On the mechanism of the α-β phase transformation of quartz |
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Authors: | H. Grimm B. Dorner |
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Affiliation: | Kernforschungsanlage Jülich, Institut für Festkörperforschung, P.B. 365, D-517 Jülich, Germany;Institut Laue-Langevin, P.B. 156, F-38042 Grenoble Cedex, France |
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Abstract: | With a simple geometrical model the atomic displacements at the transition from α- to β -quartz and the eigenvector of the soft mode at the Γ -point are related to a single (order-) parameter. The model is refined by taking into account possible distortions of the SiO4 tetrahedra. These refinements, together with considerations on the temperature dependence of the order parameter, suggest an increase of π-bond order in the Si-O bond with increasing temperature as the driving mechanism for the phase transition. The model also offers a qualitative understanding of the appearance of diffuse X-ray scattering in the Γ-M direction. |
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