HYSTERESIS MEASUREMENTS ON FERROELECTRIC COMPOSITES

Ceramic/polymer composites made of calcium-modified lead titanate grai ns in the matrix of a copolymer of vinylidene fluoride and trifluoreth ylene, in a 65:35 volume fraction percentage, respectively, were produ ced in order to obtain mechanically strong ferroelectric films with im proved piezo- and pyroelectric properties. Their poling behavior was s tudied using a modified ferroelectric hysteresis measurement setup tha t allowed for the measurement of the remanent polarization P(r) and co ercive field E(c), as a function of the peak of the sinusoidal applied field, the frequency of the excitation, and the poling temperature. T he ranges of variation of the electric field, frequency, and temperatu re were from 5 to 25 MV/m, from 0.04 to 2 Hz, and from 50 to 120-degre es-C, respectively. Estimates of the activation field and saturation p olarization were calculated based on these measurements. The observed properties in the ferroelectric composites were then compared and corr elated with the properties of the ceramic material.