High frequency transducer for vessel imaging based on lead-free Mn-doped (K0.44Na0.56)NbO3 single crystal.

We report a high frequency ultrasonic transducer up to 50MHz for vessel imaging based on a leadfree (K_0.44Na_0.56)NbO_3-0.5 mol. % Mn (Mn-KNN) single crystal, which has a high electromechanical coupling coefficient k_t of 0.64 and a large thickness frequency constant Nt of 3210 kHz ⋅ mm. 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 high -6 dB bandwidth of 74.94% was obtained at a center frequency of 50.47MHz and optimized matching conditions. The experimental results showed a center frequency of 51.8MHz with a -6 dB bandwidth of 70.2%. The excellent global performance makes this lead-free single-crystal transducer quite potential in an environmentally friendly vessel imaging transducer. [ABSTRACT FROM AUTHOR]