Growth of AlMn quasicrystals by vacuum deposition

Abstract

Thin films of AlMn quasicrystals are prepared by a successive deposition technique in a vacuum onto air-cleaved sodium chloride surfaces at a substrate temperature of 280–330°C. The growth of the quasicrystals is found as random orientated films with a grain size of 20–50 nm for Al-21 at.% Mn. For a specimen of Al-5at.% Mn grown at 280°C, quasicrystals and aluminum with (111) orientation are recognized, the lattice relation being that the [110] direction of the aluminum is parallel to the twofold axis of the quasicrystal. Heat treatment at 330°C for a few hours brings about a transformation from quasicrystalline films to an equilibrium phase Al 6Mn. High resolution electron microscopy is applied to the quasicrystal films, by which the edge length of the fundamental hexahedron of the Penrose tiling is determined to be 0.47 nm from the structural images.