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Relevant bibliographies by topics / Lanthanum silicate

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Academic literature on the topic 'Lanthanum silicate'

Author: Grafiati

Published: 4 June 2021

Last updated: 11 February 2022

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Journal articles on the topic "Lanthanum silicate"

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Mihara, Shunya, Kiyoshi Kobayashi, Takaya Akashi, and Yoshio Sakka. "Chemical Reactivity and Cathode Properties of LaCoO₃ on Lanthanum Silicate Oxyapatite Electrolyte." Key Engineering Materials 616 (June 2014): 120–28. http://dx.doi.org/10.4028/www.scientific.net/kem.616.120.

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Chemical reactivity and cathode properties of LaCoO3 were investigated using new oxide ion conductor, lanthanum silicate oxyapatite. The LaCoO3 is found to be good candidate for cathode of the lanthanum silicate oxyapatite solid-electrolyte since no chemical reaction occurred between the LaCoO3 and lanthanum silicate oxyapatite heating at 1273 K for 60 h in air. Based on electrochemical measurements, lower overpotential between the LaCoO3 and lanthanum silicate oxyapatite was confirmed compared to the overpotential at YSZ/LaCoO3 interface. From analysis on the extended interfacial conductivity as function of oxygen activity at the triple phase boundary at fixed temperature, the overpotential evaluated by impedance spectra is the rate limiting process by oxygen diffusion on the LaCoO3 surface. Comparing to the bulk conductivity of LaCoO3, the electrode resistance evaluated by impedance spectra was confirmed to be different from the electrical transport properties of the LaCoO3 bulk.

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Misso, Agatha Matos, Daniel Ricco Elias, Fernando dos Santos, and Chieko Yamagata. "Low Temperature Synthesis of Lanthanum Silicate Apatite Type by Modified Sol Gel Process." Advanced Materials Research 975 (July 2014): 143–48. http://dx.doi.org/10.4028/www.scientific.net/amr.975.143.

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Rare earth silicate apatite type is a very important and promising material for application as an electrolyte in IT-SOFC (Intermediate Temperature Solid Oxide Fuel Cell). Lanthanum silicate apatite, La9,33Si6O26, exhibits high conductivity and has high efficiency, long term stability, fuel flexibility, low emissions and relatively low cost compared to yttria stabilized zirconia (YSZ - yttria stabilized zirconia), at temperatures between 600 to 800 °C. One of the problems of YSZ is its high operating temperature which results in long starting times and problems of mechanical and chemical compatibility. The interest of investigating lanthanum silicate apatite as an electrolyte is to overcome the problems caused by high temperature operation required by YSZ electrolyte. In the present study, sol-gel method was used to synthesize La9,33Si6O26. Initially, the reagents (sodium silicate and lanthanum nitrate) were mixed to obtain colloidal silica. Then, this gel containing lanthanum nitrate was thermally treated to allow the melting of lanthanum nitrate salt distributed on colloidal silica. The aim of this study was to verify if this method permits the formation of La9,33Si6O26 pure apatite phase, in order to obtain fine powders and uniform particles for further processing and obtaining a ceramic body.

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Li, Wen Zhao, Zhi Liang Huang, Qian Zi Li, and Juan Chen. "Synthesis and Conductivity Investigation of Cu Doped Apatite Type Lanthanum Silicate Electrolyte." Key Engineering Materials 726 (January 2017): 245–49. http://dx.doi.org/10.4028/www.scientific.net/kem.726.245.

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In this paper, Cu-doped lanthanum silicate electrolyte (La9.33Si6-xCuxO26-x) precursor was synthesized by urea-nitrate combustion method using La2O3, CuO and TEOS as raw materials. The as-prepared precursor was lighted at 600 °C and sintered at 800 °C. The sintered powder samples were grinded and mixed absolutely by ball milled. Finally, we preformed and sintered powder samples to synthesis Cu-doped lanthanum silicate ceramics. Ac impedance method and analysis was used to test conductivity of as-prepared electrolyte, investigated the influence of balling time, sintering temperature and doping content on conductivity property of LSO sintered product. The final result shows that best balling time is 3 h, secondary sintering temperature is 1500 °C and the doping content is 0.3. Under this condition, the conductivity of Cu-doped lanthanum silicate electrolyte could reach 7.28×10-3 s/cm at 700 °C.

