Structure evolution and electrostrictive properties in (Bi0.5Na0.5)0.94Ba0.06TiO3-M2O5 (M = Nb, Ta, Sb) lead-free piezoceramics

The effects of M2O5 (M = Nb, Ta, Sb) addition on the phase transition and electrical properties of 0.94Bi(0.5)Na(0.5)TiO(3)-0.06BaTiO(3) (BNBT6) lead-free ceramics were studied. Results showed that M substitution into BNBT6 induced a phase transition from coexistence of ferroelectric tetragonal and rhombohedral to a relaxor pseudocubic with a significant disruption of the long-range ferroelectric order. Accordingly, large strain response of 0.42-0.43% with fatigue-free behavior, which is due to a reversible field-induced ergodic relaxor-to-ferroelectric phase transformation, was obtained at 0.5 mol% M content. Furthermore, as the compositions (x >= 0.06) lied deep in the pseudocubic region of the phase diagram, a high, purely electrostrictive effect with large electrostrictive coefficient Q(33) of 0.020-0.024 m(4)/C-2 was achieved. More interestingly, the obtained BNBT6-based electrostrictors showed good resistance to both long-term electric cycling (up to 10(6) cycles) and thermal influence (20-160 degrees C), rendering them suitable for high-precision positioning devices and other actuators. (C) 2016 Elsevier Ltd. All rights reserved.