An investigation of the solubility and diffusivity (table 117) of Ar in Ar-saturated silica fibers, performed by using a modified version of Sievert's method, furnished results which were in good agreement with previous data. At temperatures of between 525 and 675C, the solubility of Ar in the vitreous material could be described by:

S (atoms/m3atm) = 2.09 x 1021 exp[-31.5(kJ/g-atom)/RT]

The results indicated that the density of interstitial solubility sites which were available to Ar atoms was 1.1 x 1026/m3. This result was consistent with a log-normal distribution model for the size of interstitial sites. At temperatures of between 500 and 905C, the diffusivity of Ar in vitreous silica was described by:

D (m2/s) = 5.06 x 10-9 exp[-113(kJ/g-atom)/RT]

G.S.Nakayama, J.F.Shackelford: Journal of Non-Crystalline Solids, 1990, 126[3], 249-54

Table 117

Diffusion of Ar in Silica