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Yang, Xiang Yu, Bong Mook Lee, and Veena Misra. "High Mobility 4H-SiC MOSFETs Using Lanthanum Silicate Interface Engineering and ALD Deposited SiO₂." Materials Science Forum 778-780 (February 2014): 557–61. http://dx.doi.org/10.4028/www.scientific.net/msf.778-780.557.

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In this work, we have developed a novel gate stack to enhance the mobility of Si face (0001) 4H-SiC lateral MOSFETs while maintaining a high threshold voltage. The gate dielectric consists a thin lanthanum silicate layer at SiC/dielectric interface and SiO2deposited by atomic layer deposition. MOSFETs using this interface engineering technique show a peak field effect mobility of 133.5 cm2/Vs while maintaining a positive threshold voltage of above 3V. The interface state density measured on MOS capacitor with lanthanum silicate interfacial layers is reduced compared to the capacitors without the silicate. It is shown that the presence of the lanthanum at the interface reduces the formation of a lower quality SiOxinterfacial layer typically formed at the SiC surface during typical high temperature anneals. This better quality interfacial layer produces a sharp SiC/dielectric interface, which is confirmed by cross section Z-contrast STEM images.

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Noviyanti, Atiek Rostika, Nur Akbar, Iwan Hastiawan, Iman Rahayu, Haryono, Yoga Trianzar Malik, and Risdiana. "Bi Doping Effect on the Conductivity of Lanthanum Silicate Apatite." Materials Science Forum 966 (August 2019): 451–55. http://dx.doi.org/10.4028/www.scientific.net/msf.966.451.

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Lanthanum silicate apatite with various concentration of Bi-doped of La10-xBixSi6O27 were successfully synthesized by hydrothermal method in order to study effect of Bi-doped tp its structure and conductivity properties. It is found that main peaks of lanthanum silicate apatite were observed with amount of impurities. The value of conductivity at 500°C determining from AC impedance measurement was in the range between 1.99 × 10-6 S/cm and 2.03 × 10-6 S/cm. The highest conductivity was observed in the sample with x = 0.5, 1.0 and 1.5.

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Bois, Laurence, M. J. Guittet, N. Barré, P. Trocellier, S. Guillopé, M. Gautier, P. Verdier, and Y. Laurent. "Aqueous alteration of lanthanum alumino-silicate glasses." Journal of Non-Crystalline Solids 276, no. 1-3 (October 2000): 181–94. http://dx.doi.org/10.1016/s0022-3093(00)00275-1.

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Deudon, C., A. Meerschaut, and J. Rouxel. "Structure Determination of Lanthanum Seleno-Silicate, La4Se3Si2O7." Journal of Solid State Chemistry 104, no. 2 (June 1993): 282–88. http://dx.doi.org/10.1006/jssc.1993.1162.

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Shi, Qing Le, Hua Zhang, Tian Jing Li, Fang Li Yu, Hai Jun Hou, and Peng De Han. "Sintering Properties of Apatite-Type Lanthanum Silicate Electrolytes." Materials Science Forum 814 (March 2015): 65–70. http://dx.doi.org/10.4028/www.scientific.net/msf.814.65.

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The sintering properties of appetite-type lanthanum silicate La10Si6O27prepared by sol-gel process were studied. The precursor powder was sintered by one-step sintering (OSS) process, two-step sintering (TSS) process and spark-plasma sintering (SPS) process. The phase structure, microstructure, relative density, thermal expansion properties, electrochemical properties of the samples were investigated by means of the techniques including X-ray diffraction (XRD), scanning electron microscopy (SEM), Archimedes method, dilatometer, and AC impedance spectroscopy. The experimental results show that the samples sintered by SPS process can decrease the sintering temperature, shorten the sintering time, increase the density, and reduce the particle size. The appetite-type lanthanum silicate La10Si6O27 sintered by SPS process shows better sintering properties than of sintered by OSS process and TSS process, which can beneficial to the thermal expansion properties and conductivity.

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Pandis, P. K., E. Xenogiannopoulou, P. M. Sakkas, G. Sourkouni, Ch Argirusis, and V. N. Stathopoulos. "Compositional effect of Cr contamination susceptibility of La9.83Si6−x−yAlxFeyO26±δ apatite-type SOFC electrolytes in contact with CROFER 22 APU." RSC Advances 6, no. 55 (2016): 49429–35. http://dx.doi.org/10.1039/c6ra02025a.

