QUASI-irreversible changes in the polarization of vinylidene fluoride-trifluoroethylene copolymer

Copolymers of vinylidene fluoride-trifluoroethylene P(VDF-TrFE) exhibit large piezoelectric and pyroelectric effects. In addition to the most common application of the pyroelectric effect (radiant detection) it is possible to convert heat directly into electrical energy by pyroelectric conversion. Crucial to the possible application of P(VDF-TrFE) in pyroelectric energy conversion devices is the stability of the electric displacement when subjected to elevated temperatures and strong electric fields. This study is a follow up to the work of G.T. Davis et al. Ferroelectrics 57 , 73 (1984) on the stability of the remanent polarization of P(VDF-TrFE). Here it is found that the remanent polarization of P(VDF-TrFE) does not suffer quasi-irreversible reductions for temperatures less than about 100C. We believe that the improved high temperature stability of the present measurement results from a physical processing step (100C vacuum bake-out) which was not employed in previous work. The stability is discussed in light of a fatigue effect which has been observed in barium titanate.