Nanomaterial Host Bands Effect on the Photoluminescence Properties of Ce-Doped YAG Nanophosphor Synthesized by Sol-Gel Method

Cerium trivalent (Ce3+) doped YAG nano-sized phosphors have been successfully synthesized by sol-gel method using different annealing temperatures. The samples have been characterized by X-ray diffraction (XRD), thermogravimetry (TG), differential scanning calorimetry (DSC) analysis, Fourier transform infrared (FTIR) spectroscopy, and steady photoluminescence (PL) spectroscopy. X-ray diffraction analysis indicates that the pure cubic phase YAG was formed and strongly depends on the cerium content and the annealing temperature. It was found that the grain size ranges from 30 to 58 nm depending on the calcination temperature. The YAG: Ce nanophosphors showed intense, green-yellow emission, corresponding to Ce3+ 5d1→2F5/2, 2F7/2 transitions and its photoluminescence excitation spectrum contains the two Ce3+ 4f1→5d1, 5d2 bands. The crystal filed splitting energy levels positions 5d1 and 5d2 and the emission transitions blue shift with annealing temperatures have been discussed. It was found that the Ce3+ 4f1 ground state position relative to valence band maximum of YAG host nanomaterial decreases with increasing the temperature

Annealing Temperature Effect on Structural and Luminescence Spectroscopy of Y2SiO5:Ce3+ Nanomaterial Synthesized by Sol–Gel Method

Ce3+ - doped Y2SiO5 nanophosphors were successfully produced by Sol-Gel process. To study the influence of the temperature on the structure and the luminescence of Y2SiO5:Ce3+, we annealed the xerogels at the temperatures 800, 900, 950, 1000, 1050 and 1250 °C. The X-ray diffraction technique (XRD), field emission scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR) and steady photoluminescence were used to characterize the samples. The crystallite size keeps the same value in the temperature range 950-1050 °C. The room temperature steady photoluminescence emission and excitation of Ce3+ in X1-Y2SiO5:Ce3+ nanomaterial with increasing temperature were measured and investigated. At the crystallization temperature of 1250 °C, we have a new structure X2- Y2SiO5:Ce3+ with grain sizes larger than the X1-Y2SiO5:Ce3+ and also intense violet-blue emission

Synthesis and Luminescent Properties of Eu 3+

Undoped and $Eu^{3+}$-doped disodium zinc diphosphate $Na_2ZnP_2O_7$ (NZPO) single crystals are grown by the Czochralski method. X-ray diffraction, Fourier transform infrared and Raman techniques were used to check the crystallographic structure. Excitation and emission spectra were measured at room temperature and studied. The $Eu^{3+}$ ions occupy a non-centrosymmetric site with different coordination number. Very efficient energy transfer from $O-Eu^{3+}$ band state to $Eu^{3+}$ excited energy levels is highlighted

Synthesis and Luminescent Properties of Eu3+Eu^{3+} Doped Crystalline Diphosphate Na2ZnP2O7Na_2ZnP_2O_7

Undoped and $Eu^{3+}$-doped disodium zinc diphosphate $Na_2ZnP_2O_7$ (NZPO) single crystals are grown by the Czochralski method. X-ray diffraction, Fourier transform infrared and Raman techniques were used to check the crystallographic structure. Excitation and emission spectra were measured at room temperature and studied. The $Eu^{3+}$ ions occupy a non-centrosymmetric site with different coordination number. Very efficient energy transfer from $O-Eu^{3+}$ band state to $Eu^{3+}$ excited energy levels is highlighted

