Author: M. Noro, N. Tanaka, K. Mihama
Institute: Department of Applied Physics, Faculty of Engineering, Nagoya University, Nagoya 464-01, Japan
Quasicrystalline Al-Mn, Al-Cu-Fe and Al-Fe films obtained by vacuum deposition are an interesting object of study due to their unique structural and physical properties. These materials have anomalous symmetry and can exhibit characteristics different from traditional crystals.
The study of the properties of such films, including their mechanical, thermal and electrophysical characteristics, opens up prospects for application in various fields, such as protective coatings, electronics and medicine. Modern experiments on deposition and subsequent analysis of such films help to deepen the understanding of the quasi-crystalline nature, as well as to develop new technologies for their industrial application. Thin films of quasi-crystalline Al-Mn, Al-Fe and Al-Cu-Fe alloys are obtained by sequential deposition in vacuum on cleaned sodium chloride surfaces at a substrate temperature of 220–350 °C. The process of formation of quasicrystals occurs through the formation of grains of 20–50 nm in size, where the five-fold axis is perpendicular to the film plane, and the two-fold axis of the quasicrystal is oriented along the [110] directions, coinciding with the (111) direction of the aluminum film. In the Al-Fe and Al-Cu-Fe systems, a slight rotation of the five-fold axis around the two-fold axes is observed, approximately by 10°. At manganese or iron content below 10 at.%, the coexistence of aluminum and quasicrystalline grains is recorded. High-resolution electron microscopy is used to study quasicrystalline films, which allows us to propose a model of vertices with decoration based on the Penrose tiling.
The vacuum deposition process allows precise control over the film thickness and composition, which is critical for obtaining quasi-crystalline structures. In particular, the ratio of components in the alloy directly affects the stability and order of the phases at work. For example, Al-Mn films show clearly distinguishable icosahedral structures, while Al-Cu-Fe and Al-Fe can exhibit more complex quasi-periodic lattices.