Effect of sintering process on the magnetotransport properties of Ho-doped La0.67Ca0.33MnO3

A series of highly dense Ho-doped La0.67Ca0.33MnO3 (LCMO) bulk ceramic samples were processed in the temperature range 1450 to 1600 °C and performed transport measurement (temperature down to 5 K and magnetic field up to 7 T). The effect of sintering time and temperature on transport properties are reported here. The magnetization and resistance decreased as sintering temperature is increased. Surface structure and morphology were studied by XRD, SEM and TEM. XRD pattern showed the monophasic orthorhombic structure of the sample sintered within the above temperature range for a sintering period of 20 h. It is surprising and interesting to observe that at certain critical doping level transition temperature is increased significantly indicating its potential use in CMR-based device technology above room temperature. In this paper, we report that critical optimization of sintering parameter is very important to achieve enhanced transport and magnetic properties.