A computer simulation study of OH defects in Mg2SiO4 and Mg2GeO4 spinels |
| |
| Authors: | M Blanchard K Wright J D Gale |
| |
| Institution: | (1) Royal Institution of Great Britain, 21 Albemarle Street, London, W1S 4BS, UK;(2) Departments of Chemistry and Earth Sciences, University College London, Gower street, London, WC1E 6BT, UK;(3) Department of Applied Chemistry, Nanochemistry Research Institute, Curtin University of Technology, P.O. Box U1987, Perth, 6845, WA, Australia |
| |
| Abstract: | Classical atomistic simulation techniques have been used to investigate the energies of hydrogen defects in Mg2SiO4 and Mg2GeO4 spinels. Ringwoodite (γ-Mg2SiO4) is considered to be the most abundant mineral in the lower part of the transition zone and can incorporate large amounts
of water in the form of hydroxyls, whereas the germanate spinel (γ-Mg2GeO4) corresponds to a low-pressure structural analogue for ringwoodite. The calculated defect energies indicate that the most
favourable mechanisms for hydrogen incorporation are coupled either with the reduction of ferric iron or with the creation
of tetrahedral vacancies. Hydrogen will go preferentially into tetrahedral vacancies, eventually leading to the formation
of the hydrogarnet defect, before associating with other negatively charged point defects. The presence of isolated hydroxyls
is not expected. The same trend is observed for germanate, and thus γ-Mg2GeO4 could be used as a low-pressure analogue for ringwoodite in studies of water-related defects and their effect on physical
properties. |
| |
| Keywords: | Ringwoodite Mg2SiO4 spinel Mg2GeO4 spinel Hydrogen GULP |
| 本文献已被 SpringerLink 等数据库收录！ |
|
