Biaxial flexural strength of poled lead zirconate titanate under high electric field with extended field range

In the present work, as-received poled lead zirconate titanate, or PZT, was examined using ball-on-ring (BoR) mechanical testing coupled with an electric field. Electric fields in the range of ±4E_C (E_C, coercive field) with controlled loading paths were applied, and mechanical tests at a substantial number of characteristic electric field levels were conducted. Commercial electronic liquid FC-40 was used to prevent the setup from dielectric breakdown under a high electric field. Weibull strength distribution was used to interpret the mechanical strength data. The data showed that the strength levels of the PZT tested under OC (open circuit) in air and in FC-40 were almost the same. It was further revealed that, for the studied cases, the effect of loading history on the biaxial flexural strength of the PZT was significant in -E_C, but not in OC or zero field as well as 4E _C. An asymmetric V curve was observed for the characteristic strength-electric field graph, and the bottom of V curve was located near the negative coercive field. Microscopic analysis showed that surface-located volume-distributed flaws were the strength limiter and responsible for the failure of the tested PZT under electromechanical loadings.