Browsing by Author "Yüksel M."
Now showing 1 - 9 of 9
Results Per Page
Sort Options
Item Luminescence studies of zinc borates activated with different concentrations of Ce and La under x-ray and electron excitation(Elsevier Ltd, 2017) Küçük N.; Ayvacikli M.; Akça S.; Yüksel M.; Guinea J.G.; Karabulut Y.; Canimoglu A.; Topaksu M.; Can N.Several ZnB2O4 powder samples having dopants concentrations of 0.1, 0.01, 0.04 wt% Ce and La were prepared using the nitric acid method via the starting oxides. Several complementary methods such as powder X-ray diffraction (XRD), thermal analyses environmental scanning electron microscopy (ESEM), Radioluminescence (RL) and Cathodoluminescence (CL) techniques were used. Unique luminescence properties of Ce doped ZnB2O4 powder samples are reported for the first time. A new luminescence bands appearing in red part of the spectrum and having all the characteristics of Ce3+ were obtained from RL results. Changing the Ce and La concentration of 0.01–0.1 wt% leads to an increase in RL and CL intensities of Ce3+ and La3+ ions and also CL emission spectra of ZnB2O4 show gradual shift towards longer wavelength. When we compare the luminescence intensity of the samples it is seen that Ce doped ZnB2O4 has the highest intense whereas La doped ZnB2O4 has the lowest one. However, emission spectra of both Ce and La doped samples kept unchanged. © 2017 Elsevier LtdItem Thermoluminescence behavior of Sm3+ activated ZnB2O4 phosphors synthesized using low temperature chemical synthesis method(Elsevier B.V., 2018) Bulcar K.; Dogan T.; Akça S.; Yüksel M.; Ayvacikli M.; Karabulut Y.; Kucuk N.; Canimoglu A.; Can N.; Topaksu M.This study is mainly centered on thermoluminescence (TL) behavior under beta excitation at room temperature (RT) of Sm3+ activated ZnB2O4 phosphors synthesized by low temperature chemical synthesis method. The prepared phosphors were characterized by the X-ray powder diffraction (XRD) method. The effects of dopant concentration, beta radiation dose (0.115–69 Gy) and heating rate (0.5–10 °C/s) on TL intensity of Sm3+ doped ZnB2O4 phosphors and reproducibility are investigated using a lexsyg smart TL/OSL reader system. The activation energy values, E obtained from the analysis of the TL glow curve were calculated with initial rise (IR) method and peak shape (PS) method over the deconvoluted glow curves. The Ea–Tstop and CGCD methods indicated that the glow curve of this phosphor is the superposition of at least six components, which were called to as P1–P6, in the temperature range between RT and 400 °C. The results reveal that 2% Sm3+ doped ZnB2O4 gives optimum TL response, the relative intensity of the glow peak increases linearly with increase of beta dose and, the peaks of TL glow curves shift towards the higher temperature side with increase in heating rate as the total area under the glow peak remains the same. The maximum variation of reproducibility for ten successive irradiation cycles of 20.7 Gy is less than 3% from the average value and the sample doped 2% Sm3+ shows a good stability for the reusability. Additionally, the results obtained from IR and PS methods indicates that the complex glow curve is composed of six distinguishable peaks. © 2018 Elsevier B.V.Item Preparation and photoluminescence properties of aluminate phosphors produced by combustion synthesis(Elsevier Ltd, 2018) Halefoglu Y.Z.; Yüksel M.; Derin H.; Can N.; Topaksu M.; Ozturk E.; Karacaoğlu E.In this work, Eu, Nd co-doped MAl2O4:Eu, Nd (M = Ca, Sr, Ba) phosphors were synthesized at low temperatures (550 °C) by the combustion method. The crystallinity of the phosphors was monitored by X-ray diffraction (XRD) and the morphology was examined by scanning electron microscope (SEM). Synthesis of phosphors, the effect of lanthanide concentrations on light emission intensity and duration investigated by using photoluminescence (PL) measurements. Narrow orange-red emissions from 500 to 750 nm in the PL spectra are assigned to 5D0 → 7Fj (j = 0,1,2,3,…) transitions of Eu3+ ion. In contrast, the broad luminescence band of the samples in the range of 400–500 nm are attributed to the 5d-4 f transitions of Eu3+ ion in the same host materials. Investigated the effects of radiation on the severity of the trap depths of these structures. The decay curves of these phosphors show how long the phosphors are attenuated. Thermoluminescence (TL) glow curves have been recorded from room temperature to 300 °C at a constant heating rate of 1 °C/s after preheat process at 130 °C for 10 s using lexsyg smart TL/OSL reader. Nd3+ trap levels can be thought of as the lanthanide