Effect of high content of Co 3 O 4 on the structure, morphology, and electrical properties of (Cr,Sb)-doped SnO 2 varistors

Abstract The effect of Co 3 O 4 content on the microstructure, structure, and electrical properties of SnO 2 –Cr 2 O 3 –Sb 2 O 5 ceramic samples was investigated in the present work. The system under study was (99.9– X )% SnO 2 – X %Co 3 O 4 –0.05%Sb 2 O 5 –0.05% Cr 2 O 3 , 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 Co 3 O 4 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.