MCBÜ Açıkerişim Sistemi :: Browsing by Author "Topaksu, M"

Browsing by Author "Topaksu, M"

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Characterization and thermoluminescence behavior of beta irradiated NaBaBO3 phosphor synthesized by combustion method
Oglakci, M; Akça, S; Halefoglu, YZ; Dogan, T; Ayvacikli, M; Karabulut, Y; Topaksu, M; Can, N
NaBaBO3 host material was synthesized using the combustion method. In order to optimize the performance of the material, effects of sintering temperatures varying from 600 degrees to 1000 degrees C were investigated. The sintering temperature and dwell time were found to have pronounced effects on the pure NaBaBO3 material. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to confirm the phase formation and examine the surface morphology of the prepared powder material, respectively. TL behavior of NaBaBO3 was studied at various beta doses. It is seen that the sample exhibits well resolved TL glow peak at a peak temperature about 175 degrees C and corresponding TL intensity increases with the increasing beta dose. However, TL glow peak slightly shifts to lower temperature with the increasing beta dose level. This is the first TL report of a phosphor with a NaBaBO3 host. The TL kinetic parameters were estimated by the peak shape (PS) method and CGCD software. TL glow curves of NaBaBO3 consist of several traps and exhibited second order kinetics. A possible TL mechanism was also discussed using the energy level model. The obtained results can provide valuable knowledge related to the investigation of the intrinsic nature characteristics of NaBaBO3 in research fields pertaining to dosimetry.
Thermoluminescence glow curve analysis of Ca3Y2B4O12 phosphor prepared using combustion method
Hakami, J; Sonsuz, M; Kaynar, UH; Ayvacikli, M; Oglakci, M; Yüksel, M; Topaksu, M; Can, N
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.
Thermoluminescence characterization and kinetic parameters of Dy3+ activated Ca3Y2B4O12
Hakami, J; Sonsuz, M; Kaynar, UH; Ayvacikli, M; Oglakci, M; Topaksu, M; Can, N
In this study, thermoluminescence (TL) characteristics of Ca3Y2B4O12:xDy (0 < x < 0.07) phosphor samples were studied. The samples were exposed to beta irradiation in the dose range from 0.1 Gy to 100 Gy to investigate TL dose response. The concentration of Dy3+ in Ca3Y2B4O12 phosphor was optimized and found to be 1 mass % in terms of TL signal quality. The TL glow curve appears to be consisted of three peaks which were discernible at 72 degrees C, 280 C and 376 degrees C. The trapping parameters (E, b, and s) were calculated using initial rise (IR), and variable heating rate (VHR) techniques. The trapping parameters, order of kinetics, frequency factor, and figure of merit have been all determined by means of the Glow Curve Deconvolution (GCD) method (tgcd:An R package). Ca3Y2B4O12:Dy phosphor displays efficient thermoluminescence properties.
Anomalous heating rate dependence and analyses of thermoluminescence glow curves in Gd doped ZnB2O4 phosphors
Atasoz, S; Topaksu, M; Souadi, G; Can, N
Here, we report the thermoluminescence (TL) characteristics and trapping parameters under beta ray excitations of pelletized Gd-incorporated ZnB2O4 synthesized through the gel combustion method. The chemical composition of the obtained Gd incorporated ZnB2O4 was confirmed using X-ray diffraction (XRD). The best doping concentration of Gd was 0.25 mass%, which resulted in the highest luminous efficiency. The glow curves of the pellet-formed samples exposed to beta-irradiation at various doses showed glow peaks at about 79 degrees C, 133 degrees C and 276 degrees C with a heating rate of 2 degrees Cs-1. An anomalous heating rate effect was observed for the peak centered at 276 degrees C, but the TL intensity of the peak at 79 degrees C and 133 degrees C decreased with an increasing heating rate. The TL glow peaks were studied using T-m-T-stop, initial rise (IR), and variable heating rate (VHR) and Computerized glow curve deconvolution (CGCD) methods. In the range of 0.1-50 Gy, the total integral values of TL output increased linearly with increased dose. A complex glow curves are composed of six distinguishable peaks as revealed by the results obtained from IR and CGCD methods. The current results indicate that the ZnB2O4:Gd3+ phosphor is a suitable option in radiation dosimetry for environmental monitoring.
