Rotational invariants of network former and modifier cations in silicate glasses

Scott, D., Mountjoy, G. (2014) Rotational invariants of network former and modifier cations in silicate glasses. Journal of Non-Crystalline Solids, 401 . pp. 54-59. ISSN 00223093 (ISSN). (doi:10.1016/j.jnoncrysol.2014.02.022) (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided)

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Abstract

The structure of oxide glasses is described in terms of the local atomic environment of cations, and a key role is played by cation-oxygen coordination numbers (CN) and coordination polyhedra. There are no preferred axes in an isotropic material like a glass, so the description of coordination polyhedra must be rotationally invariant. Here a new analysis is presented using the second order rotational invariant Ql which are based on the spherical harmonic coefficients Clm of the coordination polyhedra. The Q l are related to crystal field strength parameters which are reported in the studies of rare earth luminescence. There are few previous studies of rotational invariants and they tend to focus on hard sphere and Lennard-Jones models, and to focus on Ql with l even. Here results are presented for Ql of Si, Na, Mg, Ca, Ba, and Eu cations in molecular dynamics models of silicate glasses including a 15,100 atom model of Eu-doped sodium silicate glass. For Si with CN = 4 the Ql are very similar to those for tetrahedra, and variations in tetrahedral distortion are apparent in different glasses. For Na with CN = 5 the Ql are similar to those for a random distribution, except for l = 1 and 2 where the non-overlap of neighbouring atoms prevents a truly random distribution. The values of Q l for Mg cations with CN = 4 and CN = 5 show similarities to those for Al cations with CN = 4 and Na cations with CN = 5 respectively. The values of Ql for Ca and Ba cations with CN = 6 differ from those for a random distribution for Ql with l � 4. For Eu with CN = 6 the Q;bsubesuband are between those for octahedral and for a trigonal prism geometries. For all cations there are significant values for Q;bsubesuband with l odd. © 2014 Elsevier B.V.

Item Type: Article
DOI/Identification number: 10.1016/j.jnoncrysol.2014.02.022
Additional information: Unmapped bibliographic data: LA - English [Field not mapped to EPrints] J2 - J Non Cryst Solids [Field not mapped to EPrints] AD - School of Physical Sciences, University of Kent, Canterbury, United Kingdom [Field not mapped to EPrints] DB - Scopus [Field not mapped to EPrints]
Uncontrolled keywords: Bond angle distribution, Cations, Rotational invariations, Silicate glasses, Spherical harmonics, Atoms, Calcium, Geometry, Glass, Harmonic analysis, Molecular dynamics, Silicates, Silicon, Bond-angle distribution, Molecular-dynamics model, Rare earth luminescence, Rotational invariations, Silicate glass, Spherical harmonic coefficient, Spherical harmonics, Tetrahedral distortions, Positive ions
Subjects: Q Science > QC Physics > QC176 Solid state physics
Q Science > QC Physics
Divisions: Faculties > Sciences > School of Physical Sciences > Functional Materials Group
Depositing User: Giles Tarver
Date Deposited: 16 Jan 2015 09:51 UTC
Last Modified: 29 May 2019 14:03 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/46588 (The current URI for this page, for reference purposes)
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