The structure of MgO-SiO2 glasses at elevated pressure (vol 24, 225403, 2012)

WILDING, Martin, GUTHRIE, Malcolm, KOHARA, Shinji, BULL, Craig L., AKOLA, Jaakko and TUCKER, Matt G. (2012). The structure of MgO-SiO2 glasses at elevated pressure (vol 24, 225403, 2012). Journal of Physics: Condensed Matter, 24 (22), p. 225403.

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Official URL: http://iopscience.iop.org/article/10.1088/0953-898...
Link to published version:: https://doi.org/10.1088/0953-8984/24/33/339501

Abstract

The magnesium silicate system is an important geophysical analogue and neutron diffraction data from glasses formed in this system may also provide an initial framework for understanding the structure-dependent properties of related liquids that are important during planetary formation. Neutron diffraction data collected in situ for a single composition (38 mol% SiO2) magnesium silicate glass sample shows local changes in structure as pressure is increased from ambient conditions to 8.6 GPa at ambient temperature. A method for obtaining the fully corrected, total structure factor, S(Q), has been developed that allows accurate structural characterization as this weakly scattering glass sample is compressed. The measured S(Q) data indicate changes in chemical ordering with pressure and the real-space transforms show an increase in Mg–O coordination number and a distortion of the local environment around magnesium ions. We have used reverse Monte Carlo methods to compare the high pressure and ambient pressure structures and also compare the high pressure form with a more silica-poor glass (Mg2SiO4) that represents the approach to a more dense, void-free and topologically ordered structure. The Mg–O coordination number increases with pressure and we also find that the degree of continuous connectivity of Si–O bonds increases via a collapse of interstices.

Item Type: Article
Additional Information: A corrigendum for this article has been published in 2012 Journal of Physics: Condensed Matter (24)33, 339501 doi: 10.1088/0953-8984/24/33/339501
Research Institute, Centre or Group - Does NOT include content added after October 2018: Materials and Engineering Research Institute > Engineering Research
Departments - Does NOT include content added after October 2018: Faculty of Science, Technology and Arts > Department of Engineering and Mathematics
Identification Number: https://doi.org/10.1088/0953-8984/24/33/339501
Depositing User: Martin Wilding
Date Deposited: 10 Jul 2018 09:11
Last Modified: 10 Jul 2018 09:11
URI: http://shura.shu.ac.uk/id/eprint/21478

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