Observation of charge ordering by X-ray anomalous scattering

Anomalous scattering technique was applied for the detection of charge ordering of Fe3O4 and Eu3S4 at low temperatures. The energy and temperature dependent features were clearly observed for forbidden and superlattice reflections in the systems. The energy-dependence curve for Fe3O4 gives a minimum intensity at E=7.122 keV, which can be related to the valence contrast by ion pairings. Energy dependence experiments on critical scattering have revealed the existence of valence-ions correlation.