Yazar "Oglakci, M." seçeneğine göre listele

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    Exploring beta irradiation responses in Sr 2+-Doped hydroxyapatite: A thermoluminescence study
    (Elsevier Sci Ltd, 2024) Bulcar, K.; Oglakci, M.; Altowyan, Abeer S.; Bilgin, R.; Yucel, A.; Sezer, S.; Can, N.
    This research investigates the structural and thermoluminescence (TL) properties of Sr 2+ -doped Ca 5 (PO 4 ) 3 OH (HAp) phosphors. X-ray diffraction (XRD) analysis confirms that HAp has a hexagonal structure with a P63/m space group. The TL behaviour of HAp:Sr 2+ phosphors is examined under beta irradiation in the temperature range of 25 -500 degrees C. The study reveals three TL glow peaks at temperatures of 75, 212, and 296 degrees C. Investigation of TL responses across heating rates (HR) ranging from 0.1 to 5 degrees C/s shows that higher HRs result in increased maximum TL peak temperatures and reduced TL intensities. This trend suggests an augmented contribution from non -radiative transitions as the heating rate increases. Importantly, no evidence of thermal quenching is found in the HAp samples. Two different methods, Hoogenstraaten 's and Booth-Bohun-Porfianovitch, yield consistent activation energy values of 0.50, 1.22, 1.67 eV, and 0.48, 1.19, 1.63 eV, respectively. Reusability assessments indicate a standard deviation of less than 5 %, confirming the reliability of the materials. T m - T stop analysis reveals a continuous distribution of trap levels. TL properties in HAp samples have been comprehensively characterized, contributing not only to enhancing our understanding of their behaviour, but also highlighting their potential applications in various areas. The findings of this study have provided valuable insight into the development of efficient catalysts that are suitable for a variety of applications.
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    Radiation-induced thermoluminescence in Ca5(PO4)3OH powder from eggshell: Trapping parameter assessment
    (Pergamon-Elsevier Science Ltd, 2024) Souadi, G.; Bulcar, K.; Yucel, A.; Oglakci, M.; Sezer, S.; Madkhali, O.; Can, N.
    This study examines the thermoluminescence (TL) properties exhibited by hydroxyapatite (HAp) samples. The HAp samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. XRD results confirm that Hap corresponds to a hexagonal structure with a space group of P63/m. The study emphasizes the critical role of appropriate band-pass filters in TL measurements and explores the dose-dependent behavior of TL glow peaks. Examining the impact of varying heating rates (HR) on TL peak intensities revealed a positive correlation between HR and TL maximum peak temperatures, accompanied by a decrease in TL intensities. Notably, no thermal quenching effect was observed in HAp samples. The activation energy values were 0.51, 1.12, and 1.57 eV for Hoogenstraaten's method and 0.55, 1.19, and 1.65 eV for the Booth-BohunPorfianovitch method, demonstrating their consistency and robustness. Additionally, Tm-Tstop analysis was employed to identify distinct trap levels and calculate their respective activation energies. This study establishes a solid foundation for characterizing TL properties in HAp samples, shedding light on their potential applications in various fields. The findings provide valuable insights for the design and development of efficient catalysts for diverse applications.
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    Thermoluminescence of hydroxyapatite from eggshell powders doped with Dy synthesized by the sonication chemical method: Effects of doping concentration and heating rate
    (Elsevier, 2023) Bulcar, K.; Oglakci, M.; Yucel, A.; Sezer, S.; Madkhali, O.; Depci, T.; Can, N.
    Hydroxyapatite (HAP) was selected as the host material and synthesized using a sonication chemical method. The effect of Dy3+ ion doping concentrations (0.25, 0.5, 1, 2, 3, 4, 5, 7, and 10 wt%) on the structure and thermoluminescence was examined. The TL properties of Dy3+ doped HAP were also studied, including dose response, repeatability, and heating rate. Based on the glow curves of samples with a heating rate of 2 degrees C/s after beta irradiation to 20 Gy, three effective peak maxima appeared to make up the glow curves located at around 84, 190, and 318 degrees C. However, four levels of activation energy were observed by Tm-Tstop analysis. The kinetic analysis of four peaks obtained via computerized glow curve deconvolution revealed trap depths of 0.80, 0.95, 1.20, and 1.51 eV, with corresponding frequency factors of 1010, 1011, 1012, and 1011 s-1, respectively. Parallel investigations using the initial rise and variable heating rate approaches yielded comparable trap depth esti-mates. The dose dependence of the glow curves was determined to be linear across the 0.1-20 Gy range.