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Sun, Zhe. "Angle-resolved photoemission studies on bi-layer colossal magnetoresistive oxides lanthanum(2-2x)strontium(1+2x)manganese(2)oxide(7)." Diss., Connect to online resource, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3239456.
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Cooper, Celeste Eaton. "Degradation in Performance of Lanthanum Strontium Manganite Based Solid Oxide Fuel Cell Cathodes Under Accelerated Testing." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case1485524881843845.
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CHIBA, RUBENS. "Sintese, processamento e caracterizacao das meia-celulas de oxido solido catodo/eletrolito de manganito de lantanio dopado com estroncio/zirconia estabilizada com itria." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9503.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Yang, Jun. "Studies on Polarization Behavior and Microstructure of Strontium-doped Lanthanum Manganite Cathodes for Solid Oxide Fuel Cells." 京都大学 (Kyoto University), 2011. http://hdl.handle.net/2433/151984.
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Gong, Minhui. "Etude des électrodes sur batterie zinc-air." Electronic Thesis or Diss., Université Paris sciences et lettres, 2021. http://www.theses.fr/2021UPSLC024.
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La batterie zinc-air devient une alternative potentielle à la batterie lithium-ion en raison de son avantage en termes de ressources, de sa densité d'énergie théorique élevée et de son faible potentiel de risque pour la sécurité. Ce travail met l'accent sur les problèmes conventionnels impliquant à la fois l'électrode à zinc et à air, visant à l'application.Pour l'électrode de zinc, deux configurations maison sont utilisées pour étudier la croissance des dendrites de zinc et l'évolution de l'hydrogène pendant le dépôt avec un électrolyte statique et en flux, respectivement. On trouve qu'une concentration élevée de zincate dans un électrolyte avec 7 M KOH (> 0,4 M ZnO) et la présence de circulation de l’électrolyte sont préférables pour réduire la croissance des dendrites. Cependant l'électrolyte en circulation générerait plus de dégagement d'hydrogène. Pour l'électrode à air, une étude de voltampèremètre cyclique détaillée de l'activité catalytique de pérovskites de lanthane- manganèse dopés au strontium (LSMO) vis-à-vis de la réaction de réduction de l'oxygène est menée. Une nouvelle méthodologie est proposée pour la comparaison de l'activité catalytique des LSMO. L'assemblage de la batterie zinc-air est également testé en formulant les électrodes avec un polymère PVDF-HFP prometteur dans les applications d’électrode à airZinc-air battery is becoming a potential alternative for lithium-ion battery owing to its resource stock advantage, high theoretical energy density, and low potential of safety risk. This work emphasizes the conventional issues involving both zinc and air electrode, aiming to application.For the zinc electrode, two homemade setups are used to study the zinc dendrite growth and hydrogen evolution during deposition with static and flowing electrolyte, respectively. It is found that high zincate concentration in electrolyte with 7 M KOH (>0.4 M ZnO) and flowing electrolyte are preferable for depressing dendrite growth. While flowing electrolyte would generate more hydrogen evolution. For the air electrode, a detailed cyclic voltametric investigation of the catalytic activity of lanthanum strontium manganese oxides (LSMO) towards oxygen reduction reaction is conducted. A new current normalization method is proposed for comparison of catalytic activity of the LSMOs. Zinc-air battery assembly is also tested, while remaining to be improved. Nevertheless, cost-effective PVDF-HFP is found to be a promising binder for air electrode formulation
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Lauret, Hervé. "Propriétés électriques et électrochimiques de manganites de lanthane dopées comme matériau de cathode pour pile à combustible à oxyde électrolyte solide." Grenoble INPG, 1994. http://www.theses.fr/1994INPG0053.
