Photoluminescence properties of y at.% Eu3+-doped Gd(NbxP1-x)O-4: A color-tunable orange-red phosphor

In this work, a simple method to prepare orange-red phosphor is introduced. A series of y at.% Eu3+-doped Gd (Nb(x)P1-x)O-4 (x = 0%, 1%, 2%, 3%, 4%, 5%, 6%, 10% and y = 5%, 7%, 9%, 11%, 13%, 14%, 15%) phosphors were prepared through solid reaction technique. The structure and optical properties of the phosphors were characterized using measurements of X-ray powder diffraction, photoluminescence excitation, photoluminescence and decay curves. The X-ray diffraction results revealed that the obtained phosphors possessed the same pure monoclinic phase as GdPO4 until the doping concentration of Nb5+ reached a maximum value of 5 at. %. With the high sensitivity of the D-5(0)-> F-7(2) transition to the symmetry of the crystal field, the relative intensity of the two emission peaks at 596 and 615 nm could be continuously adjusted by changing the Nb5+ concentration. Moreover, Judd-Ofelt calculations performed on samples doped with different Eu3+ ions concentrations showed their promise as color-tunable orange-red phosphors.