Molten salt synthesis and optical properties of Eu3+, Dy3+or Nd3+ doped NiNb2O6 columbite-type phosphors

Pure, Eu3+, Dy3+ or Nd3+-doped NiNb2O6 powders have been prepared by a molten salt synthesis method by using Li2SO4-Na2SO4 salt mixture as a flux at relatively low temperatures as compared to the solid state reaction method. X-ray diffraction patterns of pure NiNb2O6 samples indicated an orthorhombic single phase. For Eu3+-doped NiNb2O6 samples, the luminescence of Eu3+ was observed at 615 nm as red emission while Dy3+-doped NiNb2O6 showed yellow emission at 577 nm and Nd3+ doped sample exhibited a typical emission at 1064 nm varying with the Eu3+ or Nd3+ doping concentrations. These luminescence characteristics of the doped samples may be attributed to the energy transfer between rare earth ions and NiO6 octahedral groups in the columbite structure.