PZT/Epoxy 0-3 piezoelectric composites were prepared for investigating the effects of volume fraction and particle size of PZT on the dielectric, piezoelectric and acoustic properties of composites. PZT (Zr/Ti=0.525/0.475), which is active piezoelectric species in composite, was prepared from oxide mixture of PbO, $ZrO_2$ and $TiO_2$. Sintered PZT was granulated and sieved into several particle sizes. Then, PZT particles were mixed with epoxy, piezoelectrically inactive species. After poling, dielectric, piezoelectric and acoustic properties were investigated. Dielectric constant, piezoelectric strain coefficient, and acoustic impedance increased with increasing the particle size or volume fraction of PZT particles. Piezoelectric voltage coefficient was nearly constant. Defective surface layer was assumed in order to explain the effects of particle size on the properties of composite. Acoustic impedance of composite was lower than that of pure PZT, and so it was believed that PZT/epoxy composite was better than pure PZT in the use of diagnostic ultrasound transducer.
