Effects of BiMO3 on dielectric, ferroelectric, and piezoelectric properties of perovskite lead-free piezoelectric BaTiO3–(Bi0.5Na0.5)TiO3 ceramics

New lead-free piezoelectric ceramics of 0.9BaTiO3–(0.1−x)(Bi0.5Na0.5)TiO3–xBiMO3, M=Al and Ga, where x=0.00-0.10, were fabricated by the solid-state reaction technique. The effect of BiMO3 contents on the perovskite structure, phase transition, and dielectric, ferroelectric, and piezoelectric properties was investigated. X-ray diffraction patterns showed that the ceramics exhibit a monophasic perovskite phase up to x=0.06, suggesting stabilized perovskite structures with B-site aliovalent substitutions. Compositional-dependent phase transitions were observed from tetragonal to pseudo-cubic phase with increasing BiMO3 amounts. Al³⁺ ions were found to stabilize the transition temperature of the ceramics, while significantly decreasing transition temperature, and a change in the dielectric peak were found with an increasing amount of Ga³⁺. Regarding Al³⁺ substitution, the remanent polarization (Pr) values were found to decrease slightly with the Al³⁺ amount. With regard to Ga³⁺ substitution, Pr values decreased with the Ga³⁺ amount up to 0.06 and then increased slightly. The ceramics became softer with a higher degree of substitution according to the lower coercive field (Ec), when compared with 0.9BaTiO3–0.1(Bi0.5Na0.5)TiO3 ceramics. Ceramics with a lower degree of substitution and tetragonal phase showed butterfly strain loops that correlated with normal ferroelectric behavior.