Synthesis and photoluminescent behavior of Eu3+-doped alkaline-earth tungstates

• Published in: The Journal of physics and chemistry of solids Vol. 73; no. 5; pp. 635 - 640
• Main Authors: Barros, B.S., de Lima, A.C., da Silva, Z.R., Melo, D.M.A., Alves-Jr, S.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-05-2012
• Subjects: A. Optical materials; A. Oxides; B. Chemical synthesis; Chromaticity; D. Luminescence; Photoluminescence; Polymeric precursors; Roasting; Scanning electron microscopy; Spectroscopy; Thermogravimetric analysis; Tungstates; B. Chemical synthesis; A. Oxides; A. Optical materials; D. Luminescence
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2011.12.026

Eu3+-doped alkaline-earth tungstates MWO4 (M=Ca2+, Sr2+, Ba2+) were prepared by a polymeric precursor method based on the Pechini process. The polymeric precursors were calcined at 700°C for 2h in order to obtain well-crystallized powders and then characterized by X-ray diffraction (XRD), thermogravimetric analysis (TG), scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and photoluminescence spectroscopy (PL). All prepared samples showed a pure crystalline phase with scheelite-type structure confirmed by XRD. It was noted that the charge-transfer band shifted from 260 to 283nm when calcium is replaced by strontium. However, this band was not observed for Eu3+-doped barium tungstate. Upon excitation at 260nm, the emission spectra are dominated by the red 5D0→7F2 transition at 618nm. By analyzing of the emission lines, it was inferred that Eu3+ ions occupy low symmetry sites in the host lattice. It was also found that Eu3+-doped SrWO4 displays better chromaticity coordinates and greater luminescence intensity than the other samples.
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► A series of Eu3+-doped alkaline-earth tungstates were prepared by a polymeric precursor method. ► Eu3+ ions occupy low symmetry sites in the host lattice. ► The effect of the alkaline-earth ionic radius on the energy transfer from WO4 groups to Eu3+ ions was studied. ► The SrWO4:Eu3+ phosphor showed strongest luminescence intensity and better chromatic coordinates.