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Hori, Shigeo, Yasuhiro Takatani, Hiroaki Kadoura, Takeshi Uyama, Satoru Fujita, and Toshihiko Tani. "Chemical solution deposition of the highly c-axis oriented apatite type lanthanum silicate thin films." Dalton Transactions 44, no. 40 (2015): 17551–56. http://dx.doi.org/10.1039/c5dt02569a.

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Dissertations / Theses on the topic "Lanthanum silicate"

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Abram, Edward John. "Synthesis and characterisation of doped lanthanum gallate and lanthanum silicate oxide-ion conductors." Thesis, University of Sheffield, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.251374.

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Elias, Daniel Ricco. "Síntese e caracterização de pós de silicato de lantânio tipo apatita para eletrólito em SOFC." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-25022014-101948/.

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A temperatura de operação de células a combustível de óxido sólido (SOFCs) que utilizam zirconia estabilizada com itria (YSZ) como eletrólito é 1000 oC. Essa alta temperatura gera graves problemas relativos a materiais e vida util da célula. Por isso, condutores iônicos que possuem alta condutividade em temperaturas inferiores são pesquisados atualmente. Estudos mostraram que La10Si6O27 tipo apatita possui alta condutividade iônica de oxigenio, que é comparativamente maior que a de YSZ, a 500 oC, sendo, portanto, um potencial candidato como eletrólito para SOFC. O objetivo do presente trabalho é o desenvolvimento de técnicas de síntese de silicato de lantânio tipo apatita. Rotas inéditas de solgel modificada para sintetizar La9,33Si6O26 são propostas. Volumes estequiométricos de soluções de Na2SiO3 e LaCl3 foram misturados para a formação de gel de Si. Em seguida este gel foi calcinado a 900 °C, lavado, filtrado e tratado novamente a 900 °C. Em outra rota, volumes estequiométricos de soluções de Si (Na2SiO3 ou TEOS) e de La (LaCl3) foram utilizados para obtenção de gel de Si. Em seguida, hidróxido de La foi precipitado pela adição de uma base (NaOH ou NH4OH) ao gel. O material resultante foi calcinado a 900 °C, lavado, filtrado e tratado novamente a 900 °C. Pós de aglomerados fracos e alta sinterabilidade foram obtidos. DRX dos pós mostrou a estrutura de apatita monofásica a 900 oC. Morfologia de ceramica densa foi observada em imagens de MEV da superfície das pastilhas sinterizadas a 1200,1300 e 1400 oC por 4 h. Estas temperaturas e tempo de sinterização são significativas, pois no método convencional temperaturas superiores a 1700oC e tempos muito maiores são necessários para obtenção de tais cerâmicas. Densidades relativas superiores a 90% foram obtidas através dos métodos propostos. Uma conclusão importante é que TEOS, o reagente usual de alto custo, pode ser substituído por Na2SiO3, de preço muito mais baixo, para obter La9,33Si6O26 tipo apatita.
Solid oxide fuel cell (SOFCs) operating temperature that uses yttria stabilized zirconia (YSZ) as the electrolyte is 1000ºC. This high temperature causes serious problems concerning cell life and materials. Therefore, the ionic conductors which have high conductivity at lower temperature are currently researched. Studies have shown that the composition of La10Si6O27 apatite type has high oxygen ionic conductivity, which is comparably higher than that of YSZ, at 500 oC, it is therefore a potential candidate as for SOFC electrolyte. The objective of the present work is the development of lanthanum silicate with apatite type synthesis techniques. Novel modified solgel routes to synthesize La9.33Si6O26 are proposed. Stoichiometric volumes of Na2SiO3 and LaCl3 solutions were mixed for the formation of Si gel. This gel was calcined at 900 °C, washed, filtered and again thermally treated at 900 °C. In the other route, stoichiometric volumes of Si (Na2SiO3 or TEOS) and La (LaCl3) solutions were used for obtaining Si gel. Then, La hydroxide was precipitated by adding of a base (NaOH or NH4OH) to gel. Then the material was calcined at 900 °C, washed, filtered and again treated at 900 °C. Highly sinterable weakly agglomerated powders have been obtained. XRD patterns of the powders showed the single-phase apatite structure at 900 oC. Dense ceramic morphology was observed from the SEM images of surface of the pellets sintered at 1200, 1300 and 1400oC for 4h. This low temperature sintering and time of sintering are significant because the conventional method requires superior temperatures of 1700 oC to obtain the same dense ceramics. High relative densities higher than 90% was obtained via proposed methods. An Important conclusion is the TEOS, the usual high cost reagent, may be substituted by a cheap price Na2SiO3, to obtain apatite type La9.33Si6O26.

