Optical absorption and thermal diffusivity in Ge_xTe_10-x, glasses by the photoacoustic technique

Abstract

Abstract

The variation in the optical energy gap with composition in the Ge_xTe_100-x system (15≤x≤28) of glasses in bulk form has been studied using photoacoustic techniques. It is found that the optical energy gap increases with increasing composition factor x, with the rate of increase showing a slowing-down trend for compositions with x > 20. The composition dependence of the thermal diffusivity of these samples has also been measured. The thermal diffusivity is found to peak around the composition corresponding to x = 20. The observed phenomena are explained on the basis of chemical bond formation in this system of glasses. The change in the short-range order and increase in the number of Te-Te bonds with decreasing x are interpreted as being responsible for the behaviour exhibited by these materials.