Ferroelastic switching in a soft lead zirconate titanate

Poled and unpoled ferroelectric lead zirconate titanate (“soft” PZT) samples were subjected to incremental compressive stresses up to 270 MPa to examine the mechanisms by which this type of ceramic responds to large static loads. Data indicate abundant ferroelastic switching leading to substantial non-linear deformation in the region 10–60 MPa. The ferroelastic switching is time dependent leading to creep under DC or static loading conditions. The creep is transient in nature and modelled reasonably well by an Andrade power law, initially increasing with increasing stress, however above 30 MPa, exhaustion of the creep mechanism reduces the creep rate. The creep exponent is 0.16±0.03 at most stresses. Above 60 MPa, the ceramic responds as a linear elastic solid; however, there is evidence that the elastic constants change at applied stresses of greater than 90 MPa. No reverse switching occurred during unloading causing the final state of the ceramic to be mechanically poled transverse to the stress axis.