Influence mechanism of Ni₂O₃ doping on leakage current of SnO₂ varistor ceramics

Abstract

The doping of Ni2O3 has significantly enhanced the electrical properties and density of SnO2–Co3O4–Cr2O3–Nb2O5 varistor ceramics. The leakage current density is reduced to 4.73 µA/cm2, the nonlinear coefficient is 37, and the voltage gradient is 549 V/mm. The undoped varistor ceramics exhibited a considerably higher leakage current of 48.04 µA/cm2. The performance improvement comes from alterations in grain boundary parameters. The doping of an appropriate amount of Ni improves the grain boundary barrier of SnO2 varistor ceramics and makes samples obtain higher grain boundary resistance, which hinders the leakage current path and results in excellent nonohmic characteristics. The stable grain boundary barrier structure dominated by Ni enables the sample to obtain stable power loss performance under long‐term direct current (DC) bias.