Degradation mechanism in a durability test of PZT piezoelectric ceramics

In the starting step of durability testing, the elements removed in relaxin g from each electric side because of the measuring of impedance and velocit y by ultrasonic wave and density of elements. The electromechanical couplin g factor decreased with an increase in resonance resistance. The decrease o f velocity was shown due to submicron-crack and residual stress caused by l attice mismatch that occurred by domain switching. The occurrences of submi cron-crack and residual stress were suggested by the decrease of pellets be nding strength. From these results, the total discussion was performed for the degradation process.