Enhancement of Piezoelectric Properties in CaBi4Ti4O15-based Ceramics through Bi3+ Self-doping Strategy

High-temperature piezoelectric vibration sensors are the preferred choice for structural health monitoring in harsh environments such as high temperatures and complex vibrations.Bismuth layer-structured CaBi 4 Ti 4 O 15 (CBT) high-temperature piezoelectric ceramics, with high Curie temperature (T C ), are the key components for piezoelectric vibration sensors operating at temperatures exceeding 500 .However, their low piezoelectric coefficient (d 33 ) greatly limits their high-temperature applications.In this work, a novel Bi 3+ self-doping strategy was employed to enhance the piezoelectric performance of CBT ceramics.The enhancement is attributed to an increase in the number of grain boundaries, providing more sites for space charge accumulation and promoting formation of space charge polarization.Furthermore, given that space charge polarization predominantly occurs at low frequencies, dielectric temperature spectra at different frequencies were used to elucidate the mechanism by which space charge polarization enhances piezoelectric properties of CBT ceramics.Excellent overall performance was achieved for the CBT-based high-temperature piezoelectric ceramics.Among them, T C reached 778 , d 33 increased by more than 30%, reaching 20.1 pC/N, and the electrical resistivity improved by one order of magnitude (reaching 6.3310 6 cm at 500 ).These advancements provide a key functional material with excellent performance for practical applications of piezoelectric vibration sensors at 500 and above.