Study of effect of 90° domain switching on ferroelectric ceramics fracture using the moiré interferometry

Fracture behavior of ferroelectric ceramics during in-plane and out-of-plane 90° domain switching was studied using the moiré interferometry technique. The specimens used in the experiment were three-point-bending beams, each with a single through-notch, which were subjected to a mechanical load, an electrical load and a combined electrical and mechanical load, respectively. The main subject of interest is to investigate the influence of 90° domain switching induced by the electrical load on fracture toughness and material brittleness. In the experiment, compared with out-of-plane 90° domain switching, in-plane 90° domain switching occurs in the region of approximately a 45° band. It causes larger in-plane tensile strain ε_xx in almost all regions of a specimen, especially in the 45° band. In-plane 90° domain switching greatly decreases fracture toughness and weakens the material brittleness of ferroelectric ceramics. The out-of-plane 90° domain switching does not exhibit such a great influence on fracture toughness and material brittleness as the in-plane 90° domain switching does.