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 2620Vcm(-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. (C) 2008 Elsevier B.V. All rights reserved.