Influence of cyclic mechanical and electrical load on the properties of PZT(53/47) films on metallic substrates

We have investigated the mechanical and electrical fatigue of sol-gel derived PZT(53/47) thin films on metallic substrates: Up to about 5 /spl times/ 10/sup 5/ electrical switching cycles, no significant changes were found. Above this number the coercive field increased drastically and the maximum induced strain as well as the maximum and remanent polarization decreased. For the mechanical cycling, a two point bending method was used to apply transversal stress to the samples. A mechanical cyclic load corresponding to a maximum strain of /spl plusmn/0,15% was applied to the films. During cycling the piezoelectric coefficient d/sub 31/ remained constant up to about 10/sup 5/ cycles. For a higher number of cycles, a strong decrease was observed. The decrease of the d/sub 31/-values was not caused by a depolarization of the samples. Different mechanisms, which may be responsible for the deterioration of the properties during both, electrical and mechanical cycling are discussed.