Structural model of the Al[sbnd]Pd decagonal quasicrystal

Abstract

A structural model of a Al[sbnd]Pd decagonal quasicrystal has been derived from the structure of the orthorhombic Al₃Pd phase according to the fact that the transformation from the Al[sbnd]Pd decagonal quasicrystal to the Al₃Pd phase occurs during heat treatment. The structure of the Al₃Pd phase can be described as a periodic packing of subunits of a crown shape, in which each subunit is composed of four decagonal atomic columns. Two other subunits with flattened hexagonal and star shapes have also been deduced, which are composed of three and five decagonal atomic columns respectively. The structure of the Al[sbnd]Pd decagonal quasicrystal is described by the three kinds of subunit; the structure observed experimentally is a random packing of the three subunits; the ideal structure is a quasiperiodic packing of the three subunits.