Molten salt synthesis and spectral properties of Nd³⁺ doped CdNb₂O₆ columbite phosphors

Pure and Nd-doped CdNb₂O₆ particles have been prepared by a molten salt method using cadmium nitrate, niobium oxide and Li₂SO₄-Na₂SO₄ salt mixture as a flux at a relatively low temperature as compared to solid-state reaction method. X-ray diffraction patterns of the pure CdNb₂O₆ samples exhibited a single orthorhombic phase. Photoluminescence (PL) properties of all the undoped and Nd-doped samples in visible and near-infrared spectral region were studied in detail. While a strong blue emission band centered at 460 nm at room temperature was observed for the pure CdNb₂O₆, additional characteristic luminescence of Nd³⁺ at 1.06 μm was observed for Nd-doped CdNb₂O₆. Concentration quenching phenomenon was detected depending on the Nd-doping concentrations at both room and relatively low temperatures. This characteristic of the doped samples may be ascribed to the energy transfer between Nd³⁺ and niobate groups (NbO₆).