A computational study into the (tetrahedral) distortion of TX {sub 2} {alpha}-quartz materials: The effect of changing the chemical composition away from SiO{sub 2}
- Davy Faraday Research Laboratory, The Royal Institution of Great Britain, 21 Albemarle Street, London W1S 4BS (United Kingdom)
- University College London, Department of Chemistry, Christopher Ingold Laboratories, 20 Gordon Street, London WC1H 0AJ (United Kingdom)
We report a periodic density functional study into the tetrahedral distortion of a range of quartz-like TX {sub 2} materials. The total tetrahedral distortion and its most sizable contribution, the angular part (angular tetrahedral distortion), are found to be strongly dependent on the chemical composition and to increase in the order of BeF{sub 2}<SiO{sub 2}<CO{sub 2}<GeO{sub 2}<SiS{sub 2}<GeS{sub 2}. The bond stretching contribution to the total tetrahedral distortion appears to be significantly smaller and to vary more erratically with changes in the chemical composition. The sulphide materials in the study were found to have tetrahedral distortion values commonly associated in silica with experimentally unrealizable hypothetical frameworks, suggesting that such frameworks might become realizable when stepping away from silica. None of the tetrahedra were found to be strictly regular, in line with the analysis of Smith [Acta. Cryst. 16 (1963) 542-545], demonstrating that regular tetrahedra are in principle possible in quartz but that distortions from ideality are energetically advantageous. The energetic reason for this distortion is still an open question; we propose a simple electrostatic model that explains the ease with which tetrahedra can be distorted in terms of charge transfer and the relative charge on the X (O,S,F) atom. - Graphical Abstract: View on a quartz unit-cell with TX {sub 4} tetrahedra. Display Omitted.
- OSTI ID:
- 20902476
- Journal Information:
- Journal of Solid State Chemistry, Vol. 179, Issue 11; Other Information: DOI: 10.1016/j.jssc.2006.07.011; PII: S0022-4596(06)00378-1; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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