The self-diffusion of Al in a monodomain icosahedral quasi-crystal was studied, at temperatures of between 4 and 400K, by making 27Al nuclear magnetic resonance measurements of the decay of transverse nuclear spin magnetization in a spatially inhomogeneous electric-field gradient. The temperature dependence of the renormalized diffusion constant could be explained within the framework of the Kalugin-Katz phason-assisted diffusion model, where the atomic jumps occurred as a result of the presence of matching-rules violation defects. The observed self-diffusion process resembled a percolation transition, with the percolation threshold at 72K.

Self-Diffusion in Icosahedral Al72.4Pd20.5Mn7.1 and Phason Percolation at Low Temperatures Studied by 27Al NMR. J.Dolinšek, T.Apih, M.Simsic, J.M.Dubois: Physical Review Letters, 1999, 82[3], 572-5