Browsing by Author "Tuncer Arslanlar Y."
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Item Luminescence behavior and Raman characterization of jade from Turkey(2011) Tuncer Arslanlar Y.; Garcia-Guinea J.; Kibar R.; Çetin A.; Ayvacikli M.; Can N.Results are presented for the cathodoluminescence (CL), radioluminescence (RL) and thermoluminescence (TL) of jade from Turkey. Jade samples show broad band luminescence from green to red, which, using lifetime-resolved CL, reveals seven overlapping emissions, of which two are dominant. Green emission obtained using spatially resolved CL was associated with Mn2+ and emission bands centered near at 480 and 530nm were attributed to 3P0-3H4 and 1D2-3H4 transitions of Pr3+, respectively. Different shifts of the peak-wavelengths for 326 and 565nm were observed with varying jade compositions. The incorporation of the larger K ion causes non-linear variations of the cell dimensions and therefore changes in the Fe-O band distance. We suggest that stress of the jade structure can be linked to the luminescence emission at 326nm. Raman spectra have also been recorded in order to provide an unequivocal identification of the type of jade. The mechanism for the luminescence of the jade is considered. © 2011 Elsevier Ltd.Item Rare earth photoluminescence in bismuth-germanate crystals(2013) Tuncer Arslanlar Y.; Kotan Z.; Kibar R.; Canmoǧlu A.; Can N.In the present work, the photoluminescence (PL) spectra of bismuth germanate (BGO) doped with trivalent rare earth element (REE) ions with different doping concentrations (0.03 wt% Eu, 0.4 wt% Tm, and 1.1 wt% Nd) are reported in the temperature range from 10 to 300 K using different detectors, namely, photomultiplier tube (PMT), InGaAs (IGA), and Si. The luminescence in the NIR region was also measured at room temperature. Two broad emission bands attributed to undoped BGO were found at circa 1350 and 1800 nm, respectively. The broad-band emissions are replaced by narrow-band line emissions defined by the trivalent rare earth dopants. The emission spectra from rare earth ion-doped BGO extend from 500 to 2000 nm. Rare earth ions act as the dominant recombination centers and define the emission spectra. This is interpreted as resulting from direct charge transfer from intrinsic defect traps to rare earth recombination centers. The temperature-dependent luminescence of BGO doped with 0.4 wt% Tm is also presented. © 2013 Taylor & Francis Group, LLC.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.Item Thermally stimulated luminescence glow curve structure of β-irradiated CaB4O7:Dy(John Wiley and Sons Ltd, 2015) Akin A.; Ekdal E.; Tuncer Arslanlar Y.; Ayvaci M.; Karali T.; Can N.Thermally stimulated luminescence glow curves of CaB4O7:Dy samples after β-irradiation showed glow peaks at ∼335, 530 and 675 K, with a heating rate of 2 K/s. The main peak at 530 K was analyzed using the Tmax-Tstop method and was found to be composed of at least five overlapping glow peaks. A curve-fitting program was used to perform computerized glow curve deconvolution (CGCD) analysis of the complex peak of the dosimetric material of interest. The kinetic parameters, namely activation energy (E) and frequency factor (s), associated with the main glow peak of CaB4O7:Dy at 520 K were evaluated using peak shape (PS) and isothermal luminescence decay (ILD) methods. In addition, the kinetics was determined to be first order (b =1) by applying the additive dose method. The activation energies and frequency factors obtained using PS and ILD methods are calculated to be 0.72 and 0.72 eV and 8.76 × 105 and 1.44 × 106/s, respectively. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.Item Detailed luminescence (RL, PL, CL, TL) behaviors of Tb3+ and Dy3+ doped LiMgPO4 synthesized by sol-gel method(Elsevier B.V., 2020) Keskin İ.Ç.; Türemiş M.; Katı M.İ.; Gültekin S.; Tuncer Arslanlar Y.; Çetin A.; Kibar R.The un-doped, Tb3+ and, Dy3+ doped LiMgPO4 phosphors were successfully synthesized by the sol-gel method. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to characterize the light-emitting phosphors. The XRD spectra verify the phase formation of samples. The luminescence properties were analyzed by radioluminescence (RL), photoluminescence (PL), cathodoluminescence (CL) and, thermoluminescence (TL) spectra. Also, the effect of Tb3+, Dy3+ ions in LiMgPO4 was determined on the luminescence intensity in detail. The RL spectrum of un-doped LiMgPO4 consists of two broad emission bands in the 310–450 nm and 575–850 nm range. The maximum intensities of these bands were observed at 360 nm and 655 nm. The emission spectrum of Dy3+ doped LiMgPO4 under X-ray excitation show characteristic emissions of Dy3+ corresponds to 4F9/2→6Hj transitions. In addition to the 5D4→7Fj (j:6–1) transitions of Tb3+ doped LiMgPO4 phosphor, strong emissions derived from 5D3→7Fj (j:6–3) transitions were observed in the blue region. Also, these blue emissions were seen at RL, PL and, CL spectra. The optical absorption spectra were recorded and the energy band gaps were calculated 3.62 eV, 3.30 eV and, 4,01 eV for un-doped, Dy3+ and, Tb3+ doped LiMgPO4 phosphors, respectively. The phosphors irradiated with UV (254 nm) light. The main TL glow peak was observed at 288 °C for the Dy3+ doped phosphor, and the peaks at 198, 283 °C were observed for the Tb3+ doped phosphor. © 2020 Elsevier B.V.Item Kinetic parameters and luminescence properties of rare earth (Tb, Nd) doped and transition metal (Mn) doped/co-doped YAlO3 prepared via sol-gel method(Elsevier B.V., 2023) Gökçe S.; Keskin İ.Ç.; Katı M.İ.; Kibar R.; Çetin A.; Tuncer Arslanlar Y.In this work, phosphor materials with the formula YAlO3 were synthesized via sol-gel method by using the stoichiometric amounts of yttrium nitrate and aluminum nitrate as base materials. The obtained phosphors were doped/co-doped with Tb3+, Nd3+ rare earth ions and Mn2+ transition metal ion. For evaluating the influence of the dopants, the grain size and morphology of the samples by scanning electron microscopy (SEM) and the phase and crystallinity of the synthesized materials by X-ray diffraction (XRD) were investigated. Optical absorption spectra, photoluminescence (PL) and thermoluminescence (TL) were performed to determine a relationship the changing dopant on luminescence properties of YAlO3. Moreover, the kinetic parameters namely activation energy (E), order of kinetics (b) and frequency factor (s) of the synthesized pure and doped materials were calculated using Computerized Glow Curve Deconvolution (CGCD) and Peak Shape Method for a better understanding of the optical properties that change with the doping process. Strong green emission was detected in the sample doped with Mn2+ correspond to 4T1(G)→6A1(S) transition. As for YAlO3: Nd3+, characteristic emissions originated from 4G11/2 → 4I9/2 (∼423 nm), 4G9/2 → 4I9/2 (∼460 nm) and 4G7/2 → 4I9/2 (∼540 nm) transitions were seen. The optical band gap of undoped sample was calculated as 2.79 eV and depending on the presence of Nd3+ and Tb3+ dopant ions this value was decreased to the range 2.46–2.56 eV. © 2023 Elsevier B.V.