Enhanced High Temperature Stability of BNT-BKT-CBTZ Lead-Free Dielectrics

(0.8-x)Bi0.5Na0.5TiO3-0.2K(0.5)Bi(0.5)TiO(3)-xCa(0.7)Bi(0.2)Ti(0.9)Zr(0.1)O(3) (BNT-BKT-CBTZ) ceramics are prepared by a solid-state sintering method to investigate the influence of CBTZ with A-site vacancies on the high-temperature dielectric stability. XRD patterns reveal that all compositions show pure perovskite structure without any apparent secondary phase. The addition of CBTZ effectively suppresses the dielectric anomaly peak at maximum temperature (T-m) which forms a flatter dielectric platform especially that for x= 0.1, permittivity is 1606 +/- 15% in a wide temperature range from 84 degrees C to 417 degrees C with a low dielectric loss (<0.02) from 120 degrees C to 393 degrees C. The ceramics exhibit insulative nature and the activation energy (Ea) of grain conductivity calculated from Z*(f) that follows Arrhenius law is of similar to 1.73 eV. With increasing the CBTZ content, BNT-BKT-CBTZ transforms from ferroelectric to relaxor state and the ferroelectric macrodomains miniaturize to randomly oriented polar nanoregions (PNRs). For BNT-BKT-0.1CBTZ, high temperature PNRs arise at lower temperature which leads to enhanced inducing electric field for relaxor to ferroelectric phase transition and temperature-stable relaxor behavior. (c) 2019 The Electrochemical Society.