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1
Amoroso, Danila. "Étude ab-initio de solutions solides piézoélectriques (Ba,Ca)TiO3-Ba(Ti,Zr)O3." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0163/document.
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Les piézoélectriques à haute performance sont des composants clés pour les dispositifs agiles. Il a été démontré récemment que les solutions solides (Ba,Ca)(Ti,Zr)O3 (BCTZ) présentent des propriétés électromécaniques prometteuses. Cependant, les mécanismes microscopiques conduisant à de telles caractéristiques restent à éclaircir, et les investigations théoriques de BCTZ demeurent très limitées à ce jour. En conséquence, cette thèse propose d’étudier les propriétés de différentes compositions de solutions solides (Ba,Ca)TiO3-Ba(Ti,Zr)O3 au moyen de calculs de premiers principes, en mettant l’accent sur la dynamiquedu réseau et sur la compétition entre différentes phases ferroélectriques. Nous nous intéressons d’abord aux quatre composés parents BaTiO3, CaTiO3, BaZrO3 et CaZrO3, afin de comparer leurs propriétés et leurs différentes tendances à la ferroélectricité. Ensuite, le coeur de notre étude est une caractérisation systématique des systèmes binaires (Ba,Ca)TiO3 et Ba(Ti,Zr)O3 en utilisant à la fois l’approximation du cristal virtuel (VCA) et des calculs directs sur supercellules.Lorsqu’on passe continument de BaTiO3 à CaTiO3 dans (Ba,Ca)TiO3, la caractéristique principale est une transformation progressive de la ferroélectricité de type B en type A en raison d’effets stériques, lesquels déterminent en grande partie le comportement du système. En particulier, pour les petites concentrations en calcium, nous avons mis en évidence que laferroélectricité guidée par le site B est globalement affaiblie, conduisant à la disparition de la barrière d’énergie entre différents états polaires et à une polarisation quasi-isotrope. Une amélioration considérable de la réponse piézoélectrique résulte de ces caractéristiques. En passant de BaTiO3 à BaZrO3 dans Ba(Ti,Zr)O3, en revanche, le comportement est dominé parles mouvements coopératifs Zr-Ti et l’électrostatique locale. En particulier, la phase R3m est stabilisée significativement pour les faibles concentrations en zirconium. Sous l’effet d’une augmentation de la concentration en zirconium, le système montre une tendance à la réduction de la distorsion polaire; néanmoins, la ferroélectricité peut être préservée localement dans les régionsriches en titane. Grâce à un modèle électrostatique basé sur un super-réseau BaZrO3/mBaTiO3, nous avons également découvert une activation polaire inattendue pour Zr, en fonction d’un ordre atomique spécifique. Un facteur microscopique expliquant la réponse piézoélectrique exaltée dans BCTZ, pour de faibles concentrations en Ca et Zr, peut donc résider dans l’interaction entre la ferroélectricité affaiblie induite par Ti et la ferroélectricité émergente induite par Ca, interaction produisant une anisotropie minimale pour la polarisation. En outre, notre étude comparative révèle que la physique microscopique spécifique de ces solutions solides limite sévèrement l’applicabilité de l’approximation du cristal virtuel (VCA) à ces systèmesHigh-performance piezoelectrics are key components of various smart devicesand, recently, it has been discovered that (Ba,Ca)(Ti,Zr)O3 (BCTZ) solid solutions show appealingelectromechanical properties. Nevertheless, the microscopic mechanisms leading to suchfeatures are still unclear and theoretical investigations of BCTZ remain very limited. Accordingly,this thesis analyzes the properties of various compositions of (Ba,Ca)TiO3-Ba(Ti,Zr)O3solid solutions by means of first-principles calculations, with a focus on the lattice dynamicsand the competition between different ferroelectric phases. We first analyze the four parentcompounds BaTiO3, CaTiO3, BaZrO3 and CaZrO3 in order to compare their properties andtheir different tendency towards ferroelectricity. Then, the core of our study is a systematiccharacterization of the binary systems (Ba,Ca)TiO3 and Ba(Ti,Zr)O3 within both the virtualcrystal approximation (VCA) and direct supercell calculations. When going from BaTiO3 toCaTiO3 in (Ba,Ca)TiO3, the main feature is a gradual transformation from B-type to A-typeferroelectricity due to steric effects that largely determine the behavior of the system. In particular,for low Ca-concentration we found out an overall weakened B-driven ferroelectricitythat produces the vanishing of the energy barrier between different polar states and resultsin a quasi-isotropic polarization. A sizable enhancement of the piezoelectric response resultsfrom these features. When going from BaTiO3 to BaZrO3 in Ba(Ti,Zr)O3, in contrast, thebehavior is dominated by cooperative Zr-Ti motions and the local electrostatics. In particular,low Zr-concentration produces the further stabilization of the R3m-phase. Then, the systemshows the tendency to globally reduce the polar distortion with increasing Zr-concentration.Nevertheless, ferroelectricity can be locally preserved in Ti-rich regions. We also found out anunexpected polar activation of Zr as a function of specific atomic ordering explained via a basicelectrostatic model based on BaZrO3/mBaTiO3 superlattice. A microscopic factor behind theenhanced piezoelectric response in BCTZ, at low concentration of Ca and Zr, can thus be theinterplay between weakened Ti-driven and emerging Ca-driven ferroelectricity, which producesminimal anisotropy for the polarization. In addition, our comparative study reveals that thespecific microscopic physics of these solid solutions sets severe limits to the applicability of thevirtual crystal approximation (VCA) for these systems
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Kuvatov, Azamat. "Polungs- und Biegeverhalten von Ba(Ti, Sn)O3-Keramiken mit einem Funktionsgradienten." [S.l. : s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=975671650.
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Franklyn, Paul John. "Synthesis, characterisation and structural investigations of nanoparticulate forms of selected (W, Ti, Al, Ba) mixed metal oxides." Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610234.
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Bijalwan, Vijay. "Studie syntéz a přípravy bezolovnaté keramiky (Ba,Ca)(Ti,Zr)O3 v závislosti na struktuře a výsledných vlastností." Doctoral thesis, Vysoké učení technické v Brně. CEITEC VUT, 2018. http://www.nusl.cz/ntk/nusl-390293.
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V poslední době je snahou nahradit klasickou komerční olovnatou piezoelektrickou keramiku bezolovnatou, z důvodu zvýšeného zájmu o ochranu životního prostředí a zdraví. Různé typy materiálů již byly navrženy, jako například (K, Na) NbO3 (KNN), (Bi, Na) TiO3 (BNT), (Bi, Na) TiO3 – BaTiO3 (BNT-BT), ale jejich piezoelektrické vlastnosti zatím nedosáhly takových hodnot jako u olovnatý chkeramik (např. olovnatý titanát olova ((Pb Zr)TiO3). Nejvíce se olovnatým materiálů blíží bezolovnatý systém na bázi (1-x)Ba(Zr0.2Ti0.8)O3-x(Ba0.7Ca0.3)TiO3 nebo (Ba, Ca) (Zr, Ti) O3 ((1-x)BZT-xBCT, BCZT) a to díky vysokým piezoelektrickým a dielektrickým parametrům. Nevýhodou tohoto prostředku je jeho velmi vysoká teplota slinování (1520 ° C) za účelem dosažení vysokých piezoelektrických vlastností (např. Piezoelektrické konstanty d33 > 600 pC / N). Tato práce se zabývá bezolovnatou keramikou na bázi BCZT, její výrobou a vylepšením piezoelektrických vlastností dopováním CeO2. Přidáním CeO2 (y wt.%) do (Ba0.85Ca0.15) (Zr0.1Ti0.9) O3 se výrazně snížila slinovací teplota a došlo ke zhutnění při 1350°C. U této kompozice se Curieova teplota pohybovala kolem TC~105°C a velikost zrn byla v rozmezí ~ 10-13 m. Fázový přechod z romboedrické struktury na tetragonální (R-T) byl zjištěn pomocí rentgenové spektroskopie u y = 0 - 0.1 wt.%, což koreluje s výsledky Ramanovy spektrální analýzy. Mikrostrukturní a strukturní charakteristiky byly detailně studovány v korelaci s dielektrickými, feroelektrickými a piezoelektrickými vlastnostmi. Nejlepší funkční vlastnosti byly dosaženy pro keramiku BCZT – 0.07 wt.% CeO2. Tato keramika vykazovala piezoelektrický nábojový koeficient d33 = 507±20pC/N, elektromechanický planární koeficient kp = 51.8 %, dielektrickou konstantu r = 4091±100, ztrátový činitel tan = 0.02, remanentní polarizaci Pr = 13.58C/cm2, intenzitu koercitivního pole EC = 2.13kV/cm při normovaném napětí, d33* nebo Smax/Emax = 840pm/V. Dvoustupňovou kalcinační technikou bylo docíleno homogenního růstu zrn s vysokou relativní hustotou (~ 99% teoretické hustoty). Tato kompozice BCZT- CeO2 vykazovala stálé feroelektrické, dielektrické a piezoelektrické vlastností i při velikosti zrn 10 µm. Bezolovnatá piezoelektrická keramika (Ba0.85Ca0.15-y Cey) (Zr0.1Ti0.9) O3 (BCCeZT) byla dále dopována CeO2 s cílem substituce Ce4+ v místě A krystalické mřížky. Posunutí rentgenových vrcholů k vyšším úhlům naznačuje kontrakce mřížky, což by mohlo způsobit obsazení iontů ceru v místech A této soustavy. Bylo zjištěno, že velikost zrn kolem 10 - 12 m je významná pro vysokou piezoaktivitu bezolovnaté BCCeZT keramiky. Nejvyšší piezoelektrické vlastnosti tato keramika vykazovala při y;Ce = 0.00135 a slinovaná na teplotě 1350°C/4h, kdy piezoelektrické parametry byly d33 = 501±10 pC/N, kp = 38.5±1.92 %, Pr = 12.19 C/cm2, TC = 108.1 °C a s maximální deformací S do 0.14 %. Pro další studium substituce v místě A, byly vyrobeny keramické materiály (Ba1-x-y Cax Cey) (Zr0.1 Ti0.9) O3 (x:Ca = 0.05, 0.10, 0.15, 0.20 a y;Ce = 0.00135). Opět se ukázalo, že pokud byla velikost zrn ~13um, tak keramika vykazovala vysoké piezoelektrické vlastnosti (d33 = 457pC/N) pro x = 0.15 % kalcinované na teplotě 1425 °C. Když se se velikost zrn zvýšila nad 16 um, piezoelektrický nábojový koeficient d33 klesl na 200 pC/N. Rentgenová analýza ukázala změnu fázové struktury z rombické na tetragonální při zvýšení obsahu vápníku.
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Eliziário, Sayonara Andrade [UNESP]. "Síntese de perovskitas nanométricas com estrutura 'PB IND.1-x''M IND.X''TI''O IND.3'(M='BA', 'CA' e 'SR')." Universidade Estadual Paulista (UNESP), 2010. http://hdl.handle.net/11449/92042.
