz.

Cationic surfactant assisted ultrasound synthesis of Dy3+ doped CdSiO3 nanostructures for white LED application

Science.gov (United States)

Basavaraj, R. B.; Nagabhushana, H.; Lingaraju, K.; Prasad, B. Daruka

2017-05-01

In this paper we report for the first time Dy3+ (1-7 mol %) doped CdSiO3 nanophosphors prepared via facile ultrasound supported sonochemical route using EGCG (epigallocatechin gallate). The final product was well characterized by PXRD, FTIR, SEM, TEM and PL. The powder X-ray diffraction (PXRD) profiles showed monoclinic phase with highly crystalline nature. The sonication time, concentration of the surfactant play vital role in tuning the morphology. The crystallite size was calculated from PXRD patterns as well as by TEM image and it was found to 20-30 nm. The Fourier transform infrared spectroscopy (FTIR) results confirmed the presence of Si-O-Si and Si-O stretching vibrations in CdSiO3. Photoluminescence properties of Dy3+ (1-7 mol %) doped CdSiO3 excited under near ultra violet wavelength (350 nm) was studied in order to investigate the possibility of its use in white light emitting diode applications. The emission spectra consists of intra 4f transitions of Dy3+, namely 4F9/2 → 6H15/2 (480 nm), and 4F9/2 → 6H13/2 (574 nm) respectively. The 3 mol% Dy3+ doped phosphor showed maximum intensity. The Commission Internationale de I'Eclairage (CIE) and correlated color temperature (CCT) was evaluated. Further, the quantum efficiency and color purity results of the product showed high efficiency and it was highly useful in white light emitting diodes (wLEDs) applications.

Lanthanum lead boro-tellurite glasses doped with samarium trioxide for luminescent devices application

Science.gov (United States)

Madhu, A.; Eraiah, B.

2018-04-01

Boro-tellurite based glasses (10La2O3-(20-x) TeO2-30PbO-40B2O3-xSm2O3) (x = 0, 0.5, 1.0 and 2.0 mol %) doped with different concentrations of Sm3+ ions has been investigated. The optical properties have been studied through spectroscopic measurements such as absorption and luminescence. Absorption spectra reveals nine peaks due to 6H5/2→6P3/2, 4I3/2+4F5/2+4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, and 6H13/2 transitions. Luminescence spectra under the excitation of 403 nm display four emission bands due to 4G5/2→6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions of Sm3+ ions. Among them 6H7/2 bright orange -red is more intense which proves that the present glasses are potential candidates for luminescent device applications in visible range as well as optical fibre communication since its refractive index is 1.65 high compared to other glasses.

Cost-Effectiveness of First-Line Sevelamer and Lanthanum versus Calcium-Based Binders for Hyperphosphatemia of Chronic Kidney Disease.

Science.gov (United States)

Habbous, Steven; Przech, Sebastian; Martin, Janet; Garg, Amit X; Sarma, Sisira

2018-03-01

Phosphate binders are used to treat hyperphosphatemia among patients with chronic kidney disease (CKD). To conduct an economic evaluation comparing calcium-free binders sevelamer and lanthanum with calcium-based binders for patients with CKD. Effectiveness data were obtained from a recent meta-analysis of randomized trials. Effectiveness was measured as life-years gained and translated to quality-adjusted life-years (QALYs) using utility weights from the literature. A Markov model consisting of non-dialysis-dependent (NDD)-CKD, dialysis-dependent (DD)-CKD, and death was developed to estimate the incremental costs and effects of sevelamer and lanthanum versus those of calcium-based binders. A lifetime horizon was used and both costs and effects were discounted at 1.5%. All costs are presented in 2015 Canadian dollars from the Canadian public payer perspective. Results of probabilistic sensitivity analysis were presented using cost-effectiveness acceptability curves. Sensitivity analyses were conducted for risk pooling methods, omission of dialysis costs, and persistence of drug effects on mortality. Sevelamer resulted in an incremental cost-effectiveness ratio of $106,522/QALY for NDD-CKD and $133,847/QALY for DD-CKD cohorts. Excluding dialysis costs, sevelamer was cost-effective in the NDD-CKD cohort ($5,847/QALY) and the DD-CKD cohort ($11,178/QALY). Lanthanum was dominated regardless of whether dialysis costs were included. Existing evidence does not clearly support the cost-effectiveness of non-calcium-containing phosphate binders (sevelamer and lanthanum) relative to calcium-containing phosphate binders in DD-CKD patients. Our study suggests that sevelamer may be cost-effective before dialysis onset. Because of the remaining uncertainty in several clinically relevant outcomes over time in DD-CKD and NDD-CKD patients, further research is encouraged. Copyright © 2018 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier

Synthesis and Stability of Lanthanum Superhydrides

Energy Technology Data Exchange (ETDEWEB)

Geballe, Zachary M. [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Liu, Hanyu [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Mishra, Ajay K. [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Permanent address: HP& SRPD, Bhabha Atomic Research Center, Mumbai-85 India; Ahart, Muhtar [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Somayazulu, Maddury [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Meng, Yue [HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne IL 60439 USA; Baldini, Maria [Geophysical Laboratory, Carnegie Institution of Washington, Washington DC 20015 USA; Hemley, Russell J. [Institute of Materials Science and Department of Civil and Environmental Engineering, The George Washington University, Washington DC 20052 USA

2017-12-15

Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH10 having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1 Å, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized.

