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Browsing by Author "Oglakci, 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.
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.
Structural and luminescence characterization of Ce3+ and Mn2+ co-activated zinc silicate nanocrystal obtained by gel combustion synthesis
Portakal-Uçar, ZG; Oglakci, M; Yüksel, M; Ayvacikli, M; Can, N
The structural, morphological, and luminescence properties, including photoluminescence (PL) and thermoluminescence ('FL), of newly produced Zn2SiO4:Ce co-activated by Ce3+ and Mn2+ ions using the gel-combustion synthesis, are investigated in deep. To determine the co-dopant effect precisely, non-doped, Ce3+ doped, and Ce3+ and Mn2+ double doped Zn2SiO4:Ce phosphors are evaluated. The fluorescence decay curves indicate that a shorter decay time at relatively high Mn concentrations takes place. The TL glow curve readouts observed by applying the dose range between 0.1 and 2000 Gy after 150 degrees C preheat are performed at a linear heating rate of 2 degrees C/s from room temperature (RT) to 500 degrees C. An anomalous heating rate behavior is observed when the influence of different heating rates on TL characteristics is reported. An excellent agreement is found between the TL kinetic parameters analyzed by the initial rise (IR) with T-M-T(stop )analysis and computerized glow curve deconvolution (CGCD) methods.
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 photoluminescence characteristics of a novel Eu and Tb doped Li2MoO4 phosphor
Souadi, G; Kaynar, UH; Ayvacikli, M; Coban, MB; Oglakci, M; Canimoglu, A; Can, N
Li2MoO4:x Eu3+ and Li2MoO4:xTb(3+) phosphors, where x = 0.5, 1, 2, 3, 5 and 7 wt%, were synthesized through a gel-combustion method. The XRD data reveals that Eu3+ and Tb3+ doped Li2MoO4 phosphors exhibit a Rhombohedral structure belonging to the space group R3 which matched well with the standard JCPDS files (No.0120763). We present photoluminescence (PL) spectra from Eu and Tb doped Li2MoO4 under 349 nm Nd:YLF pulses laser excitation over the temperature range of 10-300 K. Undoped Li2MoO4 shows a wide broad band around 600 nm because of the intrinsic PL emission of tetrahedral of MoO42- which was in good agreement with previous findings. Under the excitation of 394 nm, the as-synthesized phosphors exhibited sharp and strong intensity PL emission signals in the red (612 nm, D-5(0) -> F-7(2) transition) and green (544 nm, D-5(4) -> F-7(5) transition), respectively. The critical doping concentration of Eu3+ and Tb3+ ions in the Li2MoO4 were estimated to be 2 wt%. The concentration quenching phenomena were discussed, and the critical distances for energy transfer have also been evaluated by the concentration quenching.
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.
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.
Characterization of thermoluminescence kinetic parameters of beta irradiated B doped Ca5(PO4)3OH powder obtained from eggshell
Depci, T; Oglakci, M; Sezer, S; Yücel, A; Dogan, T; Souadi, G; Topaksu, M; Can, N
In this study, we have synthesized B doped Ca5(PO4)3OH (HAP) by a sonication chemical method. The thermoluminescence (TL) properties of the family of synthesized samples (B doped Ca5(PO4)3OH (HAP) were investigated using an IRSL-TL 565 nm filter. This gave the highest TL intensity of each phosphor after 2 Gy beta-irradiation. Three TL glow peaks of B doped Ca5(PO4)3OH (HAP) are centered at around 84, 208 and 324 degrees C (with a heating rate of 2 degrees Cs-1). The trapping parameters such as activation energy (E), order of kinetics (b), frequency factor (s) were calculated by using initial rise (IR), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) method. The response of TL glow curves remained constant within +/- 5% deviation from the initial value after 9 cycles of reuse; but only at tenth cycle the deviation goes up to 6%.
