In this volume we aim to introduce recent progress in the study of aperiodic materials, which include icosahedral clusters, amorphous metals, quasicrys- tals, glasses, and liquids. Quasicrystals, discovered in 1984, correspond to a kind of revolution in our understanding of crystallography, wherein the five-fold rotational symmetry was prohibited in long-range ordered systems. Various interesting physicochemical properties of these materials strongly depend on structural inhomogeneity at the microscopic level, and the small angle X-ray scattering method is widely used to analyze such structures. These new materials provide fundamental improvements to materials prop- erties, and are not only scientifically interesting but also industrially impor- tant for applications such as ultrafine magnetic recording media and future electronic devices. This book contains three chapters. The first chapter, written by H. Tanaka and T. Fujiwara, deals with 'Electronic Structure in Aperiodic Materials', and reviews the application of theoretical methods to determine the elec- tronic structures and resulting properties of amorphous metals, quasicrys- tals, and liquids.The second chapter, written by Y. Waseda, K. Sugiyama, and A. H. Shinohara, covers the recent topic of 'Anomalous Small Angle X- ray Scattering for Structural Inhomogeneity of Materials', starting with its fundamentals. The third chapter, 'Icosahedral Clusters in RE(TM - Al h3 1 x x Amorphous Alloys', by K. Fukamichi, A. Fujita, T. H. Chang, E. Matsubara, and Y.
