Thermal diffusivity of IV-V-VI glassess - an evidence for the existence of a mechanical threshold

The thermal diffusivity of two sets of GexSbySe100-x-y, GexAsyTe100-x-y and SixAsyTe100-x-y glasses have been measured using the photoacoustic technique. The thermal diffusivity data of the three glass systems show maxima at the compositions corresponding to the average coordination number <r> = 2.60. These results have been interpreted in the light of the existence of a mechanical threshold and the formation and development of a layered structure in these network glasses