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Silva, Fernando dos Santos. "Estudo de síntese de silicato de lantânio tipo apatita pelo método sol-gel seguido de precipitação de Na2SiO3." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-29012019-143023/.

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Cerâmicas de silicato de lantânio tipo apatita têm sido estudadas devido ao grande interesse tecnológico para aplicação como eletrólito em células a combustível de óxido sólido de temperatura intermediária (IT-SOFC: Intermediate Temperature Solid Oxide Fuel Cell). A condutividade iônica dessas cerâmicas em temperaturas intermediárias (600-800°C) é maior do que a da YSZ (Ytria Stabilized Zirconia) utilizada como eletrólito em SOFCs de alta temperatura (800-1000°C). Neste trabalho, silicato de lantânio tipo apatita foi sintetizado pelo método sol-gel seguido de precipitação, a partir de Na2SiO3 como fonte de sílica. No método proposto, estudou-se rotas de síntese em meio ácido e básico para a formação do gel de sílica, seguida de precipitação. A fase cristalina de silicato de lantânio tipo apatita foi obtida pela calcinação de pós sintetizados a 900°C. Esta temperatura é muito inferior às praticadas em outros métodos convencionais de síntese. As análises por difração de raios X (DRX) mostraram silicato de lantânio tipo apatita como fase principal do material sintetizado na rota de síntese em pH ácido. No entanto, uma fase secundária indesejável, La2Si2O7, foi identificada quando o pó cerâmico foi calcinado a 1200°C. Por outro lado, pela rota básica, fase única de silicato de lantânio tipo apatita foi obtida após tratamento térmico dos precursores a 900 e 1200°C. Pastilha cerâmica obtida a partir dos pós obtidos e sinterizados a 1400°C por 4h, apresentaram fase cristalina pura de silicato de lantânio tipo apatita. Microscopia eletrônica de varredura (MEV) foi utilizada para observar a morfologia dos pós e microestrutura das pastilhas sinterizadas. Pós cerâmicos finos com tamanho de partículas submicrométricas e microestrutura típica de apatita foram alcançadas pelo método proposto.
Lanthanum silicate apatite-type ceramics have been studied because of the great technological interest for IT-SOFC applications as electrolyte (Intermediate Temperature Solid Oxide Fuel Cell). Ionic conductivity of those ceramics at intermediate temperatures (600-800°C) is higher than that of YSZ (Ytria Stabilized Zirconia) electrolyte used at high-temperatures (800-1000 °C) SOFCs. In this work, lanthanum silicate apatite-type was synthesized by sol-gel method followed by precipitation from Na2SiO3 as a source of silica. In the proposed method, synthesis routes in acid and basic medium to the formation of silica gel, followed by precipitation were studied. Apatite crystalline phase of lanthanum silicate ceramic was obtained by calcining the powders at 900°C. This temperature is much lower than those other conventional methods of synthesis. Analysis by x-ray diffraction (XRD) showed the lanthanum silicate apatite-type phase as the main phase of the synthesized material at the pH acid synthesis route. However, undesirable secondary phase, La2Si2O7, was recognized when the powder was calcined at 1200°C. On the other hand, by the basic route, single apatite-type phase powder was obtained after thermal treatment of the precursors at 900 and 1200°C. Ceramic pellet obtained from those powders sintered at 1400°C for 4h, presented pure apatite crystalline phase of lanthanum silicate. Scanning electron microscopy (SEM) was used to observe morphology of powders and microstructure of sintered pellets. Sub micrometric size powders and apatite typical microstructure ceramic were reached by the suggested method.

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Chen, Chao-Hsu. "Atomistic Computer Simulations of Diffusion Mechanisms in Lithium Lanthanum Titanate Solid State Electrolytes for Lithium Ion Batteries." Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700110/.

