Browsing by Author "Alajlani, Y"
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Item Novel Dy and Sm activated BaSi2O5 phosphors: Insights into the structure, intrinsic and extrinsic luminescence, and influence of doping concentrationAlajlani, Y; Can, NPure and a series of BaSi2O5:RE3+ (RE = Dy, Sm) phosphors varying with the substitution of Ba2+ were prepared using a gel-combustion method. X-ray diffraction results confirmed that all samples exhibited an orthorhombic structure. FT-IR spectra showed that the samples consist of BaCO3, SiO2 network and the presence of OH groups. The photoluminescence spectrum of non-doped BaSi2O5 showed a broad-band emission peak at 520 nm. The analysis of photoluminescence emission and comparison of the chromaticity diagrams of BaSi2O5:Dy3+ and BaSi2O5:Sm3+ phosphors were presented, and their implications are also discussed. The optimum quenching concentrations and critical distances of Dy3+ and Sm3+ ions in the BaSi2O5 were 2mol%, 22.57 angstrom and 1 mol%, 28.44 angstrom, respectively. The investigation of concentration quenching behaviour, fluorescence decay curves, and decay time indicates that the dominant mechanism type leading to concentration quenching was governed by electric dipole-dipole interactions. The concentration dependence of intensity ratio of yellow-blue emission indicated that the emission of BaSi2O5:Dy3+ phosphors fell in the white light region tuning the blue and yellow components. BaSi2O5:Sm3+ phosphors may allow one to consider as potential orange-red-emitting phosphors.Item Thermoluminescence glow curve analysis and kinetic parameters of Dy-doped BaSi2O5 phosphorAlajlani, Y; Can, NIn this paper, Dy3+ incorporated BaSi2O5 phosphors were synthesized by gel combustion method and characterized by X-ray diffraction (XRD). The effects of various heating rates on thermoluminescence (TL) kinetics and glow peak temperatures of Dy3+ incorporated BaSi2O5 phosphors exposed to beta irradiation at room temperature were investigated. The glow curves of the phosphor exposed to beta-irradiation (0.1-100 Gy) consist of four main peaks located at 87,130, 271, and 327 degrees C and exhibit a good linearity between 0.1 and 100 Gy. Three experimental techniques including variable heating rate (VHR), repeated initial rise (RIR), peak shape (PS) and computerized glow curve deconvolution (CGCD) were employed to determine TL kinetic parameters. Our findings indicate that the TL glow peaks of the phosphor obey first-order kinetics. Analysis of the main dosimetric peaks through the techniques mentioned above indicates that activation energies (E) and pre-exponential factor (s) are in the range of 0.80-1.50 eV and 1.15 x 10(8)-3.28 x 10(13) s(-1). Additionally, 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 effect on the TL intensities and glow peak temperatures of the heating rate is discussed in terms of thermal quenching. (C) 2020 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.Item Anomalous heating rate effect in GdAl3(BO3)4:Dy3+under beta radiation stimulation: Analysis of dose response and kinetic parametersAlajlani, Y; Oglakci, M; Bulcar, K; Kaynar, UH; Portakal-Uçar, ZG; Alathlawi, HJ; Ayvacikli, M; Topaksu, M; Can, NThis 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.Item Eu3+ and Dy3+ doped La2MoO6 and La2Mo2O9 phosphors: Synthesis and luminescence propertiesKaynar, ÜH; Kaynar, SC; Alajlani, Y; Ayvacikli, M; Karali, E; Karabulut, Y; Akca, S; Karali, T; Can, NWe report a detailed structural analysis and properties of the photoluminescence (PL) and thermoluminescence (TL) spectra of Eu3+ and Dy3+ incorporated into novel La2MoO6 and La2Mo2O9 phosphors synthesized successfully through gel combustion synthesis. The formation of a tetragonal phase and a cubic structure were verified for La2MoO6 and La2Mo2O9 phosphors via X-ray diffraction (XRD) studies. Dy doped samples exhibited blue and green emissions at 480 nm (F-4(9/2) -> H-6(15/2)) and 572 nm (F-4(9/2) -> H-6(13/2)), and also Eu doped samples showed a sharp emission peaks at 612 and 619 nm (D-5(0) -> F-7(2)) upon 349 nm pulse laser excitation. Peak shape (PS) technique was utilised to determine activation