Diffusion of water and carbon dioxide in some multicomponent silicate glasses

The diffusion properties of a number of multicomponent silicate glasses were studied via the kinetic thermal desorption mass spectrometry. The diffusion coefficients of water and carbon dioxide molecules were determined for the first time in the glasses at temperatures ranging between 500 and 1000°C. The diffusion coefficients of water and carbon dioxide decrease with the reduction of the content of alkali in the glasses and, in the case of alkali-free glass, approach the values typical of silica glass. The values of the diffusion coefficients of CO2 are lower and the values of the activation energy of diffusion of CO2 are higher than those of water. Knowledge of the values of the diffusion coefficients makes it possible to calculate the time required for degassing the material to the desired degree.