Doped Gd2O3 Research Articles

Tailoring the luminescent properties of Gd2O3:Tb3+ phosphor particles by codoping with Al3+ ions

Spherical-shaped, Tb3+/Al3+ codoped Gd2O3 phosphor particles were synthesized using a urea homogeneous precipitation method. Field emission scanning electron microscopy measurements confirmed the formation of nearly-uniform spherical particles with sizes in the range, 250±50nm. In this study we examined the effects of the Al3+ codoping concentration on the photoluminescence emission of Tb3+ doped Gd2O3 phosphor particles. The results confirmed that incorporating Al3+ into Gd2O3:Tb3+ phosphor is highly favorable for improving the emission of the synthesized Gd2O3:Tb3+ phosphor particles. In addition, the simple approach for the luminescence enhancement given here can be extended to the other phosphor systems.

Synthesis and Optical Properties of Eu3+ and Tb3+ Doped Gd2O3 Nanotubes

Synthesis and Optical Properties of Eu³⁺ and Tb³⁺ Doped Gd₂O₃ Nanotubes

X‐ray diffraction of cubic Gd2O3/Er under high pressure

AbstractIn this paper, we report the in situ high pressure X‐ray diffraction studies on Er3+ doped Gd2O3 in a diamond anvil cell up to 39.8 GPa at room temperature. Several phase transitions have been identified in our studies. The structural transformation from a starting cubic phase to a hexagonal phase occurred during the sample compression process, at 8.57 GPa. And the hexagonal phase was stable from 12.5 GPa up to the highest pressure in this study but was not quenchable and transformed to a monoclinic phase after pressure release. An anomalous high pressure behavior in the hexagonal type Gd2O3 phase was observed, which might be caused by an electron transition influenced by Er3+ ions doping. By fitting the compression data to the Birch–Murnaghan equation of state, the bulk moduli of the cubic and two hexagonal (at p < 19.9 GPa and p > 27.0 GPa) Gd2O3 phases were determined to be 164 ± 3, 185 ± 7, and 150 ± 10 GPa with $B'_{0} = 4$, respectively.

Luminescence properties of Dy<SUP align=right>3+</SUP> doped Gd<SUB align=right>2O<SUB align=right>3 nanoparticles prepared by glycine route: annealing effect

Dy3+ doped Gd2O3 nanoparticles were prepared by glycine-nitrate combustion route and their luminescence properties have been investigated. Through host lattice absorption at 230 nm, emission peaks at 488 (4F9/2 → 6H15/2, blue-green) and 572 nm (4F9/2 → 6H13/2, yellow) of Dy3+ are observed along with a broad emission peak at 400 nm (host). Luminescence intensity increases with increase of heat-treatment from 500°C to 900°C due to extent of reduction of particle surface defect. On increasing the concentration from 1 to 2 at.% Dy3+, luminescence intensity increases slightly and decreases with further increase of Dy3+ due to cross-relaxation among Dy3+ ions. This was supported by lifetime studies. Lifetimes for 4F9/2 level of Dy3+ in 1, 2 and 5 at.% Dy3+ doped Gd2O3 prepared at 900°C were found to be 237, 39 and 26 μs, respectively.

Effects of the Eu3+ concentration on the structural, optical and morphological properties of cubic Gd2O3 nanostructured thin films

Nanostructured Gd2O3: Eu3+ thin films were prepared by pulsed laser ablation technique. The dependence of structural, morphological and optical properties of these films on photoluminescence was systematically studied by varying the Eu3+ incorporation concentration. Micro-Raman and XRD analysis indicate that Eu3+ incorporation strongly perturbs the cubic Gd2O3 structure and suppresses the grain growth. For 0.10 mol Eu3+ doped Gd2O3 films deposited under a vacuum of 10-6 mbar when subjected to annealing at 1173 K give transparent films exhibiting intense photoemission at 612 nm due to 5D0-7F2 transition. The Eu3+ incorporation concentration above 10 mol %, decreased the luminance intensity may be due to concentration quenching effect.

