Atomistic origin of the inverse piezoelectric effect in α- and α-

Institute of Physics, University of Potsdam - D-14469 Potsdam, Germany

Received: 9 December 2002
Accepted: 14 April 2003

Abstract

In order to understand the atomistic origin of the inverse piezoelectric effect, the changes of integrated intensities of selected Bragg reflection of α- and α- were studied, which were induced by an external high electric field of up to . Because the model of the field-induced displacement of ionic sublattices against each other fails for the interpretation of experimental data, we propose a model of the inverse piezoelectric effect, which considers the strong covalent bond between and atoms in α-. Here the main effect of screening the external electric field is a change in the -- bonding angles, i.e. the rotations of rigid tetrahedra. The same model holds for α-, which is an isostructural compound to α-. For the first time a similar experiment was performed at low temperatures. Between the piezoelectric coefficient d₁₁₁ of both substances behaves nearly temperature independent. On the other hand, the field-induced change of the intensities increases for decreasing temperature. This can be interpreted by the rotation of tetrahedra, which is partially originated by the temperature decrease and by the external electric field, respectively, accompanied by a field-induced deformation of tetrahedra.