The investigation of physicochemical processes of silica glass doping with fluorine by the MCVD method

The temperature-time dependences for sintering and fluorination processes of SiO2 nanoparticles obtained by the method of chemical vapor deposition are presented. It has been revealed that at the SiF4 pressure of 1 atm, the intensive agglomeration of high-dispersive layers prevents the achievement of equilibrium between the fluorine-containing gas media and the condensed phase. The saturation of the porous layers with fluorine occurs at temperatures less than 1100A degrees C, when the sintering duration of high-dispersive particles is substantially longer than the fluorination process time.