energy, frequency factor and order of kinetics associated with the main glow curves in undoped and Eu and Dy doped samples after X-ray irradiation. The present findings suggest that Eu and Dy incorporated La2MoO6 and La2Mo2O9 phosphors are highly auspicious candidates for applications in solid-state lighting.Item Thermoluminescence response and kinetic parameters of Tb-doped GdCa4O(BO3)3 under beta irradiationAlajlani, Y; Bulcar, K; Oglakci, M; Kaynar, UH; Arslanlar, YT; Topaksu, M; Correcher, V; Can, NIn 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.Item Thermoluminescence in GdAl3(BO3)4 phosphors: Unusual heating rate dependencies, dose responses and kinetic parametersAlajlani, Y; Sonsuz, M; Barad, A; Kaynar, UH; Ayvacikli, M; Topaksu, M; Can, NThe 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.Item Thermoluminescence study and evaluation of trapping parameters of samarium doped barium silicate phosphorAlajlani, Y; Oglakci, M; Kaynar, UH; Ayvacikli, M; Portakal-Uçar, ZG; Topaksu, M; Can, NWe 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.Item Novel Dy incorporated Ca3Y2B4O12 phosphor: Insights into the structure, broadband emission, photoluminescence and cathodoluminescence characteristicsQaisi, AH; Kaynar, UH; Ayvacikli, M; Garcia-Guinea, J; Alajlani, Y; Topaksu, M; Can, NThis study reports cathodoluminescence (CL) and photoluminescence (PL) properties of undoped borate Ca3Y2B4O12 and Ca3Y2B4O12:x Dy3+ (x = 0.5, 1, 2, 3, 5, and 7) synthesized by gel combustion method. Micro-X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), CL and PL under electron beam and 359 nm pulse laser excitation, respectively were used to investigate characterization and luminescence studies of synthesized samples in the visible wavelength. As-prepared samples match the standard Ca3Y2BO4 phase that belongs to the orthorhombic system with space group Pnma (62) based on XRD results. Under electron beam excitation, this borate host shows a broad band emission from about 250 to 450 nm, peaked at 370 nm which is attributed to NBHOC. All as-prepared phosphors exhibited the characteristic PL and CL emissions of Dy3+ ions corresponding to F-4(9/2)-> H-6(J) transitions when excited with laser at 359 nm. The CL emission spectra of phosphors were identical to those of the PL spectra. Concentration quenching occurred when the doping concentration was 1 mol% in both the CL and PL spectra. The underlying reason for the concentration quenching phenomena observed in the discrete orange-yellow emission peaked at 574 nm of Dy3+ ion-doped Ca3Y2B4O12 phosphor is also discussed. According to these data, we can infer that this new borate can be used as a yellow emitting phosphor in solid-state illumination.Item Structural and thermal insights into the luminescent behavior of Dy3+-Doped BaZrO3 with alkali metal codopants under UV radiationArslanlar, YT; Alajlani, Y; Coban, MB; Kaynar, UH; Aydin, H; Örücü, H; Guinea, JG; Can, NThis study investigates the structural, thermal, and photoluminescent properties of Dy3+-doped BaZrO3 (BZO) perovskites, synthesized via a co-precipitation method, incorporating alkali metal codopants (Li+, Na+, and K+). Xray diffraction (XRD) analysis confirmed the retention of the cubic perovskite phase following doping, with Rietveld refinement further revealing minor lattice distortions due to Dy3+incorporation. The Williamson-Hall (W-H) analysis revealed average crystallite sizes of 53 nm and 66 nm for undoped and 0.01 Dy3+-doped BaZrO3, respectively, with corresponding micro-strain values of 1.79 x 10-3 and 1.81 x 10-3, suggesting lattice distortions due to incorporation of Dy3+. Fourier transform infrared (FTIR) spectroscopy confirmed the cubic perovskite structure and subtle structural modifications upon doping. Notably, the absence of moisture-related peaks highlights the effectiveness of the synthesis process, including rigorous drying and calcination steps that prevented hydrous species. Photoluminescence (PL) analysis of Dy3+-doped BaZrO3 exhibited three prominent emission peaks at 452 nm, 573 nm, and 656 nm under 368 nm excitation. These peaks correspond to the characteristic intra-4f electronic transitions of