High and Temperature-Insensitive Piezoelectric Strain in Alkali Niobate Lead-free Perovskite

With growing concern over world environmental problems and increasing legislative restriction on using lead and lead-containing materials, a feasible replacement for lead-based piezoceramics is desperately needed. Herein, we report a large piezoelectric strain (<i>d</i>₃₃*) of 470 pm/V and a high Curie temperature (<i>T</i>_c) of 243 °C in (Na_0.5K_0.5)­NbO₃-(Bi_0.5Li_0.5)­TiO₃-BaZrO₃ lead-free ceramics by doping MnO₂. Moreover, excellent temperature stability is also observed from room temperature to 170 °C (430 pm/V at 100 °C and 370 pm/V at 170 °C). Thermally stimulated depolarization currents (TSDC) analysis reveals the reduced defects and improved ferroelectricity in MnO₂-doped piezoceramics from a macroscopic view. Local poling experiments and local switching spectroscopy piezoresponse force microscopy (SS-PFM) demonstrates the enhanced ferroelectricity and domain mobility from a microscopic view. Distinct grain growth and improvement in phase angle may also account for the enhancement of piezoelectric properties