ONE-DIMENSIONAL PIEZOELECTRIC NANOSTRUCTURES AND HIGH FREQUENCY ULTRASONIC TRANSDUCERS

Abstract

One-dimensional (1D) functional nanostructures with unique morphologies and potentially enhanced properties offer an opportunity of realizing high performance transducers, sensors and energy harvester. This study demonstrated the 1D nanostructures comprising lead-free piezoelectric polymers and ceramics nanotube array using template-based bottom-up fabrication method. The ferroelectric polarization of polymer nanotubes was found to orient along the nanotubes’ long axes due to the confined growth of polymer crystals in the nanopores and gave rise to enhanced ferroelectric polarization and piezoelectric performance properties in comparison with the conventional polymeric spin-coated film. On the contrary, the diffusion and vaporization of volatile compositions from the ceramic were substantially more prominent in the nanotube structure than the bulk counterpart due to the high surface-to-volume ratio, which caused the low crystallinity and deviation from desired stoichiometry in the obtained ceramic nanotubes. Finally, the high-frequency ultrasonic transducers were demonstrated with improved performance using the piezoelectric nanostructures.