Phase equilibria at 1100°C in air and crystal structure of solid solutions in the system LaCoO3-SrCoO2.5-SrNiO3-LaNiO3

Phase equilibria in the LaCoO3-SrCoO2.5-SrNiO3-LaNiO3 system are studied at 1100degreesC in air using samples prepared by standard solid-state reactions and by the citrate route. The composition region and structure of La1-xSrxCo1-yNiyO3-delta solid solutions are determined by x-ray powder diffraction. The structure is refined by the Rietveld profile analysis method with Fullprof 2002. The solid solutions with 0 < x less than or equal to 0.5 have a rhombohedrally distorted perovskite structure (sp. gr. R3c). The rhombohedral distortion decreases with increasing Sr content, and the solid solutions with x > 0.5 have an ideal cubic structure (sp. gr. Pm3m). The composition dependences of lattice parameters for the La1-xSrxCo1-yNiyO3-delta solid solutions are presented.