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  • Küçük Resim
    Öğe
    Investigation on Cathodoluminescence Properties of Copper Implanted ZnO Samples
    (2019) Arslanlar, Yasemin Tuncer; Keskin, İlker Çetin; Katı, Mehmet İsmail; Türemiş, Murat; Çetin, Ahmet; Kibar, Rana
    ZnO single crystals has been implanted with 400 keV Cu ions at fluences of 2,5 x 1016 ions/cm2 at room temperature. The cathodoluminescence (CL) measurements of pure and Cu implanted samples has been reported at UV-visible range at both room and different temperatures. After the implantation process, the samples were annealed for 1 hour at 1000ºC. The effects of ion implantation and annealing temperature and on the CL signals were researched with the data obtained. The CL spectrum of pure ZnO exhibited two emission bands at 385 nm and 550 nm. There are some changes in the emission bands in the CL spectrum that are thought to be due to the presence of Cu ions. Also it is possible to say that the annealing temperature can strongly influence CL intensity.
  • Küçük Resim
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    The role of Eu3+ ion on luminescence, TL kinetic parameters and electrochemical behaviors of Sr0,5Ca0,5WO4 phosphor synthesized via sol-gel technique
    (TUBITAK, 2021) Kati, Mehmet İsmail; Keskin, İlker Çetin; Türemiş, Murat
    The Eu3+doped Sr0,5Ca0,5WO4 has been synthesized by the sol-gel method for the first time. The phosphors were analyzed by XRD, SEM, DTA/TG optical absorption spectra, radioluminescence (RL), photoluminescence (PL), and thermoluminescence (TL) spectra. The energy transfer mechanism was determined on Eu3+ doped Sr0,5Ca0,5WO4 phosphor. The XRD results reveal that the samples exhibit a tetragonal scheelite structure. FT-IR spectra provide the proof of scheelite structure with W-O anti-symmetric stretching vibration in [WO4]2- tetrahedrons at 750-910 cm-1. The Sr0,5Ca0,5WO4 phosphor showed a broad emission between 350-750 nm with a maximum of 506 nm. Sr0,5Ca0,5WO4:0.5Eu3+ phosphor exhibit characteristic emissions of Eu+3 (545, 592, 614, 650, and 700 nm) in the RL spectrum. The host material has excellent energy transfer efficiency for lanthanide ions. The kinetic parameters were calculated by the computerized glow curve deconvolution (CGCD) analysis method. As a result of CGCD, three peaks (Etrap:0.74-1.46 eV) for un-doped Sr0,5Ca0,5WO4 and five peaks (Etrap:0.75-1.28 eV) for Sr0,5Ca0,5WO4: Eu3+ were determined under main TL glow curve. In the cyclic voltammogram of the doped sample, an oxidation peak of about-0.4 eV, which is thought to be derived from Eu3+, was observed. Based on the results, the Sr0,5Ca0,5WO4:Eu+3 phosphors may be potential applicants for LEDs.
  • Küçük Resim Yok
    Öğe
    The Structural Characterization, Radioluminescence Results, and Thermoluminescence Kinetic Parameters of Aventurine
    (Bursa Teknik Üniversitesi, 2022) Keskin, İlker Çetin
    In this study, in which the optical and luminescence properties of aventurine, a silicate-based mineral, were examined, the crystal structure of the mineral was examined by XRD analysis, its rheological properties and the elements it contained were determined by SEM-EDX analysis, and its structural properties were examined by FT-IR analysis. In order to determine the luminescence properties, radioluminescence (RL) and thermoluminescence (TL) methods were used and kinetic parameters were calculated. In the measurements taken in bulk and powder form of Aventurine, it was observed that the powder sample had a much better spectrum intensity, it was observed that the emission around 570 nm became much more pronounced in the powder sample. On the other hand, similar emissions were detected in both samples, though at different intensities. In TL analysis, it was observed that Aventurine was responsive to both X-ray and ultraviolet radiation at three different doses. While after X-ray irradiation, Aventurine exhibited TL glow curves with peaks at maximum temperatures of 90 oC and 250 oC, under UV irradiation the TL glow curves concentrated in the high-temperature region which is around 300 oC observed. Also; the TL kinetic parameters were reported; activation energy (E), the order of kinetics (b), and frequency factor (s) of the first peak have been determined in detail by using Computerized Glow Curve Deconvolution (CGCD) method.