Cerium-activated lanthanum beryllate as a gamma detector material

International Nuclear Information System (INIS)

Czirr, J.B.; Berrondo, M.

1994-01-01

The authors have tested a single crystal of Ce-activated lanthanum beryllate BEL(Ce) as a potential gamma detector material. The density (6.1 g.cm -3 ) and decay time (50 ns) are competitive with other recently developed materials. The scintillation efficiency is 57 to 95% that of BGO. For an excitation wavelength of 340 nm, the emission spectra is a broad peak centered at 450 mn. The H 2 annealed sample is transparent for wavelengths greater than 400 mn. They are continuing a program to improve the scintillation efficiency by varying the crystal growth conditions

Solid state interaction studies on binary nitrate mixtures of uranyl nitrate hexahydrate and lanthanum nitrate hexahydrate at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Kalekar, Bhupesh; Raje, Naina, E-mail: nraje@barc.gov.in; Reddy, A.V.R.

2017-02-15

Interaction behavior of uranyl nitrate hexahydrate (UNH) and lanthanum nitrate hexahydrate (LaNH) have been investigated on the mixtures in different molar ratios of the two precursors and monitoring the reactions at elevated temperatures with thermoanalytical and X-ray diffraction measurement techniques. During the decomposition of equimolar mixture of LaNH and UNH, formation of lanthanum uranate (U{sub 0.5}La{sub 0.5})O{sub 2}, was seen by the temperature of 500 °C along with lanthanum oxide (La{sub 2}O{sub 3}) and uranium trioxide (UO{sub 3}). By the temperature of 700 °C, the formation of uranium sesquioxide (U{sub 3}O{sub 8}) was observed along with (U{sub 0.5}La{sub 0.5})O{sub 2} as end products in uranium rich mixtures. Lanthanum rich compositions decomposed by the temperature of 700 °C to give (U{sub 0.5}La{sub 0.5})O{sub 2} and La{sub 2}O{sub 3} as end products. - Highlights: • UO{sub 2}(NO{sub 3}){sub 2}.6H{sub 2}O and La(NO{sub 3}){sub 3}.6H{sub 2}O interact through their intermediates. • Formation of (U{sub 0.5}La{sub 0.5})O{sub 2} by 500 °C. • La deficient mixtures decompose to give U{sub 3}O{sub 8} and (U{sub 0.5}La{sub 0.5})O{sub 2} as end products. • La rich mixtures decompose to give La{sub 2}O{sub 3} and (U{sub 0.5}La{sub 0.5})O{sub 2} as end product.

Epigallocatechin-3-gallate increases intracellular [Ca2+] in U87 cells mainly by influx of extracellular Ca2+ and partly by release of intracellular stores.

Science.gov (United States)

Kim, Hee Jung; Yum, Keun Sang; Sung, Jong-Ho; Rhie, Duck-Joo; Kim, Myung-Jun; Min, Do Sik; Hahn, Sang June; Kim, Myung-Suk; Jo, Yang-Hyeok; Yoon, Shin Hee

2004-02-01

Green tea has been receiving considerable attention as a possible preventive agent against cancer and cardiovascular disease. Epigallocatechin-3-gallate (EGCG) is a major polyphenol component of green tea. Using digital calcium imaging and an assay for [3H]-inositol phosphates, we determined whether EGCG increases intracellular [Ca2+] ([Ca2+]i) in non-excitable human astrocytoma U87 cells. EGCG induced concentration-dependent increases in [Ca2+]i. The EGCG-induced [Ca2+]i increases were reduced to 20.9% of control by removal of extracellular Ca2+. The increases were also inhibited markedly by treatment with the non-specific Ca2+ channel inhibitors cobalt (3 mM) for 3 min and lanthanum (1 mM) for 5 min. The increases were not significantly inhibited by treatment for 10 min with the L-type Ca2+ channel blocker nifedipine (100 nM). Treatment with the inhibitor of endoplasmic reticulum Ca2+-ATPase thapsigargin (1 micro M) also significantly inhibited the EGCG-induced [Ca2+]i increases. Treatment for 15 min with the phospholipase C (PLC) inhibitor neomycin (300 micro M) attenuated the increases significantly, while the tyrosine kinase inhibitor genistein (30 micro M) had no effect. EGCG increased [3H]-inositol phosphates formation via PLC activation. Treatment for 10 min with mefenamic acid (100 micro M) and flufenamic acid (100 micro M), derivatives of diphenylamine-2-carboxylate, blocked the EGCG-induced [Ca2+]i increase in non-treated and thapsigargin-treated cells but indomethacin (100 micro M) did not affect the increases. Collectively, these data suggest that EGCG increases [Ca2+]i in non-excitable U87 cells mainly by eliciting influx of extracellular Ca2+ and partly by mobilizing intracellular Ca2+ stores by PLC activation. The EGCG-induced [Ca2+]i influx is mediated mainly through channels sensitive to diphenylamine-2-carboxylate derivatives.

Performance of intermediate temperature (600-800 °C) solid oxide fuel cell based on Sr and Mg doped lanthanum-gallate electrolyte

Science.gov (United States)

Gong, Wenquan; Gopalan, Srikanth; Pal, Uday B.