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Ce travail consiste en l'etude de materiaux de cathode pour les piles a combustible haute temperature. Ces materiaux ont pour formule generale la1-xsrxmno3 et (la1-yyy)0,5sr0,5mno3. Dans un premier chapitre nous faisons le point sur l'etat des recherches sur les piles a combustible a oxyde electrolyte solide et leurs constituants. Le deuxieme chapitre presente la synthese des echantillons ainsi que les differents dispositifs de mesures. Le chapitre trois est consacre a la caracterisation physique et electrique des echantillons. Nous avons montre en particulier que le dopage a l'yttrium diminuait le coefficient de dilatation thermique des manganites de lanthane. Pour les echantillons exempts d'yttrium une conductivite maximale est obtenue pour x=0,55. Une etude sur la reaction de reduction de l'oxygene a l'interface la1-xsrxmno3/y2o3-zro2 est menee dans le chapitre quatre. Nous confirmons l'apparition d'un effet electrocatalytique specifique a ce materiau d'electrode. Nous apportons une contribution complementaire a la comprehension du processus d'electrode: l'echantillon qui presente la plus grande activite electrocatalytique est celui qui a la plus forte conductivite electrique. Aux faibles polarisations cathodiques, superieures a -150 mv/air, nous prouvons que l'etape limitante a lieu le long du contact triple. Aux plus fortes polarisations cathodiques nous emettons l'hypothese d'une extension progressive de la reaction sur une zone annulaire autour du perimetre de contact entre le materiau de cathode et l'electrolyte. Enfin, la surface du materiau d'electrode exposee au gaz n'est pas limitante
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Hammouche, Abderrezak. "Contribution à l'étude de La(1-x)Sr(x)MnO3 comme matériau d'électrode à oxygène à haute température." Grenoble INPG, 1989. http://www.theses.fr/1989INPG0075.
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Les composes la#1##xsr#xmno#3 sont utilises comme materiau d'electrode a oxygene utilisables dans les cellules galvaniques mettant en jeu un oxyde d'electrolytes solides. Leur caracterisation physicochimique a porte sur la determination de la structure cristalline et l'etude des proprietes thermiques et electriques
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Chung, Kimberly. "Investigation of the structure and properties of lanthanum strontium nickel oxide." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 360 p, 2008. http://proquest.umi.com/pqdweb?did=1609293431&sid=5&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Price, Robert. "Metal/metal oxide co-impregnated lanthanum strontium calcium titanate anodes for solid oxide fuel cells." Thesis, University of St Andrews, 2018. http://hdl.handle.net/10023/16018.
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Solid Oxide Fuel Cells (SOFC) are electrochemical energy conversion devices which allow fuel gases, e.g. hydrogen or natural gas, to be converted to electricity and heat at much high efficiencies than combustion-based energy conversion technologies. SOFC are particularly suited to employment in stationary energy conversion applications, e.g. micro-combined heat and power (μ-CHP) and base load, which are certain to play a large role in worldwide decentralisation of power distribution and supply over the coming decades. Use of high-temperature SOFC technology within these systems is also a vital requirement in order to utilise fuel gases which are readily available in different areas of the world. Unfortunately, the limiting factor to the long-term commercialisation of SOFC systems is the redox instability, coking intolerance and sulphur poisoning of the state-of-the-art Ni-based cermet composite anode material. This research explores the ‘powder to power' development of alternative SOFC anode catalyst systems by impregnation of an A-site deficient La0.20Sr0.25Ca0.45TiO3 (LSCT[sub](A-)) anode ‘backbone' microstructure with coatings of ceria-based oxide ion conductors and metallic electrocatalyst particles, in order to create a SOFC anode which exhibits high redox stability, tolerance to sulphur poisoning and low voltage degradation rates under operating conditions. A 75 weight percent (wt. %) solids loading LSCT[sub](A-) ink, exhibiting ideal properties for screen printing of thick-film SOFC anode layers, was screen printed with 325 and 230 mesh counts (per inch) screens onto electrolyte supports. Sintering of anode layers between 1250 °C and 1350 °C for 1 to 2 hours indicated that microstructures printed with the 230 mesh screen provided a higher porosity and improved grain connectivity than those printed with the 325 mesh screen. Sintering anode layers at 1350 °C for 2 hours provided an anode microstructure with an advantageous combination of lateral grain connectivity and porosity, giving rise to an ‘effective' electrical conductivity of 17.5 S cm−1 at 850 °C. Impregnation of this optimised LSCT[sub](A-) anode scaffold with 13-16 wt. % (of the anode mass) Ce0.80Gd0.20O1.90 (CGO) and either Ni (5 wt. %), Pd, Pt, Rh or Ru (2-3 wt. %) and integration into SOFC resulted in achievement of Area Specific Resistances (ASR) of as low as 0.39 Ω cm−2, using thick (160 μm) 6ScSZ electrolytes. Durability testing of SOFC with Ni/CGO, Ni/CeO2, Pt/CGO and Rh/CGO impregnated LSCT[sub](A-) anodes was subsequently carried out in industrial button cell test rigs at HEXIS AG, Winterthur, Switzerland. Both Ni/CGO and Pt/CGO cells showed unacceptable levels of degradation (14.9% and 13.4%, respectively) during a ~960 hour period of operation, including redox/thermo/thermoredox cycling treatments. Significantly, by exchanging the CGO component for the CeO2 component in the SOFC containing Ni, the degradation over the same time period was almost halved. Most importantly, galvanostatic operation of the SOFC with a Rh/CGO impregnated anode for >3000 hours (without cycling treatments) resulted in an average voltage degradation rate of < 1.9% kh−1 which, to the author's knowledge, has not previously been reported for an alternative, SrTiO3-based anode material. Finally, transfer of the Rh/CGO impregnated LSCT[sub](A-) anode to industrial short stack (5 cells) scale at HEXIS AG revealed that operation in relevant conditions, with low gas flow rates, resulted in accelerated degradation of the Rh/CGO anode. During a 1451 hour period of galvanostatic operation, with redox cycles and overload treatments, a voltage degradation of 19.2% was observed. Redox cycling was noted to briefly recover performance of the stack before rapidly degrading back to the pre-redox cycling performance, though redox cycling does not affect this anode detrimentally. Instead, a more severe, underlying degradation mechanism, most likely caused by instability and agglomeration of Rh nanoparticles under operating conditions, is responsible for this observed degradation. Furthermore, exposure of the SOFC to fuel utilisations of >100% (overloading) had little effect on the Rh/CGO co-impregnated LSCT[sub](A-) anodes, giving a direct advantage over the standard HEXIS SOFC. Finally, elevated ohmic resistances caused by imperfect contacting with the Ni-based current collector materials highlighted that a new method of current collection must be developed for use with these anode materials.
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Gharavi-Naeini, Jafar. "Doping and temperature dependence of the Raman spectra lanthanum strontium copper oxide." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape9/PQDD_0028/NQ51865.pdf.
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Esteve, David. "Développement d'une technique de caractérisation optique appliquée au suivi in situ de la croissance d'oxydes fonctionnels par ablation laser pulsé." Paris 11, 2010. http://www.theses.fr/2010PA112385.
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Une instrumentation optique entièrement statique permettant le suivi in situ de la croissance d'oxydes fonctionnels par ablation laser pulsé, est présenté. Au travers de l'étude de deux système modèles, que sont la croissance de films minces de La₀. ₆₇Sr₀. ₃₃LMnO₃ sur des pseudo-substrats de SrTiO₃/Si et de couches minces de SrRuO₃ déposées sur des substrats de SrTiO₃ vicinaux, le dispositif proposé permet d'obtenir une précision de mesure sur les épaisseurs de l'ordre de la maille atomique (4Å), d'extraire les paramètres physiques de diffusion des espèces en surface (énergie d'activation de diffusion), mais aussi d'observer et d'identifier les modes de croissance. Ces résultats sont en parfait accord avec la simulation numérique développée, reposant sur des modèles de traitement de réflectivité de systèmes multi couches combiné avec la théorie des milieux effectifsA fully static set up allowing in situ observation of the growth of functionnal oxides grown by pulsed laser deposition, is presented. Through the study of two model systems, those are the growth of thin films of La₀. ₆₇Sr₀. ₃₃LMnO₃ on pseudo-substrate of SrTiO₃/Si and thin layers of SrRuO₃ grown on vicinal substrate of SrTiO₃, the proposed instrumentation permit to achieve a precision about one unit cell (4Å) on thickness measurments, to extract physical parameters of the diffusion of species on the surface (activation energy of diffusion), but also observing and identifying growth modes. These results are in good agreement with the numerical simulation developped, based on the treatment of the reflectivity of multi-layers systems combined with effective medium theory
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Chiba, Rubens. "Síntese, processamento e caracterização das meia-células de óxido sólido catodo/eletrólito de manganito de lantânio dopado com estrôncio/zircônia estabilizada com ítria." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85134/tde-29082011-141252/.
