Dielectric and piezoelectric properties of (Bi0.5Na0.5)TiO3-(Bi0.5K0.5)TiO3 systems

The structural, dielectric and piezoelectric properties of [Bi-0.5(Na1-x K-x)(0.5)]TiO3 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 (Bi0.5Na0.5)TiO3 (rhombohedral) and (Bi0.5K0.5)TiO3 (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(Na1-xKx)(0.5)]TiO3, similar to that observed for Pb(Zr, Ti)O-3.