Antiferroelectric-to-ferroelectric phase switching PLSnZT ceramics. II. The effect of pre-stress conditions on the strain behavior

Actuators used for large strain applications are typically placed in pre-stressed conditions to maintain their integrity during service. It is therefore important to understand the characteristics of the materials under mechanical stress. In this study the effects of pre-stresses in lead lanthanum stannate zirconate titanate (PLSnZT) were examined, with an emphasis on the phase transformation behavior. The pre-stress was applied on a thin ring-shaped sample using a stress bolt assembly. It was found that the performance of PLSnZT is very sensitive to pre-stresses along the electric field direction. Specifically, the displacement decreased by 50% from its stress-free value as soon as a small pre-stress (3MPa) was applied. Subsequent stressing produced contradicting results in the two compositions investigated. One showed continuous decrease in strain upon stressing and the other, surprisingly, showed the opposite. These observations were discussed and possible explanations were given.