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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.Öğe Beta-irradiated ZnGa2O4:Sm3+phosphor: Thermoluminescence glow curves and kinetic parameters via gel combustion synthesis(Elsevier Science Sa, 2024) Barad, A.; Topaksu, M.; Hakami, J.; Kaynar, U. H.; Akca-Ozalp, S.; Altowyan, Abeer S.; Aydin, H.This study examines the X-ray Diffraction (XRD) characteristics of Sm 3+-doped ZnGa 2 O 4 phosphor, shedding light on its structural characteristics. The XRD data reveal distinctive peaks that represent the crystal 's lattice structure. This provides the basis for a more detailed analysis of thermoluminescence (TL). Initially, the TL glow curves corresponding to different concentrations of Sm were analysed, leading to the identification of the most favorable Sm concentration. Subsequently, an investigation was conducted into the TL behavior of the material in response to varying doses within a broad spectrum of beta radiation, revealing a linear characteristic (b=1.075) across doses ranging from 0.1 Gy to 50 Gy. Following this, a reusability assessment was executed over three measurement sets, wherein it was ascertained that the deviation in peak area across ten cycles did not surpass 2 %. Furthermore, it was investigated how different heating rates ranging from 0.5 degrees C/s to 7 degrees C/s affect the TL curve of the material. To determine the TL trap parameters of the sample, Initial Rise (IR) and Computerized Glow Curve Deconvolution (CGCD) methods were employed. A consistent pattern of activation energy values was observed in both IR in the T M-T stop experiment and CGCD analyses, indicating a uniform response to distinct energy levels within the sample. In terms of providing valuable insights into the characteristics of TL, these methods were found to be very effective. This contributed to a comprehensive understanding of charge carrier dynamics within the crystal lattice. Moreover, Peaks I, II, and III showed a linear response to applied doses, indicating the material 's potential for dosimetry applications. The findings of this study not only provide insights into Sm 3+-doped ZnGd 2 O 4 phosphors ' TL properties, but also enhance our understanding of how to optimize their radiation response.Öğe Thermoluminescence behaviour and kinetic analysis of a novel Tb3+-Doped LaCa4O(BO3)3 phosphor: Impacts of heating rates and dose(Elsevier Sci Ltd, 2025) Madkhali, O.; Bulcar, K.; Barad, A.; Zelai, T.; Souadi, G.; Alathlawi, Hussain J.; Kaynar, U. H.This study employs kinetic analysis methods to comprehensively understand the thermoluminescence (TL) behaviour of Tb3+-doped LaCa4O(BO3)3 ( LACOB ), applying the Hoogenstraaten and Booth-Bohun-Parfianovitch methods, as well as the T m-T stop and Glow Curve Deconvolution (GCD) techniques. Optimal TL intensity was found at a Tb3+concentration of 2 wt%, beyond which concentration quenching occurred. The complete TL glow curve before preheating displays two peaks at approximately 70 degrees C and 286 degrees C. After preheating, only the 286 degrees C peak remains, due to its greater stability and intensity, making it the primary TL peak relevant for dosimetric applications. As the heating rate increased, the TL glow peaks shifted to higher temperatures and exhibited reduced intensity due to thermal quenching. The TL intensity exhibited superlinear behaviour at lower doses (0.5-20 Gy), followed by nearly linear behaviour at intermediate doses (30-100 Gy), and sublinear behaviour at higher doses. Anomalous fading of the TL signal was observed in LACOB:2 wt%Tb, suggesting competition with radiationless transitions. Activation energy values derived from Hoogenstraaten and Booth-Bohun-Parfianovitch methods showed close alignment, supporting the reliability of the kinetic analysis. The T m-T stop and GCD analyses with preheating identified four distinct TL glow peaks, with activation energies between 1.72 and 1.82 eV. Analysis whole glow curve revealed nine TL glow peaks overall, ranging from 1.08 to 1.82 eV, reflecting a complex trap structure with continuous energy distributions. The GCD method yielded a Figure of Merit (FOM) of 2.67 % with preheating and 2.84 without preheating, indicating a strong fit between experimental and theoretical data in both cases. The material demonstrated excellent stability and reusability, making it a strong candidate for dosimetric applications.Öğe Thermoluminescence in GdAl3(BO3)4 phosphors: Unusual heating rate dependencies, dose responses and kinetic parameters(Pergamon-Elsevier Science Ltd, 2023) Alajlani, Y.; Sonsuz, M.; Barad, A.; Kaynar, Uemit H.; Ayvacikli, M.; Topaksu, M.; Can, N.The current study focuses on the production of GdAl3(BO3)4 (GAB) phosphors using gel combustion. X-ray diffraction (XRD) and thermoluminescent (TL) methods were used to investigate the structural and thermolu-minescence (TL) features of the samples. XRD results revealed that GAB phosphors were crystallized in a rhombohedral crystal system. TL experimental data exhibited an unusual heating rate behaviour, which was explained by the semi-localized transition model, and this provides valuable insight into the properties of the GAB sample. Beta-irradiated GAB hosts exhibit two primary peaks at 106 degrees C and 277 degrees C on their TL glow curves. We have employed a variety of heating rates (VHRs), TM-Tstop method, and computerized glow curve decon-volution (CGCD) techniques. By using a combination of these techniques, we can identify the kinetic parameters of the GAB samples more accurately, including peak numbers, activation energy, and frequency factors. Both Tm- Tstop and CGCD techniques produce similar results in terms of trap numbers and trap depths. In the trap centers, electrons were trapped at 1.05 eV, 0.84 eV, 1.12 eV, 1.20 eV, 1.42 eV, 1.63 eV and 1.42 eV. There was a linear behaviour of GAB samples over a dose range of 0.1 Gy-10 Gy. GAB phosphors did not show any significant changes in TL response with repeated irradiation cycles, suggesting that it is a reliable radiation dosimeter. GAB is therefore a potential candidate for radiotherapy dose measurement based on these findings.
