ATOMIC PACKING GEOMETRIES AND LATTICE PROPERTIES OF A MODEL DECAGONAL PHASE

A model binary decagonal phase and the monoclinic Al13Fe4 phase, a crystal approximant to the decagonal phase, have been produced by using interatomic potentials. Voronoi polyhedra analysis of the structures has shown that the atomic packing geometries of the two phases are similar: (1) the most abundant edge number of the faces of the Voronoi polyhedra is 5, (2) the distributions of Voronoi volumes are separated into large and small atom sites and (3) large and small atoms have large and small coordination numbers respectively. Tetrahedra-octahedra packing analysis has shown that the atomic packing characteristics of the decagonal phase are between the two types of icosahedral phases previously studied. Vibrational density of states spectra computed for the decagonal phase have revealed no distinct anisotropy between the tenfold direction and the direction perpendicular to it.