Structural and analyses of thermoluminescence glow curves in Sm doped SrGd2O4 phosphor
Sarikci, S; Topaksu, M; Bakr, M; Can, N
In this study, SrGd2O4: xSm(3+) (x = 0%, 0.5%, 1%, 2%, 3%, 4%, and 5%) phosphors were synthesized using solid state reaction method. X-ray diffraction (XRD) measurements confirmed a orthorhombic structure (space group Pnam (62)) of synthesized compounds. Following irradiation with 10 Gy beta dose, the sample doped with 0.5% Sm exhibited the highest integrated thermoluminescence (TL) intensity with the IRSL-TL wide band blue filter. In order to evaluate dose-response, samples were irradiated with beta radiation for 0.1-10 Gy. The Hoogenstraaten's method, the initial rise method, combined with the TM-Tstop experiment, and glow curve fitting package were employed to determine the number of peaks, the trap structure, and the kinetic parameters of the thermoluminescence glow curve of Sm doped SrGd2O4 Based on the glow curve deconvolution obtained using software package, the component TL glow peaks present in the complex glow curve are composed of well-isolated five overlapping glow peaks. (c) 2022 Elsevier B.V. All rights reserved.
Synthesis and thermoluminescence study of Eu doped novel LaBO3 phosphor: Heating rate, dose response, trapping parameters
Sonsuz, M; Topaksu, M; Hakami, J; Can, N
In this study, LaBO3, one of the Lanthanum-based perovskites-type oxides, and a series of LaBO3:Eu3+ phosphor samples were synthesized by solid state reaction technique. By using XRD, samples of the synthesized samples were analysed to identify a compound that indicates orthorhombic cells belonging to the Pmcn (62) space group. After 5 Gy of beta irradiation, the sample doped with 0.5 mass % Eu showed the highest integrated thermoluminescence intensity (TL). To evaluate the dose response, samples were irradiated with beta radiation from 0.1 to 100 Gy. The studied sample exhibits linear behaviour up to doses up to 5 Gy, while above this (up to 100 Gy) shows quasi-linear behaviour before reaching saturation. The peak number, trap structure, and kinetic parameters of Eu-doped LaBO3 thermoluminescence curves were determined using an initial rise method combined with TM-Tstop experiments, various heating rates (VHR), and Glow Curve Deconvolution (GCD) method. TM-Tstop calculations suggest nine plateaus of activation with energies of 1.21 eV, 0.98 eV, 1.03 eV, 1.32 eV, 1.43 eV, 0.68 eV, 1.98 eV, 1.83 eV and 1.92 eV which constitute the main radiation storage contributions. The GCD method was used to calculate trap depths and frequency factors ranging from 0.68 to 1.95 eV and from 106 to 1015 s-1, respectively. In VHR method, one of the high temperature glow peaks exhibited unusual behaviour which was attributed to a competition between radiative and non-radiative transitions.
Thermoluminescence study and trapping parameters of beta irradiated NaBaBO3:Gd3+ phosphor
Oglakci, M; Topaksu, M; Souadi, G; Can, N
A series of Gd3+ doped NaBaBO3 phosphors were synthesized via a combustion approach. The TL data collected by means of a combination of a commercial SCHOTT BG39 and HC414/46 filters was studied to evaluate basic kinetic parameters. Tm-Tstop and, various heating rate (VHR) and computerized glow-curve deconvolution analyses were utilized to analyze collected data. Our findings indicate that luminescence process in scrutinized material may obey first-order kinetics because no shift in the experimental TL glow curves with increased dose was observed. The TL dose response of the TL glow peaks exhibited a linear characteristic up to 20 Gy. The TmTstop method revealed that the number of the component TL glow peaks in the complex glow curve with and without preheating process consisted of six well-isolated and three overlapping glow peaks, respectively. The number of peaks obtained by deconvolution was perfectly matched with those obtained by Tm-Tstop and the figure of merit (FOM) values with and without preheating were 0.84% and 1.48%, respectively. The activation energy value found for the peak at 312 degrees C using the various heating rate (VHR) method was very close to those of deconvolution method. The total loss of response of TL glow curve sensitivity was much less (only +/- 2%) after 10 cycles of reuse.
