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

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 (CaBi 2 Nb 2 O 9 , 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 ( d 33 ) 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 0.5 Ce 0.5 ) 0.08 Bi 2 Nb 1.97 (W 2/3 Mo 1/3 ) 0.03 O 9 (CLCBN-3WM) ceramic exhibits the best performance: ultra-high T C (∼ 922 °C), very high d 33 (∼ 16.1 pC/N), a large remanent polarization (∼ 11.61 μC/cm 2 ), and very good high-temperature insulation ρ (∼ 7.4 × 10 5 Ω·cm at 600 °C), as well as excellent thermal stability with its d 33 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).