Transition dependence of La2/3Ca1/3MnO3 oxide on microstructure

The effect of doping levels on the Curie temperature (TC) of R1−xAxMnO3 oxides has been studied intensively. However, the effect of microstructure on transition behavior of R1−xAxMnO3 oxides is not yet well understood. In the present work, the microstructure and transition behavior of bulk La2/3Ca1/3MnO3 colossal magnetoresistance oxide sintered at different temperatures have been investigated in detail. The results indicate that the grain size of the La2/3Ca1/3MnO3 oxide decreases as the sintering temperature decreases. A crystalline phase and an amorphous phase co-existed in the sample sintered at 1400 °C. The grains grew by a spiral-growth mechanism along a favorable direction, which resulted in lower TC. However, the sintering temperature of 1200 °C is not high enough to sinter the samples completely, although there is no difference in TC compared to 1300 °C. Sintering the La2/3Ca1/3MnO3 oxide at an optimized sintering temperature, 1300 °C, gives an optimal sinterability, which dominates the electrical and mechanical properties of the oxide.