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Solid state lithium ion electrolytes are important to the development of next generation safer and high power density lithium ion batteries. Perovskite-structured LLT is a promising solid electrolyte with high lithium ion conductivity. LLT also serves as a good model system to understand lithium ion diffusion behaviors in solids. In this thesis, molecular dynamics and related atomistic computer simulations were used to study the diffusion behavior and diffusion mechanism in bulk crystal and grain boundary in lithium lanthanum titanate (LLT) solid state electrolytes. The effects of defect concentration on the structure and lithium ion diffusion behaviors in LLT were systematically studied and the lithium ion self-diffusion and diffusion energy barrier were investigated by both dynamic simulations and static calculations using the nudged elastic band (NEB) method. The simulation results show that there exist an optimal vacancy concentration at around x=0.067 at which lithium ions have the highest diffusion coefficient and the lowest diffusion energy barrier. The lowest energy barrier from dynamics simulations was found to be around 0.22 eV, which compared favorably with 0.19 eV from static NEB calculations. It was also found that lithium ions diffuse through bottleneck structures made of oxygen ions, which expand in dimension by 8-10% when lithium ions pass through. By designing perovskite structures with large bottleneck sizes can lead to materials with higher lithium ion conductivities. The structure and diffusion behavior of lithium silicate glasses and their interfaces, due to their importance as a grain boundary phase, with LLT crystals were also investigated by using molecular dynamics simulations. The short and medium range structures of the lithium silicate glasses were characterized and the ceramic/glass interface models were obtained using MD simulations. Lithium ion diffusion behaviors in the glass and across the glass/ceramic interfaces were investigated. It was found that there existed a minor segregation of lithium ions at the glass/crystal interface. Lithium ion diffusion energy barrier at the interface was found to be dominated by the glass phase.

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Müller-Bunz, Helge. "Modifizierung von Silicaten und Boraten dreiwertiger Lanthanide durch Oxid- und Fluoridionen." [S.l. : s.n.], 2000. http://www.bsz-bw.de/cgi-bin/xvms.cgi?SWB9030359.

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Ma, Yangzhou. "Modeling and development of new materials for fuel cells solid electrolyte." Thesis, Belfort-Montbéliard, 2016. http://www.theses.fr/2016BELF0286/document.

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Les piles à combustibles à électrolyte solide de type SOFC permettent de transformer directement l’énergie de la réaction chimique de formation de l’eau à partir de l’hydrogène et de l’oxygène, en énergie électrique. De nos jours, les apatites de type silicates de terres rares présentent beaucoup d’intérêt comme électrolyte solide en raison de leurs propriétés de transport élevées avec une forte conductivité ionique et une faible énergie d'activation. Ils peuvent fonctionner de manière stable à une température intermédiaire sur une large plage de pression partielle d'oxygène en maintenant d'excellentes performances. Ils sont ainsi considérés comme de bons candidats pour les électrolytes de piles de type IT-SOFC. Parmi cette série de conducteurs, le type La-Si-O possède une conductivité plus élevée et leur performance serait modifiée par différents éléments dopants.L'objectif de cette thèse est d'étudier les effets des éléments de substitution / dopage ainsi que les méthodes de synthèse sur les propriétés structurales ainsi que sur la conductivité des apatites de type silicates de lanthane. Dans cette étude, nous utilisons une double approche: une approche de simulation et une approche expérimentale pour optimiser la pureté et les performances des matériaux d'électrolyte.Dans l'approche de simulation, le calcul basé sur la DFT (Théorie de la fonctionnelle de la densité) a été réalisée en vue d’étudier l'effet des positions de dopage: dopant Sr à La position de La et dopant Ge à la position de Si. Les résultats obtenus par le calcul concernant la conductivité ionique confirment ceux obtenus par l’expérience.Avec l’approche expérimentale, nous présentons la synthèse et la caractérisation de La10Si6O27 (LSO) dopé par Sr et élaboré par des procédés sol-gel. Les résultats montrent que la conductivité ionique est activé thermiquement et que les valeurs se situent entre 4,5 × 10-2 et 1 x 10-6 S·cm-1 à 873 K et dépend des conditions d’élaboration et de la composition de la poudre
The Solid Oxide Fuel Cell (SOFC) defined by its ceramic and oxide electrolyte, is an electrochemical energy conversion device that produces electricity directly from the chemical reaction of fuel. Nowadays, apatite type rare earths silicates and germaniums attract many interests as the solid electrolyte due to the superior transport properties with high ionic conductivity and low activation energy. They can operate stably at intermediate temperature over a wide oxygen partial pressure range and maintain excellent performances, being considered as a candidate for IT-SOFC electrolytes. Among this series of conductors, the La-Si-O type has a higher conductivity and the performance would be modified by different doping elements.The objective of this thesis is to study the effects of element substitution/doping and synthesis methods on the structural and conductivity properties of apatite type lanthanum silicates. In this study, we use a double approach: a simulation approach and an experimental approach to optimize the electrolyte materials purity and performance.Using simulation approach, a first principle calculation based on DFT (Density Functional Theory) was carried out to investigate the effect on doping positions: Sr dopant at La position and Ge dopant at Si position. The calculation results give a connection to the ionic conductivity obtained by experiments.With experimental approach, we present the synthesis and characterization of Sr-doped La10Si6O27 (LSO) prepared through an optimized water-based sol-gel process. The results show that the ionic conductivity is thermally activated and values lies between 4.5×10-2 and 1×10-6 Scm-1 at 873 K as a function of the composition and powder preparation conditions

