Role of Sulfur and Its Diffusion in Silicate Glass Melts

Sulfur diffusion D _S is reported on a technical alkali‐poor barium alumoborosilicate glass melt at 900–1400°C and on three further Na ₂ O‐modified glass melts at 900°C, using a radioactive tracer method. Whereas D _S for the base glass melt amounts to ≈1 × 10 ⁻¹⁵ m ² /s at 900°C, it increases nearly exponentially with increasing Na ₂ O content from 0 to 15 mol% by almost three orders of magnitude. Similar to other glass melts, the sulfur diffusion obtained in these melts is also closely related to the Eyring diffusivity D _n derived from viscosity. The diffusion controlling species in oxidized melts seems to be SO ₄ ²⁻ , in reduced melts S ²⁻ . SO ₃ ²⁻ does obviously not play any role in this transport process.