Yazar "Oglakci, M." seçeneğine göre listele

Listeleniyor 1 - 6 / 6
  • [ X ]
    Öğe
    Anomalous heating rate and kinetic analysis in the thermoluminescence of GdCa4O(BO3)3
    (Pergamon-Elsevier Science Ltd, 2025) Alajlani, Y.; Oglakci, M.; Barad, A.; Kaynar, U. H.; Topaksu, M.; Canimoglu, A.; Can, N.
    This study investigates the thermoluminescence (TL) properties of GdCa4O(BO3)3 phosphors under beta irradiation, highlighting their potential for dosimetric applications. A prominent glow peak at 175 degrees C was observed, demonstrating consistent sensitivity under preheating conditions. TL glow peaks were studied using variable heating rate (VHR), Tm-Tstop, initial rise (IR), and computerized glow curve deconvolution (CGCD) methods. Eight distinct trap levels with activation energies ranging from 0.92 to 1.28 eV were identified, confirming the material's diverse trap-depth distribution. The dose-response behavior exhibited superlinear characteristics, with a minimum detectable dose (MDD) of 74.4 mGy, making it suitable for low-dose monitoring. Observed anomalous heating rate effects were explained using the semi-localized transition (SLT) model. These findings position GdCa4O(BO3)3 as a promising candidate for luminescence-based technologies.
  • [ X ]
    Öğe
    Comparison of thermoluminescence characteristics of undoped and europium doped YAl3(BO3)(4) phosphor synthesized by combustion method: Anomalous heating rate, dose response and kinetic analyses
    (Pergamon-Elsevier Science Ltd, 2023) Kaynar, Umit H.; Oglakci, M.; Bulcar, K.; Benourdja, S.; Bakr, M.; Ayvacikli, M.; Canimoglu, A.
    In this study, undoped and YAl3(BO3)(4) phosphors doped with Eu3+ at varying concentrations (x = 0.5 to 7 wt%) produced by a combustion process have been thoroughly examined by using the X-ray diffraction (XRD) and thermoluminescence (TL) techniques. The crystallized phosphors were confirmed by XRD analysis, and its crystal structure was examined. XRD analyses of the synthesized phosphor is in accordance with ICSD File No 96-152-6006. TL glow curve of undoped sample produced three glow peaks located at 80 degrees C, 240 degrees C, and 360 degrees C with a heating rate of 2 degrees Cs-1 whilst Eu3+ doped one appears at 90 degrees C, 230 degrees C, and 390 degrees C. The undoped example complied with the theory as expected, namely, as the heating rate increased, the TL glow curve shifted towards lower temperatures and decreased in intensity. However, an anomalous change was observed in the sample with Eu3+ additive. The experimental findings from the dose-response of YAl3(BO3)(4):0.5 wt%Eu3+ demonstrate that the intensity of TL provided by the total area under glow curves has an acceptable linearity (r(2):0.999) up to 100 Gy. The intensity of each maximum on the TL glow curve augments proportionally as the heating rate is augmented. Possible reasons of this behaviour are discussed. Various heating rate (VHR) methods (such as Hoogenstraaten's and Booth-Bohun-Parfianovitch) have also been used to estimate kinetic parameters (e.g., energy and frequency factor), which seem to be in good agreement with each other.
  • [ X ]
    Öğe
    Samarium doped Ca(3)Y2B(4)O(12) phosphor prepared by combustion method: Anomalous heating rate effect, dosimetric features, and TL kinetic analyses
    (Elsevier, 2022) Hakami, J.; Oglakci, M.; Portakal-Ucar, Z. G.; Sonsuz, M.; Kaynar, U. H.; Ayvacikli, M.; Topaksu, M.
    The structural and thermoluminescence characteristics of samarium doped Ca3Y2B4O12 samples at various concentrations are presented. The samples were synthesized via the combustion method. The thermolumines-cence (TL) glow curves for Ca(3)Y2B(4)O(12):Sm3+ depict strong peaks at 97 and 410 C. Ca(3)Y2B(4)O(12):Sm3+ exhibited completely opposite behavior, contrary to expectations, in that the luminescence intensity of both the total and individual glow peaks increased with the heating rate throughout the TL experiments. This unusual TL glow peak pattern was discussed via the Mandowski model of semi-localized transitions. The kinetic characteristics of both prominent glow peaks were established using various analysis techniques, including variable heating rate, initial rise (IR) by using the TM-Tstop method and the fractional glow technique (FGT), and computerized glow curve deconvolution (GCD). The dose response of the high temperature peak at 410 C is linear between 0.1 and 5 Gy, and then sublinear at higher doses. In addition, the repeatability and fading results of 410 C TL peak also yielded very favorable results. These findings suggest that Ca(3)Y2B(4)O(12):Sm(3+ )has great potential in the development of high temperature dosimetric materials for beta irradiation.
