Effect of perovskite and spinel additives on zinc oxide varistors by sol-gel route

Synthesis of zinc oxide (ZnO) varistors using sol-gel (SG) route is reporte d here. Multicomponent oxides, perovskites and spinels have been used as do pants in various mole percentages. Nonlinear coefficients for the three typ es of dopants are of the order 25, 35 and 18, respectively. SEM characteriz ation of the samples prepared by SG route indicates a change in the grain-s ize of the order 4-30 mum with respect to the sintering temperature 1000-12 00 degreesC. Similarly, perovskite and spinel dopants show a variation in t he grain-size of the varistors as characteristic of temperature. Also, ther e is an improvement in the bulk density at lower sintering temperatures for the powders prepared by SG route.