Influence of Ta2O5 on the electrical properties of ZnO- and CoO-doped SnO2 varistors

Abstract

SnO 2 -based varistors doped with 0.5% cobalt, 0.5% zinc and various tantalum amounts were prepared by the solid-state route. Experimental evidence shows that small quantities of Ta 2 O 5 improve the nonlinear properties of the samples significantly. It was found that samples doped with 0.05 mol% Ta 2 O 5 exhibit the highest density (98.5%), the lowest electric breakdown field (E b = 1050 V/cm) and the highest coefficient of nonlinearity (α = 11.5). The effect of Ta 2 O 5 dopant could be explained by the substitution of Ta 5+ by Sn 4+ .