The behavior of the mixed conductor, SrFeCo0.5Oy, which exhibited an unusually high O permeability, was characterized by investigating the whole system. The samples exhibited an orthorhombic inter-grown structure which was isotypical with Fe6Sr4O13, for x-values of between 0 and 1.5. The inter-grown phase, Fe6-xCoxSr4O13, and the perovskite phase, Sr(Fe,Co)O3, coexisted for x-values of between 1.7 and 2.1. The perovskite phase formed, together with CoO impurities, at an x-value of 2.4. Within the single-phase region, with x between 0 and 1.5, the O content decreased and the total conductivity increased with x (table 67). The observation of an unusually high oxide-ion conductivity was explained in terms of crystal chemistry.

S.Guggilla, A.Manthiram: Journal of the Electrochemical Society, 1997, 144[5], L1202

Table 67

Conductivity of Fe6-xCoxSr4O13