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Os filmes cerâmicos de manganito de lantânio dopado com estrôncio (LSM) e de manganito de lantânio dopado com estrôncio/zircônia estabilizada com ítria (LSM/YSZ) são utilizados como catodos das células a combustível de óxido sólido de temperatura alta (CaCOSTA). Estes filmes cerâmicos porosos foram depositados sobre o substrato cerâmico denso de YSZ, utilizado como eletrólito, componente estrutural do módulo, assim conferindo uma configuração de meia-célula denominada auto-suporte. O estudo da meia-célula é fundamental, pois na interface catodo/eletrólito ocorre a reação de redução do oxigênio, conseqüentemente influenciando no desempenho da CaCOSTA. Neste sentido, o presente trabalho contribui para a síntese de pós de LSM e LSM/YSZ e para o processamento de filmes finos, utilizando a técnica de pulverização de pó úmido, adotada para a conformação dos filmes cerâmicos por permitir a obtenção de camadas porosas com espessuras variadas na ordem de micrômetros. Os pós de LSM foram sintetizados pela técnica de citratos e os pós de LSM/YSZ pela técnica de mistura de sólidos. Na etapa de conformação foram preparadas suspensões orgânicas de LSM e LSM/YSZ alimentada por gravidade em um aerógrafo manual. Para a conformação do substrato de YSZ utilizou-se uma prensa uniaxial hidráulica. Foram possíveis a obtenção das meia-células de óxido sólido catodo/eletrólito de estruturas cristalinas hexagonal para a fase LSM e cúbica para a fase YSZ. E as micrografias das meia-células mostram que o substrato YSZ é denso, suficiente para ser utilizado como eletrólito sólido, e os filmes de LSM e LSM/YSZ apresentam-se porosos com espessura de aproximadamente 30 μm e com boa aderência entre os catodos e o eletrólito. A presença do catodo compósito entre o catodo LSM e o substrato YSZ, possibilitou um aumento no desempenho eletroquímico na reação de redução do oxigênio.The ceramic films of strontium-doped lanthanum manganite (LSM) and strontiumdoped 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 hydraulical 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.
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Cooper, Matthew E. "Energy Production from Coal Syngas Containing H2S via Solid Oxide Fuel Cells Utilizing Lanthanum Strontium Vanadate Anodes." Ohio University / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1219867679.
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Cooper, Matthew E. "Energy production from coal syngas containing H₂S via solid oxide fuel cells utilizing lanthanum strontium vanadate anodes." Ohio : Ohio University, 2008. http://www.ohiolink.edu/etd/view.cgi?ohiou1219867679.
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Podpirka, Adrian Alexander. "Studies on Synthesis, Structural and Electrical Properties of Complex Oxide Thin Films: Ba1-xSrxTiO3 and La2-xSrxNiO4." Thesis, Harvard University, 2012. http://dissertations.umi.com/gsas.harvard:10247.
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High performance miniaturized passives are of great importance for advanced nanoelectronic packages for several applications including efficient power delivery. Low cost thin film capacitors fabricated directly on package (and/or on-chip) are an attractive approach towards realizing such devices. This thesis aims to explore fundamental frequency dependent dielectric and insulating properties of thin film high-k dielectric constant in the perovskite and perovskite-related complex oxides. Throughout this thesis, we have successfully observed the role of structure, strain and oxygen stoichiometry on the dielectric properties of thin film complex oxides, allowing a greater understanding of processing conditions and polarization mechanisms. In the first section of the thesis, we explore novel processing methods in the conventional ferroelectric, barium strontium titanate, \(Ba_{1-x}Sr_xTiO_3 (BST)\), using ultraviolet enhanced oxidation techniques in order to achieve improvements in the dielectric properties. Using this method, we also explore the growth of BST on inexpensive non-noble metals such as Ni which presents technical challenges due to the ability to oxidize at high temperatures. We observe a significant lowering of the dielectric loss while also lowering the process temperature which allows us to maintain an intimate interface between the dielectric layer and the metal electrode. The second section of this thesis explores the novel dielectric material, Lanthanum Strontium Nickelate, \(La_{2-x}Sr_xNiO_4 (LSNO)\), which exhibits a colossal dielectric response. For the first time, we report on the colossal dielectric properties of polycrystalline and epitaxial thin film LSNO. We observe a significant polarization dependence on the microstructure due to the grain/grain boundary interaction with charged carriers. We next grew epitaxial films on various insulating oxide substrates in order to decouple the grain boundary interaction. Here we observed substrate dependent dielectric properties associated with induced strain. We also observe, due to the p-type carriers in LSNO, pn junction formation when grown epitaxially on the conducting oxide degenerate n-type Nb-doped \(SrTiO_3\). Finally we explore the growth mechanism of epitaxial LSNO as a function of high oxygen content. Due to the ability for LSNO to take in interstitial oxygen, a reoriented growth is observed at a critical thickness, thereby allowing us to vary anisotropy as a function of deposition conditions.Engineering and Applied Sciences
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Lu, Yunxiang. "Study of electrochemical performance of strontium doped lanthanum cobalt oxides using electrochemical impedance spectroscopy and microelectrode array cell design /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9818.
