Effect of Sm2O3 on the microstructure and electrical properties of SnO2-based varistors

The effect of Sm2O3 on the microstructure and non-linear electrical properties of (Co, Nb)-doped SnO2-based varistors was investigated. The addition of Sm2O3 improved the non-linear characteristics of (Co, Nb)-doped SnO2-based varistors. The threshold electric field (EB) of SnO2-based varistors increased significantly from 5340 to 12,460 V cm−1 and the mean grain size decreased from 4.7 μm to 1.7 μm as Sm2O3 concentration increased up to 0.20 mol%. There was an optimal value (0.20 mol%) of the Sm2O3 concentration. The sample doped with 0.20 mol% Sm2O3 had the highest non-linear coefficient (α = 28). The addition of Sm2O3 reduced the relative density of (Co, Nb)-doped SnO2-based varistors.