Morphology-Controlled Synthesis, Physical Characterization, and Photoluminescence of Novel Self-Assembled Pomponlike White Light Phosphor: Eu³⁺-Doped Sodium Gadolinium Tungstate

Abstract

Three-dimensional pomponlike europium-doped sodium gadolinium tungstate NaGdWO4(OH) x :Eu3+ microarchitectures that exhibit efficient white-light photoluminescence properties have been successfully synthesized via a facile hydrothermal process in the presence of the surfactants cetyl trimethyl ammonium bromide, poly(vinyl pyrrolidone), and poly(ethylene glycol)-block-poly(propylene glycol)-block-ploy(ethylene glycol). The white light sodium gadolinium tungstate phosphor contains three emission bands: the blue-green band at 468 nm is ascribed to the ligand to metal charge transfer transition from O→W; the orange band at 590 nm and red band at 610 nm are attributed to the 5D0→7F1 and 5D0→7F2 transitions of Eu3+. The luminescence color can be tuned from blue to white to red by adjusting the doping concentration of Eu3+. Both scanning electron and transmission electron microscopy indicate that the obtained microspheres have a uniform particle size distribution. The three-dimensional sodium gadolium tungstate pompon-shaped structures were constructed layer-by-layer from a large number of two-dimensional nanoflakes with a mean diameter of ∼100 nm. The whole time-dependent process is interpreted as an example of self-assembly process. The emission spectra are dominated by a 5D0→7F2 transition of Eu3+. The optimum concentration for the white light was to keep the ratio of Eu3+ and Gd3+ at about 0.02.

Luminescent properties of HTP AgGd1−xW2O8:Eux3+ and AgGd1−x(W1−yMoy)2O8:Eux3+ phosphor for white LED

“…With the increasing of doping concentration of Eu 3 + , the intensity of f-f transition of Eu 3 + at 613 nm increased. Our result is similar to NaGdWO 4 (OH) x :Eu 3 +[22].The luminescent properties of the HTP AgGdW 2 O 8 and Eu 3 + -doped HTP AgGdW 2 O 8 phosphors are examined. The excitation and emission spectra of HTP AgGdW 2 O 8 are shown inFig.…”

“…370 nm, peaking at about 250 nm, which is ascribed to the charge transfer transition of O-W and O-Eu 3 +[22]. In addition, there are three tiny absorption peaks located at 394, 465, and 558 nm, respectively, which do not have considerable change when doped with the different concentration of Eu 3 + .…”

Study of the annealing temperature effect on the structural and luminescent properties of SrWO4:Eu phosphors prepared by a non-hydrolytic sol–gel process

“…In a site with inversion symmetry, the 5 D 0 → 7 F 1 transition dominates while in a site without inversion symmetry, the 5 D 0 → 7 F 2 transition dominates. The dominant emission emanates mainly from the parity forbidden electric dipole transition rather than the magnetic dipole transition which indicates that Eu 3+ ions are located at a non-site symmetry [8,22,53].…”

Synthesis and luminescence properties of Y2O3:Eu with flower-like microstructure

“…There are several crystal growth mechanisms in the solution system [38], including the classical Ostwald ripening process [39], the oriented attachment mechanism [40], and the self-sacrificed template mechanism based on Kirkendall effect [41]. For the formation of flower-like Y(OH) 3 :Eu microstructure, we believe the oriented attachment mechanism plays a key role.…”