1. Chalcogenide glass

1.1 Glassy state

A glass is a structurally amorphous solid obtained by rapidly cooling the mixture above the melting temperature. To form a glass, a polymerization process is triggered and controlled in the molten bath, increasing the viscosity of the liquid by establishing bonds that propagate over long distances. On cooling, the atoms that have remained tightly bound in the viscous liquid must not have time to diffuse to reach the most thermodynamically stable crystallized state. The glassy solid is therefore in a metastable state that has retained the structural organization of the viscous liquid. Although amorphous, glass is not completely disordered. Its structural framework is built from polyhedra specific to each family, maintaining a strong local structural order.