Piezoelectric materials are used extensively in many transducer applications. However they have limited utility in transducers used under hydrostatic conditions because of their low hydrostatic piezoelectric coefficient(d_h) have also limited utility in ultrasonic field due to small voltage coefficient(g₃₃) and large acoustic impedance.
To improve the magnitude of hydrostatic piezoelectric coefficient and voltage coefficient, the composite of piezoelectric materials and polymer with different patterns have been prepared. In addition, these composites having lower acoustic impedance and smaller dielectric constant than those of solid piezoelectric materials, make it easier to obtain good impedance matching with water of the human body.
Because of these advantages, piezoelectric composites would be used in many fields such as measuring instruments, diagnostic ultrasonic transducer, information processing instruments and acoustic devices.
Especially, these composites have advantage of making a shape using ceramic powder that cannot produce by sintering.
In this study, we produced the composites using (Pb_1-x, Bi_x)(Ti_1-y, Fe_y)O₃ powder which cannot produce by sintering because of its high tetragonality that create high inner stress. (Pb_1-x, Bi_x)(Ti_1-y, Fe_y)O₃/Epoxy 0-3 piezoelectric composites were prepared for investigating the effects of volume fraction of (Pb_1-x, Bi_x)(Ti_1-y, Fe_y)O₃ on the dielectric, piezoelectric properties of composites. (Pb_1-x Bi_x)(Ti_1-y Fe_y)O₃ powder, which has high tetragonality and voltage coefficient(g₃₃) was prepared from oxide mixture of PbO, Bi₂O₃, TiO₂ and Fe₂O₃. Then, (Pb_1-x, Bi_x)(Ti_1-y, Fe_y)O₃ particles were mixed with epoxy, piezoelectrically inactive species. After poling, dielectric, and piezoelectric properties were investigated.