Synergistic Enhancement of Piezoelectricity and Thermal Stability in AlN-doped Bi0.5Na0.5TiO3-based Ceramics

Abstract The inverse relationship between piezoelectric coefficient (d33) and depolarization temperature (Td) in Bi0.5Na0.5TiO3-based ceramics is a longstanding obstacle for their applications. In this work, synergistically enhanced d33 and Td is achieved in AlN-modified 0.84Bi0.5Na0.5TiO3-0.11Bi0.5K0.5TiO3-0.05BaTiO3 ceramics. Addition of 1 mol% AlN, increases both d33 from 165 to 234 pC/N and Td by ∼50 °C. Rietveld analysis of X-ray powder diffraction (XRD) data reveals an increase in the proportion of the tetragonal phase at 1 mol% AlN incorporation. Moreover, at this composition the modified ceramics exhibit larger grains and high-density lamellar nanodomains with sizes of 30–50 nm. Polarization reversal and domain mobility are thus significantly enhanced, contributing to the large d33. Temperature-dependent dielectric and XRD data revealed that the delayed thermal depolarization is attributed to the improved and poling-field stabilized tetragonality in the modified ceramics.