Sodium tracer diffusion in a sodium aluminosilicate glass

Sodium tracer diffusion coefficients, D N a * , have been measured using the radioactive isotope Na-22 in a commercial, ion exchangeable sodium aluminosilicate glass at different temperatures between about 200 and 400 °C. The activation enthalpy derived from sodium tracer diffusion data for the as-received glass samples was found to be about 75.5 ± 1.2 kJ/mol and the value of the logarithm of pre-exponential factor of the sodium tracer diffusion coefficient, log10 [ D N a ° / ( cm 2 / s ) ] , is − 2.58 ± 0.13. It was observed that pre-annealing the glass samples at the annealing point of 609 °C causes some reduction of the values of the sodium tracer diffusion coefficients. In addition, the glass samples investigated were found to take up water at 300 °C in wet air ( P H 2 O = 474 mbar). However, an influence of the uptake of water during diffusion-annealing in wet air on the diffusivity of sodium was not observed.