THERMAL INPUT EFFECTS ON THE MICROSTRUCTURE AND ELECTRICAL PERFORMANCE OF ZNO-CATIO3 VARISTOR CERAMICS

Abstract

Using a traditional solid-state mixed oxide method, pelletized polycrystalline zinc oxide-based varistor ceramics were prepared with calcium titanate (CaTiO3) doping. This study examined how varying sintering temperatures affect the microstructural and electrical characteristics of the composite varistors. The samples were subjected to sintering temperatures between 1100 and 1300 °C for 90 minutes. X-ray diffraction (XRD) assessment confirmed the presence of two primary phases in the synthesized compound. Scanning electron microscopy (SEM) results showed that higher sintering temperatures promoted ZnO grain growth, increasing the average grain size from 4.66 to 10.42 µm. The average relative density of the synthesized samples exceeded 94% of the theoretical density. These results were determined to correspond with the modification in electrical properties, as the specimen sintered at 1250 °C demonstrated the most favorable electrical response, of which the nonlinear coefficient, breakdown voltage, and barrier height were 3.85, 0.99 V/mm, and 0.66 eV, respectively. The study presented in this paper can be used to discover and develop new and more efficient ZnO suppressors.