  • [ X ]
    Öğe
    Structural and temperature-dependent photoluminescence properties of NaBaBO3:Ce3+,Tb3+phosphors synthesized using the combustion
    (Elsevier, 2024) Altowyan, Abeer S.; Oglakci, M.; Topaksu, M.; Ozturk, E.; Hakami, Jabir; Coban, M. B.; Keskin, M. Ozgur
    This study explores the structural and temperature-dependent photoluminescence of Ce3+ and Tb3+ doped NaBaBO3 phosphors, synthesized via combustion. Analysis of their crystal structures confirmed excellent alignment with the standard PDF#98-008-0110. Investigation into both room and lowtemperature photoluminescence revealed that the dopants have a significant effect on emission spectra. Ce3+-doped samples exhibited excitation peaks at 275 nm and 358 nm, leading to a primary emission at 419 nm, with enhanced low-temperature emission suggesting reduced non-radiative processes. Tb3+doped phosphors showed excitation from 250 to 377 nm and emissions from blue to deep red, including strong green emission at 550 nm due to 5D4?7F5 transitions. Optimal doping was found at 1 mol% for Ce3+, while Tb3+ showed increased luminescence up to 3 mol%, with concentration quenching observed beyond these points. The study indicates dipole-dipole interactions dominate Ce3+ concentration quenching, whereas Tb3+ involves both electric dipole and quadrupole interactions. This analysis provides insights into enhancing luminescent efficiency and suggests NaBaBO3:xCe3+,Tb3+ phosphors' potential in advancing white LED technology, highlighting their stable luminescent properties at low temperatures. (c) 2024 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights are reserved, including those for text and data mining, AI training, and similar technologies.
  • [ X ]
    Öğe
    Thermoluminescence glow curve analysis of Ca3Y2B4O12 phosphor prepared using combustion method
    (Pergamon-Elsevier Science Ltd, 2022) Hakami, J.; Sonsuz, M.; Kaynar, U. H.; Ayvacikli, M.; Oglakci, M.; Yueksel, M.; Topaksu, M.
    Ca3Y2B4O12 (CBYO) phosphor was synthesized using a gel combustion method. X-ray diffraction (XRD) measurement confirmed a single-phase structure (space group Pnma (62)) of synthesized compound. TL measurements were conducted between room temperature (RT) and 450 degrees C at a heating rate of 2 degrees Cs-1. Significant glow peaks were observed at 64, 116, and 242 degrees C in CYBO phosphor sample exposed to different beta doses. In the range of 0.1-100 Gy, the TL intensity of the glow peak displayed good linearity. Different methods were employed to determine the number of peaks, the trap structure, and the kinetic parameters of the thermoluminescence glow curve of CBYO; the Hoogenstraaten method, various heating rates (VHR), and glow curve deconvolution method (CGCD) implemented through tgcd:An R package. Currently available findings confirm that CYBO host is a promising candidate for environmental studies because one exhibits adequate TL dose response coupled with a good sensitivity and linearity.
  • Küçük Resim
    Öğe
    Unusual heating rates, dose responses and kinetic parameters detected on thermoluminescence from YAl3(BO3)4:Sm3+ phosphors
    (Elsevier Sci Ltd, 2023) Altowyan, Abeer S.; Kaynar, Umit H.; Bulcar, K.; Oglakci, M.; Portakal-Ucar, Z. G.; Hakami, Jabir; Topaksu, M.
    This study focused on the thermoluminescence (TL) characteristics of YAl3(BO3)(4) (YAB) phosphors modified with various contents of Sm3+ ions. The TL response of the YAB: Sm3+ phosphors exposed to beta irradiation was measured across the temperature range of 25-500 degrees C, exhibiting three TL maxima at 70, 235, and 408 degrees C. Preheating protocol was also carried out to remove the low temperature TL peak followed by further experiments with the two-remaining high-temperature peaks. In the TL measurements conducted with variable heating rates (HR) between 0.1 and 5 degrees Cs-1, an anomalous heating rate behaviour was observed. A semi-localized transition model was used to address this feature. There was a standard deviation of less than 5% in the reusability measurements. The results of the kinetic parameters obtained by initial rise (IR) and various heating rate (VHR) methods were compared with those obtained by glow curve deconvolution (GCD) method. T-m-T-stop analysis revealed a continuous distribution of trap levels with a trap depth ranging from 1.35 to 2.20 eV. Through the use of GCD, the glow curve was found to demonstrate general order kinetics and consist of seven superimposed traps. The values of the kinetic parameters obtained for the glow curve agreed with those obtained by other methods excluding the VHR method encountering an anomalous impact. The results obtained from these tests showed that the sample could be successfully used for TL dosimetry applications.