Chlorine Incorporation in Silica Glass

Chlorine incorporation in silica at high temperatures (2200degrees C) has been found to depend on the partial pressure of dissociated C1 to the 1/2 power and on the partial pressure of O sub 2 to the -1/4 power. These data, obtained by X-ray fluorescence and electron microprobe measurements of silica samples treated in various chlorine and oxygen atmospheres, suggest that each incorporated chlorine atom replaces one bridging oxygen on a silica tetrahedron while an oxygen deficient center is formed on the adjacent tetrahedron. ESR measurements also support this mechanism by showing a correlation between C1 incorporation and concentration of Ge-E' centers in germania-doped silica. Understanding chlorine incorporation is important because chlorine plays a significant role in a variety of glass manufacturing processes.