Glassy Photochromic Layers Produced by Sol-Gel Process

Inorganic - organic composite materials on the basis of Tetraethoxysilane/3-Glycidoxypropyltrimethoxysilane containing microcrystals of AgBr, AgCl or AgBr, Cl 1−x were synthesized as photochromic coatings via the sol-gel route. The bonding of halide ions to components of the matrix system, such as Bromophenyltrimethoxysilane or Chloropropyltrimethoxysilane and of Ag + -ions with complexing agents such as 18-crown-6 and Aminopropyltriethoxysilane prevents the crystallization of silver halide crystals at room temperature and leads to a controlled growth of them. In the present work results of XRD- and AFM-measurements concerning crystal growth as function of the conditions of thermal treatment and UV-VIS spectroscopic investigations of the darkening and fading behaviour of the glassy coatings are shown.