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

Abstract

The composition dependence of optical energy gap (Eg) and thermal diffusivity α in three sets of Ge–Se–Te glasses, namely, GexSe80—xTe20 (5 ≤ x ≤ 40), GexSe75—xTe25 (5 ≤ x ≤ 40), and GexSe65—xTe35 (5 ≤ x ≤ 37.5), have been studied using photoacoustic technique. The variation of α with average coordination number 〈r〉 shows a change in the slope at 〈r〉 = 2.4 and 2.67. Eg shows a local maximum at 〈r〉 = 2.67. The results are discussed on the basis of the topological and chemical threshold exhibited by covalent network glasses. The relative sensitivity of α and Eg to these phenomena is discussed.