Oxygen K-edge XANES investigation of Ni c Mg 1 − c O solid solutions

Abstract A series of Ni c Mg 1 − c O solid solutions are characterized by means of synchrotron radiation X-ray diffraction and X-ray absorption near-edgestructure spectroscopy at oxygen K-edge (532 eV). A dramatic drop of the pre-edge peak intensity is observed in the Ni c Mg 1 − c O system upon dilution. It can be attributed to a decrease of 3d 8 (Ni 2+ )-2p(O 2− ) mixing upon dilution with magnesium ions due to a decrease of the number of 3d vacancies as nickel ion is replaced by magnesium ion. Similarly, the decrease of the number of 4s and 4p vacancies also leads to a decrease of 4s4p(Ni 2+ )-2p(O 2− ) hybridization, and hence a drop of intensities of features B and C. The features E and F are more sensitive to the increase of the degree of disorder upon dilution than feature D, revealing that the latter is mainly dependent by the medium-range order