ON THE USE OF X-RAY FORBIDDEN AND OXYGEN REFLECTIONS FOR CRYSTAL PROPERTIES STUDY

The excitation of structurally forbidden X-ray Bragg reflections is due to deviations of the charge electron density of individual atoms in lattice sites from spherical symmetry. High-temperature studies of these reflections in diamond show the pronounced difference in Debye-Waller factors of valence and core electrons. Low-temperature studies of forbidden reflections in V3Si reveal the essential influence of superconducting transition on the charge electron density distribution (CED). In oxides the quasiforbidden ''oxygen'' reflections permit to control the deviations from stoichiometry.