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Mechanisms of network collapse in GeO(2) glass : high-pressure neutron diffraction with isotope substitution as arbitrator of competing models


Reference:

Wezka, K., Salmon, P. S., Zeidler, A., Whittaker, D. A. J., Drewitt, J. W. E., Klotz, S., Fischer, H. E. and Marrocchelli, D., 2012. Mechanisms of network collapse in GeO(2) glass : high-pressure neutron diffraction with isotope substitution as arbitrator of competing models. Journal of Physics-Condensed Matter, 24 (50), 502101.

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    Official URL:

    http://dx.doi.org/10.1088/0953-8984/24/50/502101

    Abstract

    The structure of the network forming glass GeO(2) 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/ρ(0) ≳ 1.16, where ρ(0) is the value at ambient pressure, network collapse proceeds via an interplay between the predominance of distorted square pyramidal GeO(5) units versus octahedral GeO(6) units as they replace tetrahedral GeO(4) 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/ρ(0) = 1 and fourfold rings when ρ/ρ(0) = 1.64.

    Details

    Item Type Articles
    CreatorsWezka, K., Salmon, P. S., Zeidler, A., Whittaker, D. A. J., Drewitt, J. W. E., Klotz, S., Fischer, H. E. and Marrocchelli, D.
    DOI10.1088/0953-8984/24/50/502101
    DepartmentsFaculty of Science > Physics
    Publisher StatementGeO2_pressure_isotopes_JPCM_v2.pdf: © IOP
    RefereedYes
    StatusPublished
    ID Code32520

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