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Guillot, Stéphanie. "Étude des paramètres principaux gouvernant les propriétés de conduction dans les apatites, électrolytes pour piles SOFC." Thesis, Lille 1, 2009. http://www.theses.fr/2009LIL10052/document.

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Cette thèse a pour objet l’élaboration et la caractérisation d’oxyapatite silicatées de lanthane, matériaux potentiellement utilisables comme électrolyte pour piles à combustible à oxyde solide. Des poudres et céramiques denses d’apatite de stœchiométries en oxygène et de compositions (substitutions) différentes ont été élaborées par réaction à l’état solide à haute température. Il ressort que quelque soit la composition, le paramètre principal qui gouverne les propriétés de conduction est la stœchiométrie en oxygène. La conductivité atteint 1,7 x 10-2 S.cm-1 à 700°C pour la composition La10Si5,5Mg0,5O26,5. La combinaison d’analyses spectroscopiques (Diffusion Raman, Résonance Magnétique Nucléaire) et de diffraction des neutrons a permis de définir un mécanisme de conduction des ions oxydes dans la structure. L’existence d’un site interstitiel localisé dans les canaux de la structure apatite en (-0,01, 0,04, 0,06) est confirmée. Un chemin de diffusion des ions oxyde de type « lacune sur le site 2a – atome interstitiel » est proposé le long de l’axe c. Ce mécanisme semble facilité par le déplacement des tétraèdres situés à la périphérie du canal
This work is devoted to the elaboration and the characterisation of apatite type lanthanum silicates as new electrolyte for SOFC fuel cells. Apatite powders and dense ceramics with different oxygen stoichiometries and compositions (substitutions) were prepared by high temperature solid state reaction. Whatever the composition, we can conclude that the key parameter which governs the conduction properties is the oxygen stoichiometry. The conductivity reaches 1.7 x 10-2 S.cm-1 at 700°C for the La10Si5,5Mg0,5O26,5 composition. By combining Raman spectroscopy, NMR and neutron diffraction, an oxide ion conduction mechanism was deduced. The existence of an interstitial site located at (-0.01, 0.04, 0.06) was confirmed. This allows to proposed a realistic oxygen diffusion pathway through this interstitial site along the c axis. Moreover, this mechanism seems to be facilitated by the displacement of tetrahedral located at the periphery of the oxide channels

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ELIAS, DANIEL R. "Síntese e caracterização de pós de silicato de lantânio tipo apatita para eletrólito em SOFC." reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10612.

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Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

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Ben, Allal Laïla. "Préparation et caractérisation de silicates hydratés de lanthane, thorium, zirconium et aluminium en relation avec le problème de l'altération par l'eau de verres contenant ces éléments." Dijon, 1992. http://www.theses.fr/1992DIJOS020.

