Degradation of the d33 piezoelectric coefficient for PZT ceramics under static and cyclic compressive loading

The degradation of the d33 piezoelectric coefficient of PZT ceramics subjected to compressive stresses along the poling direction was studied in the range from 10 to 70 MPa in static and cyclic loading. The coefficient was measured making use of the direct piezoelectric effect with the same servohydraulic test machine used to apply the stresses. The piezoelectric coefficient was measured as a function of the amplitude of the applied stress, which allowed us to isolate the intrinsic coefficient and the domain wall contribution. A hard and a soft piezoelectric ceramic were studied. The hard piezoelectric material was very resistant to degradation in the range of stress investigated. The soft material showed significant piezoelectric degradation due to stress induced depolarisation. The degradation was significantly higher for a given stress in cyclic loading than in static loading.