Non linear behavior of the permittivity and of the piezoelectric strain constant under high electric field drive

Two methods are proposed and compared for the measurement of the converse piezoelectric strain constant: A Laser Doppler Vibrometer Technique and a Capacitance Probe. The complete results obtained with the Capacitance Probe device are given for "hard" and "soft" PZT samples between 1 Hz-1 kHz and up to 700 Vp with and without a dc offset bias. The permittivity is also studied under various conditions of electric drive (ac, dc, ac + dc . . .) with the help of a LCR meter and a Schering Bridge. Many analogies between the dielectric non linearities and the piezoelectric one's are observed. In both cases the high field behavior follows the empirical Rayleigh law providing that the dc and ac influences would be separated.