A comparative study between the mixed-oxide and high-energy milling planetary method on electrical and microstructural properties for a SnO2-based ceramic system

SnO2 varistors doped with Co3O4, Cr2O3, and Sb2O5 were prepared separately by two mechanical processes: mixed-oxide and high-energy milling planetary method. A comparison on the electrical and microstructural properties of the samples obtained by both methods was made. The best results on these characteristics were achieved through the milling planetary route, obtaining a nonlinear coefficient of 33 and a breakdown field of 2620 V cm−1 at a sintering temperature of 1350 °C. The samples synthesized by this last technique showed not only high density values, reaching 90.5% of the theoretical density, but they also exhibited a homogeneous microstructure, which compete with those obtained by chemical methods, with the advantage that the milling planetary method is cheaper, faster and easier than the chemical routes.