Synthesis and photoluminescent behavior of Eu3+-doped alkaline-earth tungstates |
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Authors: | BS Barros AC de Lima ZR da Silva DMA Melo S Alves-Jr |
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Institution: | 1. School of Science and Technology, Federal University of Rio Grande do Norte, 59014-615 Natal, RN, Brazil;2. Department of Chemistry, Federal University of Rio Grande do Norte, 59078-970 Natal, RN, Brazil;3. Department of Fundamental Chemistry, Federal University of Pernambuco, 50590-470 Recife, PE, Brazil |
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Abstract: | 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 2 h 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 283 nm when calcium is replaced by strontium. However, this band was not observed for Eu3+-doped barium tungstate. Upon excitation at 260 nm, the emission spectra are dominated by the red 5D0→7F2 transition at 618 nm. 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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