Browsing by Author "Bakr M."

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    Thermoluminescence analysis of beta irradiated ZnB 2 O 4 : Pr 3+ phosphors synthesized by a wet-chemical method
    (Elsevier Ltd, 2019) Akca S.; Oglakci M.; Portakal Z.G.; Kucuk N.; Bakr M.; Topaksu M.; Can N.
    In this paper we describe the thermoluminescence (TL) characteristics of ZnB 2 O 4 :Pr 3+ phosphors with Pr concentrations varying between 0.2 and 1 mol% prepared by a wet-chemical method. The TL glow curves of the phosphor sample consisted of three peaks located at 71 °C (P1), 124 °C (P2) and 233 °C (P3). The TL intensity increased with the beta dose ranging from ∼0.1 to ∼20 Gy. Dose response, reproducibility and trapping parameters of TL glow curves were evaluated to clearly reveal thermoluminescence features. We observed that TL intensity of P2 and P3 peaks decreases as the heating rate increases. Trap parameters were estimated via the Hoogenstraaten, Booth-Bohun-Parfianovitch, the initial rise methods combined with T m −T stop experiment and TLanal CGCD program. Heating rates were varied to use in the Hoogenstraaten analyses. The T m −T stop investigations on regenerated TL signals for P1 and P2 peaks indicated that ZnB 2 O 4 :Pr 3+ phosphor has four electron trap levels with energy values in the range of 0.5–1.5 eV These four traps have first order kinetic and are formed at high temperature region. Resulting values are utilized as a reference for the CGCD procedure and the trapping parameters from the TL glow curves are calculated. The figure of merit (FOM) of the TL glow curve during curve fitting procedures is found to be 2.019%. The intensities of the main dosimetric peaks appeared at 124 °C and 233 °C exhibits good linear dose response up to 20 Gy. These results provide valuable knowledge for use of the characteristics of Pr doped ZnB 2 O 4 in dosimetry research, just need to eliminate low temperature TL peak. © 2019 Elsevier Ltd
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    Synthesis and competitive luminescence quenching mechanism of Ca3Al2O6:Ln3+ (Ln: Dy and Sm) phosphors
    (Elsevier Ltd, 2020) Bakr M.; Kaynar Ü.H.; Ayvacikli M.; Benourdja S.; Karabulut Y.; Hammoudeh A.; Can N.
    Sm3+ and Dy3+ activated Ca3Al2O6 phosphors were produced through a gel combustion method using Urea + β-Alanine, Urea, and Urea + Glycine as fuels. The crystal structure and the phase purity of the obtained materials were characterized by X-ray powder diffraction (XRD). Ca3Al2O6:Sm3+ phosphor shows characteristic emission lines (565 nm, 602 nm, 649 nm, and 714 nm) in the orange red region assigned to 4G5/2→6HJ (J = 5/2, 7/2, 9/2, 11/2) transitions of Sm3+. The strongest peak is located at 602 nm. Emission spectra of Ca3Al2O6:Dy3+ show that there are two dominant peaks centered at 480 nm and 573 nm emitting blue and yellow light. Optimum doping concentrations of Sm(NO3)3 and Dy(NO3)3 are 0.01 % and 0.03 %, respectively. The concentration quenching mechanism is verified to be a dipole-dipole interaction as the type of energy transfer among Sm3+-Sm3+ and Dy3+-Dy3+ ions. The critical distance is also calculated to be 24.19 Å and 16.77 Å, respectively. © 2020 Elsevier Ltd
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    Thermoluminescence properties of beta particle irradiated Ca3Al2O6 phosphor relative to environmental dosimetry
    (Elsevier B.V., 2020) Bakr M.; Portakal-Uçar Z.G.; Yüksel M.; Kaynar Ü.H.; 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 °C in the heating rate of 2 °C/s. The glow curves of Ca3Al2O6 sample exposed to different beta doses (0–200 Gy) exhibited a significant glow peak at about 184 °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. © 2020 Elsevier B.V.
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    Synthesis and photoluminescence characteristics of Dy incorporated MoO3 phosphor: Suppression concentration quenching
    (Elsevier Ltd, 2020) Ayvacikli M.; Kaynar Ü.H.; Karabulut Y.; Canimoglu A.; Bakr M.; Akca S.; Can N.
    A series of MoO3:Dy3+ phosphors have been synthesized via the gel-combustion method. The X-ray and photoluminescence (PL) emission spectra were employed to characterize the obtained phosphors. The prepared samples were characterized through XRD measurements and exhibited that Dy3+ ions can be successfully incorporated into the host material. The PL emission bands of Dy3+ doped MoO3 were observed at 486 nm, 574 nm and 666 nm which are assigned to the transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2, respectively. Concentration quenching were largely taken into consideration as one of the crucial aspects limiting the application range of phosphors in today's modern world. An abnormal thermal quenching dependence was reported when Dy3+ ions were incorporated into MoO3 host matrix. In order to understand the origin of this beneficial behaviour, energy transfer processes occurring via radiative and nonradiative mechanisms were investigated to elucidate this suppression of the concentration quenching. © 2020 Elsevier Ltd
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    Structural and analyses of thermoluminescence glow curves in Sm doped SrGd2O4 phosphor
    (Elsevier Ltd, 2022) Sarıkcı S.; Topaksu M.; Bakr M.; Can N.
    In this study, SrGd2O4: xSm3+ (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 wideband 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. © 2022 Elsevier B.V.
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    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
    (Elsevier Ltd, 2023) Kaynar Ü.H.; 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 °C, 240 °C, and 360 °C with a heating rate of 2°Cs−1 whilst Eu3+ doped one appears at 90 °C, 230 °C, and 390 °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 (r2:0.999) 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. © 2022 Elsevier Ltd