Synergistic enhancement of piezoelectricity and thermal stability in AlN-doped Bi0.5Na0.5TiO3-based ceramics

The inverse relationship between piezoelectric coefficient ( d 33 ) and depolarization temperature ( T d ) in Bi 0.5 Na 0.5 TiO 3 -based ceramics is a longstanding obstacle for their applications. In this work, synergistically enhanced d 33 and T d is achieved in AlN-modified 0.84Bi 0.5 Na 0.5 TiO 3 -0.11Bi 0.5 K 0.5 TiO 3 -0.05BaTiO 3 ceramics. Addition of 1 mol% AlN, increases both d 33 from 165 to 234 pC/N and T d 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 d 33 . 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.