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 (d ₃₃ *) of 470 pm/V and a high Curie temperature (T _c ) of 243 °C in (Na _0.5 K _0.5 )NbO ₃ -(Bi _0.5 Li _0.5 )TiO ₃ -BaZrO ₃ lead-free ceramics by doping MnO ₂ . 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 MnO ₂ -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.