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

The generalized vibrational density of states (GVDOS) of decagonal Al69.8Pd12.1Mn18.1 has been investigated by inelastic neutron scattering at the ILL in Grenoble for the first time. The data are compared to the GVDOS of the icosahedral phase Al71Pd19Mn10 and to the crystalline phase Al74Pd22Mn4 (ξ′). Whereas the contents of Al of these phases are nearly the same, the dynamic properties show remarkable differences. The two characteristic maxima in the GVDOS, which can be found for the icosahedral and for the structurally related crystalline phase ξ′, are not observed in the data of the decagonal phase. This indicates a significant difference in the local atomic structure of the decagonal and the icosahedral phase.