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

Abstract

Ferroelectric single crystals with tetragonal compositions Pb(Zn/sub 1/3/Nb/sub 2/3/)O/sub 3/-xPbTiO/sub 3/ (PZNT) and high T/sub C/ (1-x)BiScCo/sub 3/-xPbTiO/sub 3/ (BSPT) were grown by Flux technique, respectively. Dielectric and piezoelectric characterization revealed high thickness coupling coefficients. (k/sub t/ > 60 %) and relatively low dielectric permittivities (/spl epsi//sup 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 /spl sim/ 80 % was realized.