element that causes long composition in the phosphorescence structure at room temperature. © 2018 Elsevier LtdItem Thermoluminescence dose and heating rate dependence and kinetic analysis of ZnB2O4:0.05Dy3+ phosphor(Elsevier B.V., 2018) Balci-Yegen S.; Yüksel M.; Kucuk N.; Karabulut Y.; Ayvacikli M.; Can N.; Topaksu M.The intention of this study is to explore the thermoluminescence (TL) behavior of beta irradiated 5% Dy3+ doped zinc borate (Zn(BO2)2:0.05Dy3+) phosphor prepared using the nitric acid method. The TL glow curve corresponding from 1 Gy to 80 Gy beta irradiation (preheated at 140 °C) shows a maxima at c.a. 180 °C. The dependence of heating rate was tested and found out that thermal quenching effect was dominating on TL glow curves as the heating rate increases. The dose response of the phosphor material exposed to beta radiation was investigated. Deconvolution was applied using the peak fit method on the glow curve for optimized conditions. Also peak shape (PS), various heating rates (VHR) and computerized glow curve deconvolution (CGCD) methods were used to evaluate the trapping level parameters, namely trap depth (E), frequency factor (s) and order of kinetics (b) associated with the main glow curve in Zn(BO2)2:0.05Dy3+ phosphor after beta irradiation of 20 Gy. The values of trap depth corresponding with the TL glow peak at 180 °C were found to be 0.93 eV, 0.92 ± 0.05 and 1.05 ± 0.02 respectively. Furthermore W and c parameters characterizing thermal quenching based on the Mott-Seitz theory were determined as 0.31 ± 0.04 eV and 162.55. The TL mechanism appears more likely to get second order kinetics, suggesting the probability of re-trapping of charge carriers by emptied traps. © 2017 Elsevier B.V.Item 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(Elsevier Ltd, 2019) 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 °C and 192 °C were monitored at a heating rate of 2 °Cs−1. We observed anomalous heating rate effect for the peak centered at 192 °C whilst TL intensity of the peak at 81 °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 Tmax−Tstop 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. © 2019 Elsevier B.V.Item 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.Item Thermoluminescence of β-particle induced Bern-4M muscovite(Elsevier Ltd, 2020) Portakal-Uçar Z.G.; Akca S.; Balci-Yegen S.; Yüksel M.; Dogan T.; Souadi G.O.; Parlak O.; Topaksu M.; Can N.Bern-4M muscovite from Switzerland was investigated via X-ray diffraction (XRD), energy dispersive spectrometer (EDS) and thermoluminescence (TL). Muscovite has the theoretical formula KAl2(AlSi3O10)(FOH)2, or (KF)2(Al2O3)3(SiO2)6(H2O). Chemical analysis of the muscovite sample was carried out using EDS for major oxides. The results indicate that muscovite includes oxygen (59.1%), silicon (18.86%), and aluminum (15.22%) as major elements and contains low concentrations of potassium, magnesium, and sodium. In standard muscovites potassium use to be 10% and oxygen 47%, probably the sample was strongly lixiviated before the analysis. The thermoluminescence spectrum exhibits a wide glow peak located at 250 °C with a shoulder peak at high temperature region. Trap depth and frequency factor were calculated using Hoogenstraaten's method and found to be 1.16 eV and 1.4 × 1010 s−1, respectively. Reproducibility test indicated that the values within ±5% were obtained after 15 cycles. The storage time experiments were performed for different time periods up to 1 week for dark fading. © 2020 Elsevier LtdItem Structural and luminescence characterization of Ce3+ and Mn2+ co-activated zinc silicate nanocrystal obtained by gel combustion synthesis(Elsevier Ltd, 2021) Portakal-Uçar Z.G.; Oglakci M.; Yüksel M.; Ayvacıklı M.; Can N.The structural, morphological, and luminescence properties, including photoluminescence (PL) and thermoluminescence (TL), of newly produced Zn2SiO4 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 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 °C preheat are performed at a linear heating rate of 2 °C/s from room temperature (RT) to 500 °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 TM–Tstop analysis and computerized glow curve deconvolution (CGCD) methods. © 2020 Elsevier LtdItem Thermoluminescence glow curve analysis of Ca3Y2B4O12 phosphor prepared using combustion method(Elsevier Ltd, 2022) Hakami J.; Sonsuz M.; Kaynar U.H.; 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 °C at a heating rate of 2 °Cs−1. Significant glow peaks were observed at 64, 116, and 242 °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. © 2022 Elsevier Ltd