The Preparation And The Electric Properties Of Polymer/piezoelectric Ceramic Composites

Piezocomposites composed of piezoelectric ceramic and polymer is a new function material. It takes advantage of either constituent, such as high flexibility, low density and low acoustic velocity, so it can be matched with water, biology tissue and so on. Furthermore, it has low dielectric constant and high electromechanical coupling coefficient, which will be favorable to increase the piezoelectric hydrostatic figure of merit, the sensitivity of transducers and pyroelectric figure of merit. Because of complex effect, so it will be possible that some new properties will occur in the piezocomposite. The properties of piezocompsite depend on the properties of each constituent and connectivity primarily, so it can be tailored to meet various demands such as underwater ultrasonic, electroacoustic, ultrasonic transducers and so on.In this paper, according to the complex effect of composites (additivity, multiplicative, and composability), the developing trend of piezoelectric composites has been reviewed. The Ploymer/PZT composites have been prepared by in-situ composite method, in which porous PZT used as matrix and polymer used as the second additive. Finally, the samples were analyzed and characterized by XRD, SEM, FTIR. And the influences of piezoelectric ceramic, polymer on the piezoelectric, dielectric, ferroelectric properties were investigated systemically.PZT porous ceramics has been prepared by Burn-out plastic spheres. Open pore structure was formed in the porous ceramics. The porosity increased and the density of PZT porous ceramics decreased with the increase of pore-forming agent weight fraction. However, the porosity decreased and the density increased with the increase of the sintering temperature.Based on previous study, PZT porous ceramics as inorganic framework phase and two polymers as phase to control the performance of composites.The ploymer/PZT composites have been prepared by in-situ composite method. The dielectric, piezoelectric and ferroelectric properties of ploymer/PZT composites have been tested. The results show that polymer have great effects on the dielectric and piezoelectric properties of composites. The PMMA/PZT composite has highεvalues than that of PS/PZT composite, and the PS/PZT composite has lower tanδvalues. The dielectric, piezoelectric and ferroelectric properties of ploymer/PZT composites nonlinearly increase with the increase of PZT volume fraction. In PS/PZT composite, when the volume fraction of PZT was 63%,ε=341, tanδ=0.015, d33=150pC/N. There was still a bit of porosity, because the pores were not completely filled by polymer. In addition, when the volume fraction of PZT in ploymer/PZT composites was 63%, the porosity of composites was about 4.14%.