Dielectric and piezoelectric properties of lead-free (Na0.5Bi0.5)TiO3-(K0.5Bi0.5)TiO3-(Li0.5Bi0.5)TiO3 ceramics with Ba2+ and Ca2+ dop

In this work, (0.935-x)Bi_0.5Na_0.5TiO₃-0.05(Bi_0.5K_0.5TiO₃)-0.015(Bi_0.5Li_0.5)TiO₃-x(Ba_1-yCa_y)TiO₃(BNKLT-BCT) system by keeping the KBT and LBT ratio constant is investigated. The primary purpose of this study is to deal with the effects of barium calcium titanate (BCT) additive on dielectric and piezoelectric properties of BNKLT-BCT ceramics. In the paper, BNKLT-BCT ceramics were fabricated by conventional solid state reaction. XRD results show that the crystalline structure of the ceramics is perovskite. At the same time, a significant change of the dielectric behavior and piezoelectric properties takes place with increasing the content of barium calcium titanate. The ceramics show a rhombohedral-tetragonal morphotropic phase boundary (MPB) in the range of x = 0.05, y=0~0.04, which results in ceramics providing superior dielectric and piezoelectric properties. The values of piezoelectric constant d₃₃, dielectric constant ε_r, and mechanical quality factor Q_m of BNKLT-BCT ceramics are higher than that of BNKLT ceramics while the dielectric loss factor tanδ is lower. It is found that a small amount of barium calcium titanate additive was of great help in providing higher dielectric constant ε_r, and piezoelectric constant d₃₃.