The solid electrolyte chosen for this investigation was La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 (LSGM). To select appropriate electrode materials from a group of possible candidate materials, AC complex impedance spectroscopy studies were conducted between 600 and 800 °C on symmetrical cells that employed the LSGM electrolyte. Based on the results of the investigation, LSGM electrolyte supported solid oxide fuel cells (SOFCs) were fabricated with La 0.6Sr 0.4Co 0.8Fe 0.2O 3-La 0.9Sr 0.1Ga 0.8Mg 0.2O 3 (LSCF-LSGM) composite cathode and nickel-Ce 0.6La 0.4O 2 (Ni-LDC) composite anode having a barrier layer of Ce 0.6La 0.4O 2 (LDC) between the LSGM electrolyte and the Ni-LDC anode. Electrical performances of these cells were determined and the electrode polarization behavior as a function of cell current was modeled between 600 and 800 °C.

Effect of rare-earth dopants on the growth and structural, optical, electrical and mechanical properties of L-arginine phosphate single crystals

International Nuclear Information System (INIS)

Arjunan, S.; Bhaskaran, A.; Kumar, R. Mohan; Mohan, R.; Jayavel, R.

2010-01-01

Research highlights: → Thorium, Lanthanum and Cerium rare-earth ions were doped with L-arginine phosphate material and the crystals were grown by slow evaporation technique. → The transparency of the rare-earth doped LAP crystals has enhanced compared to pure LAP. → The powder SHG measurements revealed that the SHG output of rare-earth doped LAP crystals increases considerably compared to that of LAP. → Vicker's hardness number of as-grown crystal of LAP is higher than that of rare-earth doped LAP crystals. - Abstract: Effect of Thorium, Lanthanum and Cerium rare-earth ions on the growth and properties of L-arginine phosphate single crystals has been reported. The incorporation of rare-earth dopants into the L-arginine phosphate crystals is confirmed by Inductively Coupled Plasma-Mass Spectroscopy analysis. The unit cell parameters for pure and rare-earth doped L-arginine phosphate crystals have been estimated by powder X-ray diffraction studies. UV-visible studies revealed the transmittance percentage and cut-off wavelengths of the grown crystals. Powder second harmonic generation measurement has been carried out for pure and doped L-arginine phosphate crystals. The dielectric behavior of the grown crystals was analyzed for different frequencies at room temperature. The mechanical properties have been determined for pure and the doped L-arginine phosphate crystals.

Bordoni relaxation and magnetic transformation in cerium and cerium-lanthanum alloys

Energy Technology Data Exchange (ETDEWEB)

Postnikov, V S; Polner, G L; Sharshakov, I M

1975-11-01

The internal friction in pure cerium and cerium-base alloys with 2.5 and 12 weight percent of lanthanum added at temperature ranging from 4.2 deg up to 77/sup 0/K is described. Amplitude-independent internal friction has been measured with an inverse torsion pendulum with a specimen oscillation frequency of 1-30 hz in vacuum not less than 1.10/sup -5/ torr. A temperature of the specimen has been determined with a capacitance-type sensor and a gas gage. A curve showing the dependence of internal friction upon a temperature of pure cerium has two distinct peaks; the first at 12.5/sup 0/K, the second at 45/sup 0/K. The 12.5/sup 0/K peak is accounted for by a transition of antiferromagnetic ..beta..-Ce into a paramagnetic state. The 45/sup 0/K peak is a Bordoni maximum. The paper describes an influence of additions, specimen oscillation frequency variations, deformation and annealing upon the peak behavor. Added lanthanum reduces not only a peak temperature but a height as well. Studies of the 45/sup 0/K peak have shown that its temperature location depends upon the specimen oscillation frequency. As the frequency increases the peak tends to a range of high temperatures which confirms its relaxation nature.

Phases in lanthanum-nickel-aluminum alloys

International Nuclear Information System (INIS)

Mosley, W.C.

1992-01-01

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

Synthesis and stability of lanthanum superhydrides

Energy Technology Data Exchange (ETDEWEB)

Geballe, Zachary M.; Liu, Hanyu; Mishra, Ajay K.; Ahart, Muhtar; Somayazulu, Maddury; Baldini, Maria [Geophysical Laboratory, Carnegie Institution, Washington, DC (United States); Meng, Yue [HPCAT, Geophysical Laboratory, Carnegie Institution of Washington, Argonne, IL (United States); Hemley, Russell J. [Institute of Materials Science and Department of Civil and Environmental Engineering, The George Washington University, Washington, DC (United States)

2018-01-15

Recent theoretical calculations predict that megabar pressure stabilizes very hydrogen-rich simple compounds having new clathrate-like structures and remarkable electronic properties including room-temperature superconductivity. X-ray diffraction and optical studies demonstrate that superhydrides of lanthanum can be synthesized with La atoms in an fcc lattice at 170 GPa upon heating to about 1000 K. The results match the predicted cubic metallic phase of LaH{sub 10} having cages of thirty-two hydrogen atoms surrounding each La atom. Upon decompression, the fcc-based structure undergoes a rhombohedral distortion of the La sublattice. The superhydride phases consist of an atomic hydrogen sublattice with H-H distances of about 1.1 Aa, which are close to predictions for solid atomic metallic hydrogen at these pressures. With stability below 200 GPa, the superhydride is thus the closest analogue to solid atomic metallic hydrogen yet to be synthesized and characterized. (copyright 2018 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Green tea epigallocatechin-3-gallate modulates differentiation of naive CD4+ T cells into specific lineage effector cells

Science.gov (United States)

CD4+ T helper (Th) subsets Th1, Th9, and Th17 cells are implicated in inducing autoimmunity whereas regulatory T cells (Treg) have a protective effect. We previously showed that epigallocatechin-3-gallate (EGCG) attenuated experimental autoimmune encephalomyelitis (EAE) and altered CD4+ T cell subpo...

