DYNAMIC METHOD FOR MEASURING THE VELOCITY VARIATION OF ULTRASOUND IN PIEZOELECTRIC CERAMICS WITH STRESS

The development and application of a new dynamic method for measuring velocity variation of piezoelectric materials, especially of lead zirconate titanate (PZT) ceramics, with step and alternating stress are presented. This method enable us to separate the velocity variation due to the nonlinear eff ect from that due to temperature change, to obtain the adiabatic nonlinear coefficients, to fix the sign of the nonlinear coefficient, and to determine the coefficient of each order of velocity variation as a function of the applied stress.