Phase transition and huge field-induced strain of BaZrO₃ modified (Bi_0.5Na_0.5)_0.94Ba_0.06TiO₃ ceramics

Lead-free ferroelectric ceramics (1 − x)[0.94Bi_0.5Na_0.5TiO₃–0.06BaTiO₃]–xBaZrO₃(BNBT–xBZ, 0 ≤ x ≤ 0.05) were prepared by two-step sintering method, and the effects of BZ doping on phase structure, micro morphology and electromechanical strain were systematically investigated. The X-ray diffraction analysis reveals that the crystal structure transforms from a rhombohedral and tetragonal mixed phase to tetragonal phase with the increasing of BZ doping. The P–E loops and I–E loops demonstrate that the increase of BZ concentration destroys the ferroelectric order and brings about a phase transition from ferroelectric to antiferroelectric. BNBT–0.03BZ exhibits outstanding strain behavior featured by a high strain of 0.33% and a large d₃₃ ^* of 600 pm/V at a moderate electric field of 55 kV/cm at room temperature with a relatively low unipolar strain hysteresis of 32.31%. With the increase of BZ, the value of strain decreases but the hysteresis also becomes lower. When the BZ amount is 0.05 mol%, the value of strain is 0.16% and the unipolar strain hysteresis is 11.30%.