PREPARATION OF PEROVSKITE-TYPE OXIDE BY THERMAL-DECOMPOSITION OF DOUBLE COMPLEX, [CO(NH3)6][LA(CO3)3].H2O

The formation process of perovskite-type oxide was investigated by following the thermal decomposition behavior of double complex, [Co(NH3)6] [La(CO3)3] H2O, in the range of room temperature to 1000°C. The decomposition product at 400°C was amorphous and contained CO32- ions. Cubic perovskite-type oxide, LaCoO3, was found to form at 600°C, though CO32- ions still remained. The formation of oxide with cubic structure was almost complete at 750°C. Specific surface area of oxide calcined at this temperature was (6.5+0.3) m2 g-1. Further heating to 900°C gave the rhombohedral oxide. Specific surface areas of oxide calcined at 900 and 1000°C were (6.3±0.3) and (5.7±0.5) m2.g-1, respectively. © 1990, The Chemical Society of Japan. All rights reserved.