Crystallization of nano calcium fluoride in CaF2–Al2O3–SiO2 system

The effects of alumina and CaF2 content on the crystallization behavior, fluorine loss, phase separation mechanism and optical properties of oxyfluoride glass ceramics were investigated. Three series of glasses in which their SiO2/Al2O3 ratio was different such as 1.8, 2.18 and 2.5 were examined. Results showed that the adopted ratios played key role significantly in the mechanism of phase separation of the glass. It modified from spinodal decomposition to nucleation and growth by decreasing the mentioned ratio.UV spectroscopy showed that owing to the small size of precipitated CaF2 crystals, i.e. 20 nm, in the glass with a silicon oxide to alumina ratio of 2.18 and initial CaF2 amount of 35 mol%, it remained transparent after heat treatment at 740 °C.

Figure optionsDownload as PowerPoint slide