Phase Equilibria in the LaCoO3-LaMnO3-BaCoOz-BaMnO3 System

The phase equilibria in the LaCoO3-LaMnO3-BaCoOz-BaMnO3 system were studied at 1100°C in air by powder X-ray diffractometry of quenched samples. The existence of three phases in the BaCo1-yMnyO3-DELTA system was confirmed. Two of these phases are homogeneous in the range 0.15,y,0.30 and 0.38,y<0.55. Both have hexagonal structures (space group P63/mmc), but 10-layered and 12-layered cells, respectively. The last phase, with approximate composition BaCo0.285Mn0.715O3-DELTA, was indexed on the basis of a 21H-structure with the unit cell parameters a=5.7676(8) and c= 49.58(1) ? (space group P63/mmc). It was found that La1-xBaxMnO3±DELTA phases with 0