The effect of sintering temperature on electrical properties and accelerated aging behavior of PCCL-doped ZnO varistors

The nonlinear electrical properties and DC accelerated aging behavior of the varistors, which are composed of Pr–Co–Cr–La (PCCL)-doped ZnO ceramics, were investigated for various sintering temperatures. The increase of sintering temperature led to more densified ceramics, whereas it decreased the nonlinear properties and varistor voltage. The highest nonlinearity was obtained from 1240 °C, with 79.4 in nonlinear coefficient and 0.3 μA in leakage current. As the sintering temperature increased, the donor density increased in the range of 0.96 × 1018–2.59 × 1018 cm−3, whereas the barrier height at grain boundaries decreased in the range of 1.90–0.67 eV. The highest stability of varistors was obtained from sintering temperature of 1260 °C, in which the %ΔV1mA is +1.9%, the %Δα is −10.6% and the %ΔIL is +20% for stress state of 95V1mA/150 °C/24 h. It is assumed that the moderate sintering temperature improves the stability, together with high nonlinear properties.