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 p iezoelectric strain constant: A Laser Doppler Vibrometer Technique and a Ca pacitance Probe. The complete results obtained with the Capacitance Probe d evice 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 stud ied 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 bot h cases the high field behavior follows the empirical Rayleigh law providin g that the dc and ac influences would be separated.