Browsing by Subject "Strontium aluminate"

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    Synthesis and optical properties of Er3 and Eu3 doped SrAl2O4 phosphor ceramic
    (2011) Ayvacikli M.; Ege A.; Yerci S.; Can N.
    We report, for the first time on luminescence from a Er3 doped SrAl2O4 phosphor. Effects of Eu3 doping were also studied. The influence of rare-earth doping in crystal structure and its optical properties were analysed by means of X-ray diffraction (XRD), Raman scattering, optical absorption, excitation and emission (PL) spectroscopy, thermally stimulated luminescence (TSL) and scanning electron microscope (SEM). Luminescence spectra and luminescence decay curves for Er3 transitions in the near infrared region were recorded. The PL maximum for Eu doped SrAl2O4 is obtained at 620 nm and corresponds to the orange region of the spectrum. Diffraction patterns reveal a dominant phase, characteristic of the monoclinic SrAl2O4 compound and the presence of dopants has no effect on the basic crystal structure of SrAl 2O4. The shapes of the glow curves are different for each dopant irradiated with either a 90Sr90Y beta source, or UV light at 311 nm, and in detail the TL signals differ somewhat between Er and Eu dopants. © 2011 Elsevier B.V. All rights reserved.
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    Luminescence of dysprosium doped strontium aluminate phosphors by codoping with manganese ion
    (2014) Karabulut Y.; Canimoglu A.; Kotan Z.; Akyuz O.; Ekdal E.
    The authors report here the luminescence properties of strontium aluminate doped with dysprosium and manganese. The dysprosium, manganese co-doped powders were prepared by a solid state reaction at temperatures at 1600 C under H 2 (15%)-Ar (85%) atmosphere. The dysprosium, manganese co-doped strontium aluminate phosphors have the monoclinic structure with lattice parameters a ≈ 8.440 Å, b ≈ 8.821 Å, c ≈ 5.157 Å and β ≈ 93.4. The characteristic 4F9/2 → 6H15/2 (blue), 4F9/2 → 6H13/2 (yellow), 4F9/2 → 6H11/2 (red) and 4F9/2 → 6H9/2 (NIR) transitions of Dy3+ for different luminescence techniques (radioluminescence, photoluminescence and cathodoluminescence) were detected in the emission spectra at the room temperature. The luminescence of Mn2+ co-doped SrAl2O 4:Dy3+ exhibits a broad green-orange emission band ( 4T1 → 6A1 transition) from the synthesized phosphor particles under different excitation sources. This corresponds to the spin-forbidden transition of the d-orbital electron associated with the Mn2+ ion. Multiple emission lines observed at each of these techniques are due to the crystal field splitting of the ground state of the emitting ions. The nature of the emission lines is discussed. © 2013 Elsevier B.V. All rights reserved.
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    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.
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    Preparation and characterization of strontium aluminate/urea-formaldehyde composite: a solution for oxidation-induced darkening problem
    (Emerald Publishing, 2023) Koçak G.; Çelik Erbaş S.
    Purpose: This study aims to produce homogenously prepared polymer composites by adding two different strontium aluminate derivatives (Sr4Al14O25 and SrAl2O4) to urea-formaldehyde (UF) at different mass concentrations. In the context of this work those strontium-based derivatives were compared in terms of mechanical and luminescent characteristics. Additionally, sodium bicarbonate was integrated with the prepared composites to eliminate/minimize darkening problem, which might arise from the oxidation of Eu +2 to Eu2O3, on the surface of strontium aluminate/urea-formaldehyde composites. Design/methodology/approach: In this study, strontium aluminate/UF composite materials were produced using a compression molding technique. Their mechanical, thermomechanical and luminescence properties were investigated via various characterization methods. Particle size analysis was used to characterize phosphor derivatives, whereas scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) was conducted for morphological examination. Findings: The darkening problem was prevented by the introduction of sodium bicarbonate into the composite systems. Based on the characterization and test results, the only addition of strontium aluminate reduced the mechanical properties. However, it was seen that the introduction of sodium bicarbonate into the composites improved those properties positively. The appropriate amounts of strontium aluminate and sodium bicarbonate were determined by conducting an experimental optimization study. The optimum composition of the composite materials was obtained by introducing 2% phosphor and 3% NaHCO3. Originality/value: The approach used in this study has provided a method to solve the darkening problem, which degrades the aesthetic appearance in industrial production. © 2022, Emerald Publishing Limited.