The correlation between fatigue and material constants of PLZT ceramics

Correlations between the ferroelectric fatigue and variations in mechanical properties have been investigated by simultaneous measurement of the fatigue and the piezoelectric resonance of bar 8/65/35 PLZT ceramics. It was found that the fatigue reflects itself only in dielectric and piezoelectric properties. Namely, the remanent polarization, the complex dielectric and piezoelectric constants and the electromechanical coupling factor all start to decrease at the same number of switching cycles. On the other hand, the complex elastic compliance remains almost unchanged during fatigue process. In addition, the electrical, mechanical and electromechanical quality factors, determined at the piezoelectric resonance frequency, remain constant with the increasing number of switching cycles. This suggests that no correlation exists between the ferroelectric fatigue process and the mechanical degradation in 8/65/35 PLZT ceramics. (C) 1999 Elsevier Science Limited. All rights reserved.