NDLI: Structural and photoluminescence properties of $Eu^{3+}$ doped $α-Ag_{2}WO_{4}$ synthesized by the green coprecipitation methodology

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Nogueira, Içamira C. Pereira, Wyllamanney S. Pereira, Paula F. S. Varela, José A. Longo, Elson Rosa, Ieda L. V. Pinatti, Ivo M. Gonçalves, Rosana F.
Description	Author Affiliation: Pinatti IM ( INCTMN, LIEC, Chemistry Department of the Federal University of São Carlos, P.O. Box 676, 13565-905, São Carlos, SP, Brazil. ilvrosa@ufscar.br.)
Abstract	Europium doped silver tungstates $α-Ag_{2−3x}Eu_{x}WO_{4}$ (x = 0, 0.0025, 0.005, 0.0075 and 0.01 mol) were synthesized by the coprecipitation method at 90 °C for 30 minutes. These crystals were structurally characterized by means of X-ray diffraction (XRD), Rietveld refinement, and micro-Raman (MR) and Fourier transformed infrared (FT-IR) spectroscopies. Field emission scanning electron microscopy (FE-SEM) images were employed to observe the shape of the crystals. The optical properties were investigated by ultraviolet-visible (UV-vis) absorption and photoluminescence (PL) measurements. The XRD pattern indicated structural organization at a long range for all undoped and Eu-doped samples, while MR and FT-IR revealed that the presence of the $Eu^{3+}$ ions favors the structural organization at a short range. The Rietveld refinement showed that all the crystals are monophasic with an orthorhombic structure and the Pnn space group. The refined lattice parameters and atomic positions were employed to model the $WO_{6}$ and $AgO_{n}$ (n = 2, 4, 6 and 7) polyhedra in the unit cell. FE-SEM analysis revealed nanorod-like microcrystals with growth of metallic silver on the surface. Further, the UV-vis absorption spectra indicated the existence of intermediary energy levels within the band gap. PL spectra showed a broad band related to the $[WO_{6}]$ group and characteristic narrow peaks due to the f–f transitions of $Eu^{3+}$ as a result of efficient energy transfer from the matrix. Also, the emission line shape transitions from $^{5}D_{0}$ to $^{7}F_{J}$ (J = 0–4) levels of the $Eu^{3+}$ were noticed. Among the samples, the most intense photoluminescence results were observed for the $α-Ag_{2−3x}Eu_{x}WO_{4}$ (x = 0.0075) sample. Lifetime decays support that the $Eu^{3+}$ ions occupy at least two crystallographic sites. CIE coordinates confirmed the colors of the emission spectra which classify this material as a potential phosphor in the visible range.
ISSN	14779226
Issue Number	40
Journal	Dalton Trans.
Volume Number	44
e-ISSN	13645447
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2015-10-28
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Chemistry
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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