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CHIBA, RUBENS. "Obtencao e caracterizacao de manganito de lantanio dopado com estroncio para aplicacao em celulas a combustivel de oxido solido." reponame:Repositório Institucional do IPEN, 2005. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11234.
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Dissertacao (Mestrado)
IPEN/D
Intituto de Pesquisas Energeticas e Nucleares, IPEN/CNEN-SP
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Chen, Xiyong. "Thermo-mechanical/structural properties and oxygen permeation behavior of mixed ionic electronic conductors La(1-x)Sr(x)CoO(3-delta) /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/9893.
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RAMIREZ-SALGADO, JOEL. "Contribution à l'étude des électrodes à gaz dans un capteur potentiométrique à CO2 de deuxième espèce." Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE10113.
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Ce travail concerne l'etude de materiaux d'electrode utilisables dans des capteurs a gaz bases sur le nasicon, conducteur par ion sodium. Pour une electrode a oxygene, nous avons synthetise par sol-gel des titanates de sodium. Les mesures de conductivite et l'etude des reactions d'electrode par spectroscopie d'impedance ont permis de choisir le materiau le mieux adapte, auquel nous avons melange un lanthanide de manganese pour ameliorer sa reponse. Une premiere etude sur l'electrode a dioxyde de carbone, a base d'un melange de carbonates et d'or, donne un premier apercu sur les mecanismes de la reaction d'electrode. Des tests sur des capteurs realises par serigraphie ont donne des resultats tres encourageants pour le developpement futur des capteurs a oxygene et a dioxyde de carbone. Pour ce devenir, meme si la reponse est sous-nernstien le domaine de sensibilite va de la ppm a quelques pour cent en teneur.
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Ferrandon, Magali. "Mixed metal oxide - noble metal catalysts for total oxidation of volatile organic compounds and carbon monoxide." Doctoral thesis, Stockholm, 2001. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-3156.
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RODRIGUES, RANIERI A. "Estudo da formação de fases secundárias no compósito LSM/YSZ." reponame:Repositório Institucional do IPEN, 2007. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11563.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP
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SETZ, LUIZ F. G. "Processamento coloidal de cromito de lantanio." reponame:Repositório Institucional do IPEN, 2009. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11522.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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FLORIO, DANIEL Z. de. "Analise de eletrolitos de ZrO sub(2):Y sub(2) O sub(3) + B sub(2) O sub(3) e de eletrodos de La sub(0,8) Sr sub(0,2) Co sub (0,8) Fe sub (0,2) O sub (3-delta) por espectroscopia de impedancia." reponame:Repositório Institucional do IPEN, 2003. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11130.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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MONTEIRO, NATALIA K. "Síntese e caracterização de manganita-cromita de lantânio dopada com rutênio para anodos de células a combustível de óxidos sólidos." reponame:Repositório Institucional do IPEN, 2011. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10041.
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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Kumar, Abhoy. "Processing and Characterization of Porous Lanthanum Strontium Manganite Cathode Layers for Solid Oxide Fuel Cell Applications." Thesis, 2010. http://cgcri.csircentral.net/3234/.
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Hung, Pei-Yu, and 洪珮瑜. "Synthesis and Physical Properties of Nano Lanthanum Strontium Manganese Compounds." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/19008974378215072357.
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碩士國立臺灣大學
材料科學與工程學研究所
92
Different processes for synthesizing the La0.7Sr0.3MnO3/LaMnO3 (LSMO/LMO) powders and films were attempted in this study. The grain sizes of the samples were successfully reduced to 16nm (for powders) and 19nm (for film). The physical properties of samples with different grain sizes were studied, too. At room temperature, the negative MR ratios under a filed of 1 Tesla of the sintered, sol-gel powders and films were 6.25%, 5.95% and 3.69%, respectively. At 20K, however, the negative MR ratios under a field of 1 Tesla were 3.45%, 27.6% and 22.5%, respectively. In addition, the enhanced low field magnetoresistance (LFMR) was observed even at room temperature when LMO is present in the samples. At 20K, all the LSMO/LMO composite samples showed a large LFMR. The negative MR ratios under a field of 0.2T was about 22% for samples with LMO content＞20%. Furthermore, a significant enhancement in MR ratio is also observed in all composite films, especially in the optimal ratio of LMO/LSMO=1/3. Compared with the LSMO single layer sample, the MR ratio at low temperature (20K) can be enhanced up to 31% under an applied field of 0.2 Tesla.
