A High-Sensitivity, Broadband (1_A,1_B)-3 Single-Crystal Composite Ultrasonic Transducer

Piezocomposite ultrasonic transducers (PUTs) are extensively used in diverse technological fields, however, PUTs based on conventional 1–3 piezocomposite containing only one type of piezo pillars have met a bottleneck in further performance enhancement. Herein, based on the [011]-oriented relaxor ferroelectric Pb(In_1/3Nb_2/3)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT) crystal, a novel (1_A,1_B)-3 piezocomposite structure containing two types of single-crystal pillars- high d₃₃, k_t pillars with square cross-section (termed as 1_A) and high dhgh pillars with rectangular cross-section (termed as 1_B), alternately arranging in epoxy resin and forming a 5 × 9 array are reported. The combination effect and synergistic action of two different piezo-pillars in the piezocomposite notably broaden the working bandwidth, improve the sound sensitivity, and also produce a suppression effect to undesirable transverse vibration modes. Experimental results validate the performance enhancements of (1_A,1_B)-3 composite-based PUT: the increases in –3 dB transmitting, receiving bandwidth, and receiving sensitivity are 71.4%, 28.6%, and 26.6%, respectively, in comparison to conventional 13 single-crystal composite-based PUT. Moreover, its hydrostatic figure of merit (HFOM) dhgh (=4084.9 × 10⁻¹⁵ m² N⁻¹) is 177.3% higher than that of commercial single crystal 13 piezocomposites. The proposed design strategy represents a promising development direction of next-generation bandwidth and high-sensitivity ultrasonic transducers.