Valence-difference contrast measurements utilizing X-ray anomalous scattering

Anomalous scattering experiments with X-ray wavelengths close to an absorption edge have made it possible to determine independently the behaviour of ions in different valence states. The anomalous scattering factors of Fe²⁺ and Fe³⁺ obtained from both absorption and diffraction data have a large difference in f' between the two kinds of ions. Using a valence-difference contrast method, Bragg and diffuse scattering measurements were carried out for single crystals of Fe₃O₄ at low temperatures. The results demonstrate the ability of the contrast method to resolve charge ordering and valence fluctuation details.