Fabrication of PMN-PT/Epoxy 2–2 Composite Ultrasonic Transducers and Analysis Based on Equivalent Circuit Model

Abstract

Single-crystal (1 − x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-PT) has great potential for use in ultrasonic applications; however, it is challenging to achieve both broad bandwidth and high sensitivity owing to the mismatch in acoustic impedance between the piezoelectric materials and loading medium. Fabrication of a matching layer for transducers is challenging owing to the increase in the center frequency of the transducer. In this study, a 2–2 PMN-PT-crystal composite was designed and fabricated, exhibiting desirable piezoelectric properties and lower acoustic impedance compared with single-crystal PMN-PT. Transducers based on the 2–2 PMN-PT composite were fabricated and analyzed in detail to investigate their sensitivity and bandwidth. Moreover, the effects of a backing layer on the transducer were investigated. The measured results showed that the bandwidth improved from 21.28% to 35.54% at the cost of reduced sensitivity of the transducer. Systematic analysis of this phenomenon using an equivalent circuit based on the Mason model is presented.