Browsing by Author "Ekdal Karali E."
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Item Adsorption of thorium (IV) ions by metal ion doped ZnO nanomaterial prepared with combustion synthesis: Empirical modelling and process optimization by response surface methodology (RSM)(Elsevier Ltd, 2021) Kaynar U.H.; Çam Kaynar S.; Ekdal Karali E.; Ayvacıkli M.; Can N.Environmental problems have reached enormous dimensions, driving efforts to remove and recycle waste from energy and industrial production. In particular, removing the radionuclide contamination that occurs as the nuclear industry grows is difficult and costly, but it is vital. Technologic and economical methods and advanced facilities are needed for the separation and purification of radioactive elements arising from the nuclear industry and uranium and thorium mining. With the adsorption method, which is the most basic separation and recovery method, the use of high-capacity nanomaterials has recently gained great importance in reducing the activity of the waste, reducing its volume by transforming it into solid form, and recovering and removing liquid radioactive wastes that might harm the ecological environment. This study aimed to determine the adsorption properties of metal ion-doped nano ZnO (nano-ZnO:Al) material synthesized by the microwave-assisted gel combustion method for the adsorption of thorium (IV) from aqueous media. First, characterization processes such as XRD, SEM, BET and zeta potential were performed to observe changes in the host ZnO adsorbent structure caused by the doping process. Later, this was optimized via the response surface method (RSM), which is widely used in the characterization of the adsorption properties of thorium (IV) from aqueous solutions. Such characterization is commonly used in industrial research. We tested how pH (3–8), temperature (20–60 °C), Th (IV) concentration (25–125 mg/L) and adsorbent amount (0.01–0.1 g) affect adsorption efficiency. The best possible combinations of these parameters were determined by RSM. It was calculated by RSM that the design fits the second order (quadratic) model using the central composite design (CCD) for the design of experimental conditions. R2 and R2 adjusted values from the parameters showing the model fit were 0.9923 and 0.9856, respectively. According to the model, the experimental adsorption capacity was 192.3 mg/g for the doped-ZnO nanomaterial under the theoretically specified optimum conditions. Also, the suitability of Th (IV) adsorption to isotherms was examined and thermodynamic parameters were calculated. © 2021 Elsevier LtdItem Thermal quenching and evaluation of trapping parameters of thermoluminescence glow-peaks of beta irradiated NaBaBO3: Tb3+ for TLD applications(Elsevier B.V., 2022) Oglakci M.; Topaksu M.; Alajlani Y.; Can N.; Ekdal Karali E.Here, 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 β irradiation at various doses showed glow peaks at about 188 °C, and 288 °C with a heating rate of 2 °Cs−1. The trapping parameters (E, b, s) related with the prominent the TL glow peaks were determined using Tm-Tstop, 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 Tm-Tstop. 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 × 102, and W = 0.31 ± 0.03 eV, C = 3.11 × 102, respectively. The current results indicate that the NaBaBO3:Tb3+ phosphor is a suitable option in radiation dosimetry for environmental monitoring. © 2022 Elsevier B.V.Item Synthesis and beta particle excited thermoluminescence of BaSiF6 phosphor(Elsevier Ltd, 2022) Souadi G.; Akca-Ozalp S.; Ekdal Karali E.; Kaynar U.H.; 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 °C. Tm-Tstop, 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. © 2021Item Synthesis, characterization and enhanced photoluminescence and temperature dependence of ZrO2:Dy3+ phosphors upon incorporation of K+ ions(Elsevier Ltd, 2023) Can N.; Coban M.B.; Souadi G.; Kaynar Ü.H.; Ayvacikli M.; Garcia Guinea J.; Ekdal Karali E.This study reports the successful synthesis and comprehensive characterization of ZrO2:Dy3+ phosphors with the incorporation of K+ ions. The introduction of Dy3+ and K+ in the ZrO2 lattice as lanthanide activators demonstrates its potential as an efficient host material. The