Investigation on the calcining condition and sintering temperature of perovskite-type La0.7Ca0.3CrO3 complex oxides by a combustion method

Perovskite-type La0.7Ca0.3CrO3 composite oxides were synthesized by a combustion method. The calcining condition of the synthesized powders and sintering temperature of ceramic specimens were studied. It was found that a pure perovskite structure was direct acquired in the combustion ash and the fine morphology (∼100 nm) was observed in the sample calcined at 600 °C. In view of the relative density, microstructure and electrical conducting properties of the sintering ceramics at different temperatures, the preferred sintering temperature was ascertained to be 1300 °C, at which the sample attains a high relative density of 96.8%, showing an electrical conductivity of 53.6 S cm−1 at 800 °C and much lower activation energy of 0.122 ev. Compared with La0.7Ca0.3CrO3 synthesized by the conventional solid state reaction method, that synthesized by the combustion method exhibits fine morphology and superior sintering activity, effectively lowering the sintering temperature and enhancing electrical conducting properties of the material.