Large electrostrictive effect in ternary Bi0.5Na0.5TiO3-based solid solutions

Abstract

In the present work, a ternary solid solution (0.935-x)Bi0.5Na0.5TiO3-0.065BaTiO3-xSrTiO3 (BNBST, BNBSTx) was designed and fabricated using the traditional solid state reaction method. A morphotropic phase boundary between the ferroelectric long-range-order and relaxor pseudocubic phases was determined around x of 0.22 for poled solid solutions. The further increase of SrTiO3 substitution turned the depolarization temperature Td to below ambient temperature and led to a sharp decrease in the remnant polarization Pr and quasi-static piezoelectric constant d33. A large electrostrictive coefficient Q of 0.026 m4 C−2 was obtained for BNBST0.30, which was entirely comparable to the well-known electrostrictive material Pb(Mg1/3Nb2/3)O3, recently reported Bi0.5Na0.5TiO3-BaTiO3-K0.5Na0.5NbO3, and Bi0.5Na0.5TiO3-BaTiO3-KNbO3. Under a moderate electric field of 4 kV/mm, the electrostrictive strain can reach as high as ∼0.11%. Furthermore, the electric-field-induced strain exhibited weak temperature-dependent behavior. The large electrostrictive strain was suggested to be ascribed to the formation of relaxor pseudocubic phase developed by the SrTiO3 substitution and the high electrostrictive coefficient of BNBST ceramics makes them great potential to be applied to the environmental-friendly solid-state actuators.