Research on the correlation between the optical gap and chemical bond in sulphur and selenium co-doped chalco-halide glasses

The Ge–Ga–Se–S–CsCl glasses were prepared by the melting-quenching method. The absorption and transmission spectrum were measured under room temperature. It is found that these glasses have high broad spectral range of transparency from visible to far-infrared region (0.4–12 μm). The relationship between the optical gap and chemical composition in terms of novel chalco-halide glasses is discussed based on the Pauling's theory model, which is using the modified heats of atomization and the coordination number of the elements, to explain this phenomena for the first time.