(Na_0.8-xK_0.2Li_x)_0.5Bi_0.5Ti_0.985Ta_0.015O₃ lead-free ceramics with large strain and high recoverable energy density

The conventional solid reaction was used to synthesize (Na_0.8-xK_0.2Li_x)_0.5Bi_0.5Ti_0.985Ta_0.015O₃ (abbreviated as BNKTT-100xLi) lead-free perovskite ceramics. The influences of Li⁺ ion doping for the relaxation mechanism and piezoelectric performances of all ceramics were systematically investigated. All ceramics exhibited a single perovskite structure, accompanied with a dense surface morphology and uniform element distributions. AC impedance spectroscopy showed the single grain conduction mechanism for all samples. The maximum bipolar strain (S = 0.462%) and unipolar strain (S_u = 0.443%) for x = 0.025 sample were obtained under 80 kV/cm, and its unipolar strain achieved 0.573% at 100 °C. BNKTT-15Li ceramic exhibited outstanding energy storage performance with a recoverable energy density of 1.29 J/cm³ under applied 130 kV/cm field. It suggested that the excellent electro-strain and energy-storage properties for BNKTT-100xLi ceramics could be widely applicable to electronic equipment.