An Iron-57 Mössbauer spectral study of iron-based perovskite-type SOFC materials,

Fuel cells are widely regarded as a next-generation technology for alternative energy cycles less prone to cause climate change. One of the most promising types of fuel cells is the solid oxide fuel cell (SOFC), that offers several advantages over conventional, combustion based, power generation. Significant effort is devoted to the development of oxide electrode materials. The perovskite-type oxides Sr3-xYx(Fe1.25Ni0.75)O7-δ and Sr3-xPrx(Fe1.25Ni0.75)O7-δ are candidates for high temperature electrochemical applications, such as cathodes in SOFC. In order to improve electronic and ionic transport, substitution of the Sr by Y and Pr was carried out. These phases exhibit extended ranges of the oxygen non-stoichiometry, with 7-δ values ranging from 5.5 to 7.
Here we report the effect of the substitution of the Sr by Y or Pr on the oxygen content in the material. In order to assess the iron oxidation states and its oxygen coordination, iron-57 Mössbauer spectral analysis was carried out between 6 k and 370 k, and three different iron oxidation states have been observed.