In this paper, a underwater acoustic Tonpilz transducer with the piezoelectric single crystal(72PMN-28PT) is developed. The thickness and the number of piezoelectric elements are theoretically designed with the equivalent circuit analysis to have the desired resonance frequency. In order to compare the performances, a piezoelectric ceramic transducer is also manufactured and their electrical impedance, TVR (transmitting voltage response), RVS (receiving voltage response) and beam pattern are compared.

Magnetoelectric(ME) bulk composites with PZT- PYN- PZN/FeO1 were prepared by using a conventional ceramic methods and investigated on the ME voltage vs frequency of ac magnetic fields. We made the electric equivalent circuits by using the Maxwell-Wagner model and simulated the frequency dependence of ME voltage in low frequency region. IVIE devices were described by a series of two equivalent circuits of piezoelectric and magnetic, which have the relaxation time T due to the interaction between ME device and load resistor. Equivalent circuit of piezoelectric material is independent of frequency. However ferrite magnetic materials have Debye absorption and dipolar dispersion, whose equivalent circuit is a function of frequency. Therefore we suggest the resistance in the equivalent circuit is proportion to (1 + w2t2) and the capacitance is in inverse proportion to (1 + w w2t2) in the magnetic materials.