Broadband and high sensitive time-of-flight diffraction ultrasonic transducers based on PMNT/epoxy 1-3 piezoelectric composite.

摘要: 5–6 MHz PMNT/epoxy 1–3 composites were prepared by a modified dice-and-fill method. They exhibit excellent properties for ultrasonic transducer applications, such as ultrahigh thickness electromechanical coupling coefficient kt (85.7%), large piezoelectric d33 (1209 pC/N), and relatively low acoustic impedance Z (1.82 × 107 kg/(m2·s)). Besides, two types of Time-of-Flight Diffraction (TOFD) transducers have been designed, fabricated, characterized, which different matching layer schemes with the 4.8 5.7 106 kg/(m2·s), respectively. In detection on backwall 12.7 mm polystyrene, former exhibits higher detectivity, relative pulse-echo sensitivity −6 dB bandwidth are −21.93 102.7%, respectively, while later broader bandwidth, −24.08 117.3%, These TOFD based composite considerably improved performance over commercial PZT/epoxy transducer.