Dielectric and Piezoelectric Properties of (Bi_0.5Na_0.5)TiO₃–(Bi_0.5K_0.5)TiO₃ Systems

Abstract

The structural, dielectric and piezoelectric properties of [Bi 0.5 (Na 1- X K X ) 0.5 ]TiO 3 ceramics were studied for the compositional range, X =0–1.0. The samples were prepared by a conventional sintering technique. From X-ray diffraction results, it was found that the morphotropic phase boundary (MPB) between (Bi 0.5 Na 0.5 )TiO 3 (rhombohedral) and (Bi 0.5 K 0.5 )TiO 3 (tetragonal) exists in the range of X =0.16–0.20. Polarization-Electric field hysteresis loops show that the remanent polarization at X =0.20 (BNTK20) is larger than that at X =0.0 (BNT). Peaks of electromechanical coupling factor, dielectric constant, piezoelectric constant and elastic compliance were obtained at X =0.16–0.20 of the MPB region. Dielectric and piezoelectric properties are enhanced in the MPB region for [Bi 0.5 (Na 1- X K X ) 0.5 ]TiO 3 , similar to that observed for Pb(Zr, Ti)O 3 .