Phase transition and piezoelectric properties of lead-free (Bi1/2Na1/2)TiO3-BaTiO3 ceramics

(1-x)(Bi0.5Na0.5)TiO3-xBaTiO(3) ceramics (x=0.03, 0.06, 0.08, 0.12, 0.15, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, and 0.90) were fabricated by a conventional solid-state reaction and their phase transitions and piezoelectric properties were investigated using XRD analyses, Curie temperature, the frequency dependance of dielectric constant, and P-E curves. A complete solid solution with a perovskite structure was formed in the whole composition range of BNT-BT and more than two phase transitions arising from a compositional change were found. With increasing BaTiO3 content, the sequence of phase transitions from a rhombohedral structure to unknown tetragonal structures and finally a tetragonal structure with the space group P4mm has been established. While the rhombohedral tetragonal phase transition led to superior piezoelectric properties in BNT-BT ceramics, other phase transitions between tetragonal structures had a little effect on piezoelectric properties. The d(33), epsilon(r), k(p), k(t), and Q(m) and values lied in ranges of 40-130 pC/N, 400-900, 10-30%, 15-30%, and 50-250, respectively. (C) 2014 Elsevier Ltd and Techna Group S.r.l. All rights reserved.