Oxidation state and coordination surrounding of iron and uranium in sodium aluminum iron phosphate glasses

Abstract

The oxidation state of Fe and U and the coordination surrounding of Fe in uranium-containing sodium aluminum iron phosphate glasses were determined by analysis of the FeK and UL₃ X-ray absorption nearedge structure (XANES), X-ray photoelectron spectroscopy (XPS), and Mössbauer spectroscopy on ⁵⁷Fe nuclei. Uranium is present in the glasses in the form of U(V) and U(VI), and iron, in the form of Fe(III) and Fe(II), mainly in the distorted octahedral surrounding. The fraction of U in various oxidation states depends on the form of untroducing uranium (UO₂ or UO₃) and on the oxide concentration. With an increase in the UO₃ concentration in glasses, the fraction of U(VI) increases and the fraction Fe(III) relative to Fe(II) decreases.