Thermoluminescence glow curves of beta irradiated NaBaBO3: Ce3+ phosphor synthesized by combustion method
Oglakci, M; Topaksu, M; Can, N
NaBaBO3 samples incorporated with various concentration of Ce3+ were prepared by combustion method. The influences of rare earth doping in synthesized samples were analyzed by X-ray diffraction (XRD). Opti-mum doping concentration of NaBaBO3:Ce3+ is 0.5 %. Thermoluminescence (TL) kinetic analysis using T-m-T-stop, initial rise (IR), variable heating rate (VHR) and glow curve deconvolution (GCD) methods were performed on the glow curves of NaBaBO3:Ce3+ phosphor material. The T-m-T-stop analysis revealed that the whole glow curve measured without preheat of the prepared sample is composed of at least six overlapping glow peaks. The number of the glow peaks required to provide best fit to the glow curves of the sample are also estimated using GCD method and one found six glow peaks at all doses (FOM <= 1.84 %), which are similar to those from T-m-T-stop analysis. The dose response of NaBaBO3:Ce3+ phosphor sample exposed to beta irradiation is linear up to 10 Gy. The results from experiments indicates that main dosimetric peak of NaBaBO3:Ce3+ follows first order kinetic model, which was also supported by dose response plot. The Z effective value of this phosphor is calculated to be 46.66. Present findings confirm that NaBaBO3:Ce3+ phosphor sample is a promising candidate for applications in environmental dosimetry as one depicts good TL dose response with adequate sensitivity and linearity. (c) 2020 Elsevier B.V. All rights reserved.
Anomalous heating rate effect in GdAl3(BO3)4:Dy3+under beta radiation stimulation: Analysis of dose response and kinetic parameters
Alajlani, Y; Oglakci, M; Bulcar, K; Kaynar, UH; Portakal-Uçar, ZG; Alathlawi, HJ; Ayvacikli, M; Topaksu, M; Can, N
This study presents a comprehensive investigation into the thermoluminescence (TL) properties of Dy3+-activated gadolinium aluminate garnet (Dy3+:GdAl3(BO3)4 or Dy3+-GAB) phosphor materials. The research aims to unravel the intricate interplay among heating rate, radiation dose, and TL glow curve responses to optimize dosimetry applications. The TL response of the material is scrutinized across diverse heating rates (HR) and dose levels, while accounting for temperature lag correction. Concentration quenching effects are explored through Dy3+ concentrations spanning from 0.5 to 7 wt%, revealing the optimal doping concentration to be 3 wt%. The study underscores the critical role of choosing an appropriate band-pass filter, revealing the effectiveness of the IRSL-TL wideband blue filter's in capturing TL signals. Furthermore, the study examines kinetic parameter estimated using different approaches and shedding light on how heating rate and radiation dose affect activation energy values. Intriguingly, the study observes an anomalous heating rate effect, resulting in elevated TL peak intensities at higher HR. This effect is attributed to non-radiative transitions and the semi-localized transition model. The reusability of Dy3+-doped GAB is also examined, confirming its consistency and reproducibility across multiple uses. This study significantly contributes to the advancement of TL dosimetry methodologies and enhances our understanding of luminescent material behaviours. We utilized both the Tm-Tstop technique in conjunction with the Initial Rise (IR) method and Computerized Glow Curve Deconvolution (CGCD) techniques, revealing the presence of seven overlapping glow peaks alongside the main ones. Both methods appear to provide excellent agreement in terms of activation energy values, ranging from 0.70 to 1.50 eV for each peak. Furthermore, the findings strongly indicate the effective utilization of TL signals in radiation dosimetry applications.
