Homogeneity of melt-rocked Ge–Se glasses and the effect of impurities

The impact of glass synthesis methods on the properties of Ge–Se glasses is investigated. The homogeneity of a GeSe₄ glass produced by mechanical convection in a rocking oven for 12 h at 950°C is characterized by Raman spectroscopy and Electron Microprobe analysis. It is found that the melt-rocked glass is chemically and structurally homogeneous at all length scales investigated. In order to compare the effect of synthesis methods, another glass is produced following a static synthesis for 192 h. Their physical, structural, and dynamic properties are then characterized for comparative analysis. The molar volume and structure of both glasses are found to be identical when subjected to the same thermal history. The structural dynamics of GeSe₄ investigated by heat capacity spectroscopy is identical for the static and rocked glass and also compared with that of GeSe₉ and GeSe₃. Overall, the two synthesis methods do not lead to any difference in measured properties. Finally, the effect of impurities is investigated in three glasses. The presence of water and oxygen impurities up to 30 ppm levels is shown to have no significant effect on physical and structural properties. Hence, the presence of water impurities cannot be attributed to mismatch in physical properties.