Thermoluminescence glow curve analysis and evaluation of trapping parameters of dysprosium doped lanthanum calcium borate La2CaB10O19
Bulcar, K; Oglakci, M; Kaynar, UH; Ayvacikli, M; Souadi, G; Topaksu, M; Can, N
The present work elucidates thermoluminescence study of Dy activated lanthanum calcium borate (La2CaB10O19) phosphors and determination of trapping parameters. Two glow curves located at 132 and 295 degrees C were observed and showed a linear TL response. The kinetic parameters of the glow peaks were evaluated using variable heating rate, repeated initial rise method and Computerized Glow Curve Deconvolution. Analysis of the main dosimetric peaks reveals that the values of the activation energy and pre-exponential factor are found to be 0.78-1.145 eV and 8.59 x 10(9)-8.44 x 10(11) s(-1), respectively. The sample doped with 1% Dy3+ exhibits a good stability for the reusability. Besides, the found results indicate that the temperature maximum shifts to the higher temperature side as the heating rate increases. Contrary to previously expressed theoretical expectations, anomalous heating rate dependence was observed in Dy3+ doped La2CaB10O19 sample and a semi-localized transition model explaining the anomalous heating rate effect was employed.
Samarium doped Ca3Y2B4O12 phosphor prepared by combustion method: Anomalous heating rate effect, dosimetric features, and TL kinetic analyses
Hakami, J; Oglakci, M; Portakal-Uçar, ZG; Sonsuz, M; Kaynar, UH; Ayvacikli, M; Topaksu, M; Can, N
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.
Structural and spectroscopic properties of LaAlBO3 doped with Eu3+ ions
Halefoglu, YZ; Oglakci, M; Yuksel, M; Canimoglu, A; Topaksu, M; Can, N
In this study, we performed X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) techniques to examine the structure and morphological observation of the samples and thermoluminescence (TL) experiments to extract the trapping parameters and dosimetric properties of LaAlBO3 phosphors doped with Eu at various doping concentrations. Diffraction patterns of obtained sample were well consistent JCPDS card No 98-009-7945, indicating the formation of pure phase. The TL kinetic parameters were estimated by CGCD software. TL glow curves of LaAlBO3:Eu3+ consist of 12 trap levels and exhibited dominantly first order kinetics. Photoluminescence (PL) emission was observed in the range 400-800 nm for LaAlBO3 phosphor doped with Eu3+. The dominant emission of Eu3+ corresponding to the electric dipole transition D-5(0) -> F-7(2) is located at 616 nm. The sharp emission properties exhibited demonstrate that the LaAlBO3 is a suitable host for rare-earth ion doped phosphor material. It is observed that for the variable concentration of Eu3+ on PL studies, the PL intensity augments with increase in the dopant concentration and the concentration quenching was found after 1 mass% of Eu3+. The PL experimental results reveal that LaAlBO3:Eu3+ phosphor as an red emitting phosphor may be promising luminescence materials for the optoelectronic applications.
