Enhanced piezoresponse and electric field induced relaxor-ferroelectric phase transition in NBT-0.06BT ceramic prepared from hydrothermally synthesized nanoparticles

0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (NBT-0.06BT) nanoparticles were synthesized by hydrothermal method and subsequently used to prepare NBT-0.06BT ceramics. After poling at the electric field of 3.5 kV/mm, the piezoelectric coefficient (d33) and electromechanical coupling factor (κp) reached 171 pC/N and 0.31, respectively. The NBT-0.06BT ceramics also exhibited a large remanent polarization of 46.10 μC/cm2 and electric field induced strain of 0.243% at 8 kV/mm corresponding to normalized strain d33*=303 pm/V (Smax/Emax). The effects of polarization on crystalline phase, microstructures, dielectric properties and domain structures were investigated to reveal the origin of enhanced piezoresponse and electric field induced strain in as-prepared NBT-0.06BT ceramics. It can be observed that the tetragonal phase in NBT-0.06BT ceramics was enhanced and polar nanoregions were transformed into tweed-like structures and some lamellar domains after E-field poling. The dielectric response of NBT-0.06BT ceramics also exhibited an electric-field-induced relaxor-to-ferroelectric phase transition.