High temperature dielectrics in the ceramic system K0.5Bi0.5TiO3-Ba(Zr0.2Ti0.8)O3-Bi(Zn2/3Nb1/3)O3

Ceramics in the system (1-x)[0.5K0.5Bi0.5TiO3-0.5Ba(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 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.