Application of the Free Volume Concept to Glasses in the Ge–As–S System.

Autor: Mel'nichenko, T., Fedelesh, V., Yurkin, I.
Zdroj: Glass Physics & Chemistry; Jan2002, Vol. 28 Issue 1, p25-32, 8p
Abstrakt: The energy of hole formation Eh, the hole volume Vh, and the fraction fg of fluctuation free volume for glasses in the Ge–As–S system are calculated from the data on the elastic moduli, the microhardness H, and the glass transition temperature Tg. It is shown that the fraction of fluctuation free volume in ternary glasses is considerably larger than that in arsenic chalcogenide glasses. For the glasses studied, the Eh energies fall in the range 13–18 kJ/mol and the hole volumes are equal to (7–84) × 10–6 m3/mol. The concentration dependences of the elastic moduli and the parameters of the free volume theory for glasses in the As2S3–GeS2 system are less pronounced than those for glasses in the As–S system with small coordination numbers of glass-former ions. This is explained by the topological transition observed in glasses of this system at a high germanium content. It is demonstrated that the parameters of the fluctuation free volume theory are related to the characteristics of the boson peak in the Raman spectra. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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