POLARIZATION AND HYSTERESIS IN LOW-RESISTIVITY FERROELECTRIC COMPOSITES

A compensating technique suitable for measuring the polarization and h ysteresis in ferroelectric materials with low resistivity is reported. In this method, three different poling voltages waveforms are success ively applied to a sample while the current i, is measured. These are: a sinusoidal, a positively rectified and a negatively rectified sinus oidal voltages. The polarization hysteresis loop is then computed thro ugh the integration of the difference between the current obtained dur ing the full sinusoidal voltage loop (i.e, i(t)) and the sum of the ot her two currents (i(+) + i(-)). In this paper we use this method to de termine the remanent polarization and coercive field in a ferroelectri c composite of calcium modified lead titanate (PTCa), of a low resisti vity formulation, and a copolymer of poIyvinylidene fluoride (i.e. P(V DF/TrFE)) as a function of the temperature and field.