Oxygen self-diffusion measurements determined below and above the glass tra
nsition temperature in a cordierite glass are reported. The diffusion exper
iments were performed by the solid-gas isotope exchange method using O-18 a
s 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 th
e oxygen diffusivity in agreement with other studies. The diffusion data we
re useful for comparisons with diffusion controlled process in the same gla
ss. There is a difference between the activation enthalpies for crystal gro
wth, viscous flow, and oxygen self-diffusion. Hence, bond-breaking and mole
cular reorientation required for crystallization and the atomic transport m
echanism involved in viscous flow are not correlated in any obvious way to
oxygen diffusion in cordierite glass. (C) 1998 Elsevier Science B.V. All ri
ghts reserved.