Effect of high content of Co3O4 on the structure, morphology, and electrical properties of (Cr,Sb)-doped SnO2 varistors

The effect of Co3O4 content on the microstructure, structure, and electrical properties of SnO2-Cr2O3-Sb2O5 ceramic samples was investigated in the present work. The system under study was (99.9-X)% SnO2-X%Co3O4-0.05%Sb2O5-0.05% Cr2O3, where X=0, 0.5, 1, 2, or 4 mol%. For a thorough study of this ceramic system, thermal analysis, X-ray diffraction (XRD) with Rietveld refinement, and scanning electron microscopy (SEM) characterization were carried out. It was found that the spinel phase content increases from 3% for the lowest Co3O4 dopant concentration up to 15% as the dopant content increases to 4%. As for the electrical properties of the studied system, the samples showed high values of breakdown electric field (from 2994.51 to 3218.38 V cm(-1)) and therefore the samples may be suitable for high-voltage applications. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.