Microstructure modification in Ba-doped SnO2-based ceramics with promising thermal conductivity and electrical properties

Abstract

In this paper, the thermal conductivity of Ba-doped SnO2 varistors was tested using the heat flow method, and it was found that the thermal conductivity is related to the grain boundary barrier of the samples. Introducing the reduction of impurity phases and point defects is an effective method to enhance the thermal conductivity of SnO2-based varistors. Energy dispersive spectrograms indicate that the content of spinel Co2SnO4 doped with 1mol% Ba is the least when the arrester is operated at 40°C. The positive and negative charge defects are fully compensated, thereby reducing phonon scattering and improving the thermal conductivity of the samples. Spinel Co2SnO4 occupies the position of the effective grain boundary, so the reduction of Co2SnO4 and the compensation of positive and negative defects also effectively increase the grain boundary barrier. When the doping amount of Ba is 1mol%, the optimal potential barrier height is 1.48eV, the nonlinear coefficient is 45, the leakage current is 0.8μA/cm2 and the voltage gradient is 418V/mm.