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Chen, Yu-Jen, and 陳佑任. "Investigation in Lanthanum Strontium Cobalt Zinc Iron Oxide of Solid oxide Fuel Cells cathode materials." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/16666073466547846840.
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碩士國立臺灣科技大學
機械工程系
96
This research was focused on the Cathode material, La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d(x=0.0、0.2、0.4、0.6、0.8、1.0), to go through the half-cell test with excellent electrical conductivity of the electrolyte Ce0.78Gd0.2Sr0.02O1.9-x(GDC+Sr) developed by our laboratory. The cathode porosity of test chip/fragment was controlled to be approximately 31.25±3% for evaluating the effect on polarization loss of cathode oxygen reduction reaction and electrical chemical reaction with electrochemical impedance spectroscopy (EIS). A combination of analytical techniques were applied X-ray diffraction for interpreting the crystal structure, scanning electron microscope (SEM) for examining micro-structures, thermo mechanical analyzer (TMA) for finding thermal expansion coefficient (TEC) and (DTA/TGA) thermal analyzers for analyzing the presence of Phase & Change. The variation in component of La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d analyzed by XRD was single-based Rhombohedral Perovskite, a=b=c. The lattice constant and volume were expanded when Zinc ionic substitutes for Cobalt ionic due to the radius of Zinc was 22% being wider than that of Cobalt. According to the statistics from (DTA/TGA) thermal analysis, there was no Phase & Change when x was 0.0~1.0 at 500~800℃ which meant the interface between cathode and electrolyte was stable. In addition, based on the statistics from thermo mechanical analysis, the thermal expansion coefficient of the bulk grew as the temperature increases. Moreover, the thermal expansion coefficient decreased from 16.8 to 13.31 10-6k-1 if Zinc substituted for Cobalt. On the basis of electrical chemical alternating electrical impedance atlas method (x = 0.4, 0.6, 0.8) when Cobalt was replaced by Zinc, the cathode electrical impedance of B-site in La0.6Sr0.4(Co1-x Znx)0.2Fe0.8O3-d series was low (0.273、0.240 & 0.15 Ωcm2，800℃). The difference of cathode electrical impedance (Co -> Zn) in the high frequency region was not obvious. However, among middle and low frequency regions, the imbalance of electric charge caused by adopting the valence two Zinc to B-site instead of Cobalt with floating valence created a lot of oxygen vacancies, accelerating the circulation. Electrons were provided by cobalt switching from valence two, three, to four as well, and therefore the electrical impedance of oxygen reduction reaction was low when coexistence of B-site Zinc and Cobalt. The trend of the testing result statistics was the same as that of electrochemical analysis; such as electric current-switched density of Tafel Curve, Polarization Curve, and Cyclic Voltammetry Curve. Among the components of LSCZF, La0.6Sr0.4(Co0.2 Zn0.8)0.2Fe0.8O3-d�� �nperformed the best because the cathode electrical impedance was quite low �v(0.15 Ωcm2，800℃) and the thermal expansion coefficient (13.95 10-6k-1) is lower than LSCZF0.0(16.8 10-6k-1). Additionally the catalysis was significantly imporoved, due to the higher electric current-switched density. The overall performance of La0.6Sr0.4(Co0.2 Zn0.8)0.2Fe0.8O3-d was found to be better than that of the precursor of La0.6Sr0.4Co0.2 Fe0.8O3-�����nand La0.6Sr0.4Zn0.2 Fe0.8O3-���n,and was proposed as an innovative solid oxide Cathode material with good compatibility and catalysis.
