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3 Archives of Materials Science

3 2006

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Positron trapping in chalcogenide glasses: a comparison between arsenic sulphide and selenide.

Shpotyuk O. I., Filipecki J., Kozdras A., Popescu M., Hyla M.

Archives of Materials Science

2006

Vol. 27, nr 4

167-175

Positron annihilation lifetime measurements are performed for stoichiometric arsenic suphide. It is shown that two-state positron trapping model is valid for this glass as it has been shown previously for stoichiometric arsenic selenide. Two-component fitting parameters of LT computer program, describing positron annihilation in glassy As2S3, are close to those of glassy As2Se3. They are in good agreement with theoretically calculated distribution of nanovoid radii in these materials.

Dynamic behaviour of thermally-induced restoration effect in gamma-irradiated Ge23.5Sb11.8S64.7 glass.

Kozdras A., Golovchak R. Y., Górecki C., Boyko V. T., Vakiv M. M.

Archives of Materials Science

2006

Vol. 27, nr 4

159-165

Temperature dependence of optical transmission in fundamental optical absorption edge region is studied for typical representative of stoichiometric Sb2S3-GeS2 glasses. It is shown that this temperature behavior changes after Co60 gamma-irradiation. The observed effect is associated with Ge-S into S-S covalent bonds switching accompanied by coordination defects formation processes. This radiation-induced optical effect is fully reversible and could be erased by the annealing of the samples below transition temperature.

A unified model of physical ageing in chalcogenide glasses.

Shpotyuk O. I., Golovchak R. Y., Kozdras A., Szymura S.

Archives of Materials Science

2006

Vol. 27, nr 4

143-158

Physical ageing processes in As(Ge)-Se glasses are analyzed using the chains crossing model and the constraints theory. It is shown that short-term physical ageing in these materials is fully determined by elementary relaxation acts of inner Se atoms within Se chains leading to the straightening of the latter with further shrinkage of glass matrix. Long term physical ageing is associated with pure shrinkage of under-constrained glass network. Phenomenological model of physical ageing in As(Ge)-Se glasses is developed to explain its compositional behaviour. The main statements of the model are verified by differential scanning calorimetry for chalcogenide glasses of As-Se family.