resumo
The perovskite series Sr2CoNb1-xTixO6-delta (0 <= x <= 1) was investigated in the full compositional range to assess its potential as cathode material for solid oxide fuel cell (SOFC). The variation of transport properties and thus, the area specific resistances (ASR) are explained by a detailed investigation of the defect chemistry. Increasing the titanium content from x = 0-1 produces both oxidation of Co3+ to Co4+ (from 0 up to 40%) and oxygen vacancies (from 6.0 to 5.7 oxygen atom/formula unit), although each charge compensation mechanism predominates in different compositional ranges. Neutron diffraction reveals that samples with high Ti-contents lose a significant amount of oxygen upon heating above 600 K. Oxygen is partially recovered upon cooling as the oxygen release and uptake show noticeably different kinetics. The complex defect chemistry of these compounds, together with the compositional changes upon heating/cooling cycles and atmospheres, produce a complicated behavior of electrical conductivity. Cathodes containing Sr2CoTiO6-delta display low ASR values, 0,13 Omega cm(2) at 973 K, comparable to those of the best compounds reported so far, being a very promising cathode material for SOFC.
palavras-chave
MAGNETIC-PROPERTIES; OXYGEN REDUCTION; MICROSTRUCTURE; PEROVSKITES; ELECTRODES; SPECTROSCOPY; MECHANISM; IMPEDANCE; SERIES; SOFC
categoria
Chemistry; Science & Technology - Other Topics
autores
Azcondo, MT; Yuste, M; Perez-Flores, JC; Munoz-Gil, D; Garcia-Martin, S; Munoz-Noval, A; Orench, IP; Garcia-Alvarado, F; Amador, U
nossos autores
Daniel Muñoz Gil
Bolseiro de pós-Doutoramentoagradecimentos
We thank Ministerio de Economia y Competitividad and Comunidad de Madrid for funding the projects MAT2013-46452-C4-1-R, MAT2013-46452-C4-4-R, and S2013/MIT-2753, respectively. Agencia Estatal de Investigacion and Fondo Europeo de Desarrollo Regional are also acknowledged for financing the project MAT2016-78362-C4-1-R. We acknowledge CSIC, ILL and ESRF for financial support and facilitate the access to the BM25-SpLine line at ESRF and D1B diffractometer at ILL.