U-shaped micropores induced dielectric and piezoelectric tunability in bismuth sodium titanate-based ceramics

Bi0.5Na0.5TiO3 (abbreviated as BNT)-based ceramics are considered the promising candidates for lead-free piezoelectric materials to replace the widely used lead zirconate titanate (PZT)-based piezoelectric ceramics. Piezoelectric properties could be modulated by porous structures to meet the needs of piezoelectric energy converters. Porous (Bi0.5Na0.5)(0.94)Ba0.06TiO3 (BNT-6BT) ceramics had been prepared by using kiwi pollen as a sacrificial template for inducing U-shaped micropores. Porosity correlations of dielectric and piezoelectric properties of the porous BNT-6BT ceramics in the relative porosity range of 0-50% were obtained and analyzed. The temperature stability of the dielectric constant of porous ceramics is significantly improved, while the dielectric constant of porous ceramics decreases rapidly with the increase of the amount of pollen added, and then remains stable. The longitudinal piezoelectric coefficient d(33) and the transverse piezoelectric coefficient d(31) of porous ceramics decrease slowly with porosity. It was found that the ceramic barrier hinders the pinning effect of the micro stress and strain on domain walls, which makes the piezoelectric properties of porous ceramics well maintained. Porous BNT-based ceramics have great application value in underwater acoustic transducers and other fields.