Giant electro-strain and enhanced energy storage performance of (Y_0.5Ta_0.5)⁴⁺ co-doped 0.94(Bi_0.5Na_0.5)TiO₃-0.06BaTiO₃ lead-free ceramics

0.94(Bi_0.5Na_0.5)(Y_0.5Ta_0.5)_xTi_1-xO₃-0.06BaTiO₃ lead-free piezoelectric ceramics were prepared by a conventional solid-state reaction method to study their excellent electro-strain properties and energy storage characteristics systematically. All ceramics exhibited a dense surface morphology. The introduction of (Y_0.5Ta_0.5)⁴⁺ complex ions destroyed the long-range ferroelectric order, which reduced the T_F-R to the operating temperature, resulting in an easier field-induced transition between relaxor and ferroelectric phase. Therefore, for x = 0.01 component attained unipolar strain of 0.37% under 52 kV/cm, and the corresponding normalized strain d₃₃* was 708 pm/V. Besides, the destruction of the ferroelectric phase also induced a pinched hysteresis loop and the maximum storage density of 1.215 J/cm³ with the efficiency of 68.7% obtained at 98 kV/cm for BNYT30 ceramics. These all demonstrated that the doping of complex ions (Y_0.5Ta_0.5)⁴⁺ made the BNT-BT an outstanding candidate for actuators and energy storage devices.