Research Of Shear Mode Pmn-pt Single Crystal Transducer

Piezoelectric materials play an important role in industrial, civil medical and national defence since piezoelectric effect has been discoverd. Binary system piezoelectric ceramics Pb(ZrxTi1-x)O3 (PZT) has been wildly applied due to its superior curie temperature and stable properties. However, with the development of modern science and technology, the improvements of high performance and high quality devices have put forward higher requirement for the properties of piezoelectric materials.Trinary system novel relaxor ferroelectric single crystal (1-x) Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMN-PT) and (1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-PT) show outstanding piezoelectric properties compare to conventional piezoelectric ceramic PZT. High quality and large size PMN-PT single crystal has been grown presently, and gives superior performance in both medical imaging and underwater acoustic detection. But compared with thickness-expande vibration of PMN-PT single crystal, its shear-mode vibration attracts less attention.In this dissertation, the investigation of elastic, dielectric and piezoelectric properties in [111] poled PMN-29%PT single crystal using a resonance-antiresonance technique was obtained, from the result it has been found that PMN-PT single crystal shows excellent shear-mode piezoelectric performances. Its piezoelectric properties with time and the temperature stablilities were also analysed. Proceeding form acoustic transmission line equivalent circuit, the structure design scheme of piezoelectric ultrasonic transducer was studied. A longitudinal-mode ultrasonic transducer was fabricated and its underwate sound field characteristics were investigated. Basing on the investigation of properties in PMN-PT single crystal and the design of piezoelectric ultrasonic transducer, we fabricated a shear-mode piezoelectric transducer, and its pulse response waveform and its corresponding frequency spectrum were present.