Structure and high-temperature properties of the (Sr,Ca,Y)(Co, Mn)O3−y perovskites — perspective cathode materials for IT-SOFC

Abstract

Oxygen deficient perovskites Sr 0.75 Y 0.25 Co 1-x Mn x O 3-y , x=0.5 and 0.75, were prepared by using the citrate route at 1373-1573K for 48 h. The cubic Pm-3m perovskite structure for x=0.5 was confirmed by electron diffraction study and refined using neutron powder diffraction (NPD) data. High-temperature thermal expansion properties of the prepared compounds were studied in air using both dilatometry and high-temperature X-ray powder diffraction data (HTXRPD). They

Defect Chemistry, Electrical Properties, and Evaluation of New Oxides Sr2CoNb1−xTixO6−δ (0≤x≤1) as Cathode Materials for Solid Oxide Fuel Cells

“…This is confirmed by the behavior of Sr 2 CoNb 0.9 Ti 0.1 O 6− δ (Figure SI 15), for which the oxygen loss is negligible but its TEC is even higher than that of the x= 0.9 oxide (the corresponding values of the volume expansion coefficients are α V= 64.3(1) 10 −6 K −1 for the latter and α V= 67.8(1) 10 −6 K −1 for the former. It is reported in the literature that high values of TEC are intrinsic to cobaltites as it is owed to a spin transition of Co 3+ ; thus, the higher the content of trivalent cobalt the higher the TEC. Our results fully agree with this hypothesis.…”

The Effects of Sr Content on the Performance of Nd1–xSrxCoO3−δ Air-Electrode Materials for Intermediate Temperature Solid Oxide Fuel Cells under Operational Conditions

“…The electrical behavior of the sample with x = 1/3 is different in the low-temperature range, slightly increasing as the temperature is raised to ∼623 K, then decreasing at higher temperature due to the mass loss corresponding to the creation of oxygen vacancies and reduction of the electron–hole content. It is also expected that the significant oxygen loss of the x = 2/3 composition further decreases the electron- hole mobility, as a consequence of the lower concentration of Co–O–Co bonds and the corresponding expansion associated with the creation of oxygen vacancies. − Note that the onsets of mass loss and drop in conductivity do not occur at the same temperature in the TGA and electrical measurements. This may be attributable to the dynamic nature of TGA, which is expected to displace observance of the mass loss to a higher temperature.…”