Effect of the sintering temperature of ceramic manganites La0.7Mn1.3O3 ± Δ on their grain sizes, magnetic and electrical properties

The effect of the sintering temperature from 1070 to 1670 K of ceramic samples of lanthanum manganite La0.7Mn1.3O3 on their grain size, structure, magnetic and resistive properties has been studied. An increase in the sintering temperature to 1270 K is shown to lead to an insignificant increase in the grain size and an increase in the density, fraction of the ferromagnetic phase in a grain, and colossal magnetoresistance. The ceramics sintering at temperatures higher than 1470 K is found to sharply increase the grain size; simultaneously, the grain takes a layered structure. The grain growth at these temperatures is established to be accompanied by manganese precipitation at the grain boundaries and likely in the grain interior. The increase in the sintering temperature is accompanied by appearance of a magnetically phase heterogeneity and a decrease in the Curie temperature and magnitude of the colossal magnetoresistance effect.