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O presente trabalho teve como objetivo estudar a formação dos pós com sistemas Pb1-xBaxTiO3, Pb1-xCaxTiO3 e Pb1-xSrxTiO3, em que x = 0; 0,25; 0,5; 0,75 e 1, por intermédio do método hidrotermal associado ao aquecimento em forno de microondas. Estudos foram realizados para a obtenção de um maior entendimento das diferentes propriedades ópticas e eletrônicas das perovskitas, em função da concentração dos dopantes e dos diferentes tempos utilizados nas sínteses. A fim de verificar as suas características estruturais estes pós foram analisados por difração de raios X (DRX), espectroscopia de absorção na região do ultravioleta visível (UV-vis), espectroscopia na região do infravermelho (IV) e de fotoluminescência (FL). Os resultados de DRX confirmaram a presença da fase Pb1-xBaxTiO3 juntamente com a fase BaCO3, enquanto que as fases Pb1-xCaxTiO3 e Pb1-xSrxTiO3 apresentam-se monofásicas. As micrografias obtidas por microscopia eletrônica de varredura com canhão de elétrons por emissão de campo (FEG-MEV) indicam o mecanismo de cristalização-dissolução-recristalização para as amostras do sistema Pb0,5Ba0,5TiO3 e formação de mesocristais para as amostras de PCT. Todos os materiais sintetizados apresentaram propriedades fotoluminescentes, apresentando emissões na região de diferentes comprimentos de onda, sugerindo que as amostras possuem propriedades estruturais que dependem do cátion adicionado. Dessa forma, a emissão pode ser atribuída a distorções nos clusters [TiO6], bem como a existência de clusters complexos de [TiO5], [BaO11], [CaO11] e [SrO11] associados as vacâncias de oxigênio. Testes de aplicação de ferroeletricidade foram realizados, porém as amostras sofreram baixa densificação devido a volatilização do chumbo, no aquecimento em forno convencional
In this work, were studied the formation of powders by microwave hydrothermal method in systems Pb1-xBaxTiO3, Pb1-xCaxTiO3 and Pb1-xSrxTiO3, where x = 0, 0.25, 0.5, 0, 75 and 1. Studies were conducted to obtain a greater understanding of the different optical and electronic properties of perovskites, depending on the concentration of dopants and different times used in the synthesis. These powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy field emission gun (FEG-SEM), ultraviolet visible spectroscopy (UV-vis) infrared spectroscopy (IV) and photoluminescence spectroscopy (PL). The XRD patterns confirmed the second phase BaCO3 in Pb1-xBaxTiO3, while the phase Pb1-xSrxTiO3 present single-phase and the phase Pb1-xCaxTiO3 present two structural phases of same composition at 140 °C. FEG-SEM micrographs indicate the mechanism of crystallization-dissolution-recrystallization for samples of the system Pb0,5Ba0,5TiO3 and „„non-classical crystallization‟‟ with mesocrystal formation for samples of the system PCT. All materials synthesized showed photoluminescent properties, showing regions emissions of different wavelengths, suggesting that samples have structural properties that depend on the cation added. Thus, the emission can be attributed distortions in the clusters [TiO6], and existence of complex clusters [TiO5], [BaO11], [CaO11] e [SrO11] associated oxygen vacancies. Tests were performed applying ferroelectricity, but the samples were subjected to low densification due to volatilization of lead in the conventional oven heating
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Eliziário, Sayonara Andrade. "Síntese de perovskitas nanométricas com estrutura 'PB IND.1-x''M IND.X''TI''O IND.3'(M='BA', 'CA' e 'SR') /." Araraquara [s.n.], 2010. http://hdl.handle.net/11449/92042.
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Resumo: O presente trabalho teve como objetivo estudar a formação dos pós com sistemas Pb1-xBaxTiO3, Pb1-xCaxTiO3 e Pb1-xSrxTiO3, em que x = 0; 0,25; 0,5; 0,75 e 1, por intermédio do método hidrotermal associado ao aquecimento em forno de microondas. Estudos foram realizados para a obtenção de um maior entendimento das diferentes propriedades ópticas e eletrônicas das perovskitas, em função da concentração dos dopantes e dos diferentes tempos utilizados nas sínteses. A fim de verificar as suas características estruturais estes pós foram analisados por difração de raios X (DRX), espectroscopia de absorção na região do ultravioleta visível (UV-vis), espectroscopia na região do infravermelho (IV) e de fotoluminescência (FL). Os resultados de DRX confirmaram a presença da fase Pb1-xBaxTiO3 juntamente com a fase BaCO3, enquanto que as fases Pb1-xCaxTiO3 e Pb1-xSrxTiO3 apresentam-se monofásicas. As micrografias obtidas por microscopia eletrônica de varredura com canhão de elétrons por emissão de campo (FEG-MEV) indicam o mecanismo de cristalização-dissolução-recristalização para as amostras do sistema Pb0,5Ba0,5TiO3 e formação de mesocristais para as amostras de PCT. Todos os materiais sintetizados apresentaram propriedades fotoluminescentes, apresentando emissões na região de diferentes comprimentos de onda, sugerindo que as amostras possuem propriedades estruturais que dependem do cátion adicionado. Dessa forma, a emissão pode ser atribuída a distorções nos clusters [TiO6], bem como a existência de clusters complexos de [TiO5], [BaO11], [CaO11] e [SrO11] associados as vacâncias de oxigênio. Testes de aplicação de ferroeletricidade foram realizados, porém as amostras sofreram baixa densificação devido a volatilização do chumbo, no aquecimento em forno convencionalAbstract: In this work, were studied the formation of powders by microwave hydrothermal method in systems Pb1-xBaxTiO3, Pb1-xCaxTiO3 and Pb1-xSrxTiO3, where x = 0, 0.25, 0.5, 0, 75 and 1. Studies were conducted to obtain a greater understanding of the different optical and electronic properties of perovskites, depending on the concentration of dopants and different times used in the synthesis. These powders were analyzed by X-ray diffraction (XRD), scanning electron microscopy field emission gun (FEG-SEM), ultraviolet visible spectroscopy (UV-vis) infrared spectroscopy (IV) and photoluminescence spectroscopy (PL). The XRD patterns confirmed the second phase BaCO3 in Pb1-xBaxTiO3, while the phase Pb1-xSrxTiO3 present single-phase and the phase Pb1-xCaxTiO3 present two structural phases of same composition at 140 °C. FEG-SEM micrographs indicate the mechanism of crystallization-dissolution-recrystallization for samples of the system Pb0,5Ba0,5TiO3 and „„non-classical crystallization‟‟ with mesocrystal formation for samples of the system PCT. All materials synthesized showed photoluminescent properties, showing regions emissions of different wavelengths, suggesting that samples have structural properties that depend on the cation added. Thus, the emission can be attributed distortions in the clusters [TiO6], and existence of complex clusters [TiO5], [BaO11], [CaO11] e [SrO11] associated oxygen vacancies. Tests were performed applying ferroelectricity, but the samples were subjected to low densification due to volatilization of lead in the conventional oven heating
Orientador: Elson Longo da Silva
Coorientador: Paulo Roberto Bueno
Banca: Paulo Noronha Lisboa Filho
Banca: Paulo Sergio Pizani
Banca: Jose Waldo Martinez Espinosa
Banca: Cristiano Morita Barado
Doutor
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TEYMOURI, AIDMOHAMMAD. "Etude des proprietes catalytiques de perovskites abo#3 (a=ba, sr, ca; b=ti, zr, sn) en couplage oxydant du methane." Université Louis Pasteur (Strasbourg) (1971-2008), 1994. http://www.theses.fr/1994STR13093.
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La reactivite en couplage oxydant du methane (formation d'ethane et d'ethylene) a ete etudiee sur des composes a structure definie, perovskite abo#3 (a=ba, sr, ca; b=ti, zr, sn). La premiere partie du travail comprend l'etude de la preparation des perovskites et la caracterisation primaire (rx, ft-ir, b. E. T. , m. E. B. ). Differentes preparations sol-gel a partir de precurseurs oxydes et a partir de precurseurs chlores ont ete obtenues. L'ensemble des preparations montre que l'addition de l'element chlore dans la preparation est tres favorable pour la selectivite en c#2. Cette remarque est d'autant plus verifiee que le comportement de la perovskite, voie oxyde est plus oxydant. L'addition de molecules chlorees organiques dans les gaz reactionnels confirme l'influence du chlore sur l'augmentation de la selectivite en c#2. Des mesures d'esca, de microanalyse ont permis de montrer les variations de composition entre surface et cur du catalyseur. Des mesures de t. P. D. Ont mis en evidence plusieurs types d'oxygene adsorbes sur la surface, montre des differences importantes d'adsorption entre precurseurs chlores et oxygenes. Ces differences sont retrouvees lors des mesures de basicite de surface par adsorption d'acide benzoique ou de co#2. L'ensemble de ces travaux a conduit a proposer un schema reactionnel pour la reaction et a edicter quelques regles permettant l'obtention de catalyseurs perovskites performants en couplage oxydant
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Daniele, Stéphane. "Synthese, caracterisation et evaluation par le procede sol-gel d'alcoxydes heterometalliques ln-m-ti (ln = lanthanides, m = ba, pb) : precurseurs pour ceramiques dielectriques et electrooptiques." Nice, 1995. http://www.theses.fr/1995NICE4827.
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Une serie d'alcoxydes heterometalliques bati et pbti de stoechiometrie 1:1 (ba#2ti#2(thd)#4(oet)#8(hoet)#2, ba#2ti#2(acac)#4(oet)#8 et pb#2ti#2oz(o#ipr)#8 avec z = o#ipr, oac, acac) a ete obtenue selon differentes voies d'acces. L'evaluation de ces precurseurs par le procede sol-gel a conduit aux perovskites batio#3 et pbtio#3 a 700 et 500c respectivement. L'utilisation de l'acetone et la presence de ligands b-dicetonates a permis d'obtenir des sols a priori interessants pour l'elaboration de films. L'acetone a egalement joue le role d'agent de condensation en milieu non hydrolytique. Differentes voies d'acces aux alcoxydes homometalliques de praseodyme et de gadolinium ont ete explorees. Ln#5o(o#ipr)#1#3 et ln#3(o#tbu)#9(ho#tbu)#2 se sont averes etre des formulations valables pour tous les lanthanides. Leur utilisation a permis d'obtenir respectivement des alcoxydes heterometalliques de stoechiomietries ln#4m' (m' = ti, zr, ln) et ln#3m (m = ba, pb, k). La reactivite des molecules d'alcool de ln#3(o#tbu)#9(ho#tbu)#2 vis-a-vis de composes a liaisons labiles (m-n, m-c) est un moyen pour contourner l'inertie ou la non disponibilite de certains alcoxydes, zinc et nickel en particulier. Le synthon ln-k a permis la synthese d'un compose ln-cu par reaction de metathese avec cucl#2. Enfin l'hydrolyse du compose la-ba donne, a temperature ambiante, une phase cristallisee metastable inconnue pour le systeme la#2o#3-bao. Les acetates sont egalement des precurseurs d'oxydes. Les acetates d'yttrium et de gadolinium reagissent avec differents alcoxydes m(or)#4 (m = ti, zr ; r = #ipr, c#2h#4ome) pour former des acetatoalcoxydes heterometalliques de stoechiometries lnzr#3, lnzr, ln#3zr#2 et lnti#7. L'hydrolyse de gdzr#3(oac)#3(o#ipr)#1#0#2 conduit a la cristallisation, des 600c, de la zircone cubique dopee a 25% par gd#2o#3
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Fompeyrine, Jean. "Propriétés structurales et magnétiques de quelques phases dérivées de la perovskite dans les systèmes La-Ti-O et Ba(M,M') - F-Cl (M,M'élément 3 D)." Phd thesis, Université Sciences et Technologies - Bordeaux I, 1995. http://tel.archives-ouvertes.fr/tel-00148927.
