Accessing short and intermediate range orders of silicate glasses by infrared spectroscopy

The characterization of short and intermediate range orders in glasses is a very active field since this knowledge is of main importance for understanding how order impacts their properties. The chemical simplicity of binary silicate glasses makes them model systems that are suitable to show how their dielectric functions include such kind of information. We show that it is possible to extract from infrared reflectivity measurements no solely quantitative information on short range order, i.e. populations of Q$^{n}$ tetrahedral units (n : number of bridging oxygens) but also intermediate range information like the presence and evolution of 3D network silicate clusters and silicate sheet clusters. Examples will be given for alkaline silicates glasses and discussed in the light of predictions obtained from structural glass models and literature results.