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Kan, Shih-hsuan, and 甘世暄. "Investigation of Lanthanum Praseodymium Strontium Cobalt Iron Oxide as Cathode Materials for Solid Oxide Fuel Cells." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/v4nun8.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
95
The perovskite-structured oxide La0.6Sr0.4Co0.2Fe0.8O3-δ(LSCF) was widely used as cathodic electrode material in SOFC, but, according to the high thermal expansion coefficient, La0.6Sr0.4Co0.2Fe0.8O3-δ need to be modified for better thermal matchness and electrical properties. In this study, praseodymium element which has smaller ionic radius substituted La site and lattice structure, microstructure, thermal expansion coefficient, conductivity, electric over potential, electrochemical reaction and catalysis activation were researched. In order to estimate the durability, the cell was operated under high temperature (800 ℃) for a long time (200 hr) to investigate the performance of cathodic electrode. From the XRD results, the higher praseodymium element doped specimeus posses higher content of am orthorhombic phase and co-exist with a rhombohedra phase in specimen. From the Differential thermal analysis(DTA), Endothermic peaks was not found when the specimeus were tested under dopant quantity of (z) ranging from 0.0 to 0.5 and temperature ranged from 200 to 900 ℃. From thermal mechanical analysis, as the testing temperature raised, thermal expansion increased linearly and ranged in 14.7∼15.98×10-6K-1. The conductivity of LPSCF tested by four-point probe resistance measurement did not affected by Pr doping content in LSCF. While tested under 600 ℃∼800 ℃, the conductivity of LPSCFmaintained at 220 S/cm which is higher than those of LSM and LSF material systems performed. The overpotential behavior and AC impedance analysis of (La0.7Pr0.3)0.6Sr0.4Co0.2Fe0.8O3-δ under 800 ℃ showed the overpotential and polarization resistance of 11.7 mV and 2.3 Ω•cm2, respectively. As the specimens were tested in reduction environment, high density of exchanging current of about 20.05 mA/cm2 was achieved, suggesting that LPSCF provided high cathodic reaction zones junctions and numerous diffusing pathways for oxygen ions to access triple phase boundary. Specimens were tested under 800 ℃ for 200 hours to investigate the decaying condition, the performance of LPSCF, such as thermal expansion coefficient, conductivity, over potential, polarization resistance, catalysis activation and aging ability were superior to those of La0.6Sr0.4Co0.2Fe0.8O3-δ .
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Sahu, Swonsl Sitam. "Preparation and Characterization of Lanthanum Oxide Doped Barium Strontium Titanate Para Electric Glass Ceramics." Thesis, 2015. http://ethesis.nitrkl.ac.in/6871/1/Preparation_Das_2015_(2).pdf.
Full textAbstract:
(Ba0.3Sr0.7)TiO3-2SiO2-B2O3-K2O based borosilicate glass with and without 0.1 mol % La2O3 was successfully developed by melt-quench method. XRD and FTIR spectra of the glass sample confirms the formation of amorphous structure and presence of stretching and deformation vibrations of B-O-Si linkage and Si–O–Si bridges, respectively. Differential scanning calorimetry (DSC) of glass samples reveals that addition of 0.1 mol % La2O3 elevates the onset of crystallization temperature from ~600°C to ~670°C. Controlled crystallization of the glasses ~750-780°C for 3h leads to the formation of desired perovskite SrBaTiO3 glass-ceramics. SEM-EDS analysis of the undoped glass-ceramic sample shows the formation of micron sized flower-like and needle shaped crystals. However, addition of 0.1 mol % La2O3 modify the crystal structure to blocky precipitates. Results from dielectric measurements suggest that space charge polarization mechanism is likely responsible for the large observed dielectric constant (~700) of the 0.1 mol % La2O3 doped glass ceramics sample at low frequencies.
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"Oxygen effects in lanthanum calcium manganese oxide: 氧含量在鑭鈣錳氧化物中的作用." 1997. http://library.cuhk.edu.hk/record=b6073112.
Full textAbstract:
by Yang, Fei.Thesis (Ph.D.)--Chinese University of Hong Kong, 1997.
Includes bibliographical references.
Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web.
Mode of access: World Wide Web.
Abstracts in English and Chinese.
by Yang, Fei.
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Baral, Antara. "Molten-salt Synthesis Of Nanocrystalline Strontium Antimony Manganese Oxide (Sr2SbMnO6) : A Gaint Dielectric Constant Material." Thesis, 2009. https://etd.iisc.ac.in/handle/2005/949.
Full textAbstract:
High dielectric constant materials are of technological importance as they lead to the miniaturization of the electronic devices. For instance, in the case of memory devices based on capacitive components, such as static and dynamic random access memories, the dielectric constant will ultimately decide the level of miniaturization.
In this context, the observation of anomalously high dielectric constant (>10) in the double perovskite Sr2SbMnO6 (SSM) over wide frequency (100 Hz1 MHz) and (190373 K) temperature range has attracted a great deal of attention. However, unfortunately their dielectric losses were also high which limit their use for possible capacitor and related applications. The dielectric loss however was known to decrease with decreasing crystallite size in electroceramics.
