Oxygen vacancies contributing to intragranular electrical conduction of yttria-stabilized zirconia (YSZ) ceramics

Kurumada, M.; Hara, H.; Iguchi, E.

doi:10.1016/j.actamat.2005.06.027

Cited by 68 publications

(33 citation statements)

References 41 publications

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“…The Arrhenius plot for σ t , (b), is not linear, consistent with that reported for various YSZ samples on many other occasions. 3,7,8,10,28,29 This non-linearity is widely attributed to trapping of oxygen vacancies in vacancy-dopant complexes at low temperatures: 30 at higher temperatures, dissociation of the complexes occurs and the trapping enthalpy is not included in the activation energy. The total conductivity, σ t , at high temperatures, would therefore represent the hopping of free vacancies.…”

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confidence: 99%

Electrical Properties of Yttria-Stabilized Zirconia, YSZ Single Crystal: Local AC and Long Range DC Conduction

Vendrell

West

2018

J. Electrochem. Soc.

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Widely-used complex plane analysis of impedance data is insufficiently sensitive to characterize fully the bulk properties of YSZ single crystal. Instead, more extensive data analysis is needed which uses a combination of parallel, admittance-based formalisms and series, impedance-based formalisms. Bulk electrical properties are measured at higher frequencies and contain contributions from both long range conduction and local dielectric relaxation. At lower frequencies, electrode-sample contact impedances are measured and are included in full equivalent circuit analysis. The impedance of YSZ crystal of composition 8 mol% Y 2 O 3 in the (110) orientation, with Pt electrodes, was measured over the temperature range 150-750 • C and frequency range 0.01 Hz-3 MHz. Full data analysis required (i) a parallel constant phase element (CPE)-resistance (R) combination to model the electrode response, (ii) a series R-C element to represent local reorientation of defect dipoles and (iii) a R-C-CPE element to represent long range oxide-ion conduction; (ii) and (iii) together model the bulk response. The dielectric element underpins all discussions about defect structure and properties of YSZ but has not been included previously in analysis of impedance data. The new equivalent circuit that is proposed should allow better separation of bulk and grain boundary impedances of YSZ ceramics. Yttria-stabilized zirconia (YSZ) is a very well-known oxide ion conductor that is used as the solid electrolyte in solid oxide fuel cells and oxygen gas sensors.1-3 It usually takes the form of a high-density ceramic in which the bulk resistance in series with a grain boundary resistance gives the overall sample resistance. 4 In almost all cases, the grain boundary resistance is present and cannot be eliminated readily by attention to ceramic processing conditions. The nature of the grain boundary impedance is often unclear, although significant compositional differences from the bulk, associated with dopant segregation, may be involved. 5,6 In order to measure sample impedances, sample-electrode contacts are necessary and therefore, appropriate consideration of their associated impedances forms part of the overall impedance analysis. For YSZ, contact impedances include contributions from the blocking of oxide ions at the sample-electrode interface, charge transfer resistances associated with the O 2− /O 2 redox couple and the diffusion of O 2 molecules between the surrounding atmosphere and the sampleelectrode interface. Usually, electrode contact impedances are wellseparated on a frequency scale from bulk/grain boundary impedances because they have much higher associated capacitances, C: typically (1-10) × 10 −6 F for the electrode contact compared with ∼ 1 × 10 −10 F for a grain boundary capacitance and (2-3) × 10 −12 F for a bulk capacitance. Relaxation frequencies, ω, are given ideally by ωτ = 1, where τ = RC and therefore, the frequency maxima of impedance semicircles, arcs or peaks associated with bulk/grain boundary impedances are usuall...

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confidence: 99%

Electrical Properties of Yttria-Stabilized Zirconia, YSZ Single Crystal: Local AC and Long Range DC Conduction

Vendrell

West

2018

J. Electrochem. Soc.

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“…Dielectric relaxations due to ionic displacement induced by the migration of oxygen vacancies have been reported in some oxygen ionic conductors [7,8]. The study of dielectric properties present the valuable information on the behavior of localized charge carriers that lead to high ionic conduction.…”

Section: Introductionmentioning

confidence: 98%

Dielectric and electrical properties of gadolinia doped ceria

Liu¹

2009

Journal of Alloys and Compounds

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“…A pilha a combustível é um dispositivo eletroquímico, que realiza a conversão de energia gerada por uma reação eletroquímica em energia elétrica, sendo um método altamente eficiente de geração de eletricidade e, em alguns casos, de calor [1]. Trata-se de uma tecnologia extremamente eficiente e de concepção ambiental, pois emite concentrações desprezíveis de NO x , quando comparados a outros processos de combustão [2,3].…”

