Rare earth tungsten bronzes: a new method of synthesis. Perspectives for their application as inert matrices for transmutation of long-life actinide elements

A new method of synthesis of oxide tungsten bronzes containing lanthanide (Ln) Nd and Eu, based on thermal degradation of polyoxotungstate compounds, is proposed. The simplicity of the method allows to consider this class of compounds with chemical formula, LnxWO3, as potential inert target for incineration or transmutation of minor actinides, Am and Cm, in neutron reactors. Nd and Eu were used as analogues of transplutonium elements. Powder Xray diffraction patterns of compounds synthesized reveal a cubic perovskite structure. The lanthanide content in bronzes was determined by optical spectroscopy analysis. The experimental density of the pressed bronze samples was estimated at 6.58 g cm-3, i.e., 89% of the crystallographic value. The thermal stability of the bronzes synthesized was checked up to 900°C in an inert atmosphere. Leaching tests were performed for europium bronzes in nitric acid solutions using luminescence technique.