Synthesis and beta particle excited thermoluminescence of BaSiF6 phosphor
Souadi, G; Akca-Ozalp, S; Karali, EE; Kaynar, UH; Ayvacikli, M; Topaksu, M; Can, N
BaSiF6 phosphor was synthesized by a gel combustion method. The crystalline size was found to be 54.17 +/- 4.36 nm using Williamson-Hall (W-H) approximation. The TL data collected by means of a combination of a commercial BG39 and HC575/25 filters was studied to evaluate basic kinetic parameters. Three TL glow peaks of BaSiF6 phosphors are centered at around 84, 190 and 322 degrees C. T-m-T-stop, various heating rate (VHR) and computerized glow-curve deconvolution (CGCD) method were utilized to analyse collected data. Our findings indicate that luminescence process in scrutinized material may obey second order kinetics. The TL dose response of the TL glow peaks exhibits a linear characteristic up to 100 Gy. Deconvolution of the glow curve reveals that the number of the component TL glow peaks in the complex glow curve is composed of well-isolated six overlapping glow peaks. The FOM value is 2.32.
Thermoluminescence behaviour of europium doped magnesium silicate after beta exposure
Uçar, ZGP; Kaynar, UH; Dogan, T; Souadi, GO; Ayvacikli, M; Canimoglu, A; Topaksu, M; Can, N
This article presents a detailed analysis of beta ray exposed thermoluminescence response of a series of Eu3+ doped (0.5-10 mol%) Mg2SiO4 nanocrystalline samples successfully synthesized through solid state reaction method. Optimizing the doping concentration of Eu3+ ion in Mg2SiO4 phosphor was found as 3 mol%. Two main peaks were seen at 246 degrees C and 374 degrees C and also low temperature peak at 78 degrees C. The intensities of these peaks were increased linearly with increasing beta absorbed dose. T-m-T-stop method was used to reveal trap levels. Variable heating rate and computerized glow curve deconvolution methods were also used to evaluate the number of peaks and kinetic parameters, namely activation energy and frequency factor. The results of a series of experiments carried out to investigate some fading characteristics of Mg2SiO4:Eu3+ were also presented. The findings suggest that thermoluminescence properties of Mg2SiO4:Eu(3+ )makes this material suitable and promising dosimetric phosphor material for medical applications.
Tb-doped MgAl2O4 phosphors: A study of structural and luminescence characteristics
Halefoglu, YZ; Souadi, G; Ayvacikli, M; Bulcar, K; Topaksu, M; Canimoglu, A; Madkhali, O; Karmouch, R; Can, N
In the MgO-Al2O3 system, magnesium aluminate spinel (MgAl2O4) is a technologically significant compound due to its unique properties, including a high melting point, low thermal conductivity, excellent thermal shock resistance, chemical inertness, and robust mechanical strength. This compound has diverse applications in re-fractory materials, catalyst supports, moisture sensors, nuclear techniques, insulating materials, and even mili-tary applications. While rare-earth elements are commonly used as dopants in luminescent materials, limited research exists on doping of Tb3+ ions in magnesium aluminate. This study investigates the luminescence properties of Tb3+ doped synthesis magnesium aluminate materials, shedding light on this underexplored area. The combustion method is employed for synthesis, known for producing nano-sized powders with exceptional luminescent properties. Additionally, this study explores Sm3+ ion doping in magnesium aluminate materials and their luminescence properties. Using the combustion synthesis method, structural attributes of Tb3+-doped MgAl2O4 nanophosphors are meticulously examined. Through X-ray diffraction (XRD) and Fourier-transform infrared (FTIR) analyses, coupled with excitation and emission spectra, a comprehensive investigation of the luminescent provide behavior at room temperature is provided. The XRD data reveal Tb3+ doped MgAl2O4 phosphors exhibit a single phase with face centred cubic structure belonging to the Fd3 m space group, consistent with the standard JCPDS files (No. 21-1152). Excitation and emission spectra offer valuable insights into the energy transitions within the Tb3+-doped MgAl2O4 phosphors. Furthermore, the study explores the effects of varying Tb3+ ion concentrations on the luminescent properties, revealing an optimal doping concentration of 5 wt% Tb for maximizing emission intensity. Concentration quenching, primarily attributed to dipole-dipole (d-q) interactions, is observed at higher Sm3+ concentrations. In conclusion, this research enhances our understanding of rare-earth ion doping in luminescent materials and highlights the potential applications of Tb3+-doped MgAl2O4 nanophosphors, which offer promise for various technological applications, including lighting and displays.
