Self-diffusion in icosahedral Al72.4Pd20.5Mn7.1 and phason percolation at low temperatures studied by 27Al NMR

Aluminum self-diffusion in a monodomain icosahedral quasicrystal Al72.4Pd20.5Mn7.1 has been studied at temperatures between 4 and 400 K by Al-27 NMR measurements of the decay of transverse nuclear spin magnetization in a spatially inhomogeneous electric field gradient. Temperature dependence of the renormalized diffusion constant can be explained in the framework of the Kalugin-Katz phason-assisted diffusion model where the atomic jumps occur as a result of the presence of matching-rules violation defects. The observed self-diffusion process resembles a percolation transition with the percolation threshold at 72 K. [S0031-9007(98)08203-9].