Fluoride and Oxyfluoride Glasses

Fluoride glasses are one of the first glass systems studied by molecular dynamics (MD) simulations due to its highly ionic nature in chemical bonding that enable effective description of interatomic interactions with point charges and pairwise potentials. In this chapter, applications of MD simulations to the study of fluoride glasses and mixed anion oxyhalide glasses are summarized. Various empirical potentials and simulation procedure for fluoride and oxyfluoride glasses are explained. Then the structures of zirconium fluoride (ZrF 4 )-based fluoride glasses from MD simulations are presented. Structural features such as cation coordinations, structural role of cations, and fluorine environments are discussed. Calculations of optical spectra for rare earth-doped fluoride glasses are reported. This is followed by a summary of recent MD simulations of oxyfluoride glasses. Results of several aluminosilicate oxyfluoride glasses are presented. The capability to directly observe nanoscale phase separation of these glasses in MD simulations and their correlation to the crystal nucleation and growth are discussed. Applications of ab initio MD on simulations of halide glasses are also introduced. In summary, MD simulations provide a wealth of structural information of fluoride and oxyfluoride glasses that help to understand features from optical emission spectra to phase separation and possible crystal formation in these glasses.