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

Pure, Eu 3+ , Dy 3+ or Nd 3+ -doped NiNb 2 O 6 powders have been prepared by a molten salt synthesis method by using Li 2 SO 4 –Na 2 SO 4 salt mixture as a flux at relatively low temperatures as compared to the solid state reaction method. X-ray diffraction patterns of pure NiNb 2 O 6 samples indicated an orthorhombic single phase. For Eu 3+ -doped NiNb 2 O 6 samples, the luminescence of Eu 3+ was observed at 615 nm as red emission while Dy 3+ -doped NiNb 2 O 6 showed yellow emission at 577 nm and Nd 3+ doped sample exhibited a typical emission at 1064 nm varying with the Eu 3+ or Nd 3+ doping concentrations. These luminescence characteristics of the doped samples may be attributed to the energy transfer between rare earth ions and NiO 6 octahedral groups in the columbite structure.