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Ce travail a permis de mettre en évidence l'influence de différents facteurs tels que le pH, le rapport molaire SiO2/K2O, le sens de mélange des réactifs sur la nature et la composition de silicates et polysilicates de différents éléments polyvalents. Ces éléments ont été choisis, dans le cadre d'un contrat avec le C. E. A. , pour leurs propriétés chimiques proches de celles de certains radionucléides : ce fut le cas pour le lanthane et le thorium ou en raison de leur présence dans la fritte, comme le zirconium et l'aluminium, lors de la fabrication des blocs de verres incluant ces éléments et les oxydes de radionucléides en vue de leur immobilisation comme déchets radioactifs. L'évolution de la composition des corps obtenus en fonction des facteurs cités ci-dessus a été suivie au moyen de différentes méthodes analytiques: analyse chimique quantitative, sonde à dispersion d'énergie, diffraction des rayons X peu opérante du fait de l'état amorphe des composés formes ; en revanche, la spectrométrie de vibration infrarouge a permis de mettre en évidence la formation des ponts siloxanes et les degrés de polymérisation plus ou moins importants des entités structurales silicatées et de les différencier du cas où, par abaissement préalable du pH du réactif, il se forme un gel de silice adsorbant les cations polyvalents sous forme d'hydroxydes. Les résultats obtenus permettent de simuler les composés susceptibles de se produire superficiellement quand le verre nucléaire se trouve au contact de l'eau.

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Henneberg, Eva. "Thermodynamische und kinetische Untersuchungen im System La-Si-H-(Cl)." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola&quot, 2009. http://nbn-resolving.de/urn:nbn:de:swb:105-7723129.

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Ausgehend von den binären Systemen La-H und La-Si, wurde das Hydrierungs- und Dehydrierungsverhalten von La5Si3, LaSi und LaSi2 mittels thermogravimetrischer und thermoanalytischer Methoden eingehend untersucht und mit den Aussagen thermodynamischer Gleichgewichtsberechnungen verglichen. Die synthetisierten Silicide und Reaktionsprodukte wurden mittels Röntgenpulverdiffraktometrie charakterisiert. La als starker Hydridbildner dominiert die Eigenschaften seiner Silicide. Ein hoher La-Gehalt führt zu einer starken H2-Affinität des Silicids. Zusätzlich zu den berechneten binären Phasen kommt es zur Bildung von stabilen und metastabilen ternären Hydriden. Während LaSi2 über einen weiten Druck- und Temperaturbereich nicht mit H2 reagiert, nimmt La5Si3 schon bei niedrigen Temperaturen in einer mehrstufigen Reaktion unter Zerfall der Ausgangsverbindung Wasserstoff auf. Die Hydrierung von LaSi verläuft reversibel unter Bildung eines stabilen ternären Hydrides. Die Synthese von La-Siliciden aus LaH3 und Si ist in Abhängigkeit vom La-Gehalt schon bei milden Temperaturen möglich.

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Book chapters on the topic "Lanthanum silicate"

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Kato, Sumio, Takuya Yoshizawa, Kimihiro Yokoyama, Kenya Kosagawa, Masataka Ogasawara, Shinichi Nakata, Takashi Wakabayashi, and Yuunosuke Nakahara. "Preparation of Apatite-type Lanthanum Silicate Supported Catalysts for Pollutant Gas Purification." In Science and Technology in Catalysis 2006, 617–18. Elsevier, 2007. http://dx.doi.org/10.1016/b978-0-444-53202-2.50168-8.

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"Recent Advances in Synthesis of Lanthanum Silicate Apatite Powders as New Oxygen-Ion Conductor for IT-SOFCs: A Review." In Frontiers in Ceramic Science, edited by Chieko Yamagata, Daniel R. Elias, Agatha M. Misso, and Fernando S. Santos, 42–69. BENTHAM SCIENCE PUBLISHERS, 2017. http://dx.doi.org/10.2174/9781681084312117010008.

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Wallau, Martin, Rogério A. A. Melo, and Ernesto A. Urquieta-González. "Influence of aluminium, lanthanum and cerium on the thermal and hydrothermal stability of MCM-41-Type silicates." In Nanotechnology in Mesostructured Materials, Proceedings of the 3rd International Materials Symposium, 303–6. Elsevier, 2003. http://dx.doi.org/10.1016/s0167-2991(03)80385-3.

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Conference papers on the topic "Lanthanum silicate"

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Wu, Zhifang, Ping Shum, Xuguang Shao, Hailiang Zhang, Tianye Huang, Nan Zhang, Georges Humbert, et al. "Grating Effect in Lanthanum Aluminum Silicate Glass Fiber." In CLEO: Science and Innovations. Washington, D.C.: OSA, 2015. http://dx.doi.org/10.1364/cleo_si.2015.sm3l.2.

