High Temperature Dielectrics in the Ceramic System K₀.₅Bi₀.₅TiO₃-Ba(Zr₀.₂Ti₀.₈)O₃-Bi(Zn₂⁄₃Nb₁⁄₃)O₃

摘要

Ceramics in the system (1-x)[0.5 K₀.₅Bi₀.₅TiO₃-0.5Ba(Zr₀.₂Ti₀.₈)O₃]-xBi(Zn₂⁄₃Nb₁⁄₃)O₃ have been fabricated by a solid-state processing route for compositions x ≤ 0.3. The materials are relaxor dielectrics. The temperature of maximum relative permittivity, Tm, decreased from 150 °C for composition x = 0, to 70 °C for x = 0.2. The x = 0.2 sample displayed a wide temperature range of stable relative permittivity, εr, such that εr = 805 ± 15% from −20 °C to 600 °C (1 kHz). Dielectric loss tangent was ≤ 0.02 from 50 °C to 450 °C (1 kHz), but due to the tanδ dispersion peak, the value increased to 0.09 as temperatures fell from 50 °C to −20 °C. Values of dc resistivity were of the order of ~ 109 Ω m at 300 °C. These properties are promising in the context of developing new high temperature capacitor materials.