Enhancing electrical properties of high-Curie temperature piezoelectric ceramics BNT-PZT and their mechanism

Due to the urgent demands for high-Curie temperature (T_C/T_m) piezoelectric materials in geothermal exploration, aerospace and related fields, high-T_C/T_m ferroelectrics have attracted booming research attention. The high-T_m 0.25Bi(Ni_1/2Ti_1/2)O₃-0.75 Pb(Zr_1/2Ti_1/2)O₃ (0.25BNT-0.75PZT) ceramics were prepared by solid-state sintering method and via partial oxalate route, where the 0.25BNT-0.75PZT ceramics prepared via the partial oxalate route exhibit better electrical properties (T_m = 232 °C (10 kHz), ε_m = 10963, P_r = 26.14 μC/cm², E_c = 15.61 kV/cm, d₃₃ = 521 pC/N, d₃₃* = 553.3 pm/V, K_p = 47.1%, and Q_m = 21.6). The nano-scale domain configuration of the ceramics was revealed by piezoelectric force microscopy (PFM), and the relationship between the micro-structure and macro-electrical properties was analyzed. The ferroelectric phase transition mechanism was studied by temperature dependent Raman spectroscopy. The reduction of energy barrier of lattice distortion and polarization deflection is caused by nanometer-sized domain structure, low symmetric polar nano-regions and/or coexistence of multi-ferroelectric phases, contributing to the excellent electrical properties of the 0.25BNT-0.75PZT ceramics prepared via the partial oxalate route.