Gd 2 O 3 : Eu 3 + particles prepared by glycine-nitrate combustion: Phase, concentration, annealing, and luminescence studies

Eu 3 + doped Gd2O3 particles have been prepared by glycine-nitrate combustion route. Eu–O charge transfer peak shifts to higher wavelength from 260 to 273 nm with increasing Eu3+ concentration, whereas the linewidth at half maximum intensity varies with Eu3+ concentrations and annealing temperatures as well. Lifetime for D50 level of Eu3+ increases with annealing temperature from 500 to 900 °C, and this is related to decreasing surface to volume atomic ratio of particles. Asymmetric ratio defined by the ratio of intensity of electrical dipole transition to that of magnetic dipole transition is found to be 10, which is more than the reported values (3–4) indicating enhancement in luminescence by this synthesis route.

Structural and Luminescence Properties of Nanocrystalline Eu3+-doped Gd2O3

ABSTRACTThe present work addresses the synthesis and characterization of red emitting Gd2-xEuxO3 nanocrystalline phosphors by a modified sol-gel based method. The effects of the annealing temperature and atomic fraction of Eu3+ ions, ‘x’, on the structural and luminescence properties of the produced oxides have been systematically investigated. X-ray diffraction analyses revealed that crystalline cubic-Gd2O3 host structure was obtained when the intermediates (x=0.01-0.30) were annealed at different temperatures in air. Photoluminescence spectra of doped Gd2O3 powders showed all transitions of Eu3+ species, being the 5D0→7F2 transition the most intense. On a common sample-weight basis, the highest photoluminescence intensity was obtained at ‘x’ = 0.15. The energy transfer from host to dopant was verified for all evaluated ‘x’ values, which suggest the actual incorporation of Eu species into the Gd-oxide lattice. It was also found that the photoluminescence intensity was strongly dependent on the annealing temperature and dopant concentration.

Growth and characterization of red-green-blue cathodoluminescent ceramic films

Gd 2 O 3 and Y2O3 films, respectively, doped with Eu3+, Tb3+, and Tm3+ have been grown by the electron beam physical vapor codeposition technique on optically polished quartz substrates. The film samples have been doped at different concentrations by the corresponding rare-earth oxides. The concentration range explored is from 0.9% to 9.8% on 18 samples. For each film sample an extended characterization has been performed by thin film-x-ray diffraction, scanning electron microscopy, energy dispersion spectroscopy, cathodoluminescence spectroscopy, and color coordinate analysis. Y2O3 films display the most intense red-green-blue (RGB) emission and their film morphology and structure are more compact and crystalline with respect to Gd2O3 monoclinic films. Eu3+ and Tb3+ doped Y2O3 films grow oriented along the (222) direction. The ratios between the intensities of the electric dipole and magnetic dipole transitions have been also evaluated. The blue emission of Tm3+ doped Gd2O3 is lacking in the dopant concentration range from 1.6% to 7.6%, whereas it is present in Tm3+ doped Y2O3 films, at approximately the same dopant concentration range (1.9%–9.8%). Commission Internationale de l’Eclairage plot of the color coordinates of all the RGB film samples has been reported together with the RGB phosphor standard used in cathodic ray tube TV screens.

Rare earth based clusters for nanoscale light source

We investigate the fundamental properties of films resulting from the deposition of Eu3+ doped Gd2O3 clusters. We first report that the crystalline structure of clusters with diameter as low as 2.8 nm is still BCC (as in the bulk phase at ambient temperature and pressure). No phase transition to monoclinic structure is observed. We show that contamination from air (formation of hydroxide) is important and leads to the modification of the luminescence of the Eu3+ ions. Furthermore, films protected from this contamination have been fabricated and show a new feature (broad peak at 625 nm). It means that contamination is not the only mechanism responsible for the modification of the light emission spectrum. The crystal field symmetry breaking induced by the surface also plays a major role. Eventually, we show that the widening of the optical gap continues for these very small clusters. We discuss this effect in the frame of the quantum confinement model.