Solubility of porous MgF2 films in water: influence of glass substrates

MgF 2 antireflective coatings exposed to cold water show an increase of porosity and film delamination after prolonged soaking times. The related structural changes within the material were characterized by scanning electron microscopy and ellipsometric porosimetry. The glass substrate type used, namely its sodium content, has a pronounced effect on the film microstructure and its long-term solubility. The stability of MgF 2 films could significantly be improved by Na-doping of the coating solutions. Graphical Abstract Porous MgF 2 prepared by sol-gel processing dissolve and delaminate after prolonged exposure to water at room temperature. This behavior is influenced by different glass substrates; film stability can be significantly improved by doping of sodium to the coating solutions.