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Schuster, K., D. Litzkendorf, S. Grimm, J. Kobelke, A. Schwuchow, A. Ludwig, M. Leich, et al. "Study of lanthanum aluminum silicate glasses for passive and active optical fibers." In SPIE OPTO, edited by Michel J. F. Digonnet, Shibin Jiang, and J. Christopher Dries. SPIE, 2013. http://dx.doi.org/10.1117/12.2004011.

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Wei Gao, Hanlin Liao, and Christian Coddet. "Microstructure and mechanical properties of lanthanum silicate coatings prepared by atmospheric plasma spraying." In 2008 IEEE 35th International Conference on Plasma Science (ICOPS). IEEE, 2008. http://dx.doi.org/10.1109/plasma.2008.4590888.

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Irzhak, D., D. Roshchupkin, and L. Ortega. "Temperature dependence of X-ray diffraction on lanthanum-gallium silicate crystal modulated by surface acoustic wave." In 2013 IEEE International Ultrasonics Symposium (IUS). IEEE, 2013. http://dx.doi.org/10.1109/ultsym.2013.0057.

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Absah, H. Q. H. H., S. A. M. Ali, M. Anwar, A. M. Abdalla, A. H. Karim, M. R. Somali, J. Y. Park, and A. K. Azad. "Synthesis and Characterization of La9.95Ba0.05Si5.8Zn0.2O26.775 Co-doped Lanthanum Silicate Electrolyte For Intermediate Temperature Solid Oxide Fuel Cells." In 7th Brunei International Conference on Engineering and Technology 2018 (BICET 2018). Institution of Engineering and Technology, 2018. http://dx.doi.org/10.1049/cp.2018.1544.

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Yang, Xiangyu, Bongmook Lee, and Veena Misra. "Effect of post deposition annealing for high mobility 4H-SiC MOSFET utilizing lanthanum silicate and atomic layer deposited SiO2." In 2014 IEEE Workshop on Wide Bandgap Power Devices and Applications (WiPDA). IEEE, 2014. http://dx.doi.org/10.1109/wipda.2014.6964637.

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Noviyanti, Atiek Rostika, Bambang Prijamboedi, I. Nyoman Marsih, Rino R. Mukti, and Ismunandar. "Conductivity and solid state ²⁹Si NMR studies of apatite-type lanthanum silicate prepared by hydrothermal method." In 2011 2nd International Conference on Instrumentation, Communications, Information Technology, and Biomedical Engineering (ICICI-BME). IEEE, 2011. http://dx.doi.org/10.1109/icici-bme.2011.6108653.

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Smitha, Venu Sreekala, and Krishna Gopakumar Warrier. "Sol-gel derived functional coatings of titania-silica-lanthanum phosphate nanocomposite." In International Conference on Nanoscience, Engineering and Technology (ICONSET 2011). IEEE, 2011. http://dx.doi.org/10.1109/iconset.2011.6167976.

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Lee, Felix, Sam Goljahi, Ian McKinley, Christopher S. Lynch, and Laurent Pilon. "Pyroelectric Energy Harvesting Using the Olsen Cycle on Relaxor Ferroelectric 8/65/35 PLZT." In ASME 2012 Third International Conference on Micro/Nanoscale Heat and Mass Transfer. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/mnhmt2012-75152.

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Waste heat can be directly converted into electrical energy by performing the Olsen cycle on pyroelectric materials. The Olsen cycle consists of two isothermal and two isoelectric field processes in the electric displacement versus electric field diagram. This paper reports on the energy harvested by lanthanum doped lead zirconate titanate (8/65/35 PLZT) subjected to the Olsen cycle. The material was alternatively dipped into a cold and a hot silicone oil bath under specified electric fields. A maximum energy density of 770 J/L per cycle corresponding to a power density of 9.6 W/L was obtained for temperatures between 25 and 160°C and electric fields cycled between 0.2 and 4.5 MV/m.

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Jiang, F., Y. K. Leong, M. Martyniuk, A. Keating, and J. M. Dell. "Dispersion of lanthanum hexaboride nanoparticles in water and in sol-gel silica arrays." In Devices (COMMAD). IEEE, 2010. http://dx.doi.org/10.1109/commad.2010.5699718.

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