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    Thermoluminescence kinetic parameters of beta irradiated the zinc gallate phosphor using different methods
    (Elsevier Sci Ltd, 2023) Altowyan, Abeer S.; Sonsuz, M.; Kaynar, Umit H.; Hakami, Jabir; Ayvacikli, M.; Topaksu, M.; Can, N.
    The ZnGa2O4 phosphor material was synthesised through the gel combustion method, and its structural characteristics were studied via X-ray powder diffraction (XRD) and energy-dispersive X-ray spectroscopy (EDX). The XRD result indicates the generation of ZnGa2O4 in spinal cubic phase with a 25 nm crystalline size. The synthesized phosphor was irradiated using a90Sr/90Y source with a dose range of 0.1 Gy-100 Gy. For measuring thermoluminescence (TL), a linear heating rate of 2 degrees Cs ? 1 was applied to the sample in a temperature range of 25 degrees C-450 degrees C. The TL experiment revealed two peak maxima located at 180 degrees C and 304 degrees C and a shoulder around 70 degrees C. By preheating at 110 degrees C, the low temperature peak at 70 degrees C is removed. Both the depth and frequency factors of electron traps were determined using various heating rates (VHR), Tm-Tstop combined with initial rise (IR), and Computerised Glow Curve Deconvolution (CGCD). In both the Tm-Tstop and CGCD methods, six overlapping glow peaks were detected below the main glow peaks. The calculated activation energy values and peak maximum temperatures agree well with each other. The depths of electron traps calculated by different methods were found to be between 0.4 and 1.4 eV. We observed that both peak maximum temperatures and the area under glow peaks gradually decreased with an increase in the heating rate. Both Peak 1 and Peak 2 show sublinear relationship between 0.1-5Gy and 10-100 Gy. The findings of the present study show that the phosphors can serve as effective TLDs.
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    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.