Nanomechanical measurements of PLZT ceramic during switching events

Abstract

In this work, we track changes in the elastic modulus during switching-piezoresponse microscopy (SPRM) measurements on relaxor ceramic Pb0.88La0.08Zr0.6Ti0.4O3 (∼100 μm thick). SPRM measures the local strain in a nanometric volume of the material surface caused by an electric field sent through the tip probe. By tracking the contact resonance, it is possible to determine the contact normal stiffness and hence the elastic modulus. The results show that the applied field induces, in addition to the ferroelectric switching, a change in elastic properties that is reflected as a defined hysteretic elastic loop, indicating a softening and hardening of the material. Variations in the elastic modulus of about 5–10 GPa during ferroelectric switching are possibly induced by a rhombohedral to tetragonal phase transformation, and vice versa, during polarization switching. To reduce the contributions of charge injection through the probe, electrostriction, and electrostatic charges in the evaluated nanometric volume, our results are reported in the off-field condition. Our results broaden the understanding of the elastic behavior of relaxor ferroelectric systems.