VISCOSITY OF GEO2-DOPED SILICA GLASSES

The viscosity of GeO2-doped silica glasses is experimentally evaluated and found to be expressed as a function of the monoexponential form e ta0 exp(- ADELTAe), where eta0 is the viscosity of pure silica glass, A is a positive constant, and DELTAe is an equivalent relative-index d ifference that is introduced for a silica glass with nonuniform dopant distribution in its cross section. The constant A for GeO2-doped sili ca glasses is found to be about 0.5, which is much smaller than that f or fluorine-doped silica glasses and has almost no temperature depende nce between 1400-degrees-C and 2200-degrees-C.