BSPT- and PZNT-based high frequency single element transducers for medical ultrasonic imaging

Ferroelectric single crystals with tetragonal compositions Pb(Zn₁3/Nb₂3/)O₃-xPbTiO₃ (PZNT) and high T_C (1-x)BiScCo₃-xPbTiO₃ (BSPT) were grown by Flux technique, respectively. Dielectric and piezoelectric characterization revealed high thickness coupling coefficients. (k_t > 60 %) and relatively low dielectric permittivities (ε^s < 300) qualifying them as candidates for high frequency (> 20 MHZ) single element transducers. Modeling based on the KLM equivalent circuit was performed resulting in projected bandwidth > 60 % for BSPT and > 70 % for PZNT and therefore high sensitivity. Single element transducers were fabricated with suitable matching and backing layers. For a PZNT transducer with a 35 MHz center frequency, a bandwidth of ∼ 80 % was realized.