Research on Thermal Properties of Insulator-Metal Transition at Room Temperature in Sm1-xCaxMnO3

The high-purity electron-doped manganites Sm_1-xCa_xMnO₃ nanopowder were prepared by the solid-state reaction method, then the bulk material were obtained through granulation, molding, calcining, grinding and polishing. SCMO nanoparticles with 200 nm were obtained by the sol-gal process. The phase and surface morphology of these materials were characterized by X-ray diffraction and Scanning electron microscope and other experiments. The variable resistivity of the bulk materials were measured by two-wire method in the temperature range of 100–420K. The thermal conductivity was measured by the Laser Flash method. The results show that different doping ratios can change the phase transition temperature of the metal-insulation state. The temperature changed from 0 to 50 °C. The T_MI could be regulated to room temperature. When the temperature is high than the T_MI, it performs as metal state, on the contrary, it performs as an insulating state.