High-temperature dielectrics based on 0.95(0.94Bi0.5Na0.5TiO3-0.07BiAlO3)-0.05K0.5Na0.5NbO3.

The high temperature capacitors operated in some harsh conditions require dielectric ceramics with stable permittivity, low dielectric loss and high resistivity to temperatures above 200 °C. In this work, high temperature dielectrics based on (1-x-y)Bi 0.5 Na 0.5 TiO 3 -xBiAlO 3 -yK 0.5 Na 0.5 NbO 3 ceramics were designed and prepared. The introduction of BiAlO 3 leads to the reduction of dielectric loss due to the formation of defect dipoles. And the introduction of K 0.5 Na 0.5 NbO 3 leads to the disruption of long-range ferroelectric order, which is helpful to increase the temperature stability of permittivity. The composition of x = 0.07 and y = 0.05 has a stable permittivity between 86.5 °C and 324.5 °C and dielectric loss below 0.02 in the temperature range of 110 °C–336 °C. Therefore, this system will be one of promising candidates of dielectrics used for high-temperature capacitors. [ABSTRACT FROM AUTHOR]