Oxygen self-diffusion measurements determined below and above the glass transition temperature in a cordierite glass are reported. The diffusion experiments were performed by the solid-gas isotope exchange method using O-18 as a tracer in H-2-(H2O)-O-18 and Ar/O-18(2) atmospheres. The O-18 diffusion profiles were established by secondary ion mass spectrometry (SIMS) after appropriate diffusion annealing. The oxygen diffusion coefficients changed at the glass transition temperature as expected. The atmosphere affected the oxygen diffusivity in agreement with other studies. The diffusion data were useful for comparisons with diffusion controlled process in the same glass. There is a difference between the activation enthalpies for crystal growth, viscous flow, and oxygen self-diffusion. Hence, bond-breaking and molecular reorientation required for crystallization and the atomic transport mechanism involved in viscous flow are not correlated in any obvious way to oxygen diffusion in cordierite glass. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 12]
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