Dy3+ ions, specifically, 4I13/2 to 6H15/2, 4F9/2 to 6H13/2, and 4F9/2 to 6H11/2, representing blue, yellow, and red emissions, respectively. Photoluminescence decay studies showed multi-exponential behavior, with the average lifetime decreasing from 641 mu s in undoped BZO to 492 mu s in Dy3+- doped samples attributed to enhanced non-radiative recombination pathways. Among the codopants, Li+ demonstrated the most significant improvement in luminescence intensity and thermal stability by mitigating defects and optimizing charge compensation.Item Enhancing the blue luminescence behaviour of the Li co -doped novel phosphor ZnB 2 O 4: Tm 3+Kucuk, N; Kaynar, ÜH; Akca, S; Alajlani, Y; Yin, L; Wang, Y; Guinea, JG; Bulcar, K; Dogan, T; Karabulut, Y; Ayvacikli, M; Canimoglu, A; Topaksu, M; Can, NItem Structural and temperature dependence luminescence characteristics of RE (RE=Eu3+, Dy3+, Sm3+and Tb3+) in the new gadolinium aluminate borate phosphorMadkhali, O; Kaynar, H; Alajlani, Y; Coban, MB; Guinea, JG; Ayvacikli, M; Pierson, JF; Can, NGdAl3(BO3)4:Dy3+, Sm3+, Eu3+, and Tb3+ samples were successfully achieved via a sol-gel combustion method. The observed XRD analysis confirms the formation of the desired GAB host, indicating rhombohedral structures that agree well with JPCD card number 72-1985. The FTIR analyses show the detection of B -O stretching and B -O -B bending modes as well as Al -O and Gd -O bonds in the phosphor samples. Energy dispersive spectroscopy (EDS) analysis reveals that Sm, Eu, Dy, and Tb have been successfully doped into GdAl3(BO3)4. The observed broad intrinsic luminescence band can be caused by oxygen-induced luminescence defects in the GAB host with hydrous precursors. The luminescence properties of rare earth ion-doped GdAl3(BO3)4 samples are analysed by photoluminescence spectra, showing their optimal doping concentrations and critical distances of Dy3+, Eu3+, Sm3+ and Tb3+ are 2 wt% -25.8 angstrom, 7 wt% -17 angstrom, 1 wt% -32.59 angstrom, and 7 wt% -17.03 angstrom. Additionally, the energy transfer mechanism for luminescence quenching was determined as dipole-dipole (for Dy3+, Eu3+, and Tb3+) or dipole-quadrupole (for Sm3+) and the cross-relaxation process. GdAl3(BO3)4 samples obtained by doping with different RE3+ ions exhibit intense light emissions with different colors originating from different RE3+ ions under 349 nm excitation. When doped with different concentrations of RE3+ ions, the luminescence properties of the samples changed. The synthesized luminescence materials have potential ap-plications in lighting and display technologies.Item Thermal quenching and evaluation of trapping parameters of thermoluminescence glow-peaks of beta irradiated NaBaBO3: Tb3+ for TLD applicationsOglakci, M; Topaksu, M; Alajlani, Y; Can, N; Karali, EEHere, we report the thermoluminescence (TL) characteristics and trapping parameters under beta ray excitations of pelletized Tb incorporated NaBaBO3 synthesized through the gel combustion method. The chemical composition of this new phosphor was confirmed using X-ray diffraction (XRD). The best doping concentration of Tb was 2 mass%, which results 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 188 degrees C, and 288 degrees C with a heating rate of 2 degrees Cs-1. The trapping parameters (E, b, s) related with the prominent the TL glow peaks were determined using T-m-T-stop, initial rise (IR), computerized glow curve deconvolution (CGCD), and variable heating rate (VHR) methods. In the range of 0.1-40 Gy, the total integral values of TL output enlarge linearly with increased dose. The GCD approach was also used to calculate the number of the glow peaks necessary to ensure an appropriate match to the TL response of the phosphor sample and seven TL glow peaks were estimated for all doses (FOM 1.75%), similar to the analysis of T-m-T-stop. The thermal quenching parameters of Tb activated NaBaBO3 for the 1st and 2nd peaks are measured to be W = 0.39 +/- 0.04 eV, C = 3.11 x 10(2), and W = 0.31 +/- 0.03 eV, C = 3.11 x 10(2), respectively. The current results indicate that the NaBaBO3:Tb3+ phosphor is a suitable option in radiation dosimetry for environmental monitoring.