Abstract

In this study, we investigated the crystal defects and grain boundary properties in a ZZCCC (ZnO-Zn₂BiVO₆-Co₃O₄-Cr₂O₃-CaCO₃) varistor, with the liquid-phase sintering aid Zn₂BiVO₆ developed by our laboratory. The ZZCCC varistor sintered at 1,200℃ exhibited excellent nonlinear current-voltage characteristics (α=63), with oxygen vacancy (V₀^·; 0.35 eV) as a main defect, and an apparent activation energy of 1.1 eV with an electrically single grain boundary. Therefore, among the various additives to improve the electrical properties of ZnO varistors, if Zn₂BiVO₆ is used as a liquid phase sintering aid, it will be ideal to use Co for the oxygen vacancy and Ca for the electrically single grain boundary. This will allow the good properties of ZnO varistors to be maintained up to high sintering temperatures.

• Keywords: ZnO varistor, Impedance spectroscopy, Defect, Grain boundary, Zn₂BiVO₆