X-RAY-ABSORPTION STUDY OF TETRAVALENT DY COMPOUNDS - CS2RBDYF7 AND CS2KDYF7

We report on X-ray absorption near-edge structure (XANES) studies at the Dy-L(I-III) thresholds of the tetravalent Dy compounds Cs2RbDyF7 and Cs2KDyF7. In analogy to XANES spectra of other tetravalent lanthanide (Ln) compounds, LnO2 and LnF4 (Ln = Ce, Pr, Tb), the observed spectral shapes consist of components from two different 4f configurations in the final state. This reflects strong covalent mixing of the 4f electrons in Dy(IV) compounds. The Dy(IV)-4f8 L(III) white-line component is found to be further split into two lines, presumably resulting from crystal-field splitting of the 5d final state. With an additional XANES study of the divalent compound DyBr2, Dy is now the only Ln element, where three different valence states have been investigated by high-energy spectroscopy.