Transition threshold in GexSb10Se90−x glasses

GexSb10Se90−x glasses with Ge content from 7.5 to 32.5 at. % have been prepared by melt-quench technique, and the physical parameters including glass transition temperature (Tg), density (ρ), compactness (C), shear elastic moduli (Cs), compression elastic moduli (Cc), refractive index (n), and optical bandgap (Eg) have been investigated. While all these physical parameters show threshold behavior in the glass with a chemically stoichiometric composition. Raman spectra analysis also indicates that, with increasing Ge content, Se-chains or rings gradually disappear until all Se-atoms are consumed in the glass with a chemically stoichiometric composition. With further increasing Ge content, homopolar Ge-Ge and Sb-Sb bonds are formed and the chemical order in the glasses is violated. The threshold behavior of the physical properties in the GexSb10Se90−x glasses can be traced to demixing of networks above the chemically stoichiometric composition.