Effects of Ta2O5 on the microstructure and electrical properties of ZnO linear resistance ceramics

Abstract

ZnO linear resistance ceramics were synthesized from ZnO–Al₂O₃–MgO–TiO₂–SiO₂–Ta₂O₅ by a conventional ceramics method. Effects of Ta₂O₅ on the phase composition, microstructures, and electrical properties of ZnO linear resistive ceramics were investigated. The results show that doping with appropriate amount of Ta₂O₅ can refine the grains of the main crystalline phase ZnO and the secondary crystalline phase ZnAl₂O₄ in terms of microstructure, and also can reduce the grain boundary barrier and optimize the I–V characteristics in terms of electrical properties. In addition, the doping of Ta₂O₅ can improve the stability of the resistivity , and the impedance frequency indicates that the doping of Ta₂O₅ makes the sample suitable for high-frequency electric fields. The resistivity of the sample doped with 0.2 mol% Ta₂O₅ is 56.2 Ω·cm, and this sample has the best grain boundary barrier height, nonlinear coefficient and temperature coefficient of resistance of 0.054 eV, 1.04 and −3.48 × 10⁻³ °C⁻¹, respectively.