Influence of In₂O₃ Doping Amount on Electrical Properties of Sb-based SnO₂ Varistors

(98.85-x)SnO₂-1CoO-0.05Cr₂O₃-0.1Sb₂O₅-xIn₂O₃ (x=0, 0.05, 0.10, 0.15, mole fraction/%) Sb-based SnO₂ varistors were prepared by sintering SnO₂ powder, CoO powder, Cr₂O₃ powder, Sb₂O₅ powder and In₂O₃ powder at a pressure of 100 MPa and a temperature of 1 300 ℃. The effect of In₂O₃ doping amount on the microstructure and electrical properties of varistors was studied. The results show that with increasing In₂O₃ doping amount, the average grain size of Sb-based SnO₂ varistors decreased, the density increased first and then decreased, the nonlinear coefficient, applied density, interfacial state density and barrier height all increased first and then decreased, the leakage current density decreased first and then increased, and the voltage gradient increased. When the mole fraction of doped In₂O₃ was 0.10%, the varistor had the largest density of 6.82 g·cm^-3 and the excellent electrical properties with voltage gradient, nonlinear coefficient, leakage current density, applied density, interfacial state density and barrier height of 851 V·mm^-1,32.36,1.19 μA·cm^-2,4.4×10²³ m^-3,3.2×10¹⁶ m^-2 and 1.44 eV, respectively.