LUMINESCENCE SPECTRA AND CRYSTAL FIELD CALCULATION OF Pr 3+ ION IN CRYSTAL LiYF 4

Abstract Luminescence of LiYF 4 : Pr 3+ in the visible and near ultraviolet region is investigated. In the visible region, the emissions observed were attributed to intra-4f 2 -configuration transitions. It has been shown that these transitions take place predominantly from 3 P 0 level and nonradiative relaxation rate between 3 P 0 and 1 D 2 is weak even at room temperature. The emission and excitation bands observed in the ultraviolet region were assigned to 4f 2 4f5d interconfigurational transitions. The energy levels of Pr 3+ 4f 2 configuration are fitted by using the crystal field method. The set of free-ion and crystal field parameters corresponding to the best fits allow to reproduce satisfactorily the experimental spectra

Photoluminescence and energy transfer of Tm³⁺ doped LiIn (WO₄)₂ blue phosphors

Room temperature steady and time resolved emission spectra of LiIn1−xTmx(WO4)2 (where thulium concentration is 0, 0.5, 1, 5 and 10 at%) blue phosphors, under UV excitation energy have been investigated. The concentration quenching effect on the blue emission, due to the (WO4)−2 groups and 1G4→3H6 emission transition of Tm3+ were studied. Two energy transfer mechanisms are shown. The first takes place between excited (WO4)−2 groups and the 1G4 energy level of Tm3+, and is mainly analyzed by phonon-assisted energy transfer. The second mechanism is due to an energy transfer from the excited Tm3+ ions to the surrounding ground state Tm3+ ions. The non-exponential decay curves of the 1G4 level observed for higher concentrations are analyzed by the Inokuti–Hirayama model. We think that the quenching effect between Tm3+ ions is mainly linked to the dipole–dipole interactions

Synthesis of GdBO3:Eu3+ nanophosphors via acetylacetone assisted aqueous sol–gel route: Effect of some synthesis parameters

International audienceNano-sized Eu 3+-doped GdBO 3 vaterite type nanophosphors have been synthesized successfully via acetylacetone assisted aqueous sol-gel route. Systematic investigation of the influence of Eu 3+ ion content and pH value of the suspension of precursors on structural, morphological and luminescence spectroscopic properties has been performed. X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, field emission-scanning electron microscopy (FE-SEM), Thermogravimetric and differential thermal gravimetry (TG/DTA), room temperature steady and time resolved photoluminescence (PL) spectroscopy techniques were employed to characterize the obtained powder samples. It has been found that the Eu 3+ ion content and pH value precursors suspension have important effect on the structural, morphology and emission properties. The XRD analysis reveals that GdBO 3 : 10% mol Eu 3+ synthesized at pH = 2 and pH = 10 exhibit the quasipurest P6 3 /mmc vaterite structure. The vibrational absorption of (BO 3) 3group is assigned to the GdBO 3 with calcite type or other vaterite structure namely triclinic and monoclinic. The morphologies of GdBO 3 particles size increases with increasing of pH value. All sample present only the orange-red colors emission from 5 D 0 levels to the 7 F J levels (J = 0-3) of Eu 3+ ion. Furthermore, it was found that 10% concentration of Eu 3+ presents the quenching of emission in GdBO 3. Also, it was that the emission intensity was affected by the pH value and sample with pH = 10 exhibits the highest emission intensity. The asymmetry ratio parameter R between red and orange emission intensities in function of Eu 3+ content and pH value is determinate and discussed

SPECTROSCOPIC PROPRIETIES OF CRYSTALS MF2 (M=Cd, Sr, Ba) DOPED TO RARE EARTH IONS

<p>In the present work, we are interested by studying the spectroscopic properties for optical applications, mainly laser amplification, of MF2 crystals, where M is an alkaline earth (Ba, Sr) or Cadmium (Cd) doped with rare earth ions (Tb³⁺, Er³⁺, Ho³⁺). So far, we present the absorption and emission properties and also the fluorescence dynamics at room temperature of visible and near infrared transitions of the Er³⁺ ion doping these matrices. We also use the formalism of Judd-Ofelt by use of absorption spectra recorded at room temperature in order to identify the spectroscopic properties inherent in all radiative transitions which can occur.</p