Analysis of Pyroelectricity of Poly(vinylidene fluoride) by Residual Charge Measuring Technique

The machnism of the pyroelectricity of poled β-PVDF was studied, introducing a newly-developed method of measuring the residual charge density on the electrodes sandwiching the poled film. Homocharge or heterocharge in the dielectric can be easily distinguished and quantified by the new technique. The dependence of the poling parameters (electric field, temperature, time) on the residual charge density was investigated in detail, and poled β-PVDF proved to be a strong heterocharge-electret. The heterocharge is probably due to dipole orientation in the β-form crystalline region. The mechanism of the pyroelectricity is attributed to thermal reversibility of the density of heterocharge generated by poling from a comparison of the effect of the sample temperature on the residual charge density and the pyroelectric effect on the Thermally-Stimulated-Current.