The intensity of X-ray diffuse scattering was measured at room temperature for fcc Au-Cr alloys whose compositions are 20. and 8.4 at.% Cr. Diffuse maxima due to atomic short-range order (ASRO) were observed at the 11/20 and its equivalent positions for the three specimens, while their intensities decrease with decreasing Cr content. From computer-simulated arrangements of Cr atoms in an fcc lattice, based on the observed ASRO parameters, the Cr atoms were found to have a preference for lining up along‹100› directions for the Au-20.2 at.% Cr alloy. On the other hand, the Cr atoms tend to have random positions for the Au-8.4 at.% Cr alloy and have an intermediate arrangement for the Au-12.6 at.% Cr alloy. The relationship bet ween the ASRO state and t he magnet is propert y in fcc Au-Cr alloys is discussed
There are many compounds with 1, 7-interaction in polycyclic aromatic hydrocarbons. The molecular structures of some of them have been determined by X-ray diffraction. They are largely deformed from the planar structure by the strain due to 1, 7-interaction. Such 1, 7-interactions are relaxed by two modes, which are defined as angle expansion mode and twisted mode. In these compounds, unusual physical and chemical properties have been also found, and are interpreted in terms of nonplanarity. Other interesting strained molecules are also briefly described.
Fundamental aspects of X-ray crystal truncation rod scattering from crystal surfaces are reviewed The use of imaging plate which has been developed by Fuji-film Co. as a two dimenssional digital recorder is shown to have several advantages for the measurement of the CTR scattering. The possible applications of this scattering to the characterization of the surface of semi-conductor crystals are presented
One-dimensional quasilat t ices such as the second and third order Fibonacci lattices, Thue-Morse lattices etc, have been grown by molecular beam epitaxy. The fine structures in the X-ray diffraction patterns from these crystals are discussed in terms of their selfsimilarities.