Lanthanum oxyfluoride nanostructures prepared by modified sonochemical method and their use in the fields of optoelectronics and biotechnology

Directory of Open Access Journals (Sweden)

C. Suresh

2018-02-01

Full Text Available Dysprosium doped lanthanum oxyfluoride nanostructures were prepared by modified sonochemical method using Aloe Vera gel as a bio-surfactant. The morphology of the product was systematically studied by varying different experimental parameters including concentration of surfactant, sonication time, pH and sonication power. It was found that some of these above parameters play a key role in tuning the morphology of the product. The photoluminescence studies exhibited characteristic emission peaks at ∼483 nm, 574 nm and 674 nm attributed to 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2 transitions of Dy3+ ions respectively. The optimal concentration of Dy3+ ions was found to be ∼3 mol%. The photometric studies revealed that the prepared samples were quite useful for the fabrication of white light emitting diodes. The optimized product was also tested for their capability as an antigen against the bacterial and fungal pathogens. The present method of preparation may be scaled up easily to the larger production for industrial applications. The optimized sample showed an effective visualization of latent fingerprints on various forensic relevant materials and also showed effective antimicrobial potential for applications in nanobiotechnology.

Preferable adsorption of phosphate using lanthanum-incorporated porous zeolite: Characteristics and mechanism

Science.gov (United States)

He, Yinhai; Lin, Hai; Dong, Yingbo; Wang, Liang

2017-12-01

The adsorbent, where lanthanum oxide was incorporated onto porous zeolite (La-Z), of preferable adsorption towards phosphate was prepared by hydrothermal synthesis. Based on pH effect results, La-Z would effectively sequestrate phosphate over wider pH range of 3.0-7.0, alkaline conditions were unfavorable for phosphate. The adsorption of phosphate was not significantly influenced by ionic strength and by coexisting anions of chloride, nitrate and sulfate but bicarbonate showed slightly greater negative effects, indicating La-Z possessed highly selectivity to phosphate. Adsorption of phosphate could be well fitted by pseudo-second-order model and the process was mainly controlled by intra-particle diffusion. Equilibrium adsorption demonstrated that Langmuir model was more suitable than Freundlich model for description phosphate adsorption and the adsorption capacity was 17.2 mg P g-1, which exhibited 95% utilization of incorporated La. Over 95% phosphate was eliminated in real effluent treatment when the dose was 2 g L-1. The underlying mechanism for phosphate capture was probed with Zeta potential and X-ray photoelectron spectroscope analysis, and the formation of La-P inner-sphere complexation was testified to be the dominant pathway. All the results suggested that the porous zeolite-supported lanthanum oxide can serve as a promising adsorbent for phosphate removal in realistic application.

Internal-standard method for the determination of uranium, thorium, lanthanum and europium in carbonaceous shale and monazite by epithermal neutron activation analysis

Energy Technology Data Exchange (ETDEWEB)

Chen, Shuenn-Gang; Tsai, Hui-Tuh; Wu, Shaw-Chii [Institute of Nuclear Energy Research, Lung-Tan (Taiwan, Republic of China)

1981-10-03

An internal-standard method was applied for the determination of uranium, thorium, lanthanum and europium is carbonaceous shale samples and monazite sand by epithermal neutron activation analysis using gold as an internal standard element. The samples were irradiated in a zero-power reactor at the Institute of Nuclear Energy Research and measured with a high-resolution Ge(Li) detector. The detection limit is 0.1 ppm for uranium and europium, 1 ppm for thorium, 5 ppm for lanthanum, and the realative error of all elements is within +-2.6%.

Fabrication and functionalization of magnesium nanoparticle for lipase immobilization in n-propyl gallate synthesis

Directory of Open Access Journals (Sweden)

Abhishek Sharma

2017-10-01

Full Text Available An extracellular lipase partially purified from Bacillus thermoamylovorans BHK67 was effectively immobilized onto modified magnetic MgFe2O4 nanoparticles (NPs. NPs were prepared by the sol-gel auto-combustion method and characterized by Fourier transform infrared (FTIR spectroscopy, X-ray diffraction (XRD, Ultra-Violet–Visible Spectroscopy (UV–vis and atomic force microscopy (AFM. Protein loading reached a saturated amount of about 0.20 mg lipase per milligram of MgFe2O4 NPs with 78.9% binding efficiency. The NPs-bound lipase also showed stability following exposure to n-propanol and iso-propanol or FeCl2 and MgCl2 metal ions at (1 mM at 55 °C. NPs-bound lipase also retained 50% of its original hydrolytic activity even after 8th cycle, as well as after 12 h of incubation at 55 °C. NPs-bound lipase in an esterification reaction of n-propanol and gallic acid (25 mM performed for 12 h at 55 °C produced n-propyl gallate with a conversion rate of 82%. Synthesized n-propyl gallate possessed strong antioxidant activity, which was confirmed by DPPH assay, and in addition has anticancerous activity which was tested on a human L132 cell line.

