New NTC thermistors based on LaCrO_3-Mg(Al_(0.7)Cr_(0.3))_2O_4 composite ceramics

摘要

In this study, the xLaCrO_3-(1-x) Mg(Al_(0.7)Cr_(0.3))_2O_4 (x=0.1, 0.2, 0.3, 0.4) negative temperature coefficient composite ceramics were fabricated through conventional solid state reaction at 1650°C. X-ray diffraction analysis has revealed that the sintered ceramics are consisted of cubic spinel Mg(Al_(0.7)Cr_(0.3))_2O_4 phase and orthorhombic perovskite LaCrO_3 phase. The obtained values of p_(300) and B_(400/800) and E_a are m tne range of 1.55X 10~2-1.41 X10~8 Ωcm, 756-11317 K, 0.065-0.976 eV, respectively. The electrical properties of these ceramics can be adjusted by the LaCrO_3 contents. Such ceramics could be suitable for high temperature NTC thermistor application.