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L'investigation du système La4TI3O12-LaTiO3 a permis de mettre en évidence une nouvelle série homologue de formulation LanTin-xO3n. Les structures de ces phases ont été caractérisées par diffraction des rayons X sur poudre et par microscopie électronique en transmission. Elles dérivent de différents polytypes de perovskites hexagonales et présentent une distorsion structurale due a la rotation coopérative des octaèdres autour de leurs axes ternaires. Une nouvelle serie de composes Ba2MM' F7Cl (M, M' = Mn, Fe, Co, Ni, Zn), dont les structures ont été déterminées par diffraction des rayons X sur monocristal, a été par ailleurs mis en évidence. Une étude comparative des propriétés structurales et magnétiques avec celles des composés de la série BaMF4 a été effectuée (filiation structurale résultant de différentes rotations coopératives des octaèdres, mesures d' aimantation sur poudre et monocristal, détermination des structures magnétiques de Ba2Co2F7Cl et Ba2Ni2F7Cl par diffraction des neutrons). Un nouveau chlorofluorure du cuivre a également été caractérise sur le plan structural et magnétique. Dans ce cas, une filiation structurale avec la structure de l'apatite et avec celle de phases derivees est proposée.
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Mesquita, Alexandre. "Síntese e caracterização estrutural e dielétrica de compostos ferroelétricos \'PB IND.1-X\'\'R IND.X\'\'ZR IND.0,40\'\'TI IND.0,60\'\'O IND.3\' (R = La, Ba)." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/88/88131/tde-19042011-172117/.
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O titanato e zirconato de chumbo \'PB\'(\'ZR\'1-y\'TI\'y)\'O IND.3\' é um material ferroelétrico de estrutura perovskita que tem sido aplicado como transdutores, amplificadores, sensores piezoelétricos, piroelétricos e memórias ferroelétricas. É bem estabelecido que a incorporação de íons de \'LA POT.3+\' ou \'BA POT.2+\' nos sítios ocupados pelo \'PB\' no sistema \'PB\'(\'ZR\'1-y\'TI\'y)\'O\' (PZT), formando os sistemas \'PB\'1-x\'LA\'x\'ZR\'1-y\'TI\'y\'O IND.3\' (PLZT) e \'PB\'1-x\'BA\'x\'ZR\'1-y\'TI\'y\'O IND.3\' (PBZT), provoca mudanças significativas nas suas propriedades. No entanto, poucos trabalhos tem sido dedicados a esses sistemas contendo altas concentrações de \'TI\', principalmente no que se refere à estrutura desses materiais. Assim, este trabalho teve por objetivo analisar as propriedades estruturais e suas correlações com as propriedades dielétricas dos sistemas \'PB\'1-x\'LA\'x\'ZR\'0,40\'TI\'0,60\'O IND.3\' (PLZT100x) e \'PB\'1-x\'BA\'x\'ZR\'0,40\'TI\'0,60\'O IND.3\' (PBZT100x) em função da composição e da temperatura. Foram preparadas amostras cerâmicas por meio de sinterização convencional com x variando entre 0,05 e 0,21 para o sistema PLZT e entre 0,10 e 0,50 para o sistema PBZT. Em relação à estrutura a longa distância, medidas de difração de raios X mostraram uma diminuição no grau de tetragonalidade com o aumento da concentração dos cátions substituintes, que foi atribuída à formação de vacâncias no sítio A (caso do \'LA\') e diferença entre o raio iônico (caso do \'BA\'). Estas alterações estruturais em função da composição foram também responsáveis pelo aumento do grau de difusidade das curvas de permissividade dielétrica e pela observação de um estado ferroelétrico relaxor nas amostras contendo altas concentrações de \'LA\' e \'BA\'. Em relação à estrutural local, os resultados obtidos através da técnica de espectroscopia de absorção de raios X (XAS) nas bordas \'K\' do \'TI\' e LIII do \'PB\' mostraram que a incorporação de átomos de \'LA\' ou \'BA\' à estrutura do PZT leva a uma redução no deslocamento do átomo de \'TI\' em relação ao centro do octaedro \'TI\'O IND.6\' e mudanças na ordem local do átomo de \'PB\'. No que tange as composições contendo 21% at. de \'LA\' e 50% at. de \'BA\', diferentemente dos resultados de DRX que mostraram uma simetria cúbica, a técnica de XAS mostrou uma simetria local tetragonal. Em bom acordo com os resultados obtidos pela técnica de espectroscopia Raman, espectros EXAFS medidos em altas temperaturas mostraram também que a estrutura local não é compatível com uma estrutura de simetria cúbica. Espectros XANES medidos na borda \'K\' do oxigênio revelaram uma redução no grau de hibridização entre os estados 2p do \'O\' com 6sp do \'PB\' à medida que a concentração de \'LA\' ou \'BA\' aumenta, que estaria relacionada com o surgimento de comportamento relaxor. Amostras cerâmicas densas nanoestruturadas de composição PZT, PLZT11 e PBZT10 foram preparadas pelo método de spark plasma sintering (SPS) a fim de analisar a influência do tamanho de grão. Foi verificado que as amostras sinterizadas por SPS apresentam tamanho de grão em torno de 60 nm. A caracterização dielétrica destas amostras mostra que a redução do tamanho de grão causa uma redução no valor de máximo da permissividade dielétrica e características difusas da permissividade em função da temperatura devido ao aumento das regiões de contorno de grão.Lead titanate zirconate (\'PB\'(\'ZR\'1-x\'TI\'x)\'O IND.3\') are ferroelectric materials with perovskite structure which has been used as transducers, capacitors, piezoelectric and pyroelectric sensors and ferroelectric memories. The substitution of \'PB POT.+2\' ions by \'LA POT.+3\' or \'BA POT.+2\' ions in the \'PB\'(\'ZR\'1-x\'TI\'x)\'O IND.3\' (PZT) system, which leads to the formation of the \'PB\'1-x\'LA\'x\'ZR\'1-y\'TI\'y\'O IND.3\' (PLZT) and the \'PB\'1-x\'BA\'x\'ZR\'1-y\'TI\'y\'O IND.3\' (PBZT) systems, induces several changes in the electric and structural properties of these materials. However, PLZT or PBZT systems based on \'TI\'-rich compositions have not been thoroughly investigated and the literature contains few reports concerning their structure. Thus, the main objectives of this doctoral thesis were the synthesis and structural characterization of \'PB\'1-x\'R\'x\'ZR\'0.40\'TI\'0.60\'O IND.3\' ferroelectric ceramic samples, with R = \'BA\' and \'LA\' and x between 0.00 to 0.50 (PLZT100x and PBZT100x). The characterization with X-ray diffraction technique of these samples showed a decrease of the tetragonality degree with increase of the doping cation concentration, which was related to the appearance of defects caused by the incorporation of \'LA\' or \'BA\' cations. These structural modifications were also responsible by the increase of the diffuseness at the dielectric permittivity and a relaxor behavior as a function of the \'LA\' or \'BA\' concentration. Concerning the local structure, XANES spectra in the absorption edge of various elements in PLZT and PBZT samples were performed. In the cases of \'TI\' \'K\'-edge absorption, the doping of \'LA\' and \'BA\' atoms in the PZT structure leads to a reduction of the displacement of \'TI\' atom in the center of the \'TI\'O IND.6\' octahedron. However, even when the crystal structure is cubic, a local octahedron distortion remains. EXAFS measurements in \'PB\' LIII-edge and \'ZR\' \'K\'-edge were performed and also indicate that local structure around lead or zirconium atoms is also affected by the introduction of \'LA\' and \'BA\' atoms in the PZT structure. In addition, XANES spectra measured at \'O\' \'K\'-edge revealed a reduction in the hybridization degree between \'O\' 2p and \'PB\' 6sp states with the addition of \'LA\' or \'BA\' atoms to the structure of PZT. It has been shown that hybridization between these states is essential to ferroelectricity and this reduction would be related to the relaxor behavior. PLZT and PBZT systems were also studied depending on the size of particle size in a nanometer scale. Thus samples PZT, PLZT11 and PBZT10 compositions were prepared using the synthesis method of precursor polymers and the process of sintering by spark plasma. A pronounced decrease in the values of maximum permittivity was observed and the dielectric curve as a function of the temperature exhibits a diffuse behavior. This size-induced diffuse phase transition and the reduction of the permittivity magnitude could be related to the differences between the core grain and the grain boundaries.
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Mandaji, Debora dos Santos. "Emissário submarino de Santos: contribuição nos sedimentos de fundo para Al, Mg, K, Ca, Fe, Ti, Na, Si, Ba, Cu, Zn, Cr, Mn, Co, Ni e S." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/44/44142/tde-02092008-163850/.
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Após a construção do Emissário Submarino de Esgoto de Santos, todo efluente da cidade de Santos e parte de São Vicente passou a ser descartado na Baía de Santos após Pré-condicionamento. Diante desse aspecto a CETESB iniciou monitoramento de controle sobre os materiais que estão sendo lançados pelo emissário. Nessa dissertação foram estudadas amostras de sedimentos no entorno dessa malha de monitoramento. A partir de duas coletas em períodos distintos - Abril de 2004 e Outubro de 2004 - obtiveram-se 20 amostras de sedimentos. Nessas amostras foram realizadas análises granulométricas e químicas (elementos maiores e traços determinados por DRX e ICPOES para 16 elementos com predomínio de metais). Os resultados granulométricos obtidos nas amostras de sedimentos mostraram serem esses constituídos predominantemente por areias e sedimentos em suspensão. A dispersão dessas frações sofre influência direta do fluxo dos materiais descartados pelo emissário. Dos diversos elementos analisados detectou-se que o Cobalto (Co) e Enxofre (S) ultrapassaram os limites de referência utilizados. O elemento Bário exibiu sempre concentrações elevadas nas análises realizadas. Foi notado, por outro lado, que a distribuição dos elementos Cu, Zn, Cr, Mn e Ni, sempre exibiu maiores concentrações no período de maior pluviosidade. Esses resultados corroboram para a indicação que alguns desses elementos químicos (Cu, Zn, Cr, Mn e Ni) devem provir de materiais intemperizados de rochas do entorno e que outros elementos (Co e S) possuem uma contribuição antropogênica sobre os sedimentos depositados pelo emissário. A determinação das razões C/N e C/S não permitiu determinar se a carga de efluentes do emissário contribui para o aumento do teor de matéria orgânica. Os resultados obtidos e interpretações realizadas conduzem a confirmar a influência do emissário sobre os sedimentos de fundo do seu entorno. Esses diversos resultados apontam para uma indicação de que o tratamento dos efluentes na Estação de Pré-Condicionamento de Esgoto de Santos não é o ideal, visto que alguns elementos considerados poluentes encontram-se depositados nos sedimentos analisados.After the construction of the Ocean Outfall of Santos\'s sewage, all of Santos\'s and part of São Vicente\'s effluents started to be discarded in the Santos Bay after Preconditioning. In light of that aspect, CETESB began a monitoring control of the materials dumped through the emissary. In this dissertation sediments samples in the environment of that monitoring mesh. From two collections in different periods - April 2004 and October 2004 - 20 samples of sediments were obtained. Granulometric and chemical analyses (larger and trace elements for DRX and ICP-OES for 16 elements with prevalence of metals) were developed. The granulometric results obtained in the sediment samples showed that those were predominantly constituted by sands and sediments in suspension. The dispersion of the prior fractions suffers direct influence of the flow of discarded materials by the emissary. Of the several analyzed elements, it was detected that the Cobalt (Co) and Sulfur (S) concentrations surplused the reference limits. The element Barium (Ba) was always highly concentrated in analysis. It was noticed, on the other hand, that the distribution of the elements Copper (Cu), Zinc (Zn), Chromium (Cr), Manganese (Mn) and Nickel (Ni), always exhibited larger concentrations in the period of greater rainfall. Those results corroborate the indicators that some of those chemical elements (Cu, Zn, Cr, Mn and Ni) comes from materials of naturally eroded rocks and that other elements (Co and S) were deposited by the emissary, constituting anthropogenic actions. The determination of the Carbon/Nitrogen (C/N) and Carbon/Sulfur (C/S) reasons didn\'t determine if the deposit of the emissary\'s effluents contributes in the increase of the concentration of organic matter. The results and interpretations obtained in the experiments confirm the emissary\'s influence on the environment\'s bottom sediments. Those results point that the effluent treatment in the Sewer\'s Pre-conditioning Station in Santos is not ideal, because some elements, considered pollutants, are found in deposits in the analyzed sediments.
