Ultrasonic measurement of the linear and the nonlinear elastic properties of PZT ceramics

The nonlinear elastic behavior of PZT ceramics is observed from room temperature to temperatures above the Curie temperature. The nonlinearity parameter is measured in two different PZT ceramics and is compared and contrasted with velocity and attenuation of ultrasonic waves in the samples. There is a peak in the nonlinearity parameter near the Curie temperature in both polarized and unpolarized PZT ceramics. For the first time, a frequency dependence of the nonlinearity parameter is measured. Anomalously large third harmonics of an initially sinusoidal ultrasonic wave suggests that the nonlinear equation normally used to describe the behavior of single crystals is only approximately valid for description of PZT.