Fused quartz is essentially impermeable to most gases, but helium, hydrogen, deuterium and neon may diffuse through the glass. The rate of diffusion increases at higher temperatures and differential pressures.
Estimated Permeability Constants Through Fused Silica at 700 °C
- Helium 2.1 x 10-8 cm3 mm/cm2 sec. cm of Hg
- Hydrogen 2.1 x 10-9 cm3 mm/cm2 sec. cm of Hg
- Deuterium 1.7 x 10-9 cm3 mm/cm2 sec. cm of Hg
- Neon 9.5 x 10-10 cm3 mm/cm2 sec. cm of Hg
Diffusion Through Quartz
For semiconductor applications, the diffusion of various ions through the quartz is of critical importance. The attached table shows the time for various ions to diffuse through different thicknesses of quartz. These calculated values are based on the diffusion coefficient and a temperature of 1000 °C.
For more information regarding permeation time of fused quartz, click here.
For more information regarding the use guidelines for fused quartz, click here.