Corrections to theoretical glass transition temperature models and interpretations with application examples to chalcogenide glass

The glass transition temperature, Tg, is one of the most important physical attributes of glass in general and optical glasses in particular. Issues associated with refractive index stability, Modulation Transfer Function and upper use temperature of a lens system rely heavily on correct knowledge of Tg. While most oxide glass researchers and engineers understand the scientific meaning and application of Tg, confusion seems to exist within the chalcogenide glass community. This paper reviews the development history of theoretical models employed in determining the glass transition temperature and activation energy of transition for infrared chalcogenide optical glasses. It introduces corrections to these models to improve the fidelity and applicability of the equations used by many researchers. Our new models and equations are demonstrated through practical examples applied to a recently developed chalcogenide glass family. We believe that our models may also be used by oxide, halide and polymer glass scientists who employ DSC data.