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Fompeyrine, Jean. "Propriétés structurales et magnétiques de quelques phases dérivées de la perovskite dans les systèmes La-Ti-O et Ba-(M,M') - F-Cl (M,M' élément 3D)." Bordeaux 1, 1995. http://www.theses.fr/1995BOR10625.
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L'investigation du système La4TI3O12-LaTiO3 a permis de mettre en évidence une nouvelle série homologue de formulation LanTin-xO3n. Les structures de ces phases ont été caractérisées par diffraction des rayons X sur poudre et par microscopie électronique en transmission. Elles dérivent de différents polytypes de perovskites hexagonales et présentent une distorsion structurale due a la rotation coopérative des octaèdres autour de leurs axes ternaires. Une nouvelle serie de composes Ba2MM' F7Cl (M, M' = Mn, Fe, Co, Ni, Zn), dont les structures ont été déterminées par diffraction des rayons X sur monocristal, a été par ailleurs mis en évidence. Une étude comparative des propriétés structurales et magnétiques avec celles des composés de la série BaMF4 a été effectuée (filiation structurale résultant de différentes rotations coopératives des octaèdres, mesures d' aimantation sur poudre et monocristal, détermination des structures magnétiques de Ba2Co2F7Cl et Ba2Ni2F7Cl par diffraction des neutrons). Un nouveau chlorofluorure du cuivre a également été caractérise sur le plan structural et magnétique. Dans ce cas, une filiation structurale avec la structure de l'apatite et avec celle de phases derivees est proposée.
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Körfer, Sylvia [Verfasser], Manfred [Akademischer Betreuer] Martin, and Wolfgang [Akademischer Betreuer] Stahl. "Untersuchungen zur Fremdionendiffusion von Zr und Sr sowie zur Selbstdiffusion von $^50}$Ti und $^130}$Ba in Bariumtitanat (BaTiO$_{3}$) – Einkristallen / Sylvia Körfer ; Manfred Martin, Wolfgang Stahl." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1211590801/34.
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Körfer, Sylvia Verfasser], Manfred [Akademischer Betreuer] [Martin, and Wolfgang [Akademischer Betreuer] Stahl. "Untersuchungen zur Fremdionendiffusion von Zr und Sr sowie zur Selbstdiffusion von $^50}$Ti und $^130}$Ba in Bariumtitanat (BaTiO$_{3}$) – Einkristallen / Sylvia Körfer ; Manfred Martin, Wolfgang Stahl." Aachen : Universitätsbibliothek der RWTH Aachen, 2018. http://d-nb.info/1211590801/34.
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CONFALONIERI, GIORGIA. "LOCAL DISORDER IN THE STRUCTURE OF BA(TI,CE)O3 PEROVSKITE BY MEANS OF POWDER DIFFRACTION AND TOTAL SCATTERING. EFFECT OF TEMPERATURE, DOPING CONCENTRATION AND GRAIN SIZE." Doctoral thesis, Università degli Studi di Milano, 2017. http://hdl.handle.net/2434/478906.
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Nowadays BaTiO3 is considered as one of the most relevant environmental-friend ferroelectric and, thank to the chemical substitutions at the Ba2+ and/or Ti4+ sites, its properties are usually tailor to meet a big variety of devices and performance requirements. A classical example is the solid solution BaTi1-xMIVxO3, where M could be Sn, Zr, Hf, Ce etc., whose ferroelectric behavior shows an almost continuous variation with composition. The study of these compounds is then essential to improve their characteristics and make their suitable in more applications. Considering that their properties are deeply linked to the structure and especially to structural defects, average and local structural analyses are essential to better understand the origins of different polar behaviours and to have a real control on these materials. Despite this need, only BaTi1-xZrxO3 (BTZ) system, which is one of the most popular dielectrics used in multilayer ceramic capacitors, has been investigated in some detail. Although the similarity to BTZ suggests that BaTi1-xCexO3 (BTC) may be promising as lead free actuator materials, studies on this solid solution are almost limited. Thus in this research the BTC solid solution has been structurally investigated in order to provide knowledge lacks. Different ceramic samples with different doping amounts and different polar behaviours (from normal ferroelecric to relaxor via diffuse phase transition) have been investigated at different temperatures. In addition, taking into account the current tendency in miniaturized devices required in microelectronics, also chemical equivalent nano powders have been considered to explore not only doping effects, but also that of size. Pair Distribution Function (PDF) with different type of approaches (as carbox, biphasic and so on) has been employed coupled with TEM analysis and Raman spectroscopy. A complete description of that BaTi1-xCexO3 materials is given underlining links between polar behaviours, temperature, doping and size effects.
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Moura, Filho Francisco [UNESP]. "Comportamento dielétrico e ferroéletrico de cerâmicas BA('TI IND1-X''ZR IND.X)'O IND.3' modificadas com íons vanádio e tungstênio obtidos a partir de mistura de óxidos." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/102578.
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O objetivo central deste trabalho foi obter cerâmicas de Ba(Ti1-xZrx)O3 puras e modificadas com íons vanádio (V5+) ou tungstênio (W6+) pelo método convencional de mistura de óxidos com elevada permissividade dielétrica. A fase pura foi obtida controlandose a temperatura de sinterização e quantidade de aditivos. Inicialmente, preparou-se e caracterizou-se as cerâmicas de Ba(Ti1-xZrx)O3, com x variando de 0,05 até 0,15. A composição com uma única transição de fase ferroelétrica-paraelétrica foi a escolhida para substituição com vanádio e tungstênio. Investigou-se a influência dos íons vanádio e tungstênio nas propriedades estruturais, morfológicas e elétricas das cerâmicas BZT10 sinterizadas, entre 1200oC e 1350oC com isoterma de 4 horas. A adição dos íons V5+ ou íons W6+ substituindo Ti4+ ou Zr4+, na rede da cerâmica BZT10, promoveu a densificação deslocando significativamente os valores da temperatura de sinterização do BZT10 puro de 1550oC para 1200oC. As propriedades elétricas foram avaliadas para as cerâmicas monofásicas de BZT10 modificada com íons V5+ ou W6+ e sinterizadas a 1350oC, 1200oC, respectivamente. Os valores otimizados para as cerâmica BZT10:2V e BZT10:2W indicam permissividades dielétricas da ordem (ε) 15160 e 6420 a 10 kHz, polarização de 8,50 e 3,10μC/cm2 com 4,194x1017 e 1,474x1017 (spins/g), respectivamente. Os resultados obtidos para a cerâmica BZT10:2V indicam potencial aplicação em memórias FeRaM, enquanto os resultados obtidos para cerâmica BZT10:2W apresentam comportamento relaxor e transição de fase difusa, com potencial aplicação em memórias DRAM.
The main objective of this work was to obtain pure Ba(Ti1-xZrx)O3 and modified with vanadium and tungsten with high permittivity by the mixture oxide method. Single phase was obtained by controlling the temperature and amount of additive. In a first step, Ba(Ti1-xZrx)O3 ceramics with x varying from 0,05 to 0,15 were prepared and characterized. The ceramics with only one phase transition ferroelectric-paraelectric was chosen for modification with vanadium and tungsten. The influence of vanadium and tungsten in the structural, morphological and electrical properties of BZT ceramics sintered from 1200oC to 1350oC for 4 hours was investigated. The addition of V5+ or W6+ exchanging Ti4+ or Zr4+ in the BZT10 lattice, promotes the densification, changing the sintering temperature of pure BZT from 1550oC to 1200oC. BZT:2V and BZT:2W ceramics have dielectric permittivity of (ε) 15160 and 6420 at 10 kHz, remnant polarization equal to 8.50 and 3.10μC/cm2 with spins quantity equal to 4.194x1017 and 1.474x1017 (spins/g), respectively. BZT:2V ceramics have potential applications for FeRAM memory while BZT10:2W ceramics present relaxor behavior with a diffuse phase transition, being potential application in DRAM memory.
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Moura, Filho Francisco. "Comportamento dielétrico e ferroéletrico de cerâmicas BA('TI IND1-X''ZR IND.X)'O IND.3' modificadas com íons vanádio e tungstênio obtidos a partir de mistura de óxidos/." Araraquara : [s.n.], 2008. http://hdl.handle.net/11449/102578.
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Resumo: O objetivo central deste trabalho foi obter cerâmicas de Ba(Ti1-xZrx)O3 puras e modificadas com íons vanádio (V5+) ou tungstênio (W6+) pelo método convencional de mistura de óxidos com elevada permissividade dielétrica. A fase pura foi obtida controlandose a temperatura de sinterização e quantidade de aditivos. Inicialmente, preparou-se e caracterizou-se as cerâmicas de Ba(Ti1-xZrx)O3, com x variando de 0,05 até 0,15. A composição com uma única transição de fase ferroelétrica-paraelétrica foi a escolhida para substituição com vanádio e tungstênio. Investigou-se a influência dos íons vanádio e tungstênio nas propriedades estruturais, morfológicas e elétricas das cerâmicas BZT10 sinterizadas, entre 1200oC e 1350oC com isoterma de 4 horas. A adição dos íons V5+ ou íons W6+ substituindo Ti4+ ou Zr4+, na rede da cerâmica BZT10, promoveu a densificação deslocando significativamente os valores da temperatura de sinterização do BZT10 puro de 1550oC para 1200oC. As propriedades elétricas foram avaliadas para as cerâmicas monofásicas de BZT10 modificada com íons V5+ ou W6+ e sinterizadas a 1350oC, 1200oC, respectivamente. Os valores otimizados para as cerâmica BZT10:2V e BZT10:2W indicam permissividades dielétricas da ordem (ε) 15160 e 6420 a 10 kHz, polarização de 8,50 e 3,10μC/cm2 com 4,194x1017 e 1,474x1017 (spins/g), respectivamente. Os resultados obtidos para a cerâmica BZT10:2V indicam potencial aplicação em memórias FeRaM, enquanto os resultados obtidos para cerâmica BZT10:2W apresentam comportamento relaxor e transição de fase difusa, com potencial aplicação em memórias DRAM.Abstract: The main objective of this work was to obtain pure Ba(Ti1-xZrx)O3 and modified with vanadium and tungsten with high permittivity by the mixture oxide method. Single phase was obtained by controlling the temperature and amount of additive. In a first step, Ba(Ti1-xZrx)O3 ceramics with x varying from 0,05 to 0,15 were prepared and characterized. The ceramics with only one phase transition ferroelectric-paraelectric was chosen for modification with vanadium and tungsten. The influence of vanadium and tungsten in the structural, morphological and electrical properties of BZT ceramics sintered from 1200oC to 1350oC for 4 hours was investigated. The addition of V5+ or W6+ exchanging Ti4+ or Zr4+ in the BZT10 lattice, promotes the densification, changing the sintering temperature of pure BZT from 1550oC to 1200oC. BZT:2V and BZT:2W ceramics have dielectric permittivity of (ε) 15160 and 6420 at 10 kHz, remnant polarization equal to 8.50 and 3.10μC/cm2 with spins quantity equal to 4.194x1017 and 1.474x1017 (spins/g), respectively. BZT:2V ceramics have potential applications for FeRAM memory while BZT10:2W ceramics present relaxor behavior with a diffuse phase transition, being potential application in DRAM memory.
