Thermochemical Stability, Electrical Conductivity, and Seebeck Coefficient of Sr-Doped LaCo0.2Fe0.8O3-δ

Abstract Phase stability, oxygen content, electrical conductivity, and Seebeck coefficient of La 1- x Sr x Co 0.2 Fe 0.8 O 3-δ ( x = 0, 0.2, 0.4) were studied as a function of temperature and oxygen activity. The thermochemical properties of these compositions under a reducing atmosphere appear to follow the boundaries set between the two end members, LaFeO 3 and LaCoO 3 , but the electrical properties are closer to those of LaFeO 3 . The Sr content ( x ≤ 0.4) does not seem to have a significant effect on the high-temperature phase stability. Dissociation of these compositions under a reducing atmosphere occurred gradually by the formation of transient compounds. The major transient compounds formed during dissociation could be represented by a general formula of (La, Sr) (Fe, Co)O 4 . Upon further reduction, these oxides dissociated to La 2 O 3 , SrO, Co, and Fe.