Microcrack clouds in fatigued electrostrictive 9.5/65/35 PLZT

The formation of microcracks during cyclic bipolar fatigue is shown for pur ely dielectric electrostrictive 9.5/65/35 transparent lead-lanthanum-zircon ate-titan ate (PLZT). The optically transparent material allows for the dir ect observation of broken grain facets. The maximum reached polarisation de creases by 30% after 3 x 10(6) cycles. The formation of microcrack clouds a t the specimen edges and at macroscopic cracks are shown. No cracks were fo und in sample regions without obvious flaws present. By estimating the crac ked volume, comparisons with FEM from previous studys allow to calculate th e influence of the observed cracking on the polarization. As a consequence, the observed microcracks are considered to be mainly responsible for polar isation degradation. (C) 2001 Elsevier Science Ltd. All rights reserved.