Aerosol-deposited KNN–LSO lead-free piezoelectric thick film for high frequency transducer applications

In this report, we fabricated and characterized a high frequency transducer with lead-free piezoelectric thick film, 0.948(K0.5Na0.5)NbO3–0.052LiSbO3, formed on a platinized silicon substrate by aerosol-deposition. X-ray diffraction analysis and scanning electron microscopy revealed that the film had well-crystallized perovskite structure and was dense and crack-free microstructure. The film showed the dielectric constant of 766 at 1 kHz and the remnant polarization of 13.2 μC/cm2. The film was used to fabricate a high frequency needle transducer with an aperture size of ∼200 μm. The center frequency of the transducer was 197 MHz and the −6 dB bandwidth was 50% which was comparable to the PZT-based transducers. A 6-μm tungsten wire phantom was imaged to assess the −6 dB axial and lateral resolution of the transducer, which were found to be 12 and 66 μm, respectively.