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)[0.5K(0.5)Bi(0.5)TiO(3)-0.5Ba(Zr0.2Ti0.8)O-3]-xBi(Zn2/3Nb1/3)O-3 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, T-m, decreased from 150 degrees C for composition x=0, to 70 degrees C for x=0.2. The x=0.2 sample displayed a wide temperature range of stable relative permittivity, epsilon(r), such that epsilon(r)=805 +/- 15% from -20 to 600 degrees C (1 kHz). Dielectric loss tangent was <= 0.02 from 50 degrees C to 450 degrees C (1 kHz), but due to the tan delta dispersion peak, the value increased to 0.09 as temperatures fell from 50 degrees C to -20 degrees C. Values of dc resistivity were of the order of similar to 10(9) Omega m at 300 degrees C. These properties are promising in the context of developing new high temperature capacitor materials.