Medium-range structural properties of vitreous germania obtained through first-principles analysis of vibrational spectra

We analyze the principal vibrational spectra of vitreous GeO2 and derive therefrom structural properties referring to length scales beyond the basic tetrahedral unit. We generate a model structure that yields a neutron structure factor in accord with experiment. The inelastic-neutron, the infrared, and the Raman spectra, calculated within a density-functional approach, also agree with respective experimental spectra. The accord for the Raman spectrum supports a Ge-O-Ge angle distribution centered at 135 degrees. The Raman feature X-2 is found to result from vibrations in three-membered rings, and therefore constitutes a distinctive characteristic of the medium-range structure.


Published in:
Physical Review Letters, 95, 7, 075505
Year:
2005
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 Record created 2009-10-08, last modified 2018-03-17


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