A study on thermoluminescence behaviour of Eu doped LaB3O6 irradiated with beta particles
Halefoglu, YZ; Oglakci, M; Portakal, ZG; Akca, S; Souadi, GO; Canimoglu, A; Topaksu, M; Can, N
Lantanium triborate (LaB3O6) samples doped with Eu3+ ions are synthesized via combustion route. This study primarily reports the thermoluminescence (TL) behaviour of LaB3O6 host. X-ray diffraction (XRD) pattern reveals that LaB3O6 exhibits a single phase matched with JCPDS card 98-002-3609. Dose response, reusability and trap parameters of TL glow curves are evaluated to clearly reveal the TL features. The results show that the peak positions of TL glow curves are affected by varying the concentration of Eu. The experimental results obtained from the dose-response of LaB3O6:Eu3+ (1%) which has given high TL intensity reveal that the intensity of TL given by the total area under glow curves shows a good linearity (b = 0.997) up to 20 Gy. In addition, the minimum detectable dose (MDD) value has been calculated as 1.45 mGy with a standard deviation of 0.8%. Main TL peak maxima is observed around 197 degrees C with heating rate (HR) of 2 degrees Cs-1. An anomalous HR effect is observed for this peak in the range of 0.5-20 degrees Cs-1 with beta dose of 5 Gy. To find the overlapping peak numbers and determine the kinetic parameters of the main peak of LaB3O6:Eu3+ (1%), Initial Rise (IR) method using T-m - T-stop experiment and CGCD analysis have been performed for HRs of 0.5 and 2 degrees Cs-1. It can be said that the results of the methods are in good agreement when same trap numbers (at least eight separate peaks for both) and close energy values are taken into consideration. Deconvolution procedure of LaB3O6: Eu3+(1%) is performed using general order kinetic equation by R studio 'tgcd'. Additionally, the lifetimes of each deconvolved peaks by CGCD of Eu activated LaB3O6 (1%) have been calculated. Based on the results it can be put forth that TL characteristics of Eu doped LaB3O6 can be used as a promising material for thermoluminescence dosimetry-environmental applications.
Thermoluminescence study and evaluation of trapping parameters of samarium doped barium silicate phosphor
Alajlani, Y; Oglakci, M; Kaynar, UH; Ayvacikli, M; Portakal-Uçar, ZG; Topaksu, M; Can, N
We report the detailed analysis of thermoluminescence (TL) glow curves and the evaluation of kinetic parameters of Sm3+-incorporated BaSi(2)O(5.)The effect of various heating rates on TL kinetics and glow peak temperatures of Sm3+-doped BaSi2O5 phosphors exposed to beta particle irradiation at room temperature are investigated. The glow curve of the phosphor exposed to beta-irradiation consists of two main peaks with maxima at about 91 degrees C and 193 degrees C and exhibits good linearity between 1 and 10 Gy. The activation energies and frequency factors of trap centers involved in the TL emission were calculated from the TL glow curve of the sample by means of variable heating rate (VHR), repeated initial rise (RIR), and computerized glow-curve deconvolution (CGCD). Analysis of the main dosimetric peak techniques indicate that activation energies (E) and pre-exponential factor (s) vary between 0.93 and 1.72 eV, 10(10) and 10(13) s(-1). It is found that the temperature of the glow peaks shifts toward the higher temperatures and the TL intensity smoothly decreases as the heating rate increases. The behavior of the TL intensities and glow peak temperatures as a function of the heating rate are discussed with regards to thermal quenching.
Kinetic parameters and anomalies in heating rate effects of the thermoluminescence from rock salt from Tuzluca in Turkey
Bulcar, K; Oglakci, M; Hakami, J; Topaksu, M; Can, N; Alma, MH
In this work, thermoluminescence (TL) characteristics and kinetic parameters of naturally occurring rock salts were presented. The samples were crushed and compressed into pellets before being irradiated with beta radiation doses ranging between 0.1 Gy and 15 Gy. TL responses exhibited four peaks at about 95 degrees C, 182 degrees C, 265 degrees C, and 360 degrees C in the glow curve. By increasing the heating rates, we observed an increase in the peak maximum temperature and the area of each peak as well as in the full width half maximum (FWHM), which shows an anomalous heating-rate effect. Taking a rock salt sample, the standard deviation was less than 1%, which was a good indication of repeatability. Using the initial rise (IR) and variable heating rate (VHR) approaches, the trapping parameters were calculated. The findings suggest that salt samples from the Tuzluca district in Turkey may be useful as radiation dosimeters.
Structural and temperature-dependent photoluminescence properties of NaBaBO3:Ce3+,Tb3+phosphors synthesized using the combustion
Altowyan, AS; Oglakci, M; Topaksu, M; Ozturk, E; Hakami, J; Coban, MB; Keskin, MO; Ayvacikli, M; Kaynar, UH; Canimoglu, A; Can, N
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.

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