Orientador: Maria Aparecida Zaghete Bertochi
Coorientador: Alexandre Zirpoli Simões
Banca: Fenelon Martinho Lima Pontes
Banca: José Antonio Eiras
Banca: Marcelo Luiz Simões
Banca: Manuel Henrique Lente
Doutor
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Bernhardt, Sylvie. "Gyromètre a fibre a double conjugaison de phase - étude d'un nouveau matériau photorefractif - réalisation d'un démonstrateur." Phd thesis, Université Paris Sud - Paris XI, 2001. http://pastel.archives-ouvertes.fr/pastel-00715875.
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Le remplacement de la fibre monomode a maintien de polarisation par de la fibre monomode standard dans les gyroscopes a fibre est un véritable enjeu économique. En effet, il permettrait a ces systèmes d'être compétitifs au niveau du coût sur le marche des centrales de navigations inertielles actuellement domine par les gyroscopes laser. Cependant, les problèmes de non réciprocités et d'effondrement du signal provoqués par l'utilisation de ce type de fibre n'ont pas été résolus de façon satisfaisante à ce jour. C'est a ce niveau que l'utilisation de la double conjugaison de phase apparaît comme une solution intéressante. L'objectif de ce travail consistait à valider cette solution d'une part en mettant au point un cristal photoréfractif adapte à cette application et d'autre part en insérant un miroir a double conjugaison de phase dans un gyroscope commercial fonctionnant a 850 mn. Dans un premier temps, nous avons donc etudie un nouveau cristal photorefractif : le titanate de barium calcium (bct) dont l'interet repose sur le fait qu'il ne subit pas de transition de phase de 120\ a 98\ c, contrairement au cristal de titanate de baryum dont il est dérivé. Ce cristal, généralement utilise pour la conjugaison de phase en raison de sa bonne efficacité est en effet détruit si sa température devient inférieure a 10\ c. Notre étude a permis de démontrer les bonnes propriétés photorefractives de ce matériau (coefficients electro-optiques élevés, sensibilité proche infrarouge) et de comprendre les différences de comportement par rapport au titanate de baryum. Dans un second temps, nous avons étudié et optimise un miroir a double conjugaison de phase réalisé avec un cristal de titanate de baryum que nous avons ensuite insere dans un gyromètre a fibre. Ainsi, nous avons pu montrer que le gyrometre a double conjugaison de phase permet de mesurer des rotations et n'introduit pas de non-reciprocités supérieures a la précision du montage que nous avons utilise (200 \/h).
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Parola, Stéphane. "Acces aux materiaux oxyde a base de bismuth par la voie sol-gel. Synthese et caracterisation de precurseurs heterometalliques du type bi (iii) -m (m = ti, nb, ba, sr, ca)." Nice, 1996. http://www.theses.fr/1996NICE5015.
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Un grand nombre de materiaux oxyde a base de bismuth presente des proprietes interessantes. Nos travaux ont essentiellement porte sur des systemes conduisant a des ceramiques ferroelectriques et supraconductrices. Des alcoxydes bi-m (m = ti, nb, sr) et des b-dicetonatoalcoxydes associant le bismuth a des alcalino-terreux ont ete prepares et caracterises par ftir, rmn du proton et du carbone 13, analyse elementaire, diffraction des rayons x sur monocristaux et sur poudre, waxs, microscopie electronique. La structure moleculaire des composes bi#1#6nb#1#0o#1#6 (o#ipr)#6#8, biti#2o(o#ipr)#9, bi#4ba#4o#2(oet)#1#2(thd)#4 et bi(o#ipr)#2(acac)#2 a ete etablie par diffraction des rayons x sur monocristaux. Le systeme bismuth-titane est developpe dans le but d'obtenir la phase bi#4ti#3o#1#2. Un alcoxyde bi#4ti#3o#4(oet)#1#6 a ete prepare et sa structure etudiee par diffusion des rayons x aux grands angles. Ce compose conduit apres hydrolyse et traitement thermique a 450c a la phase bi#4ti#3o#1#2 pure. Des couches minces de ce materiau ont ete realisees a partir d'une solution de 2-methixyethanolates de bismuth et de titane, et leur caracterisation a ete effectuee par diffraction des rayons x, microscopie electronique et mesures de cycles d'hysteresis
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Hayn, Silke [Verfasser], Karsten [Akademischer Betreuer] Albe, Jürgen [Akademischer Betreuer] Rödel, Hans-Joachim [Akademischer Betreuer] Kleebe, and Gerd [Akademischer Betreuer] Buntkowsky. "First-principles calculations on the structural and thermodynamic stability of (Na1/2Bi1/2,Ba)TiO3 and Pb(Zr,Ti)O3 / Silke Hayn. Betreuer: Karsten Albe ; Jürgen Rödel ; Hans-Joachim Kleebe ; Gerd Buntkowsky." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2013. http://d-nb.info/1108093310/34.
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Prades, Tena Marta. "Materiales ferroeléctricos basados en BaTiO3 y Ba2(Nd,Sm)Ti2Nb3O15. Caracterización eléctrica por espectroscopia de impedancia." Doctoral thesis, Universitat Jaume I, 2011. http://hdl.handle.net/10803/10552.
Full textAbstract:
Esta tesis versa en la síntesis, mediante métodos de baja temperatura(sol-gel y solvotermal), la caracterización y el estudio de las propiedades eléctricas, mediante Espectroscopia de Impedancia, de dos tipos de materiales ferroeléctricos: el óxido mixto de titanio y bario, BaTiO3(BT), dopado con diferentes iones (con estructura perovsquita), y la familia de compuestos Ba2LnTi2Nb3O15 (Ln = ión lantánido), con estructura de bronce de tungsteno tetragonal (TTB). Los principales resultados en el primer sistema estudiado (BT) es el descubrimiento de un nuevo fenómeno en materiales dopados con iones aceptores relacionado con la respuesta no-óhmica de su resistencia al aplicar un pequeño voltaje dc, tanto de la frontera como del interior de grano, lo que los hace prometedores para aplicaciones tales como dispositivos de memoria (similares a los memristores), de protección o sensores. Respecto al segundo sistema estudiado (TTB), el principal resultado fue la inusual histéresis térmica en la transición ferroeléctrica y la gran diferencia entre la temperatura de transición y la temperatura de Curie-Weiss. En todos los materiales se ha analizado en detalle la relación
existente entre estructura, composición y propiedad.
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Kreisel, Jens. "Étude d'hexaferrites de baryum substitués BaFe(12-2x)AxCoxO19(A=Ir,Ti) : synthèse de monocristaux, structures cristallines et magnétiques, spectroscopie Raman." Grenoble INPG, 1999. http://www.theses.fr/1999INPG0044.
Full textAbstract:
L'hexaferrite de baryum m, bafe#1#2o#1#9, possede une anisotropie magnetique axiale tres forte, c'est de ce fait un excellent materiaux de base pour aimant permanent. En substituant les cations fe#3#+ par le couple ti#4#+/co#2#+ ou ir#4#+/co#2#+ on reduit l'anisotropie magneto-cristalline qui devient planaire pour un taux critique. Nous avons effectue la premiere etude d'hexaferrites m par spectroscopie raman. L'utilisation des approches isotypique et isomorphique nous a permis d'identifier les modes vibrationnels de certains polyedres dans la structure de bam. Par ailleurs, les spectres raman enregistres entre 300 a 1000 k montrent que la spectroscopie raman permet de mettre en evidence des transitions magnetiques. L'analyse par spectroscopie raman des monocristaux d'hexaferrites substitues, bafe#1#2# ## #2#xir#xco#xo#1#9 et bafe#1#2# ## #2#xti#xco#xo#1#9, a permis de mieux definir le modele de structure nucleaire. Nous avons egalement entrepris une etude raman de films minces de bafe#1#2o#1#9, qui montre l'interet de la spectroscopie raman comme technique d'analyse de couches minces d'hexaferrite, complementaire de la diffraction des rx. Une etude realisee par diffraction neutronique a permis de suivre le changement d'anisotropie magnetique a l'echelle microscopique et d'etablir les structures nucleaires et magnetiques. Les resultats montrent, que le changement d'anisotropie des deux solutions solides conduit entre de 200 et 300 k a des structures magnetiques similaires. Vers les basses temperatures, au contraire, le changement d'anisotropie des cristaux substitues ir#4#+ peut etre decrit par une inclinaison collective des moments de 0 a 90, tandis que le changement d'anisotropie de la substitution ti#4#+ passe par plusieurs structures complexes (helices, agrandissement de la maille, etc. ). L'ensemble des mesures magnetique et neutronique montre que le changement rapide d'anisotropie observe dans bafe#1#2# ## #2#xir#xco#xo#1#9 est principalement du a la substitution du site bipyramidal par ir. L'etude comparee des deux solutions solides montre que le cation co#2#+ ne joue pas le role determinant dans le changement d'anisotropie de bam qui lui est souvent attribue. Enfin, les differences de structures magnetiques des deux composes sont probablement a l'origine du pouvoir d'absorption des ondes hyperfrequence different.
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Valdivieso, Françoise. "Mécanismes de transformations : Synthèse et grossissement de grains du titanate de baryum." Phd thesis, Grenoble INPG, 1995. http://tel.archives-ouvertes.fr/tel-00842990.
Full textAbstract:
Ce travail a été consacré à l'étude de deux transformations: d'une part l'évolution texturale d'une poudre de titanate de baryum, d'autre part une voie de synthèse de cet oxyde à partir de nitrate de baryum et de dioxyde de titane a l'état solide. Nous avons montré que la vitesse absolue de chacune de ces transformations peut être reliée à la vitesse spécifique du phénomène, calculée à l'aide d'une modélisation physico-chimique et qui s'exprime en fonction des contraintes expérimentales (pressions partielles de gaz, rapport Ba/Ti,. . . ). Une étude cinétique de l'influence de ces contraintes a donc été réalisée pour chaque transformation. Dans le cas du grossissement de grains, cette étude a révèle un effet accélérateur de la vapeur d'eau et du rapport Ba/Ti sur la chute de surface spécifique du titanate de baryum. En ce qui concerne la réaction de synthèse, l'étude expérimentale (par thermogravimétrie) a mis en évidence un effet très fortement ralentisseur du monoxyde d'azote et un effet ralentisseur moindre de l'oxygène. Des modèles physico-chimiques ont été proposes, qui ont conduit à l'expression de vitesses théoriques pour chaque transformation, et ont permis de rendre compte des résultats expérimentaux, qualitativement dans le cas de la synthèse, et de manière quantitative pour le grossissement de grains. Deux voies parallèles de transport de matière ont d'ailleurs été mises en évidence dans ce dernier cas, l'une faisant intervenir un effet catalytique de la vapeur d'eau, l'autre se déroulant par l'intermédiaire des défauts intrinsèques seulement (les lacunes d'oxygène).
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Mager, Loic. "Correction de fronts d'onde de faisceaux lasers impulsionnels par mélange d'ondes photoréfractif." Phd thesis, Université Paris-Nord - Paris XIII, 1994. http://pastel.archives-ouvertes.fr/pastel-00716165.
