Effects of La-Deficiency and Substitution of Fe for Co in Solid-State Reaction between LaCoO_3-δ and Al₂O₃

Abstract

The solid-state reaction between La_1-xCo_1-yFe_yO_3-δ (x=0.0, 0.1; y=0.0, 0.5) and Al₂O₃ was investigated by X-ray diffraction, transmission electron microscopy, and electron energy loss spectroscopy. LaAlO₃ and spinel phases formed from a mixture of LaCoO₃ and Al₂O₃ with the increase in the reaction temperature. However, substitution of Fe for Co and La-site deficiency in LaCoO₃ inhibited the formation of LaAlO₃ and spinel phases. Moreover, the electron diffraction pattern of LaCoO₃ after the reaction suggests the possibility that the solid-state reaction enhance the formation of the La-site deficiency of La_1-xCoO₃.