High-temperature dielectrics based on (1 − x)[0.94Bi0.5Na0.5TiO3–0.06BaTiO3–0.03AgNbO3]–xK0.5Na0.5NbO3

Abstract

High temperature dielectrics based on (1 − x)[0.94Bi0.5Na0.5TiO3–0.06BaTiO3–0.03AgNbO3]–xK0.5Na0.5NbO3 (BNTBTAN–100xKNN, x = 0.01, 0.02, 0.03, 0.04) are prepared. The effects of K0.5Na0.5NbO3 contents on temperature stability of dielectric properties of BNTBTAN–100xKNN ceramics in the temperature range between 25 and 500 °C are studied. By incorporation of certain amount of AgNbO3, the required K0.5Na0.5NbO3 contents to disrupt the correlation among polar nanoregions in Bi0.5Na0.5TiO3 is reduced, thus this system not only has stable permittivity, but more importantly, behaves high insulting behavior, leading to the lower dielectric loss at high temperature. In particular, BNTBTAN–4KNN exhibits high dielectric permittivity (~ 2452), low dielectric loss (≤ 0.02) in the temperature range between 126 and 319 °C and small variation (Δe′/e′150 °C ≤ 15%) in dielectric permittivity from 51 to 371 °C. Therefore, our work provides a new promising candidate of materials for capacitors which can be operated at high temperature.