Density and concentration fluctuations in F-doped SiO2 glass

The fictive temperature, T-f, and fluorine concentration dependences of structure fluctuation in SiO2 glass was investigated by small-angle x-ray scattering measurement. Regardless of F concentration, density fluctuation in SiO2 glass is proportional to T-f and depends on structural relaxation. Concentration fluctuation does not depend on T-f and is almost proportional to F concentration. And it implies that F is incorporated into the glass structure at temperatures considerably higher than the T-f on which glass structure freezes. Contributions of the density and concentration fluctuations to the structure fluctuation were estimated. (C) 2004 American Institute of Physics.