Structure and properties of Ge–Sb–S–CsCl glass–ceramics

• A method on the modification of the material properties of chalcolgenide glasses.
• An evidence on how different sub-phases were formed.
• A study on the mechanical hardness and optical losses in mid-infrared region.

We annealed Ge–Sb–S–CsCl glass and investigated the evolution of the structural, optical and mechanical properties as a function of annealing temperature. It was found that, for the glass annealed at 280 °C for 210 h, a CsCl crystalline phase with mono-dispersedly spherical shape was formed; while for the glass annealed at 370 °C for 5 h, both β-GeS2 and CsCl crystalline phases with irregular distribution of large grains was observed. While the density and the microhardness of the glasses increase with increasing annealing temperature, it was found that, optical loss in the glass annealed at 370 °C for 5 h was much larger than that annealed at 280 °C for 210 h.