Crystal structure, luminescence properties and energy transfer of Eu super(3+)/Dy super(3+) doped GdNbTiO sub(6) broad band excited phosphors

GdNbTiO sub(6) is used as a host material for phosphors for the first time. Lanthanide ion (Eu super(3+)/Dy super(3+)) doped GdNbTiO sub(6) phosphors were prepared by solid-state reaction, and the crystal structure, luminescence properties, and relevant luminescence mechanisms were investigated. The crystal structure of Eu super(3+)/Dy super(3+) doped GdNbTiO sub(6) was refined from powder XRD data by the Rietveld method, which is made up of irregular (Gd/Eu/Dy) super(3+)O sub(8) super(13-) polyhedra and slightly distorted Nb(Ti)O sub(6) octahedra forming a layered structure. The luminescence properties of the GdNbTiO sub(6):Eu super(3+)/Dy super(3+) phosphors were studied under ultraviolet (UV) and vacuum ultraviolet (VUV) excitation. The GdNbTiO sub(6) host shows a broad emission band about the 400-650 nm region centered at 509 nm owing to the Nb(Ti)O sub(6) octahedral groups, which has spectral overlap with f-f excitation transitions of Eu super(3+)/Dy super(3+) in the doped samples. For red phosphor GdNbTiO sub(6):Eu super(3+), a dominant emission peak at 614 nm was attributed to the super(5)D sub(0) arrow right super(7)F sub(2) transition of Eu super(3+), which confirmed that Eu super(3+) ions are located at sites without inversion symmetry. The phosphor GdNbTiO sub(6):Dy super(3+) shows bright yellow-green emission prevailing at 577 nm upon 273 nm excitation. With increasing activator concentration, the emission derived from the characteristic f-f transitions of Eu super(3+)/Dy super(3+) is enhanced while the host emission is weakened, which is due to the energy transfer from the host to Eu super(3+)/Dy super(3+). Considering the facile synthesis and excellent Eu super(3+)/Dy super(3+) doped luminescence properties of this compound, self-activated GdNbTiO sub(6) may be a good candidate as a host phosphor for use in various optical devices.