[Structure and luminescence properties of Ga2O3 : Cr3+ by Al doping].

Science.gov (United States)

Wang, Xian-Sheng; Wan, Min-Hua; Wang, Yin-Hai; Zhao, Hui; Hu, Zheng-Fa; Li, Hai-Ling

2013-11-01

The Al doping gallate phosphor (Ga(1-x)Al(x))2O3 : Cr3+ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) was synthesized by a high temperature solid-state reaction method. The X-ray diffractions show that the phase of the phosphors remains to be Ga2 O3 structure with increase in the contents of Al3+ ion. Beside, the fact that the X-ray diffraction peak shifts towards big angles with increasing Al3+ ions content shows that Al3+ ions entered the Ga2 O3 lattice. The peaks of the excitation spectra located at 258, 300, 410 and 550 nm are attributed to the band to band transition of the matrix, charge transfer band transition, and 4A2 --> 4T1 and 4A2 --> 4T2 transition of Cr3+ ions, respectively. Those excitation spectrum peak positions show different degrees of blue shift with the increase in the Al3+ ions content. The blue shift of the first two peaks are due to the band gap energy of substrate and the electronegativity between Cr3+ ions and ligands increasing, respectively. The blue shift of the energy level transition of Cr3+ ion is attributed to crystal field strength increasing. The Cr3+ ion luminescence changes from a broadband emission to a narrow-band emission with Al3+ doping, because the emission of Cr3+ ion changed from 4 T2 --> 4A2 to 2E --> 4A2 transition with the crystal field change after Al3+ ions doping. The Al3+ ions doping improved the long afterglow luminescence properties of samples, and the sample showed a longer visible near infrared when Al3+ ions content reaches 0.5. The thermoluminescence curve shows the sample with suitable trap energy level, and this is also the cause of the long afterglow luminescence materials.

La modified TiO{sub 2} photoanode and its effect on DSSC performance: A comparative study of doping and surface treatment on deep and surface charge trapping

Energy Technology Data Exchange (ETDEWEB)

Ako, Rajour Tanyi [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Ekanayake, Piyasiri, E-mail: piyasiri.ekanayake@ubd.edu.bn [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Centre for Advanced Material and Energy Sciences (CAMES), Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Tan, Ai Ling [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Young, David James [Faculty of Science, Universiti Brunei Darussalam, Jalan Tungku Link, BE1410, Negara Brunei Darussalam (Brunei Darussalam); Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland, 4558 (Australia); Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research - A*STAR, #08-03, 2 Fusionopolis Way, Innovis, 138634 (Singapore)

2016-04-01

The effect of Lanthanum ions (La{sup 3+}) on charge trapping in dye-sensitized solar cell (DSSC) photoanodes has been investigated with doped and surface-treated TiO{sub 2} nanoparticles. Doped nanoparticles consisting of 0.5 mol.% Mg and La co-doped TiO{sub 2}, 0.5 mol.% Mg doped TiO{sub 2} and pure TiO{sub 2} were synthesized by the sol gel method. Surface-treated nanoparticles of Mg doped TiO{sub 2} and pure TiO{sub 2} were prepared by ball milling in 0.05 M aqueous La{sup 3+} solution. All materials were analyzed by XRD, XPS and UV–Vis DRS. Cell performance, surface free energy state changes and electron injection efficiency of DSSCs based on these nanoparticles were evaluated using current –voltage measurements, EIS and Incident photon to current conversion efficiency. Doped materials had La and Mg ions incorporated into the TiO{sub 2} lattice, while no lattice changes were observed for the surface-treated materials. Less visible light was absorbed by treated oxides compared with doped oxide samples. The overall power conversion efficiencies (PCE) of DSSC photoanodes based on doped materials were twice those of photoanodes fabricated from treated nanoparticles. Doping establishes deep traps that reduce the recombination of electron–hole (e–h) pairs. Conversely, the presence of absorbed oxygen in treated materials enhances e–h recombination with electrolyte at surface trap sites. - Highlights: • DSSC performance is investigated using photoanodes of doped and La{sup 3+} surface treated TiO{sub 2}. • TiO{sub 2} and Mg–TiO{sub 2} treated with La{sup 3+} absorbed less visible light. • A high concentration of absorbed oxygen on surface treated oxides reduced band bending. • Increased surface free energy in the modified DSSC anodes is caused more by Mg{sup 2+} at Ti{sup 4+} than by La{sup 3+} at the surfaces. • Near surface charge traps due to La{sup 3+} treatment promotes e–h recombination.

