A family of hexagonal approximants of decagonal quasicrystals

By means of high resolution electron microscopy, the hexagonal phases with about the same c=12.4–12.6 Å but different a parameters (κ:17.674 Å; λ:28.382 Å; ν:40.687 Å) in Al-rich Al–TM (TM: transitional metal) alloys were found to consist of similar icosahedral cluster of about 30 Å in size. Using the known atomic sites of κ and λ in this cluster, the crystal structure of ν was solved by direct methods of X-ray diffraction analysis. Various icosahedral connections in this cluster were analyzed.