Development of chemical and topological structure in aluminosilicate liquids and glasses at high pressure. (9th February 2015)

• Record Type: Journal Article
• Authors: Drewitt, James W E; Jahn, Sandro; Sanloup, Chrystèle; de Grouchy, Charlotte; Garbarino, Gaston; Hennet, Louis
• Is Part Of: Journal of physics. Volume 27:Number 10(2015)
• Publication Date: 2015-02-09
• Subjects: high pressure -- liquid structure -- aluminosilicates -- diamond anvil cell -- diffraction -- synchrotron -- non-crystalline; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/0953-8984/27/10/105103
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: The high pressure structure of liquid and glassy anorthite (CaAl2 Si2 O8 ) and calcium aluminate (CaAl2 O4 ) glass was measured by using in situ synchrotron x-ray diffraction in a diamond anvil cell up to 32.4(2) GPa. The results, combined with ab initio molecular dynamics and classical molecular dynamics simulations using a polarizable ion model, reveal a continuous increase in Al coordination by oxygen, with 5-fold coordinated Al dominating at 15 GPa and a preponderance of 6-fold coordinated Al at higher pressures. The development of a peak in the measured total structure factors at 3.1 Å −1 is interpreted as a signature of changes in topological order. During compression, cation-centred polyhedra develop edge- and face- sharing networks. Above 10 GPa, following the pressure-induced breakdown of the network structure, the anions adopt a structure similar to a random close packing of hard spheres.