Microstructure and Electrical Properties of In₂O₃, La₂O₃ and Ga₂O₃ Doped ZnO-Bi₂O₃-MnO₂-SiO₂-TiO₂ Varistor Ceramics

Abstract

ceramics with addition of X 2 O 3 (X = In, La, Ga) were manufactured through the conventional solid-state method and their phase transformation, microstructure, band gap, and electrical properties were investigated by X-ray diffractometer, Scanning electron microscopy, Fourier transform infrared spectroscopy, and solid UV absorption spectrometry, respectively. The results show that ZnO-Bi 2 O 3 -MnO 2 -SiO 2 -TiO 2 -0.15 mol% X 2 O 3 ceramics can be successfully produced at a very low temperature of 875 °C. When X 2 O 3 , especially Ga 2 O 3 , is doped into ZnO varistors, the grain sizes of specimens are refined. The grain size of ZnO-based varistor ceramics with Ga 2 O 3 doping decreases obviously from 4.31 to 3.10 μm, and the voltage gradient increases from 763.1 to 1047.5 V mm −1 . The nonlinear coefficient of ZnO-based varistor ceramics with In 2 O 3 doping increases from 26.5 to 36.7.