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Nous avons démontré que la correction de fronts d'onde de faisceaux lasers impulsionnels (nanoseconde) pouvait être réalisée par mélange d'ondes dans un cristal photoréfractif. Nous avons commence par déterminer le matériau photoréfractif le mieux adapte pour cette application. Pour des raisons d'efficacité photoréfractive et de tenue en puissance, notre choix s'est porte sur le titanate de baryum. Cela a conditionne le choix de la longueur d'onde utilisée (532 nm) pour cette démonstration. Nous avons étudié un premier dispositif de correction base sur le transfert d'énergie d'un faisceau fort vers un faisceau faible qui, par mélange d'ondes photoréfractif, peut être obtenu sans qu'il y ait de transfert de phase. Dans cette étude nous avons mesure les variations de l'amplification en fonction de différents paramètres (cohérence temporelle, rapport des énergies des faisceaux) et observe les variations de l'effet photorefractif en fonction de la densité de puissance dans le titanate de baryum. Nous avons aussi démontré la correction des déformations introduites par un objet de phase et cela pour différentes densités d'énergie incidente. Une deuxième méthode de correction est basée sur la compensation d'un aberrateur de phase par double passage. On a commence par préciser la notion de conjugaison de phase. Puis, nous avons étudié en particulier un miroir a conjugaison de phase auto pompe, l'oscillateur a boucle de réaction, qui fonctionne sur le principe du mélange a quatre ondes dans un cristal photoréfractif. Nous avons montre expérimentalement que des transformations des faisceaux dans la boucle de réaction améliorent la qualite de la conjugaison de phase et nous avons réalisé la compensation d'objets de phase par double passage en régime impulsionnel. La dernière partie est consacrée a l'étude comparative des deux dispositifs tels qu'ils pourront être mis en oeuvre pour la correction dynamique des lentilles thermiques dans les amplificateurs lasers solides.
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Ho, CHI PANG, and 何志鵬. "Synthesis and Characterization of Hexagonal (Ba,Sr)(Ti,Ga)O3." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/59041800190273672028.
Full textAbstract:
碩士中國文化大學
材料科學與奈米科技研究所
98
The (Ba,Sr)(Ti,Ga)O3 samples are synthesized by the solid state method in air and the parent components BaTi1-xGaxO3 (ABO3) are substituted Ba for Sr (x=0.1, 0.2 and Sr: 1%~9%) in this work. The structure of samples are changed from hexagonal to mixed phases then tetragonal through the A-site substituting process, which is consistent with the thermodynamic prediction on literature. The all samples can form the pure hexagonal structure when the Sr-concentration is lower than 2%, and the mixed phase region is decreasing with Sr-doping level increasing. In the higher Sr-doping region, the structures of samples are tetragonal only. The hexagonal structure of (Ba,Sr)(Ti,Ga)O3 samples are increasing with the sintering temperature increasing in the lower Sr-doping region, but the tetragonal structure is dominant in the higher Sr-doping region. This is consistent with the result of room temperature Raman spectrum measurements. Because the Raman spectrum is reported that the tetragonal modes of BaTiO3 will go away and the intensity of hexagonal modes of BaTiO3 systems are increasing with sintering temperature increasing. During the substituting proceeding, because the ion-radius of Sr2+ is smaller than Ba2+, the volume of unit cell of (Ba,Sr)(Ti,Ga)O3 samples are decreasing with the Sr-concentration increasing. Although the atomic weight of Sr is lighter than Ba, but the density of samples aren’t also decreasing with Sr-doping level increasing, because the hexagonal phase is a metastable structure on thermodynamic, which is due to tetragonal phase replacing hexagonal phase in higher doping region at room temperature. The microwave property measurement are showed that because the main phase of samples will change from hexagonal to tetragonal with the Sr-doping level increasing, which is due to the Qxf value and K value of samples are dramatic dropping with Sr-concentration increasing. It means that if the samples are included the tetragonal structure, whose Qxf value and K value are hugely decreasing, so it also proofs that the hexagonal BaTiO3 material has very good microwave property and a large potential for application.
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XIE, MING-JUN, and 謝明君. "Superionductivity in the (TI,Pb) (Ba,Sr)2 CuO5 systems." Thesis, 1989. http://ndltd.ncl.edu.tw/handle/52788247135811186700.
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Wang, Tzu Hsiang, and 王子翔. "Synthesis and Characterization of (Ba,Ti) Substituted BiFeO3 Multiferroic Ceramics." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/26720423799274273711.
Full textAbstract:
博士輔仁大學
應用科學與工程研究所博士班
100
A one-dimensional conductivity barrier model with intrinsic barrier B every lattice constant a and extrinsic barrier B+Δ is introduced to describe the dielectric response and conductivity as functions of temperature and frequency. Temperature- and frequency-dependent dielectric permittivity (ε′) and conductivity (σ′) have been studied on multiferroic BiFeO3 (BFO), (1-x)BiFeO3-(x)BaTiO3 (BFO-BT), and (Bi1-xBax)(Fe1-xTix)O3 [BFO-(Ba,Ti)] ceramics, which were synthesized by the solid state reaction method. A frequency-dependent dispersion of dielectric maximum appears in the lower temperature region. This phenomenon is likely activated by the antiferromagnetic (AFM)-paramagnetic (PM) transition. Good qualitative fits of dielectric permittivity and conductivity are obtained with the interior grain sizes d of 20-40 nm. BFO-BT and BFO-(Ba,Ti) ceramics show higher intrinsic barriers B about 11000 K than B=8200 K in BiFeO3. The phase transition of BFO is rhombohedral (R)-orthorhombic (O)-cubic (C) and the Curie temperature (Tc) is near 850 ℃. The structure transition sequence of BFO-BT and BFO-(Ba,Ti) ceramics is R to C upon heating. The Curie temperatures in BFO-BT and BFO-(Ba,Ti) ceramics shift toward lower temperatures due to the contents of (Ba,Ti). The lattice constant in BFO is about 3.9699 Å and increases with increasing the (Ba,Ti) contents. The local minima of R distortion angle (αR) in BFO, BFO-BT, and BFO-(Ba,Ti) occur in the region of 300-500 ℃, implying ionic displacements. The temperature regions also associate with Nèel temperature (TN). This anomaly is likely resulted from the antiferromagnetic (AFM)–paramagnetic (PM) transition and is responsible for the broad frequency-dependent dielectric maximum. The dielectric permittivities are about 33 in BFO and 321 in BFO-30%BT for 1 MHz at room temperature. The dielectric loss decreases as BT increases. The real part of conductivity in BFO shows a deviation from the linear relation near Tm and αR. The deviation temperature shifts to lower temperature with increasing BT contents. BFO and BFO-BT ceramics exhibit a similar antiferromagnetic (AFM) behavior. BFO-5%(Ba,Ti) shows the weak ferromagnetic behavior. The magnetic hysteresis loop of possible iron oxide in BFO-10%(Ba,Ti) was observed due to higher sintering temperature.
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Wen-An, Lan. "A Study of Ferroelectric Ba(Zr,Ti)O3 Thin Film Varactors." 2006. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0016-1303200709284817.
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Lan, Wen-An, and 藍文安. "A Study of Ferroelectric Ba(Zr,Ti)O3 Thin Film Varactors." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/54262041506247480797.
Full textAbstract:
博士國立清華大學
材料科學工程學系
94
The dielectric constant of ferroelectric material, Ba(Zr,Ti)O3, (BZT) changes with external dc biasing voltage. Based on this tunable characteristic, it is useful to fabricate the varactors, tunable filters and phase shifter devices. In this research, two kinds of ferroelectric varactors were investigated, i.e. structures made with parallel and coplanar electrodes, and the study includes three topics: (1) the influences of bottom electrodes in parallel structure, (2) the influences of interfacial layer in the ferroelectric varactors fabricated on high-resistivity silicon (HR-Si), (3) the influences of high-k and low loss buffered layer and annealing condition in the ferroelectric varactors fabricated on high-resistivity silicon. In the first topic, three kinds of bottom electrode with different thickness were studied; including Pt, LaNiO3/Pt and LaNiO3/Au/Pt. Increasing the Pt thickness reduces effectively the total loss and raises the figure-of-merit (FOM) value. The conductive oxide, LaNiO3 (LNO) layer, enhances the textured crystallinity and increases the breakdown voltage, resulting in higher tunability of capacitance and FOM value. In the second topic, the BZT films deposited on HR-Si with or without tetraethylorthosilane (TEOS) SiO2 as buffer layer were studied. The influences of electrical characteristics were measured by impedance and network analyzer at high and microwave frequencies, respectively. The results at high frequency show that the tunability of coplanar varactors results from the depletion and accumulation of carriers in Si, which can be modeled by two back-to-back MOS capacitors in series connection. At microwave frequencies, positive tunability, i.e. [C(V)-C(0)]/C(0) > 0, was observed and can be explained by an equivalent circuit in relation to the formation of positively-charged defects at the interfacial layer and the modulation of carrier accumulation at the interface in Si. In the third topic, the Ta2O5 and (Ta2O5)1-x(TiO2)x layers were used to investigate the influences of high-k and low loss buffer layer. The results show that the thicker buffer layer and lower dielectric constant result in lower tunability. Moreover, the reduction of Ta5+ and formation of oxygen vacancies induce the change of carrier distribution at interface in Si, giving rise to different tunability at microwave frequencies. The positively-charged defects in the interfacial layer attract the electrons accumulated on the surface of silicon which screen the microwave from penetrating into the HR-Si, and affect the capacitive effect of HR-Si in series connection to the varactor. In addition, annealing in O2 annihilates the oxygen vacancies and oxidize the cations of BZT films causing the reduction of carrier accumulation and tunability. Annealing in N2 increases the oxygen vacancies and the reduction of cations in BZT films causing the raise of charged defects and injected carriers giving rise to hystersis behavior.
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Chen, Chung-Yung, and 陳仲苑. "Prepared Ba(Ti,Sn)O3 thin film on Si by magnetron R.F.sputter." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/57126328927476319514.
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HE, YIN-GUAN, and 何殷權. "STUDIES ON THE (BA,SR)(TI,ZR)O��-BASED BOUNDARY LAYER DEVICES." Thesis, 1990. http://ndltd.ncl.edu.tw/handle/50436087847196136882.
Full textAbstract:
博士國立成功大學
電機工程研究所
79
By adding Sr and Zr into BaTiO3, the formation mechanism and physical properties of the (Ba, Sr)(Ti,Zr)O3 ceramic solid solution (addreviated as BAZT) are investigated. Based on these compositions, high permittivity dielectrics with diffuse-phase transition are obtained. If vanadium is added into the calcined BSZT dielectric powder, the NTC thermistor is obtained after sintering in reducing atmosphere. Besides, semiconducting BSZT ceramics are fabricated by n-type doping and then sintered in reducing atmosphere. For B: capacitor, selected metal oxides are then diffused into the grain boundary of the semiconducting ceramics to form an insulating layer. For PCTR, heat-treatment is conducted in oxygen atmosphere at elevated temperature. The grain boundary characteristics of there BL devices are well investigated qualitatively and quantitatively. 本論文之主旨在於以鋯鈦酸鋇鍶（簡稱BSZT）為基本材料，研究其相關物理特性及其 在晶界層元件應用上之電特性。藉由調整鋯的含量，在室溫下將可獲得高介電常數且 具擴散型相轉移之介電材料。如果添加n-型摻雜，且在還原氣氛中燒結，則可製成低 電阻之陶瓷體，作為晶界層電容器之基板。若改添加五氧化二金磚於煆燒後之介電粉 末，同樣在還原氣氛中燒結，則可在晶界形成具NTCR特性之沈淅相，形成熱阻器。至 於在晶界層電氣用品器之製作上，可使用銅及鉍之氧化物混合塗料作為擴散源，進行 二次燒結。氧化物沿晶界擴散的結果將減緩氧在晶界之擴散，而擴散溫度的高低及周 圍氣氛亦將影響晶界電特性。另一方面，在未擴散氧化物之情況下，若將低電阻陶瓷 在高溫且含氧的氣氛中作熱處理，則將顯現PCTR特性，同時其電特性亦受熱處理條件 的影響。因熱處理而吸附在晶界上的氧原子所形成的電子捕捉態位密度，將隨著熱處 理時間之平方根成正比。本論文實現以一基本材料發展多種晶界層電子元件之構想， 並針對上述各種晶界電性之控制，提供定性之定量的分析。
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Chi-LinWu and 吳其霖. "Microstructure analysis on (Ba,Ca)(Ti,Zr)O3 base MLCC by constrained sintering." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/12405171940377064174.
