Germanium sulphide glasses (GeS2) are transparent in a wide range from near UV to min-IR (0.4um-10um) [1]. Due to their low phonon energy (~400cm1), high refractive index (>2.0) and nonlinear optical properties, GeS2-based glasses can be used for both passive transmission and for active applications such as fibre lasers, amplifiers and nonlinear switches [2-4]. In order to fabricate low loss optical fibres, it is essential to understand the viscous and crystallisation behaviour of these glasses. In this paper, a binary (80GeS2-20Ga2S3) and a ternary (79GeS2-analyser) and TMA (thermo-mechanical analyser) techniques. The activation enthalpy for shear viscosity was calculated by examining the dependence of the glass transition temperature (Tg) on the DTA heating rate. The sheer viscosity was calculated from the DTA data by applying the Moynihan equation, and was compared with the viscosity measured by TMA. The t-t-t curves were constructed on the basis of the thermal analysis data.
