A comparative study of the atomic dynamics of icosahedral and decagonal ZnMgY

A comparative investigation of the atomic dynamics of an icosahedral and a decagonal quasicrystal from the same alloy family, here the ZnMgRE/Y Frank–Kasper type of quasicrystals, has been performed for the first time. The i- and d-alloy were studied at 296 and 200 K, respectively at the ISIS neutron spallation source (UK) in a large region of energy and momentum transfers using neutron inelastic scattering (NIS). The quantitative comparisons of the single particle dynamics of the two ZnMgY samples via the generalized vibrational density of states shows a considerable difference in the intensity of the sub-bands constituting the main energy bands, but only small shifts of these bands and subbands in energy. We attribute the differences observed in the single particle dynamics more to differences in the short range structure of decagonal and icosahedral ZnMgY, leading to a stronger grouping of the local density of the states in the case of the decagonal alloy, than to their different aperiodic long range order.