Full textAbstract:
碩士國立成功大學
電機工程學系專班
98
Based on BCTZ by MLCC BME process, to add constraint layers inside on the samples to control the shrinkage. Besides, apply rapid sintering concept to resist inner electrode shrinkage during sintering. Depending on this concept, expect to get good continuity of inner electrode. According to results, constraint layers added can be useful to control grain growth of BCTZ. At the same time, rapid sintering performs good continuity of inner electrode and repression of grain growth.
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Mekonnen, Mulualem Abebe. "Structure property correlation studies on Ca-modified Ba(Ti, Zr/Sn)O3 piezoceramics." Thesis, 2018. https://etd.iisc.ac.in/handle/2005/5416.
Full textAbstract:
In this thesis we have investigated the structure, property correlation of the lead-free piezoelectric ceramic of (Ba,Ca) (Ti,Zr/Sn)O3 system. A self-consistent set of experimental techniques such as X-ray powder diffraction, neutron powder diffraction, scanning electron microscope, electric field and temperature dependent dielectric and ferroelectric measurements were used to study these systems.
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Chen, Chung I., and 陳仲宜. "Study of Preparation And Properties of Ba(Ti,Zr)O3 High Dielectric Thin Film." Thesis, 1998. http://ndltd.ncl.edu.tw/handle/01922457963392027063.
Full textAbstract:
碩士國立成功大學
材料科學(工程)學系
86
In this study, Ba(Ti ,Zr)O3 thin film were prepared by R.F. magnetron sputtering onto N-type (100) Si substrate.The film were deposited at low temperature. Composition, crystallization, microstructure and electrical properties of thin film are characterized as function of components of target, R.F. power, ambient pressure and the partial pressure of O2 .Experimental results shows that deposition rate and crystallization of thin film were increased with optimum sputtering parameters. The higher substrate temperature led to better crystallization. The permittivity increased with the Zr content of thin film, substrate temperature and R.F. power, and the maximum value is 282.The relaxor behavior of BZT thin film became dominant with increasing the Zr content of thin film.The I-V curve shows that leakage current was effectively improved by increasing the Zr content . Paraelectric phase was determined by the hysteresis curve. In conclusion, BZT thin film can be applied to memory device.
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Peets, Darren. "Growth of TI₂Ba₂CuO₆[sub ±δ] single crystals by the self-flux method." Thesis, 2002. http://hdl.handle.net/2429/13343.
Full textAbstract:
Crystals of the overdoped cuprate superconductor TI₂Ba₂CuO₆[sub ±δ], with T[sub c]'s ranging
from 5K to 90K, have been grown by a copper-rich self-flux method and characterized
by X-ray Diffraction and with a SQUID magnetometer. The as-grown T[sub c]’s
were several Kelvin wide, the crystals studied were found to be multi-domain, and
the c-axis lattice parameter was found to be 23.143(2) Å for a T[sub c] = 5K crystal.
The successful growth of TI₂Ba₂CuO₆[sub ±δ] hinged on the ability to exclude carbon
while containing the thallium oxides.
This study of TI₂Ba₂CuO₆[sub ±δ], while still in its infancy, has the potential to reveal
a great deal about the cuprate superconductors.
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Chu, Li-Wen, and 朱立文. "Preparation and Dispersion of Ultra-Fine Ba-Ti-O Dielectric Powders by Chemical Methods." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/68661067860602445898.
Full textAbstract:
博士國立清華大學
化學工程學系
94
The purposes of this thesis include two main researching fields. Firstly, the preparation of nano-sized Ba2Ti9O20 microwave dielectric materials via chemical synthesized processes was studied, which consisted of modified co-precipitation (MCP), inverse-microemulsion (IME) and hydrothermal process. After the precursors of Ba2Ti9O20 obtained, these precursors were processed by the thermal treatments (clacination & sintering) in different atmospheres (O2, air, N2 and N2/H2), sintered ceramics were obtained with various microwave dielectric properties and phase transformation. According to the above experimental results, the novel composition of Ba2Ti9O20 precursor was developed to decrease the temperature of Ba2Ti9O20 formation effectively. Secondly, a valuable research was carried out on the application of nano-powders by using a well-dispersed nano-BaTiO3 nonaqueous suspension with high solid content. Different kinds of synthesized phosphate esters were used as dispersants and added respectively in the nano-BaTiO3 nonaqueous suspension to identify the optimal molecular structure and proper amount of phosphate ester. Moreover, this powder slurry of nano-BaTiO3 was used to manufacture an ultra-thin ceramic film for MLCC. Summaries of all the topics in this thesis, are described as follows: (1) Modified co-precipitation process (MCP), which combines the automatic pH -value control system and supersonic spraying of co-precipitants, was used to synthesize nano-sized Ba2Ti9O20 precursors (~48.8 nm). Kinetics for crystallization process is markedly enhanced when the O2 atmosphere was replaced with air in the calcinations and sintering processes. When O2-processed, high density Ba2Ti9O20 materials (>94%T.D.), possessing good microwave properties (K=38.7 and Q×F=30,502), were obtained by sintering the sample at 1200℃/4 h, which was lower than the sintering temperature when processed in air (i.e., 1250℃/4 h) and nitrogen. (2) Double inverse-microemulsion (IME) process is also used for synthesizing nano-sized Ba2Ti9O20 powders. The crystallization of thus obtained powders and the microwave dielectric properties of the sintered materials were examined. The IME-derived powders were of nano-size (~21.5 nm) and possessed high activity. The BaTi5O11, intermediate phase had resulted when the IME-derived powders were calcined at 800℃(4 h) in air. However, high density Ba2Ti9O20 materials with pure triclinic phase (Hollandite-like) can still be obtained by sintering such a BaTi5O11 pre-dominated powders at 1250℃/4 h. The phase transformation kinetics for the IME-derived powders was markedly enhanced when the air replaced with O2 during calcination and sintering processes. Both the calcination and densification temperatures were lowered by around 50℃ compared to the processes undertaken in air. The microwave dielectric properties of sintered materials increase with the density of the samples, resulting in large dielectric constant (K＝39) and high quality factor (Q×f ＝28,000 GHz) for the samples possessing a density higher than 95%T.D., regardless of sintering atmosphere. Over firing dissociates Ba2Ti9O20 materials and results in poor quality factor. (3) A hydrothermal process has also been successfully utilized for the preparation of Hollandite-like Ba2Ti9O20 precursors. TEM investigation, in conjunction with chemical analyses on reacted powders, indicates that Ti4+-species were first dissolved in the solution and then reacted with Ba2+-species to form perovskite phased BaTiO3 in the hydrothermal process. Excessively large particle size for the starting TiO2 (anatase powders) results in insufficient Ti-ions in the solvent and incomplete reaction with Ba2+-species, which leads to Ba2+-deficit powder mixture. A residual TiO2 phase thus results after calcination. Only small TiO2 particles (40 nm) can result in sufficient Ti4+-species in the solution, which fully react with Ba2+-species and lead to TiO2/BaTiO3-ratio of the correct stoichiometry to form Ba2Ti9O20. TiO2/BaTiO3 powder mixtures, prepared in this way possess high activity and can be converted into pure Ba2Ti9O20 materials. After calcination and sintering processes (1300℃/ 4 h), such materials possess high sintered density (93.3% T.D) and good microwave dielectric properties (K = 36 and Q×f = 28000). (4) Evolution of the phases during the calcination in mixed oxide processing of BaTiO3 and TiO2 mixture were investigated. Based on the observations, a reaction sequence of the constituent phases was proposed and a modified process has suggested viz. to utilize BaTi4O9 and BaTi5O11 mixture instead of BaTiO3 and TiO2 mixture as starting materials. The phase transformation kinetics is thus greatly enhanced. While the reaction of 2BaTiO3/7TiO2 mixture (type I, ~138 nm) requires 1100oC/4 h to completely transfer the mixture into Ba2Ti9O20 Hollandite-like phase, it needs only 1000 oC /4 h to fulfill the phase transformation process for the BaTi5O11/BaTi4O9 mixture (type III, ~88 nm). When directly sintering the materials prepared from these powder mixture, type III mixture leads to higher siterability and more uniform granular structure, as compared with the type I mixture. Furthermore, local microwave dielectric properties measured by evanescent microwave probe (EMP) reveals that the grains of type III Ba2Ti9O20 materials possess larger dielectric constant than that of type I, indicating that the type III powders not only of higher sinterability but also react much better in forming Hollandite-like phase. (5) The stability of nano-sized barium titanate (BaTiO3) nonaqueous suspension with different solvents and phosphate esters has been investigated by means of zeta potential, adsorption, sedimentation and viscosity measurements. Without dispersant addition, the viscosity of the solvent is an essential dispersing factor for stabilizing the nano-sized BaTiO3 suspensions. Three typical phosphate esters were synthesized, including mono-alkyl, di-alkyl, and ethoxy type. The results of phosphate ester adsorption and suspension sedimentation corroborate that the specific amount of 2-ethoxy ethyl dihydrogen phosphate as a dispersant can provide the longest stable status for BaTiO3 (50 nm) contained (40 wt%) in 1-methoxy-2-propanol. Analyzing the influence of suspension dispersion for powder particle size, we found out that longer molecular chain of dispersant is required for larger powder (200 nm), but the additional amount of dispersant was less than the smaller one (50 nm). The nano-sized BaTiO3 non-aqueous suspension was successfully used to manufacture the ultra-thin ceramic film (2.6~2.8 micrometer) by tape casting and applied to multi-layer ceramic device.
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Lai, Chao-Chic, and 賴昭志. "The Microwave Properties of the Low Temperature Sintering Ba-Ti-O Ceramics and Applications." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/53308545856869616804.
Full textAbstract:
碩士國立成功大學
電機工程學系
89
Microwave dielectric ceramics of Ba2Ti9O20 were prepared by adding SiO2, B2O3, PBS, and CuO as a liquid phase sintering aid. Well crystalline of BaTi4O9 powders can be prepared by Pechini method and get a nano-meter particle of 100-200 nm at 850C from the gels. Using both two methods, dense and single-phase Ba2Ti9O20 and BaTi4O9 dielectric ceramics could be fabricated at a sintering temperature below 1200C. Although the additions to Ba2Ti9O20 ceramics results in a decrease of the dielectric properties, the sintered Ba2Ti9O20 ceramics still exhibit much better dielectric properties than that of pure Ba2Ti9O20 ceramics at low sintering temperature. On the other hand, two ceramic dielectric materials (Al2O3 and Ba2Ti9O20) are fabricated to the substrate of filter. The frequency of coupled line band-pass filter is 5 GHz and the bandwidth is 5%. The designed structure is simulated by using IE3D.
