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Porous MgF2 antireflective λ/4 films were prepared by sol–gel processing and coated with an additional top layer by electron beam evaporation. Scanning Electron Microscopy was applied to characterize the microstructure of the bilayer assembly. It can be shown that the top layer has a protective effect in terms of abrasion resistance and reduced solubility in water. In a second step the thickness of the two film systems has been matched to achieve optimum antireflection properties. Highlights: MgF2 was evaporated on sol–gel derived porous antireflective MgF2 coatings. The microstructure of the bilayer assemblies was characterized by scanning electron microscopy (SEM). The evaporated layer provides improved abrasion resistance and reduced water solubility. [ABSTRACT FROM AUTHOR]

MgF2 coating solutions were prepared by the fluorolytic processing of Mg(OEt)2 and MgCl2. Parts of these sols are solvothermally treated in an autoclave at 160 °C. The two respective precursors were used to prepare porous λ/4 antireflective films by dip-coating on soda-lime and borosilicate glass substrates. UV–Vis spectroscopy and X-Ray diffraction (XRD) were applied to characterize the films as a function of annealing temperature. Samples treated at 500 °C underwent testing of abrasion resistance and water solubility. Highlights: Parallel investigation of MgF2 antireflective coatings prepared from as-prepared sols and sols that have been solvothermally treated. Systematic comparison of results obtained on soda-lime and borosilicate glass substrates. Testing of abrasion resistance of porous films. [ABSTRACT FROM AUTHOR]