Revealing high temperature structural behavior behind the enhanced piezoelectric properties of lead-free 0.7BiFeO3-0.3BaTiO3 ceramics by in-situ process

Local domain evolution plays a vital role in modulating the high-temperature piezoelectricity of ferroelectric ceramics. Herein, 0.7BiFeO3-0.3BaTiO3-xBi(Zn0.5Ti0.5)O3 (referred to as BF-BT-xBZT, 0.00≤x≤0.05) high temperature lead free piezoelectric ceramics were prepared by a solid-phase method. All ceramics are at the morphotropic phase boundary (MPB), with an overall decreasing trend of the R/Pc phase fraction upon heating. STEM reveals the in-situ heterogeneity of polar nanodomains. Due to the modulation with proper R/PC ratio and a multilayer nanodomain ratio, the in-situ d33 and Tdr values increase from 495 pC/N and 314 °C to 502 pC/N and 360 °C with increasing content of (Zn1/2Ti1/2)3+ from x=0 to x=0.04 while maintaining a high Curie temperature (Tc>470 °C). This study provides a new paradigm for studying the in-situ depolarization behavior of lead-free perovskite materials and to optimizing the high-temperature piezoelectric properties by tuning the domain scale.