Europhys. Lett.
Volume 62, Number 6, June 2003
Page(s) 834 - 840
Section Condensed matter: structure, mechanical and thermal properties
Published online 01 June 2003
DOI: 10.1209/epl/i2003-00448-8
Europhys. Lett., 62 (6) , pp. 834-840 (2003)

Atomistic origin of the inverse piezoelectric effect in ${\alpha}$- $\chem{SiO_2}$ and ${\alpha}$- $\chem{GaPO_4}$

J. Davaasambuu, A. Pucher, V. Kochin and U. Pietsch

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

(Received 9 December 2002; accepted in final form 14 April 2003)

In order to understand the atomistic origin of the inverse piezoelectric effect, the changes of integrated intensities of selected Bragg reflection of ${\alpha}$- $\chem{SiO_2}$ and ${\alpha}$- $\chem{GaPO_4}$ were studied, which were induced by an external high electric field of up to $E=\pm 8$ $\un{kV/mm}$. 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 $\chem{Si}$ and $\chem{O}$ atoms in ${\alpha}$- $\chem{SiO_2}$. Here the main effect of screening the external electric field is a change in the $\chem{Si}$- $\chem{O}$- $\chem{Si}$ bonding angles, i.e. the rotations of rigid $\chem{SiO_4}$ tetrahedra. The same model holds for ${\alpha}$- $\chem{GaPO_4}$, which is an isostructural compound to ${\alpha}$- $\chem{SiO_2}$. For the first time a similar experiment was performed at low temperatures. Between $50\un{K}\le T \le
300\un{K}$ 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.

61.10.Nz - X-ray diffraction.
71.20.Ps - Other inorganic compounds.
77.65.-j - Piezoelectricity and electromechanical effects.

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