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Pressure Raman Effects and Internal Stress in Network Glasses

Fei Wang·Sergey Mamedov·P. Boolchand·B. Goodman·Meera Chandrasekhar
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Abstract

Raman scattering from binary GexSe1-x glasses under hydrostatic pressure shows onset of a steady increase in the frequency of modes of corner-sharing GeSe4 tetrahedral units when the external pressure P exceeds a threshold value Pc. The threshold pressure Pc(x) decreases with x in the 0.15 < x < 0.20 range, nearly vanishes in the 0.20 < x < 0.25 range, and then increases in the 0.25 < x < 1/3 range. These Pc(x) trends closely track those in the non-reversing enthalpy, DeltaHnr(x), near glass transitions (Tgs), and in particular, both DeltaHnr(x) and Pc(x) vanish in the reversibility window (0.20 < x < 0.25). It is suggested that Pc provides a measure of stress at the Raman active units; and its vanishing in the reversibility window suggests that these units are part of an isostatically rigid backbone. Isostaticity also accounts for the non-aging behavior of glasses observed in the reversibility window.

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Fei Wang, Sergey Mamedov, P. Boolchand, B. Goodman, Meera Chandrasekhar. 2005-03-12. Pressure Raman Effects and Internal Stress in Network Glasses. https://arxiv.org/abs/cond-mat/0408502

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