structural integrity of ZrO2 remains unaltered following the doping process. Fourier-transform infrared spectroscopy (FTIR) analysis confirms the presence of Zr-O and O-H stretching, along with H2O bending modes in the phosphor sample. The wide luminescence band seen at 460 nm is attributed to luminescence defects in the ZrO2 induced by oxygen, and the presence of water molecules. Photoluminescence (PL) spectra analysis reveals pronounced emission peaks at 491 and 578 nm, corresponding to 4F9/2 → 6H15/2 and 4F9/2 → 6H13/2 transitions, respectively, upon excitation at 349 nm. Optimizing the Dy3+ doping concentration to 0.4 wt% and achieving a critical distance of 31.82 Å resulted in efficient energy transfer. Notably, co-doping K+ as a charge compensator significantly enhances the luminescence intensity. Moreover, at lower temperatures, direct excitation of Dy3+ ions through our pump wavelength, coupled with exciton-mediated energy transfer, leads to a remarkable increase in PL intensity. Tailoring the doping concentrations effectively shifts the emission spectrum of the phosphor mixture, aligning with the standard white light illumination coordinates (0.333, 0.333). This property positions the material as a promising candidate for applications in white light-emitting diodes (WLEDs) and various high-quality lighting applications. The enhanced photoluminescence and temperature dependence observed in ZrO2:Dy3+ phosphors upon the incorporation of K+ ions pave the way for their potential utilization in advanced luminescent devices. © 2023 Elsevier Ltd and Techna Group S.r.l.Item Enhancement of luminescence and thermal stability in Eu3+-doped K3Y(BO2)6 with Li+ and Na+ co-doping(Elsevier B.V., 2024) Kaynar U.H.; Aydin H.; Altowyan A.S.; Hakami J.; Coban M.B.; Ayvacikli M.; Ekdal Karali E.; Canimoglu A.; Can N.Eu3+-doped and Li+/Na+ co-doped K3Y(BO2)6 (KYBO) phosphors were synthesized through a microwave-assisted sol–gel method, and their structural and photoluminescent (PL) characteristics were examined. X-ray diffraction (XRD) and Rietveld refinement confirm effective dopant incorporation and preservation of the crystalline structure. Fourier Transform Infrared (FTIR) spectroscopy indicates the maintenance of the borate structure, confirming the structural integrity of the phosphors upon doping. The addition of Li+ and Na+ co-dopants notably enhances luminescent efficiency and thermal stability, making these phosphors promising candidates for solid-state lighting (SSL) applications. PL analysis reveals strong red emission peaks at 612 nm, attributed to the 5Do → 7F2 transition of Eu3+ ions. The study indicates that electric dipole-quadrupole interactions are the primary mechanism for energy migration, with a critical distance of approximately 22.68 Å. This mechanism contributes to concentration quenching at higher doping levels. High temperature PL measurements indicated an activation energy of 0.1389 eV for thermal quenching in the Li+ co-doped sample. Additionally, the Na+ co-doped sample exhibited an abnormal thermal stability behavior, with an even higher activation energy of 0.2536 eV. This suggests that Na+ co-doping significantly enhances the thermal resilience of the phosphor, making it more suitable for high-power light-emitting applications that operate under extreme conditions. CIE chromaticity diagrams highlight the potential for optimizing Eu3+ doping levels, combined with Li+ and Na+ co-doping, to improve luminescent performance and thermal stability for advanced SSL applications. © 2024 The Society of Powder Technology JapanItem Corrigendum to “Enhancement of luminescence and thermal stability in Eu3+-doped K3Y(BO2)6 with Li+ and Na+co-doping” [Adv. Powder Technol. 35 (2024) 104695] (Advanced Powder Technology (2024) 35(11), (S0921883124003716), (10.1016/j.apt.2024.104695))(Elsevier B.V., 2024) Kaynar U.H.; Aydin H.; Altowyan A.S.; Hakami J.; Coban M.B.; Ayvacikli M.; Ekdal Karali E.; Canimoglu A.; Can N.The authors regret in the original publication, the name of one of the corresponding authors was incorrectly listed as A.S. Altowyan. The correct name should be Abeer S. Altowyan. The authors would like to apologise for any inconvenience caused. © 2024 The Society of Powder Technology Japan