Enhancement of piezoelectric properties and temperature stability of high-Curie temperature CaBi2Nb2O9 ceramics

Abstract

Next-generation jet engines, metal forging processes, and non-destructive monitoring of nuclear power plants demand piezoelectric sensors with ultra-high operating temperature, exceptional sensitivity, and outstanding temperature stability. Bismuth calcium niobate (CaBi₂Nb₂O₉, CBNO) is considered a candidate for high-temperature piezoelectric materials due to high-Curie temperature (T_C) near 900 °C. However, pure CBNO shows a poor piezoelectric coefficient (d₃₃) and low high-temperature resistivity (ρ). In this work, the piezoelectricity, ferroelectricity, and resistivity of CBNO ceramics were significantly improved by constructing pseudo-tetragonal boundary through the co-substitution of Li/Ce at A site and W/Mo at B site. Remarkably, Ca_0.92(Li_0.5Ce_0.5)_0.08Bi₂Nb_1.97(W_2/3Mo_1/3)_0.03O₉ (CLCBN-3WM) ceramic exhibits the best performance: ultra-high T_C (∼ 922 °C), very high d₃₃ (∼ 16.1 pC/N), a large remanent polarization (∼ 11.61 μC/cm²), and very good high-temperature insulation ρ (∼ 7.4 × 10⁵ Ω·cm at 600 °C), as well as excellent thermal stability with its d₃₃ value degeneration from 16.1 pC/N to 15.1 pC/N from room temperature to 800 °C (less than 7.0 %). These results indicate that CLCBN-3WM ceramics have significant potential for using in electromechanical transducers operating at high temperatures (600 °C or higher).