Comparative studies on thermoluminescence characteristics of non-doped Mg2SiO4 prepared via a solid-state reaction technique and wet-chemical method: An unusual heating rate dependence
Dogan, T; Akça, S; Yüksel, M; Kucuk, N; Ayvacikli, M; Karabulut, Y; Canimoglu, A; Topaksu, M; Can, N
Magnesium orthosilicate (Mg2SiO4) was synthesized via a traditional solid-state reaction and a wet chemical route. This study primarily reported the thermoluminescence (TL) behavior of Mg2SiO4 host. X-ray diffraction pattern revealed that Mg2SiO4 exhibits orthorhombic structure matched with JCPDS card 900-6398. Dose response, reproducibility and trap parameters of TL glow curves were evaluated to clearly reveal TL features. Two TL glow peaks situated at 81 degrees C and 192 degrees C were monitored at a heating rate of 2 degrees Cs-1. We observed anomalous heating rate effect for the peak centered at 192 degrees C whilst TL intensity of the peak at 81 degrees C decreases with elevating heating rate. Trap depths of the electrons within the trap centers were found to be 1.04 +/- 0.01eV and 1.37 +/- 0.01eV for both methods using peak shape (PS) method. Distribution of trap centers was examined using the T-max - T-stop method and this case indicated that the glow curves consist of single TL peaks. The intensity of TL glow curves exhibited a good linear dose response under total area up to 20 Gy. A comparison of the two preparation techniques revealed that TL characteristics of this phosphor are partly dependent and Mg2SiO4 could be a promising material for dosimetric application. (C) 2019 Elsevier B.V. All rights reserved.
Thermoluminescence response and kinetic parameters of Tb-doped GdCa4O(BO3)3 under beta irradiation
Alajlani, Y; Bulcar, K; Oglakci, M; Kaynar, UH; Arslanlar, YT; Topaksu, M; Correcher, V; Can, N
In this study, the thermoluminescence (TL) properties of Tb3+-doped GdCa4O(BO3)(3) (GdCOB) are investigated with focus on the effects of optical filter selection, preheating, dopant concentration, irradiation dose, heating rate on these properties. Trapping parameters of the traps responsible for the peaks in the phosphor were also determined. The IRSL-TL-565 nm filter was identified as optimal filter for isolating the characteristic green emission of Tb3+ and improving the signal-to-noise ratio. Among the studied dopant concentrations (1, 2, 3, 5, and 7 wt%), 3 wt% Tb3+ was found to maximize TL intensity. Beyond this concentration, quenching effects became dominant, leading to reduced TL efficiency. At 3 wt% doping, TL glow peaks were observed at approximately 80 and 190 degrees C following a 50 Gy beta dose with a heating rate of 2 degrees C/s, with the primary peak (similar to 190 degrees C) favorable for minimizing thermal fading. The TL response of the primary peak was linear with dose within 5-500 Gy. The peak's TL intensity is affected by thermal quenching effects. Reusing of an aliquot of the phosphor ten times produced responses with 0.45 % maximum deviation from their mean. Additionally, the peak temperature (T-m) exhibited a slight decrease beyond 100 Gy, which can be attributed to charge carrier interactions, trap filling effects, and potential thermal quenching at higher doses. Heating rate experiments showed the expected shift of peak temperatures to higher values, emphasizing the need to correct for temperature lag in kinetic analyses. Computerized glow curve deconvolution (CGCD) indicated the presence of at least eight distinct trapping levels with activation energies ranging from 0.90 to 1.69 eV, revealing a complex trap structure. Overall, with its high TL intensity, linear dose response, and aliquot reusability, Tb3+-doped GdCOB is a promising phosphor for personal dosimetry, environmental radiation monitoring, and medical imaging.
