KNNS-BNZH Lead-free 1-3 Piezoelectric Composite for Ultrasonic and Photoacoustic Imaging.

In this paper, lead-free 0.965(K0.45Na0.55) (Nb0.96Sb0.04)O3-0.0375Bi0.5Na0.5Zr0.85Hf0.15O3(KNNS-BNZH)/epoxy 1-3 composite was designed and fabricated with dice-and-fill method. The composite material exhibited a high thickness electromechanical coupling coefficient (kt=0.7), high piezoelectric constant (d33=350 pC N-1), relatively low mechanical quality factor (Qm=5), and relatively low acoustic impedance. An ultrasonic transducer with a center frequency of 5 MHz was produced based on the 1-3 KNNS-BNZH/epoxy composite, showing a broad bandwidth of 80% (-6 dB) and two-way insertion loss of -30 dB. Ultrasonic and photoacoustic images were further demonstrated. The outstanding performance of the 1-3 KNNS-BNZH/epoxy composite transducer competitive to PZT-based transducers suggests that the lead-free material can serve as a promising alternative to Pb-based piezoelectric materials for ultrasonic applications.