Structural, photoluminescence and radioluminescence properties of Eu{sup 3+} doped La{sub 2}Hf{sub 2}O{sub 7} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Wahid, Kareem; Pokhrel, Madhab; Mao, Yuanbing, E-mail: yuanbing.mao@utrgv.edu

2017-01-15

This study presents the structural, optical, and radioluminescent characterization of newly synthesized europium-doped lanthanum hafnate (La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+}, x=0 to 35) nanoparticles (NPs) for use as phosphors and scintillation materials. Samples prepared through a combined co-precipitation and molten salt synthetic process were found to crystalize in the pyrochlore phase, a radiation tolerant structure related to the fluorite structure. These samples exhibit red luminescence under ultraviolet and X-ray excitation. Under these excitations, the optical intensity and quantum yield of the La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+} NPs depend on the Eu{sup 3+} concentration and are maximized at 5%. It is proposed that there is a trade-off between the quenching due to defect states/cross-relaxation and dopant concentration. An optimal dopant concentration allows the La{sub 2}Hf{sub 2}O{sub 7}:5 mol%Eu{sup 3+} NPs to show the best luminescent properties of all the samples. - Graphical abstract: Incident X-ray and UV photons interact with La{sub 2}Hf{sub 2}O{sub 7}: xmol%Eu{sup 3+}(x=1–35) nanoparticles (NPs) to yield strong red luminescence centered at 612 nm. Colored spheres inside NP diagram represent pyrochlore coordination environment of La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+}. Blue, red, yellow, green and black spheres represent hafnium(IV) atoms, lanthanum(III)/europium(III) atoms, oxygen atoms at 48f site, oxygen atoms at 8b site and oxygen vacancies, respectively. - Highlights: • La{sub 2}Hf{sub 2}O{sub 7}:xmol%Eu{sup 3+} (x=0–35) nanoparticles with weakly-ordered pyrochlore structures were synthesized. • Optically and X-ray excited emission spectra showed strong luminescence centered at 612 nm. • Photoluminescence quantum yield increases with doping concentration up to 5% and decreases at higher concentrations.

In situ XANES cell used for the study of lanthanum strontium cuprate deNOx catalysts

DEFF Research Database (Denmark)

Hagen, Anke

2011-01-01

, maintaining charge neutrality, with the concentration of oxygen vacancies likely increasing at substitution ratios larger than Sr/La>0.08. During heating in air, the valence of copper ions in the structure increased. Upon exposure to NO at 500 °C the valence of copper ions in a lanthanum strontium cuprate...

Bioactivity-guided fractionation of an antidiarrheal Chinese herb Rhodiola kirilowii (Regel) Maxim reveals (-)-epicatechin-3-gallate and (-)-epigallocatechin-3-gallate as inhibitors of cystic fibrosis transmembrane conductance regulator.

Science.gov (United States)

Chen, Lei; Yu, Bo; Zhang, Yaofang; Gao, Xin; Zhu, Liang; Ma, Tonghui; Yang, Hong

2015-01-01

Cystic fibrosis transmembrane conductance regulator (CFTR) is the principal apical route for transepithelial fluid transport induced by enterotoxin. Inhibition of CFTR has been confirmed as a pharmaceutical approach for the treatment of secretory diarrhea. Many traditional Chinese herbal medicines, like Rhodiola kirilowii (Regel) Maxim, have long been used for the treatment of secretory diarrhea. However, the active ingredients responsible for their therapeutic effectiveness remain unknown. The purpose of this study is to identify CFTR inhibitors from Rhodiola kirilowii (Regel) Maxim via bioactivity-directed isolation strategy. We first identified fractions of Rhodiola kirilowii (Regel) Maxim that inhibited CFTR Cl- channel activity. Further bioactivity-directed fractionation led to the identification of (-)-epigallocatechin-3-gallate (EGCG) as CFTR Cl- channel inhibitor. Analysis of 5 commercially available EGCG analogs including (+)-catechins (C), (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin-3-gallate (ECG) and EGCG revealed that ECG also had CFTR inhibitory activity. EGCG dose-dependently and reversibly inhibited CFTR Cl- channel activity in transfected FRT cells with an IC50 value around 100 μM. In ex vivo studies, EGCG and ECG inhibited CFTR-mediated short-circuit currents in isolated rat colonic mucosa in a dose-dependent manner. In an intestinal closed-loop model in mice, intraluminal application of EGCG (10 μg) and ECG (10 μg) significantly reduced cholera toxin-induced intestinal fluid secretion. CFTR Cl- channel is a molecular target of natural compounds EGCG and ECG. CFTR inhibition may account, at least in part, for the antidiarrheal activity of Rhodiola kirilowii (Regel) Maxim. EGCG and ECG could be new lead compounds for development of CFTR-related diseases such as secretory diarrhea.

Skin Protective Effect of Epigallocatechin Gallate

Directory of Open Access Journals (Sweden)

Eunji Kim

2018-01-01

Full Text Available Epigallocatechin gallate (EGCG is a catechin and an abundant polyphenol in green tea. Although several papers have evaluated EGCG as a cosmetic constituent, the skin hydration effect of EGCG is poorly understood. We aimed to investigate the mechanism by which EGCG promotes skin hydration by measuring hyaluronic acid synthase (HAS and hyaluronidase (HYAL gene expression and antioxidant and anti-pigmentation properties using cell proliferation assay, Western blotting analysis, luciferase assay, 2,2-diphenyl-1-picrylhydrazyl (DPPH assay, and reverse transcription polymerase chain reaction (RT-PCR analysis. RT-PCR showed that EGCG increased the expression of natural moisturizing factor-related genes filaggrin (FLG, transglutaminase-1, HAS-1, and HAS-2. Under UVB irradiation conditions, the expression level of HYAL was decreased in HaCaT cells. Furthermore, we confirmed the antioxidant activity of EGCG and also showed a preventive effect against radical-evoked apoptosis by downregulation of caspase-8 and -3 in HaCaT cells. EGCG reduced melanin secretion and production in melanoma cells. Together, these results suggest that EGCG might be used as a cosmetic ingredient with positive effects on skin hydration, moisture retention, and wrinkle formation, in addition to radical scavenging activity and reduction of melanin generation.

