The Effect of B2O3 Doping on the Properties of Electrical and Thermal Conductivity for SnO2 Varistors

This study investigates SnO2-based varistors in the SnO2-Co3O4-Cr2O3-Nb2O5 system with varying B2O3 doping concentrations to optimize both electrical properties and thermal conductivity. The experimental formulation involved doping B2O3 with fixed concentration ratios of Co3O4, Cr2O3, and Nb2O5 (ranging from 0 mol% to 0.35 mol%), and the microstructure, electrical properties, and thermoelectric coefficient of the samples were measured in order to identify the optimal doping proportion. The varistor doped with 0.25 mol% B2O3 exhibited optimal performance, demonstrating a maximum voltage gradient of 525 V/mm, a minimum leakage current density of 11.2 μA/cm2, and a peak nonlinear coefficient of 36. Furthermore, the optimized formulation achieved enhanced thermal performance with a maximum thermal conductivity of 6.13 W·m−1·K−1.