The structure and conductivity of LaMn1-zCrzO3 and (La,A)(1-y)Mn1-zCrzO3 (A=Sr, Ca) as air cathodes in solid oxide fuel cells

Abstract

Doped LaMnO3 systems are used as cathodes in solid oxide fuel cells, mainly due to their high electronic conductivity, thermal matching to the electrolyte material and good catalytic activity towards oxygen reduction. Lanthanum deficient LaMnO3 has been shown to have a higher electronic conductivity than stoichiometric LaMnO3, however, the material has been found to sinter more readily causing a reduction in the efficiency of the cathode. This paper discusses the effect of imparting non-stoichiometry to the LaMnO3 system with the incorporation of a B site dopant, Cr. The paper examines the effect on the conductivity and phase present with increased Cr content, a nd shows that Cr in LaMn1-zCrzO3, up to z = 0.15, does not produce an unacceptably large decrease in the electronic conductivity, especially for a Ca doped, A site deficient system. Thus, a B site doped system is considered as a possible candidate for solid oxide fuel cell cathode systems.