Properties of La0.5Sr0.5CoO3 thin films grown by laser ablation

International Nuclear Information System (INIS)

Drozdov, Yu.N.; Klyuenkov, E.B.; Salashenko, N.N.; Suslov, L.A.

1997-01-01

The epitaxial films of lanthanum-strontium cobaltate La 0.5 Sr 0.5 CoO 3 (LSCO) are obtained on the neodium gallate and strontium titanate substrates. It is established that the LSCO layer lattice has tetragonal distortion, the degree where of depends on the oxygen deficit. The LSCO specific resistance at room temperature is approximately equal to 200 μOhm cm. The resistance dependence on temperature is of metal character. The possibility is shown of utilizing the LSCO as electrode material by fabrication of condenser structures on the basis of DbZr 1-x Ti x O 3 ferroelectric films

Crystal structure, dielectric, ferroelectric and energy storage properties of La-doped BaTiO3 semiconducting ceramics

Directory of Open Access Journals (Sweden)

Venkata Sreenivas Puli

2015-09-01

Full Text Available Polycrystalline La-doped BaTiO3 (Ba(1-xLax\tTiO3 [x=0,0.0005,0.001,0.003] ceramics (denoted as BTO,BLT1,BLT2,BLT3 were synthesized by conventional solid-state reaction method and characterized by X-ray diffraction (XRD, scanning electron microscopy (SEM, and Raman spectroscopy. XRD and Raman spectra revealed single-phase tetragonal perovskite crystalline structure. Well-saturated polarization–electric field (P–E hysteresis loops were observed with the measurement frequency of 50 Hz at room temperature and confirmed ferroelectric nature of these ceramics and a high recoverable electrical energy storage density of 0.350 J/cm3 with energy efficiency (n∼9%, which is useful in energy storage capacitor applications. Dielectric studies revealed anomalies around 415–420 K and near the Curie temperature. The latter is attributed to the ferroelectric to paraelectric phase transition. Better dielectric performances were obtained for La-doped samples sintered at 1350°C for 4 h. Grain growth is inhibited with lanthanum (La incorporation into the BTO lattice. Room temperature semiconducting behavior with positive temperature coefficient of resistivity (PTCR behavior at TC is attributed to electron compensation mechanism.

Moving the Plasmon of LaB₆ from IR to Near-IR via Eu-Doping.

Science.gov (United States)

Mattox, Tracy M; Coffman, D Keith; Roh, Inwhan; Sims, Christopher; Urban, Jeffrey J

2018-02-01

Lanthanum hexaboride (LaB₆) has become a material of intense interest in recent years due to its low work function, thermal stability and intriguing optical properties. LaB₆ is also a semiconductor plasmonic material with the ability to support strong plasmon modes. Some of these modes uniquely stretch into the infrared, allowing the material to absorb around 1000 nm, which is of great interest to the window industry. It is well known that the plasmon of LaB₆ can be tuned by controlling particle size and shape. In this work, we explore the options available to further tune the optical properties by describing how metal vacancies and Eu doping concentrations are additional knobs for tuning the absorbance from the near-IR to far-IR in La 1-x Eu x B₆ (x = 0, 0.2, 0.5, 0.8, and 1.0). We also report that there is a direct correlation between Eu concentration and metal vacancies within the Eu 1-x La x B₆.

Catalytic activity of lanthanum oxide for the reduction of cyclohexanone

International Nuclear Information System (INIS)

Sugunan, S.; Sherly, K.B.

1994-01-01

Lanthanum oxides, La 2 O 3 has been found to be an effective catalyst for the liquid phase reduction of cyclohexanone. The catalytic activities of La 2 O 3 activated at 300, 500 and 800 degC and its mixed oxides with alumina for the reduction of cylcohexanone with 2-propanol have been determined and the data parallel that of the electron donating properties of the catalysts. The electron donating properties of the catalysts have been determined from the adsorption of electron acceptors of different electron affinities on the surface of these oxides. (author). 15 refs., 2 figs., 1 tab

Effects of polyaluminum chloride and lanthanum-modified bentonite on the growth rates of three Cylindrospermopsis raciborskii strains

NARCIS (Netherlands)

Araújo, Fabiana; van Oosterhout, Frank; Becker, Vanessa; Attayde, José Luiz; Lürling, Miquel

2018-01-01

In tropical and subtropical lakes, eutrophication often leads to nuisance blooms of Cylindrospermopsis raciborskii. In laboratory experiments, we tested the combined effects of flocculant polyaluminum chloride (PAC) and lanthanum-modified bentonite (LMB) on the sinking and growth rates of three C.

effect of post-precipitation treatment on the pore-structure stability of sol-gel derived lanthanum zirconate

