Ferroelectric Properties and Transmission Response ofPZN-PT Single Crystals for Underwater Communication

Single crystal of Pb[(Zn1/3Nb2/3)0.91Ti0.09]O3 (PZN-PT) at the composition of morphotropicphase boundary (MPB) shows a very high electromechanical coupling coefficient, piezoelectriccoefficient, and dielectric constant compared to conventional PZT ceramics. These exceptionalproperties of these single crystals find enormous applications in medical ultrasound imaging andunderwater communication (Sonar). The growth of PZN-PT single crystals has been carried outby bottom-supported flux Bridgman method. There are many growth issues to be addressedduring the process of growth. The grown crystals are oriented and cut along <001> directionwith the crystal dimension of 8 x 6 x 1.5 mm3 for further analysis. The oriented crystals were poledat a rate of 1 kV/mm. The poled crystals have been characterised for dielectric, strain andpiezoelectric values. Further, the poled specimen were tested for transmitting response at variousfrequencies in acoustic test facility and the difficulties in their growth