Investigation of self-heating and dissipative effects in ferroelectric ceramics subjected to compressive mechanical cyclic loading

In this study the behavior of a soft PZT ceramic subjected to compressive cyclic loadings is investigated with the aim of providing an insight into different dissipative processes which affect the ferroelastic cyclic behavior of the material. Two quantitative imaging techniques, infrared (IR) thermography and digital image correlation (DIC), are employed to measure superficial temperature and in-plane displacement of the sample under mechanical cyclic loadings. Thermal and strain responses are further deduced from these measurements. This allows to quantify the energy dissipated by the material during applied mechanical loadings. Self-heating (SH) and DIC measurements reveal that, even in the piezoelectric regime, the level of dissipation is significant. This suggests that PZT ceramic response under cyclic compression is significantly influenced by domain switching mechanisms. The two imaging techniques are shown to be efficient tools to identify domain wall activity in ferroelectric ceramics and can be advantageously substituted for polarization measurements when polarization variations are too small to be detected. It is also shown that, due to the initial compressive stress experienced by all specimens, the domain wall activity under cyclic uniaxial compressive stress is almost independent of the initial polarization state of the material.