NARCIS (Netherlands)

Nair, Jalajakumari; Kumar, K.N.P.; Nair, P.; van Ommen, J.G.; Ross, J.R.H.; Ross, Julian R.H.; Burggraaf, Anthonie J.; Burggraaf, Anthonie

1998-01-01

The importance of post-precipitation treatments (pore-fluid exchange and its removal) on the evolution of the texture of coprecipitated lanthanum zirconate has been investigated. The nature of the pore fluid and the type of fluid-removal (drying) process have shown a profound effect on the aggregate

Fabrication of La-doped TiO2 Film Electrode and investigation of its electrocatalytic activity for furfural reduction

International Nuclear Information System (INIS)

Wang, Fengwu; Xu, Mai; Wei, Lin; Wei, Yijun; Hu, Yunhu; Fang, Wenyan; Zhu, Chuan Gao

2015-01-01

Lanthanum trivalent ions (La 3+ ) doped nano-TiO 2 film electrode was prepared by the sol–gel method. The prepared electrode was characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV). The electrocatalytic properties of the roughened TiO 2 film electrode towards the electrocatalytic reduction of furfural to furfural alcohol were evaluated by CV and preparative electrolysis experiments. The results of the optimum molar ratio of La: Ti was 0.005:1. Experimental evidence was presented that the La nano-TiO 2 electrode exhibited higher electrocatalytic activity for the reduction of furfural than the undoped nano-TiO 2 electrode in N,N-dimethylformamide medium. Bulk electrolysis studies were also carried out for the reduction of furfural and the product was confirmed by NMR

Highly enhanced adsorption of Congo red by functionalized finger-citron-leaf-based porous carbon.

Science.gov (United States)

Zhao, Gui-Hua; Fang, Yao-Yao; Dai, Wei; Ma, Na

2018-01-01

A novel high-performance porous carbon material, lanthanum(III)-doped finger-citron-leaf-based porous carbon (La/FPC), has been synthesized and used as an adsorbent for anion dye Congo red (CR). The La/FPC was characterized by nitrogen adsorption and desorption isotherms, scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The adsorption performance of CR by the FPC and La/FPC composites with different contents of lanthanum(III) were evaluated in fixed-bed breakthrough experiments and batch tests at room temperature (298 K). The La/FPC had a high CR uptake capacity, which was superior to those previously reported for other adsorbents. The La/FPC sorbents can be easily regenerated using an ethanol elution technique, and after five cycles the reused La/FPC maintained about 98% of its original CR adsorption capacity. The adsorption kinetics of CR onto the lanthanum(III)-doped FPCs followed a pseudo-second-order kinetic model and fitted well with a Langmuir adsorption isotherm. La/FPC is a promising adsorbent for the removal of the anionic dyes from wastewater.

Synthesis and investigation of saturated vapor pressure of lanthanum, praseodymium and neodymium tris-isopropylcyclopentadienyls

International Nuclear Information System (INIS)

Devyatykh, G.G.; Chernyaev, N.P.; Zverev, Yu.B.; Gavrishchuk, E.M.; Runovskaya, I.V.; Krupnova, Eh.F.; Chesnokova, S.G.

1980-01-01

Lanthanum, praseodymium and neodymium tris-isopropylcyclopentadienyls are synthesized with corresponding unhydrous chlorides in tetrahydrofuran solution. Saturated vapour pressure of substances obtained is studied in the 150-262 deg C range by the statistic method using a compensation zero-manometer. Vapour pressure of the compounds in question is shown to increase with the growth of the rare earth element number [ru

Propyl gallate synthesis using acidophilic tannase and simultaneous production of tannase and gallic acid by marine Aspergillus awamori BTMFW032.

Science.gov (United States)

Beena, P S; Basheer, Soorej M; Bhat, Sarita G; Bahkali, Ali H; Chandrasekaran, M

2011-07-01

Marine Aspergillus awamori BTMFW032, recently reported by us, produce acidophilic tannase as extracellular enzyme. Here, we report the application of this enzyme for synthesis of propyl gallate by direct transesterification of tannic acid and in tea cream solubilisation besides the simultaneous production of gallic acid along with tannase under submerged fermentation by this fungus. This acidophilic tannase enabled synthesis of propyl gallate by direct transesterification of tannic acid using propanol as organic reaction media under low water conditions. The identity of the product was confirmed with thin layer chromatography and Fourier transform infrared spectroscopy. It was noted that 699 U/ml of enzyme could give 60% solubilisation of tea cream within 1 h. Enzyme production medium was optimized adopting Box-Behnken design for simultaneous synthesis of tannase and gallic acid. Process variables including tannic acid, sodium chloride, ferrous sulphate, dipotassium hydrogen phosphate, incubation period and agitation were recognized as the critical factors that influenced tannase and gallic acid production. The model obtained predicted 4,824.61 U/ml of tannase and 136.206 μg/ml gallic acid after 48 h of incubation, whereas optimized medium supported 5,085 U/ml tannase and 372.6 μg/ml of gallic acid production after 36 and 84 h of incubation, respectively, with a 15-fold increase in both enzyme and gallic acid production. Results indicated scope for utilization of this acidophilic tannase for transesterification of tannic acid into propyl gallate, tea cream solubilisation and simultaneous production of gallic acid along with tannase.