Browsing by Author "De Godoy M.P.F."
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Item Radioluminescence and photoluminescence characterization of Eu and Tb doped barium stannate phosphor ceramics(2014) Ayvacikli M.; Canimoglu A.; Karabulut Y.; Kotan Z.; Herval L.K.S.; De Godoy M.P.F.; Galvão Gobato Y.; Henini M.; Can N.In this paper, we report on structural and optical properties of terbium and europium doped barium stannate phosphors (BaSnO3) synthesised by conventional solid state reaction method. We have studied those materials by using X-ray diffraction (XRD), radioluminescence (RL) and photoluminescence (PL) techniques. XRD patterns confirm that the BaSnO3 sintered at 1400 C exhibit orthorhombic structure and that the Tb3+ and Eu3+ substitution of Ba2+ does not change the structure of the BaSnO 3 host. The optical emission spectrum is characterized a broad band centered at 897 nm (1.38 eV), with a high-energy tail approximately 750 nm from the host lattice. Other emission signals that are characteristic of the 3 + oxidation state of rare earth elements were generated by Eu and Tb doping. Luminescence measurements show that the series of emission states 5D4 → 7F6, 5D 4 → 7F5, 5D4 → 7F4 and 5D4 → 7F3 corresponding to the typical 4f → 4f infra-configuration forbidden transitions of Tb3+ are appeared and the major emission peak at 540 nm is due to 5D4 → 7F5 transitions of Tb3+. On the other hand, the emission spectrum of Eu doped BaSnO3 phosphor exhibits a series of emission bands, which are attributed to the 5D0 → 7Fj (j = 0-4) transitions of Eu3+ ions. The dominant emission of Eu3+ corresponding to the electric dipole transition 5D0 → 7F2 is located at 613 nm. The sharp emission properties exhibited demonstrate that the BaSnO3 is a suitable host for rare-earth ion doped phosphor material. This work clearly confirms the unusual near infrared (NIR) PL discovered by H. Mizoguchi et al. in BaSnO3 at room temperature. © 2014 Elsevier B.V. All rights reserved.Item Enhancement of the luminescence intensity by co-doping Mn2+ into Er3+-doped SrAl2O4(Elsevier, 2015) De Herval L.K.S.; Tuncer Arslanlar Y.; Ayvacikli M.; Iikawa F.; Nobrega J.A.; Pizani P.S.; Galvão Gobato Y.; Can N.; Henini M.; De Godoy M.P.F.Structural and optical properties of erbium- and manganese-doped strontium aluminates (SrAl2O4) phosphor materials synthesized by a solid state reaction were investigated. The samples presented the fundamental optical transitions due to Er3+ and Mn2+ which are typical features of the well-diluted doping process. A significant enhancement of the Er3+ optical emission band at 1530 nm was observed when the matrix is co-doped with Mn. Photoluminescence intensity under ultraviolet excitation was three times larger as compared to samples without Mn content. A model of energy transfer mechanism from Mn2+ to Er3+ ions due to optical energy matching is proposed to explain the experimental results. This result, presented first time, can be applied as useful tool for developments in optical communications. © 2015 Elsevier B.V. All rights reserved.