Mechanisms of network collapse in GeO2 glass: high-pressure neutron diffraction with isotope substitution as arbitrator of competing models

The structure of the network forming glass GeO2 is investigated by making the first application of the method of in situ neutron diffraction with isotope substitution at pressures increasing from ambient to 8 GPa. Of the various models, the experimental results are in quantitative agreement only wit...

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Bibliographic Details
Published in:Journal of physics. Condensed matter 2012-12, Vol.24 (50), p.502101-502101
Main Authors: Wezka, Kamil, Salmon, Philip S, Zeidler, Anita, Whittaker, Dean A J, Drewitt, James W E, Klotz, Stefan, Fischer, Henry E, Marrocchelli, Dario
Format: Article
Language:English
Subjects:
Condensed Matter
Condensed matter: structure, mechanical and thermal properties
Disordered solids
Exact sciences and technology
Glasses
Other
Physics
Structure of solids and liquids
crystallography
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Summary:The structure of the network forming glass GeO2 is investigated by making the first application of the method of in situ neutron diffraction with isotope substitution at pressures increasing from ambient to 8 GPa. Of the various models, the experimental results are in quantitative agreement only with molecular dynamics simulations made using interaction potentials that include dipole-polarization effects. When the reduced density ρ ρ0 1.16, where ρ0 is the value at ambient pressure, network collapse proceeds via an interplay between the predominance of distorted square pyramidal GeO5 units versus octahedral GeO6 units as they replace tetrahedral GeO4 units. This replacement necessitates the formation of threefold coordinated oxygen atoms and leads to an increase with density in the number of small rings, where a preference is shown for sixfold rings when ρ ρ0 = 1 and fourfold rings when ρ ρ0 = 1.64.
ISSN:0953-8984
1361-648X
DOI:10.1088/0953-8984/24/50/502101