Eu3+-activated Na2Gd(PO4)(MoO4): A novel high-brightness redemitting phosphor with high color purity and quantum efficiency for white light-emitting diodes

A series of Eu(3+)activated Na2Gd(PO4)(MoO4) red-emitting phosphors were prepared by a facile hightemperature solid-state reaction method. The synthesized samples were characterized by X-ray diffraction, field-emission scanning electron microscope, photoluminescence (PL) spectra, luminescence decay curves and temperature-dependent emission spectra. Under the excitation of 396 nm, the resultant samples exhibited the characteristic emissions of Eu3+ ions corresponding to the D-5(0)/F-7(J) transitions. The optimal doping concentration of Eu3+ ions was determined to be 50 mol%. The critical distance was around 8.98 and the concentration quenching was dominated by quadrup-quadrupole interaction. Furthermore, the prepared samples also possessed good color coordinate (0.653, 0.346) and high color purity of 92%. The temperature-dependent PL spectra suggested that the resultant products possessed good thermal stability and the activation energy was found to be 0.22 eV. Additionally, the internal quantum efficiency and the external quantum efficiency of the phosphors was measured to be 90% and 37%, respectively. These results demonstrated that the Eu3+-activated Na2Gd(PO4)(MoO4) phosphors are very appropriate red-emitting phosphors for applications in near-ultraviolet-excited white LEDs. (C) 2017 Elsevier B. V.All rights reserved.