Characterization of sol–gel synthesised lead-free (1 − x)Na0.5Bi0.5TiO3–xBaTiO3-based ceramics

The crystal structure, microstructure, dielectric and ferroelectric properties of (1 − x)Na0.5Bi0.5TiO3–xBaTiO3 ceramics with x = 0, 0.03, 0.05, 0.07 and 0.1 are investigated. A structural variation according to the system composition was investigated by X-ray diffraction (XRD) analyses. The results revealed that the synthesis temperature for pure perovskite phase powder prepared by the present sol–gel process is much lower (800 °C), and a rhombohedral–tetragonal morphotropic phase boundary (MPB) is found for x = 0.07 composition which showing the highest remanent polarization value and the smallest coercive field. The optimum dielectric and piezoelectric properties were found with the 0.93Na0.5Bi0.5TiO3–0.07BaTiO3 composition. The piezoelectric constant d33 is 120 pC/N and good polarization behaviour was observed with remanent polarization (Pr) of 12.18 pC/cm2, coercive field (Ec) of 2.11 kV/mm, and enhanced dielectric properties ɛr > 1500 at room temperature. The 0.93Na0.5Bi0.5TiO3–0.07BaTiO3-based ceramic is a promising lead-free piezoelectric candidate for applications in different devices.

► BaTiO3-doped Bi0.5Na0.5TiO3 powders were synthesized by a sol–gel method. ► Our results reveal that the 0.93Na0.5Bi0.5TiO3–0.07BaTiO3 ceramic exhibits good polarization behaviour, interesting piezoelectric, dielectric and ferroelectric properties at room temperature (d33 = 120 pC/N, ɛr = 1600, tan δ < 0.05, Tc = 240 °C.