Optical and Thermal Diffusivity Measurement of Ge±Se±Te Glasses by Photoacoustic Technique

The composition dependence of optical energy gap \u85Eg and thermal diffusivity \u85a in three sets of Ge±Se±Te glasses, namely, GexSe80ÿxTe20 \u855 x 40, GexSe75ÿxTe25 \u855 x 40 and GexSe65ÿxTe35 5 x 37:5, have been studied using photoacoustic technique. The variation of a with average coordination number hri shows a change in the slope at hri 2:4 and 2.67. Eg shows a local maximum at hri 2:67. The results are discussed on the basis of the topological and chemi-cal threshold exhibited by covalent network glasses. The relative sensitivity of a and Eg to these phenomena is discussed. 1