Dielectric Properties of (Ba0.8-xBi0.2)(Zn0.1Ti0.9)O3 Ceramics for High Temperature Applications

A number of Pb-free BaTiO3 - Bi(Zn1/2Ti1/2)O-3 solid solutions have been studied by Huang et al. [1]. Compositions close to 0.8BaTiO(3) - 0.2Bi(Zn1/2Ti1/2)O-3 revealed pseudo-cubic symmetry and showed a linear dielectric response. The existence of a nearly flat temperature dependence of the relative permittivity over the temperature range of 100 degrees C to 350 degrees C was also obtained. In this study, the effects of cation non-stoichiometry and doping were investigated in an attempt to optimize the insulation resistance for high temperature capacitor applications. The dielectric response of (Ba0.8-xBi0.2)(Zn0.1Ti0.9)O-3 ceramics where 0 <= x <= 0.08 as well as ZrO2- and Mn2O3-doped ceramics were investigated. The optimum compositions exhibited a relative permittivity in excess of 1150 and low loss tangent (tan delta < 0.05) that persisted up to a temperature of 460 degrees C. The temperature dependence of resistivity also revealed the improved insulation resistance of Ba-deficient compositions. Additionally, an ionic conduction mechanism was suggested to be responsible for the resistivity at high temperatures.