Effect of BiAlO3 concentration on the dielectric and piezoelectric properties of lead-free (Bi0.5Na0.5)0.94Ba0.06TiO3 piezoelectric ceramics

In this paper, lead-free (1-x)(Bi0.5Na0.5)0.94Ba0.06TiO3-xBiAlO3 (BNBT-BA, x = 0, 0.010, 0.015, 0.020, 0.025, and 0.030) piezoelectric ceramics were synthesized using a conventional solid-state reaction method. The effect of BiAlO3 concentration on dielectric, ferroelectric and piezoelectric properties were investigated. The ferroelectric and piezoelectric properties of BNBT ceramics are significantly influenced by the presence of BA. In the composition range studied, X-ray diffraction revealed a perovskite phase with the coexistence of rhombohedral and tetragonal phases. The temperature dependence of dielectric properties showed that the depolarization temperature (Td) shifted towards lower temperatures and that the degree of diffuseness of the phase transition around Td and Tm became more obvious with increasing BiAlO3 content. The remanent polarization increased with increasing BA, and reached a maximum value of 30 μC/cm2 at x = 0.020. As a result, at x = 0.020, the piezoelectric constant (d33) and the electromechanical coupling factor (kp) of the ceramics attained maximum values of 188 pC/N and 34.4 %, respectively. These results indicate that BNBT-BA ceramics is a promising candidate for lead-free piezoelectric materials.