Investigations on local structures in new Bi2−2xLa2xUO6 (x = 0–0.05) solid solutions: a combined XRD, EXAFS, PL and EPR study

Abstract

La doped Bi₂UO₆ solid solutions of the general formula Bi_2−2xLa_2xUO₆ (x = 0–0.05) were prepared by the solid state reaction of Bi₂O₃, La(OH)₃ and U₃O₈ in a stoichiometric ratio. These solid solutions were characterized by X-ray diffraction, Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Spectroscopy (XANES) studies. It was found that La goes to the Bi sites of the Bi₂UO₆ lattice during the formation of these solid solutions. For further confirmation, a photoluminescence (PL) study on an iso-structural Bi_1.96Eu_0.04UO₆ was performed, and this supports the above observation. The solid solutions were also probed by EPR studies. The PL and EPR studies suggest that there are doping induced oxygen vacancies in these solid solutions.