A POLING STUDY OF PZT/P(VDF-TRFE) COPOLYMER 0-3-COMPOSITES

0-3 composites of lead zirconate titanate (PZT) and P(VDF-TrFE) (piezoelectric copolymer of polyvinylidene fluoride and trifluoroethylene) with different volume fraction of piezoelectric ceramic were fabricated. The composites must be polarized by exposure to a high electric field to elicit piezoelectric response. One of the major consideration for poling a composite is the ratio of the resistivities of constituent phases since it governs the effective poling field across each phase. It is observed that the resistivity of the copolymer shows hysteresis upon heating and cooling, and abrupt changes are found at its Curie transition temperature upon heating (Tc up arrow) and on cooling (Tc down arrow). Previous reports stated that PZT/copolymer 0-3 composites of 50 volume percent ceramic do not exhibit piezoelectric response because the piezoelectric constants of the two materials are opposite in sign and cancellation occurs. In the present work, different poling conditions are used to pole the two phases oppositely so that the piezoelectric responses of the two phases reinforce each other. Details of poling and the resulting composite properties are reported.