Microcrack clouds in fatigued electrostrictive 9.5/65/35 PLZT

The formation of microcracks during cyclic bipolar fatigue is shown for purely dielectric electrostrictive 9.5/65/35 transparent lead–lanthanum–zirconate–titanate (PLZT). The optically transparent material allows for the direct observation of broken grain facets. The maximum reached polarisation decreases by 30% after 3×106 cycles. The formation of microcrack clouds at the specimen edges and at macroscopic cracks are shown. No cracks were found in sample regions without obvious flaws present. By estimating the cracked volume, comparisons with FEM from previous studys allow to calculate the influence of the observed cracking on the polarization. As a consequence, the observed microcracks are considered to be mainly responsible for polarisation degradation.