Luminescencemetry of Acid-Base and Redox Reactions of Vanadate Ions in Molten Salts Dissolved Rare Earth Ions

摘要

In the pofnak[Na_(0.81)K_(0.19)(PO_3)_(0.75)F_(0.25)] melts with dissolvedV_2O_5, the two spiecies of VO_2~+ and VO~(3+) could be defined as luminescence centers. The values of optical basicity of the solid and molten pofnak at 525 °C were estimated at about 0.42 and 0.48, respectively from their luminescence. The vanadium bronze ions in which the mixed valence of V~(5+)and V~(4+) coexisted, such as V_2O_3~(3+) and V_2O_5~-produced by acid-base reaction among VO_2~+ , VO~(2+) and O~(2-) were discerned in alkaline bisulfate melts dissolving vanadate and europium ions. The amount of the soluble rare earth metal ions was considerably increased by the addition of vanadium oxides in molten salt. This solubility increase was attributed to acid-base and redox reactions between vanadium oxides and reare earth metal oxides in molten salts.