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 degrees C. In this work, high temperature dielectrics based on (1-x-y)Bi0.5Na0.5TiO3-xBiAlO(3)-yK(0.5)Na(0.5)NbO(3) ceramics were designed and prepared. The introduction of BiAlO3 leads to the reduction of dielectric loss due to the formation of defect dipoles. And the introduction of K0.5Na0.5NbO3 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 degrees C and 324.5 degrees C and dielectric loss below 0.02 in the temperature range of 110 degrees C-336 degrees C. Therefore, this system will be one of promising candidates of dielectrics used for high-temperature capacitors.