Section: Introductionunclassified

“…Trata-se de uma tecnologia extremamente eficiente e de concepção ambiental, pois emite concentrações desprezíveis de NO x , quando comparados a outros processos de combustão [2,3]. As diferentes tecnologias de pilha a combustível têm basicamente o mesmo princípio: são compostas por dois eletrodos porosos -o ânodo (terminal negativo) onde ocorre a reação com o combustível e o cátodo (terminal positivo) onde flui o oxigênio, separados por um eletrólito (material impermeável que permite movimento aos íons positivos entre os eletrodos) [1][2][3][4][5][6].…”

Section: Introductionunclassified

Deposição de filmes de ZEI 8% em mol por sistema de spray pirólise modificado

Toniato

2008

Matéria (Rio J.)

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RESUMONeste trabalho, foram produzidos filmes de zircônia estabilizada com ítria com 8 % em mol (ZEI), que podem aplicados como eletrólitos para pilhas a combustível de óxido sólido (PaCOS), abrasivos e proteção anti-corrosiva, depositados em substrato de quartzo pela técnica de spray pirólise e tratados termicamente a 1000ºC. Para obtenção dos filmes, foi utilizado um sistema de deposição por spray-pirólise modificado segundo patente depositada no INPI, que se comparado ao sistema tradicional onde o bico atomizador fica estático durante o processo de deposição, resulta na produção de filmes de melhor homogeneidade, rugosidade e na redução dos defeitos morfológicos, como as trincas e fissuras. As melhorias no aparelho de deposição forneceram, também, melhor controle sobre os parâmetros de deposição quando comparado ao sistema tradicional, como a taxa e temperatura de deposição. A estrutura do filme foi analisada através de difração de raios X, que se apresentaram policristalinos e de acordo com a identificação realizada com o padrão JCPDS # 821246, os filmes de YSZ estão arranjados em uma estrutura cúbica de face centrada do tipo fluorita, e com orientação preferencial dos grãos no plano (111). A morfologia dos filmes foi analisada por imagens de microscopia ótica e microscopia de força atômica, sendo comparada às trincas, a rugosidade e distribuição de grãos, para os filmes após o tratamento térmico. Os melhores resultados foram obtidos para os filmes depositados pelo método de spray pirólise modificado quando comparado ao sistema tradicional. Palavras-chaves: ZEI, eletrólitos, PaCOS e MESP®. Deposition of YSZ 8 mol% films by modified spray pyrolysis system ABSTRACTIn this work zirconia stabilized with itria films 8 mol% (8YSZ) had been produced, applied as electrolytes for solid oxide fuel cell (SOFC), deposited in quartz substrate spray-pyrolysis technique and treated at 1000ºC. For attainment of films a system deposition for spray-pyrolysis modified according to patent deposited in INPI was used, that if compared with traditional system where atomized is static during deposition process, results in production of films more homogeneous, roughness and reduction of morphologic defects, at cracks. The improvements in deposition apparatus had also supplied better control of deposition parameters when compared with traditional system, with solution flow rate and temperature of deposition. The structure of films had been analyzed through X-ray diffractometry (XRD) results indicated that polycrystals films, structure cubical centered face of fluorite type with preferential orientation of grains in plan (111) identification through of standard JCPDS # 821246. The films morphology was analyzed by optical microscopy and atomic force microscopy, being compared cracks, roughness and distribution of grains, for films after thermal treatment. The results indicate that the use deposited in modified method of spray-pyrolysis (MESP®) appropriate deposited films the deposited were dense, crack-free and well adhered to the subs...

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Oxygen vacancies contributing to intragranular electrical conduction of yttria-stabilized zirconia (YSZ) ceramics

Cited by 68 publications

References 41 publications

Electrical Properties of Yttria-Stabilized Zirconia, YSZ Single Crystal: Local AC and Long Range DC Conduction

Electrical Properties of Yttria-Stabilized Zirconia, YSZ Single Crystal: Local AC and Long Range DC Conduction

Dielectric and electrical properties of gadolinia doped ceria

Deposição de filmes de ZEI 8% em mol por sistema de spray pirólise modificado

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