Structure of Quasi Crystals in Terms of Atomic Clusters

Abstract

Experimental results showing that icosahedral atomic clusters, known to exist in complex crystalline phases, can be also considered in the structure of related quasicrystalline phases. Three parts are presented: i) the observation of the existence of 5-fold polyatomic clusters in icosahedral quasicrystals by local spectroscopies and electron microscopy investigation techniques. ii) the direct analysis of diffraction experiments in hyperspaces, and in particular the determination of the atomic surfaces, which are shown to restore after cut by the physical space several types of polyatomic clusters. iii) the construction of atomic structure models of some icosahedral quasicrystals based on the connection of cluster units according to specific rules. Several ways of modeling are described. The atomic order of the models is analysed as well as their diffraction properties.