Therefore, the present work has been focused on the synthesis of nanocrystalline SSM powders by moltensalt route. The characterization of the ceramics fabricated from these powders for their microstructural and dielectric properties. A cubic phase of SSM powder was obtained by calcining the as synthesized powders at 900°C/10h by using sulphate flux. The crystallite size was ~ 60 nm. The activation energy associated with the particle growth was found to be 95 ± 5 kJmol-1 . The ceramic sintered at 1075°C/16h exhibited high dielectric constant (>10at 1 kHz) with low loss (0.72 at 1 kHz) at room temperature. The results are interpreted in terms of a twolayer model with conducting grains partitioned from each other by poorly conducting grain boundaries. Using this model, we attributed the two electrical responses in impedance and modulus formalisms to the grain and grain boundary effects, respectively, while the detected Debyelike relaxation and large dielectric constant were explained in terms of MaxwellWagner relaxation.
32
Baral, Antara. "Molten-salt Synthesis Of Nanocrystalline Strontium Antimony Manganese Oxide (Sr2SbMnO6) : A Gaint Dielectric Constant Material." Thesis, 2009. http://hdl.handle.net/2005/949.
Full textAbstract:
High dielectric constant materials are of technological importance as they lead to the miniaturization of the electronic devices. For instance, in the case of memory devices based on capacitive components, such as static and dynamic random access memories, the dielectric constant will ultimately decide the level of miniaturization.
In this context, the observation of anomalously high dielectric constant (>10) in the double perovskite Sr2SbMnO6 (SSM) over wide frequency (100 Hz1 MHz) and (190373 K) temperature range has attracted a great deal of attention. However, unfortunately their dielectric losses were also high which limit their use for possible capacitor and related applications. The dielectric loss however was known to decrease with decreasing crystallite size in electroceramics.
Therefore, the present work has been focused on the synthesis of nanocrystalline SSM powders by moltensalt route. The characterization of the ceramics fabricated from these powders for their microstructural and dielectric properties. A cubic phase of SSM powder was obtained by calcining the as synthesized powders at 900°C/10h by using sulphate flux. The crystallite size was ~ 60 nm. The activation energy associated with the particle growth was found to be 95 ± 5 kJmol-1 . The ceramic sintered at 1075°C/16h exhibited high dielectric constant (>10at 1 kHz) with low loss (0.72 at 1 kHz) at room temperature. The results are interpreted in terms of a twolayer model with conducting grains partitioned from each other by poorly conducting grain boundaries. Using this model, we attributed the two electrical responses in impedance and modulus formalisms to the grain and grain boundary effects, respectively, while the detected Debyelike relaxation and large dielectric constant were explained in terms of MaxwellWagner relaxation.
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"Using silver as a binder for synthesis of magnetoresistive lanthanum calcium manganese oxide =: 用银作粘合剂来合成镧钙锰氧磁致电阻材料." 2000. http://library.cuhk.edu.hk/record=b5890275.
Full textAbstract:
Zhou Lingzhao.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.
Includes bibliographical references (leaves 84-85).
Text in English; abstracts in English and Chinese.
Zhou Lingzhao.
Chapter Chapter 1 --- Introduction
Chapter 1.1 --- Magnetoresistance effect --- p.1
Chapter 1.2 --- Giant magnetoresistance (GMR) effect --- p.2
Chapter 1.3 --- CMR effect in rare earth manganites --- p.2
Chapter 1.4 --- Main research in this thesis --- p.5
Chapter Chapter 2 --- Synthesis technology
Chapter 2.1 --- Conventional solid state reaction --- p.8
Chapter 2.2 --- Powder preparation --- p.10
Chapter 2.3 --- Shaping --- p.13
Chapter 2.4 --- Sintering --- p.14
Chapter 2.5 --- Fabrication method in this experiment --- p.20
Chapter 2.6 --- Characterization method --- p.22
Chapter Chapter 3 --- Stoichiometry problems in LCMO
Chapter 3.1 --- Doping effects in La2/3Ca1/3MnO3 --- p.24
Chapter 3.2 --- La stoichiometry in La2/3Ca1/3MnO3 --- p.28
Chapter 3.3 --- Mn stoichiometry in La2/3Ca1/3MnO3 --- p.28
Chapter 3.4 --- Oxygen stoichiometry in La2/3Ca1/3MnO3 --- p.32
Chapter Chapter 4 --- Search for binders in the synthesis of La2/3Ca1/3MnO3
Chapter 4.1 --- Solid state reaction --- p.38
Chapter 4.2 --- Density --- p.39
Chapter 4.3 --- Crystal structure --- p.41
Chapter 4.4 --- SEM analyses --- p.48
Chapter 4.5 --- Resistivity and magnetoresistance --- p.54
Chapter 4.6 --- Small polaron transport --- p.72
Chapter 4.7 --- Conclusion --- p.81