A molecular dynamics study of the atomic structure of (CaO)x(Al2O3)1-x glass with x=0.625 close to the eutectic

Thomas, B.W.M. and Mead, R.N. and Mountjoy, G. (2006) A molecular dynamics study of the atomic structure of (CaO)x(Al2O3)1-x glass with x=0.625 close to the eutectic. Journal of Physics: Condensed Matter, 18 . pp. 4697-4708. ISSN 0953-8984. (The full text of this publication is not available from this repository)

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Official URL
http://dx.doi.org/ 10.1088/0953-8984/18/19/021

Abstract

Aluminate glasses are difficult to prepare as they do not contain traditional network formers, but they are promising materials for optical applications. The atomic structure of calcium aluminate glasses has been studied using several experimental techniques. The current study uses molecular dynamics to obtain a model of a (CaO)0.625(Al2O3)0.375 glass close to the eutectic. The glass consists of a tetrahedral alumina network with average network polymerization \langle Q^{n}\rangle of n = 3.3. Ca acts as a network modifier with average coordination of 6.2. Ca is typically coordinated to three bridging oxygens (Ob) and three non-bridging oxygens (Onb), with Ca–Onb bonds noticeably shorter than the Ca–Ob bonds. A new method of analysing modifier cation coordination is presented, which specifically shows the distribution of Ca coordination NCaO in terms of combinations of NCaOb and NCaOnb. Ob is most often coordinated to two Al plus two Ca, and Onb is most often coordinated to one Al plus three Ca. The typical coordinations of Ca, Ob, and Onb all have a noticeable similarity to those for the 5CaO·3Al2O3 crystal. The Ca–Ca distribution shows a clear similarity to that for (CaO)0.5(SiO2)0.5 glass, and this is attributed to the equal atomic number densities of Ca in these glasses.

Item Type: Article
Subjects: Q Science
Divisions: Faculties > Science Technology and Medical Studies > School of Physical Sciences > Functional Materials Group
Depositing User: Gavin Mountjoy
Date Deposited: 10 Sep 2008 14:20
Last Modified: 14 Jan 2010 14:38
Resource URI: http://kar.kent.ac.uk/id/eprint/9915 (The current URI for this page, for reference purposes)
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