Cathodoluminescence and thermoluminescence of ZnB2O4:Eu3+ phosphors prepared via wet-chemical synthesis
Dogan, T; Tormo, L; Akca, S; Kucuk, N; Guinea, JG; Karabulut, Y; Ayvacikli, M; Oglakci, M; Topaksu, M; Can, N
In present work, a series of Eu doped zinc borate, ZnB2O4, phosphors prepared via wet chemical synthesis and their structural, surface morphology, cathodoluminescence (CL) and thermoluminescence (TL) properties have been studied. Phase purity and crystal structure of as-prepared samples are confirmed by X-ray diffraction measurements (XRD) and they were well consistent with PDF card No. 39-1126, indicating the formation of pure phase. The thermoluminescence (TL) behaviors of Eu activated ZnB2O4 host lattice are studied for various beta doses ranging from 0.1 to 10 Gy. The high-temperature peak of Eu activated sample located at 192 degrees C exhibited a linear dose response in the range of 0.1-10 Gy. Initial rise (IR) and peak shape (PS) methods were used to determine the activation energies of the trapping centres. The effects of the variable heating rate on TL behaviour of Eu activated ZnB2O4 were also studied. When excited using an electron beam induced light emission (i.e cathodoluminescence, CL) at room temperature (RT), the as-prepared phosphors generate reddish-orange color due to predominant emission peaks of Eu3+ ions located at 576-710 nm assigned to the D-5(0)-> F-7(J) (J=1,2,3, and 4) transitions. The maximum CL intensity for Eu3+ ions at 614 nm with transition D-5(0)-> F-7(2) was reached Eu3+ concentration of 5 mol%; quenching occurred at higher concentrations. Strong emission peak for Eu3+ ions at 614 nm with transition D-5(0)-> F-7(2) is observed. The CL experimental data indicate that ZnB2O4:Eu3+ phosphor as an orange-red emitting phosphor may be promising luminescence materials for the optoelectronic applications.
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
Kaynar, UH; Oglakci, M; Bulcar, K; Benourdja, S; Bakr, M; Ayvacikli, M; Canimoglu, A; Topaksu, M; Can, N
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.
Anomalous dose behaviour of thermoluminescence glow curves and kinetic analysis of beta irradiated YAl3(BO3)4:Tb phosphor
Souadi, G; Bulcar, K; Kaynar, UH; Ayvacikli, M; Topaksu, M; Cam-Kaynar, S; Can, N
With the aid of thermoluminescence (TL), we have extensively studied YAl3(BO3)4 host matrices incorporated with Tb3+ at different doping contents, which have been produced by combustion. The measured the TL glow curves exposed to beta rays at different doses consisted of four broad peaks located at around 76, 126, 230, and 378 degrees C. The peak maximum of the 230 degrees C TL peak shifts toward higher temperatures after 5 Gy beta irradiation while the other peak maxima almost remain constant. It is peculiar that 230 degrees C peak maximum shifts to higher temperatures with increased radiation dose and can be attributed to the multiple phases of the sample. A TL glow curve exhibits a proportional increase in intensity with increased the heating rate. A discussion of the possible causes of this pattern is provided. Observed peaks using the TmTstop method are due to the presence of a quasicontinuous distribution of traps. The parameters of the traps have also been estimated using various heating rate methods in excellent agreement with one another.
