Study of the inverse flexoelectric phenomena in ceramic lead magnesium niobate-lead titanate

The inverse flexoelectric phenomenon describes the generation of a mechanical deformation in an insulating solid by an applied gradient of the electric field. Lead magnesium niobate-lead titanate (PMNT) ceramic permits study of the inverse flexoelectric behavior because of its large flexoelectric coefficient. Special conical samples were prepared for the generation of a high electric field gradient and cylindrical samples with uniform field. A strong deformation is caused by the electrostrictive behavior of PMNT ceramic. An asymmetric butterfly-shaped strain dependence on electric field is observed at wide temperature range on the conical samples. For evaluation of converse flexoelectric coefficient mu(33) (in matrix notation) it is necessary to know elastic properties of ceramic. The ultrasonic measurements on ceramic samples were performed for this purpose. In this letter we also report measurements of temperature dependence of flexoelectric coefficient mu(33). The measurements confirmed a great enhancement of mu(33) coefficient in PMN ceramics, which cannot be explained exclusively by the high permittivity of the ceramic.