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Wang, Chia-Jung, and 王嘉榮. "Fabrication and Characteristics of (Ba,Sr)(Ti,Zr)O3 High Dielectric Constant Thin Films." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/82762875707635956947.
Full textAbstract:
碩士國立中山大學
電機工程學系研究所
91
ABSTRACT In this study, the reactive rf magnetron sputtering was used to deposit (Ba,Sr)(Ti,Zr)O3 (BSTZ) thin films on Pt/SiO2/Si substrate. The optimal sputtering parameters were found to be RF power of 160W、sputtering pressure of 10 mTorr、substrate temperature of 580°C and oxygen concentration (O2/O2+Ar) of 40%. The physical characteristics of BSTZ thin films deposited on Pt/SiO2/Si substrate with different sputtering parameters were obtained by the analyses of XRD, SEM and AFM. The characteristics and dielectric constant of thin films were discussed. The electrical properties of BSTZ thin films using HP4194A and HP4156C semiconductor parameters analyzer were estimated through the measurement of leakage current on MIM structure. The dependences of dielectric constants on applied voltage、frequency and temperature were discussed. From the experimental results, it reveals that the dielectric constant with optimal sputtering parameters was about 191, and the leakage current of thin film was about 3x10-8 A/cm2 when the applied electrical field of thin film was at 0.1 MV/cm. Besides, the Curie temperature (Tc) of BSTZ thin film was confirmed to be about 20°C and the dielectric constants of BSTZ thin films exhibited little change under different temperature(0~80°C) and frequency (~1MHz). * student ** advisor
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Kuvatov, Azamat [Verfasser]. "Polungs- und Biegeverhalten von Ba(Ti,Sn)O3-Keramiken mit einem Funktionsgradienten / von Azamat Kuvatov." 2005. http://d-nb.info/975671650/34.
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ZHOU, YU-SHANG, and 周玉商. "The investigation of (Ba, Sr)(Ti, Sn)O3 as a boundary layer insulating ceramuic capacitor." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/63889221200216594883.
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Liu, Chi-Yang, and 劉冀陽. "Direct Sintering Process for A5B4O15 (A=Ba, La; B=Ti, Sn, Nb) Microwave Dielectric Ceramics." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/95zv67.
Full textAbstract:
碩士崑山科技大學
電子工程研究所
96
A5B4O15 (A=Ba, La; B=Ti, Sn, Nb) microwave dielectric ceramics prepared using a direct sintering process were investigated. The mixture of raw materials was pressed and sintered directly without any calcination stage involved. Effects of CuO addition were also studied. Ba2La3Ti3NbO15 (BLTN1) phase could be obtained after 2-6 h sintering at 1430-1500oC, BaLa2Ti3O10 phase was also found. Density of BLTN1 reached 6.08g/cm3 for 6 h sintering at 1500oC. The sintering temperature can be effectively reduced to 1350oC in BLTN1 ceramics with 2 wt％CuO additions (BLTN1C). BaLa2Ti3O10 and La2Ti2O7 phase were found in BLTN1C ceramics. Density of BLTN1C reached 6.22g/cm3 for 4 h sintering at 1430oC, and εr=42-50 was found. Single phase Ba3La2Ti2Nb2O15 (BLTN2) could be obtained after 2-6 h sintering at 1400-1470oC. Density reached 6.21g/cm3 for 6 h sintering at 1470oC. The sintering temperature can be effectively reduced to 1200oC in BLTN2 ceramics with 2 wt％CuO additions (BLTN2C). Dense BLTN2C of 6.29g/cm3 was obtained for 6 h sintering of 1270oC, and the properties εr=48-55 was found. Two phases Ba4LaTiNb3O15 and Ba4LaSnNb3O15 were found in Ba4La(Sn0.75Ti0.25)Nb3O15 (BLSTN) ceramics. Density reached 6.35g/cm3 for 4 h sintering at 1470oC.
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Kuo, Ya-Ling, and 郭雅翎. "Fe-, Nb-, and Ti-doped (Pb,Ba)ZrO3 thin film prepared by sol-gel process." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/38687843837957635254.
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Yang, Cheng-Fu, and 楊證富. "Properties of Low Sintering Temperature (Ba,Sr)(Ti,Zr)O3 Based Ceramics and Related Devices." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/39811175502091021929.
Full textAbstract:
博士國立成功大學
電機工程研究所
81
In this dissertation, four succeeding main topic are studied. The first topic is tried to lower the temperature required to densify the (Ba0.8Sr0.2)(Ti0.9Zr0.1)O3 ( BSTZ ) with studying its dielectric properties at different amount of CuO added and different calcining temperature. For 1050oC calcination, the calcined powder contains BaTiO3, SrTiO3 and some raw materials such as ZrO2 and BaCO3. With sintering, some residual raw materials form unknown phase and/or low-dielectric-constant compounds with CuO, causing the liquid phase effect of CuO to disappear. For 1170oC calcination, the calcined powder compl- etely forms ABO phases containing (Ba,Sr)TiO3 and BaZrO3. The sintering temperature for densification of ceramics is lowered, and the firing characteristics critically depend on the amount of CuO added and the sintering temperature. In the second topic, by using the results in topic one, in order to lower the temperature required to densify (Ba1-xSrx) (Ti1-yZry)O3( BSTZ-series ) and Ba(Ti1-xZrx)O3 ( BTZ-series ) and to avoid the formation of a low dielectric constant phase, copper oxide is added as liquid-phase propmoter after BSTZ- series and BTZ-series are calcined. The puepose of this study was to form a (Ba1-xSrx)(Ti1-yZry)O3 composition which had maximum permittivity at about 25oC. However, for different amounts of CuO added, the dielectric constant increases with increasing amount of CuO at lowering sintering temperature ( below ∼ 1100oC ). When a higher sintering temperature is used ( above ∼ 1200oC ), the dielectric constant reaches a maximum at ∼ 1wt%-CuO-added ceramics, and decreases slightly on further additon of CuO.
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盧典佑. "The effect of Ba/Ti ratio on the dielectric properties of Barium Titanate-based capacitors." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/81380868784961838205.
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Chen-ChingChu and 朱振慶. "Development of non-core-shell (Ba,Ca)(Ti,Zr)O3 base MLCC with Ni electrodes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/48941195489073008372.
Full textAbstract:
碩士國立成功大學
電機工程學系專班
98
Based on BCTZ by MLCC BME process, using BaTiO3 as constraining layers, to add constraining layers on the samples to control grain growth, and then to get the good dielectric constant and TCC. Besides, apply rapid sintering concept to resist inner electrode shrinkage during sintering. Depending on this concept, expect to get good continuity of inner electrode to gain higher capacitance. According to results, containing layers added can be useful to control grain growth of BCTZ. At the same time, rapid sintering performs good continuity of inner electrode and good outliner of sample by constraining sintering.
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林奐汝. "The Effect of Bottom Electrode on Ferroelectric Thin Films Ba(Zr,Ti)O3 as Microwave Varactors." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/43508829725598829166.
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Kuo, Pau-Sheng, and 郭寶聲. "Effects of Ba/Ti Ratios on the Sintering Behavior, Microstructure and Dielectric Properties of BaTiO3 Ceramics." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/40022173533394728329.
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Hsin-IHo and 何欣宜. "Microstructure and dielectric properties of (Ba,Ca)(Ti,Zr)O3 system prepared by two-step sintering." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/72888855607150373630.
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Yan-FuChiu and 邱彥富. "A study on low firing (Ba, Ca) (Ti, Zr) O3 dielectric cofired with Cu inner electrode." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/82550464829942827117.
Full textAbstract:
碩士國立成功大學
電機工程學系碩博士班
101
In this paper, the high dielectric constant and the high density of (Ba,Ca)(Ti,Zr)O3(BCTZ) ceramic using the sintering aid for co-firing with copper electrode was investigated. The SiO2 and Li2CO3 were used to reduce the sintering temperature below 1050℃ for 2hr in the reducing atmosphere due to the promote liquid-phase sintering. The additional amount of SiO2 and Li2CO3 have been optimized to achieve optimum dielectric characteristics and uniform grain size distribution. However, it was found that the excess amount of Li2CO3 resulted from the secondary phase, which led to the dielectric constant and insulation resistance of the BCTZ were decreased and the dielectric loss of BCTZ was increased. It was demonstrated that the secondary phase (Ba1.55Ca0.45Si1O4) was examined by High-Resolution Transmission Electron Microscopy and energy-dispersive spectrometry (HRTEM-EDS). The high dielectric constant up to 9700, dielectric loss of 23×10-4 and high insulation resistance up to 5×1010 of (Ba,Ca)(Ti,Zr)O3 of the specimen were sintered at 1050℃ for 2hr with copper electrode in the reducing atmosphere.
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Lee, Yi-Chih, and 李宜芝. "The microstructure and dielectric properties of Ba-Ti-O by adding ZnO to BaO-B2O3-SiO2 glass systemThe microstructure and dielectric properties of Ba-Ti-O micowave ceramics by adding ZnO to BaO-B2O3-SiO2 glass system." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/02254907873647516630.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
97
In the article, we investigate the sintering behavior, microstructures and electrical properties of low-temperature firable BaO-B2O3-SiO2-ZnO glass-added BaTi4O9 microwave dielectric materials with Cu paste in a reducing atmosphere. We fixed the BaO-B2O3-SiO2 content and varying the ZnO contents for studying the effect of glass compositions on the sintering behavior, microstructures and dielectric properties of low-temperature friable samples. The experiment results show that all of the four glass recipes A,B,C,D can not only reduce effectively sintering temperatures, but also improve the discoloring question of samples by restraining the diffusion of Cu-electrode during sintering process. According to the forgoing results, it is necessary to modify further the proportion of glass additions for obtaining better microwave dielectric properties, such as quality factor (Qf), at microwave frequency regime. Base on the analysis results of X-ray diffractometry and electrical properties of the samples, it was found that the Qf value is high as the BaTi4O9 host phase has been maintained. Beside, the improved Qf value can be obtained due to the Cu3Ti3O phase, resulting from Cu reacts with Ti element of the BaTi4O9 ceramics, which existed and to be a interlayer between electrode and ceramics so that it can provide a gradual transformation zone to alleviate the structural transition and to promote the Qf value. Moreover, ZnO and B2O3 not only be a liquid phase promoter to give a assistance in sintering procedure but also form Zn(BO2)2 second phase to reduce dielectric constant. With the glass recipes A and B, whose content range are B2O3: 8.256×10-3∼8.412×10-3 wt%, SiO2: 7.08×10-3∼7.216×10-3 wt%, BaO: 1.5044×10-2∼1.5332×10-2 wt%, ZnO: 9.04×10-3∼9.62×10-3 wt%, the Qf value of the samples can be improved to 5737.8∼5881.5, and the DF value can be also decreased to 0.00024∼0.000265. According to the forgoing results, it can be expected to modify further the proportion of glass addition for achieving a higher Qf value. Subsequently, it is find that when the compositions of glass addition are B2O3: 9.288×10-3∼1.15665×10-2 wt%, SiO2: 7.965×10-3∼9.922×10-3 wt%, BaO: 7.965×10-3∼9.922×10-3 wt%, ZnO: 1.08225×10-2∼1.243×10-2 wt%, the Qf value of the samples can be improved markedly to 6368(GHz).