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Structural heterogeneity and pressure-relaxation in compressed borosilicate glasses by in situ small angle X-ray scattering
We report on Brillouin and in situ small angle X-ray scattering (SAXS) analyses of topological heterogeneity in compressed sodium borosilicate glasses. SAXS intensity extrapolated to very low angular regimes, I ( q = 0), is related to compressibility. From Brillouin scattering and analyses of the el...
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Published in: | The Journal of chemical physics 2011-05, Vol.134 (20), p.204502-204502-6 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | We report on Brillouin and
in situ
small angle X-ray scattering (SAXS) analyses of topological heterogeneity in compressed sodium borosilicate glasses. SAXS intensity extrapolated to very low angular regimes,
I
(
q
= 0), is related to compressibility. From Brillouin scattering and analyses of the elastic properties of the glass, the Landau-Placzek ratio is determined and taken as a direct reflection of the amplitude of frozen-in density fluctuations. It is demonstrated that with increasing fictive pressure, topological (mid- and long-range) homogeneity of the glass increases significantly. Heating and cooling as well as isothermal scans were performed to follow the evolution of density fluctuations upon pressure recovery. For a sample with a fictive pressure
p
f
of 470 MPa, complete recovery to
p
f
= 0.1 MPa was observed to occur close to the glass transition temperature. The values of fictive and apparent fictive temperature, respectively, as obtained via the intersection method from plots of
I
(
q
= 0) vs. temperature were found in good agreement with previous calorimetric analyses. Isothermal scans suggest that mid- and long-range recovery govern macroscopic density relaxation. |
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ISSN: | 0021-9606 1089-7690 |
DOI: | 10.1063/1.3593399 |