Design and fabrication of high frequency ultrasonic transducer based on lead-free Mn-doped (K0.44Na0.56)NbO3 single crystal

In this work, a high-frequency lead-free ultrasonic transducer was designed and fabricated based on high-performance (K0.44Na0.56)NbO3-0.5 mol%Mn (Mn-KNN) piezoelectric single crystal. The Krimholtz, Leedom, and Mattaei (KLM) equivalent circuit model was utilized to simulate and optimize the pulse-echo response combined with PiezoCAD software. Theoretically a ∼20 MHz medical ultrasonic transducer with an optimized bandwidth up to 85.1% was obtained. The experimental results exhibited a center frequency of 20.9 MHz with −6 dB bandwidth of 65.3%. The excellent acoustic performance makes this lead-free single-crystal transducer potential for practical applications.