Separate poling of inclusions and matrix in PT/P(VDF-TrFE) 0-3 composites

Abstract

A procedure for separate poling of the ceramic particles and the copolymer matrix of 0-3 composites has been developed. 2.5 μm thick films of 56/44 mol-% vinylidene fluoride-trifluoroethylene (P(VDF-TrFE)) copolymer embedded with 8 volume-% lead titanate (PT) ceramic particles were investigated. First, the ceramic particles in the composite are polarized under a DC-field at temperatures above the Curie temperature of the copolymer. In the second step the P(VDF-TrFE) matrix is poled at room temperature in an AC-field at a frequency of 1 Hz. The degree of poling of the composite is then investigated by the measurement of the second order permittivity and the pyroelectric coefficient over a temperature range covering the ferroelectric and paraelectric phase of the copolymer matrix. The results show that the polarization of the ceramic is unchanged by the subsequent AC poling of the copolymer matrix.