Temperature-insensitive high piezoelectricity in a (Bi0.5K0.5)TiO3–PbTiO3–PbZrO3 ternary system

Abstract

Piezoelectric actuators operating in harsh environments require piezoelectric ceramics with high and temperature-insensitive piezoelectric responses, which poses a significant challenge due to the inverse correlation between the piezoelectric d₃₃ and the Curie temperature (T_C). In this study, a novel ternary system of Bi_0.5K_0.5TiO₃–PbTiO₃–PbZrO₃ (BKT–PT–PZ) is explored for high-temperature piezoelectric materials by considering the local structural heterogeneity and tolerance factor. The ferroelectric, piezoelectric, and dielectric properties, phase structure and temperature stability of xBKT–0.32PT–(0.68 − x)PZ (0.13 ≤ x ≤ 0.17) are systematically studied. The optimal piezoelectric d₃₃ value exceeding 350 pC N⁻¹, maintained up to 320 °C, is achieved at x = 0.15. Significantly, a large strain of 0.24% is obtained at 4 kV mm⁻¹, corresponding to a piezoelectric strain response of 682 pm V⁻¹. The strain variation within 20% observed in the range of 25–275 °C demonstrates excellent temperature stability. In situ high-energy synchrotron X-ray diffraction (SXRD) and piezoresponse force microscopy (PFM) indicate that the lattice strain and stable nanosized domains (up to 200 °C) is contributed to the high piezoelectricity and excellent temperature-insensitive properties, respectively. This outstanding feature positions it as a strong candidate for the next generation of piezoelectric actuators.