Research On The Performance Optimization And Source Level Enhancement Of Relaxor-PT Ferroelectric Single Crystal Underwater Acoustic Projector

Lead-based relaxor-PT ferroelectric single crystals of rhombohedral phase,such as Pb(Zn_1/3Nb_2/3)O₃-Pb Ti O₃ and Pb(Mg_1/3Nb_2/3)O₃-Pb Ti O₃,exhibit excellent piezoelectric properties and are candidate active materials for high-performance underwater projectors.However,their low coercive field would cause depolarization under high ac drive field,making them unsuitable for high power application.The present project proposed an effective method to make use of axial compressive stress to subpress the depolarization behavior and improve the electric stability of relaxor-PT ferroelectric single crystals.Through theoretical and experimental study,the effect of axial compressive stress on the depolarization and phase transformation behavior of[011]polarization 32-mode PZN-5.5%PT single crystals has been investigated.The effect of axial compressive stress on the material properties of the crystals has also been studied.The present results show that through application of appropriate compressive stress along the[100]crystal direction,the depolarization of the single crystal can be effectively suppressed,which allows higher AC drive field to be applied to the underwater acoustic projector.The present work further shows that when optimal compressive pre-stress is applied,it is possible to increase the source level of the underwater acoustic projector to 11.2d B while maintaining the transmitting voltage response unchanged,without using DC bias,or using more single crystals,or altering the structure of the underwater acoustic projector.