Thermoluminescence properties of beta particle irradiated Ca3Al2O6 phosphor relative to environmental dosimetry
Bakr, M; Portakal-Uçar, ZG; Yüksel, M; Kaynar, ÜH; Ayvacikli, M; Benourdja, S; Canimoglu, A; Topaksu, M; Hammoudeh, A; Can, N
Undoped Ca3Al2O6 phosphor was successfully synthesized through a gel-combustion method using different fuels. It was characterized by X-ray diffraction (XRD) technique and its cubic phase structure was confirmed from XRD pattern. TL data were recorded from room temperature (RT) to 500 degrees C in the heating rate of 2 degrees C/s. The glow curves of Ca3Al2O6 sample exposed to different beta doses (0-200 Gy) exhibited a significant glow peak at about 184 degrees C. The TL intensity of the glow peak exhibited very good linearity between 0.1 and 10 Gy. Following this, it was decreased at higher doses which was referred to this effect as monotonic dose dependence. Initial rise (IR), peak shape (PS), and variable heating rate (VHR) methods were used to estimate trapping parameters. Computerized glow curve deconvolution (CGCD) method via TLAnal software was also applied to estimate the number of peaks and kinetic parameters corresponding to the main glow curve in Ca3Al2O6 sample. The trapping activation energy of the main dosimetric peak was calculated to be around 1.30 eV for all methods. Present findings confirm that Ca3Al2O6 host is a promising candidate for applications in environmental dosimetry as one depicts good TL dose response with adequate sensitivity and linearity.
Thermoluminescence characteristics of a novel Li2MoO4 phosphor: Heating rate, dose response and kinetic parameters
Souadi, G; Kaynar, UH; Oglakci, M; Sonsuz, M; Ayvacikli, M; Topaksu, M; Canimoglu, A; Can, N
Lithium molybdate (Li2MoO4) phosphor was synthesized by a gel combustion method and its thermoluminescence properties were studied with the irradiation of beta. Various Heating Rate (VHR), Initial Rise (IR), and Computerized Glow Curve Deconvolution (CGCD) methods were used to determine the kinetic parameters (activation energy E (eV), frequency factor s (s(-1)), and kinetic order b) of the visible glow peaks. According to the kinetic study, the TL glow curve is made up of seven separate peaks with activation energies of 1.05, 0.76, 0.40, 0.60, 0.78, 1.81 and 1.25 eV and these peaks follow general-order kinetics. The results clearly showed that undoped Li2MoO4 has a potential to be considered in dosimetric applications where high doses have to be monitored as in the case of clinical dosimetry.
Synthesis and thermoluminescence behavior of novel Sm3+ doped YCa4O(BO3)3 under beta irradiation
Altowyan, AS; Sonsuz, M; Kaynar, UH; Hakami, J; Portakal-Uçar, ZG; Ayvacikli, M; Topaksu, M; Can, N
This study investigates the luminescent properties and dosimetric potential of YCa 4 O(BO 3 ) 3 :0.5%Sm 3+ phosphor synthesized via the combustion method. Dose -response investigations unveil a noteworthy linear increment in thermoluminescence (TL) intensity, emphasizing a remarkable linearity spanning a broad dose range from 0.1 to 300 Gy. Unusual heating rate effects are explored, revealing a shift in TL glow curve peak temperature (i.e 200 degrees C) towards higher temperatures with increasing heating rate. Speculative models, including Kinetic Trapping Effect, Thermal Quenching Compensation, and Defect Activation Energy Changes, are proposed. The study employs the T max - T stop method to identify characterize glow curve peaks, and the Initial Rise method for the lowtemperature segment analysis, revealing seven distinct trap levels at various depths within the bandgap. Glow curve deconvolution using the Complex Glow Curve Deconvolution (CGCD) method delineates a multi -peak structure, offering valuable insights into luminescent mechanisms. The model exhibits a Figure of Merit (FOM) of 1.71%, within an acceptable range, affirming its reliability. However, interpretation of the activation energy and frequency factor values suggests intricate site processes, necessitating a nuanced analysis to understand the material 's luminescent characteristics. The YCa 4 O(BO 3 ) 3 :0.5%Sm 3+ phosphor demonstrates promising characteristics for precise dosimetry, with linear dose response, absence of saturation effects, and intriguing heating rate behavior.

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