Yazar "Portakal, Z. G." seçeneğine göre listele
Listeleniyor 1 - 4 / 4
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe A study on thermoluminescence behaviour of Eu doped LaB3O6 irradiated with beta particles(Pergamon-Elsevier Science Ltd, 2020) Halefoglu, Y. Z.; Oglakci, M.; Portakal, Z. G.; Akca, S.; Souadi, G. O.; Canimoglu, A.; Topaksu, M.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.Öğe Doping Sm3+ into ZnB2O4 phosphors and their structural and cathodoluminescence properties(ELSEVIER SCIENCE SA, 2018) Kucuk, N.; Bulcar, K.; Dogan, T.; Garcia Guinea, J.; Portakal, Z. G.; Karabulut, Y.; Can, N.In this study, ZnB2O4:xSm(3+) (0.01 <= x <= 0.05 mol) powder phosphors have been synthesized by low temperature chemical synthesis method. The structure and morphological observation of the phosphor samples were systematically monitored by X-ray powder diffraction (XRD) and environmental scanning electron microscope (ESEM) coupled to an energy dispersive X-ray spectrometer (EDS). The all diffraction peaks are well assigned to standard data card (PDF#39-1126). Emission properties of the samples were explored using light emission induced by an electron beam (i.e cathodoluminescence, CL) at room temperature (RT). When excited with electron beam, CL spectral measurements of scrutinized phosphors exhibit orange-red luminescence at 572 nm, 606 nm and 658 nm due to various transition from ground state to H-6(5/2),H-6(7/2) and (4)G(5/2) states, respectively. The transition (4)G(5/2) -> H-6(7/2) located at 606 nm can occur as hypersensitive transition having the selection rule Delta J = +/- 1. The observed peaks are in the region of yellow reddish light of Sm3+. Experimental results verify that the optimum Sm3+ content in terms of intense luminescence for this series of phosphors was 2%. Beyond 2% of Sm3+ ions concentration, luminescence quenching occurs due to an enhanced probability of the energy transfer from one Sm3+ to another that matches in energy via cross-relaxation and dipole-dipole interactions according to Dexter theory. A suitable energy transfer model between two adjacent Sm3+ ions in the ZnB2O4 phosphors was accomplished by the electric dipole-dipole interaction. The critical transfer distance (R-c) for non-radiative energy transfer was found to be 21.52 angstrom at 2 mol % Sm3+ doped ZnB2O4. Additionally, thermoluminescence (TL) glow curves of undoped and Sm activated ZnB2O4 under beta irradiation of 10 Gy are also discussed here. (C) 2018 Elsevier B.V. All rights reserved.Öğe Luminescence characteristics of Dy3+ incorporated zinc borate powders(Elsevier, 2017) Portakal, Z. G.; Dogan, T.; Yegen, S. Balci; Kucuk, N.; Ayvacikli, M.; Garcia Guine, J.; Canimoglu, A.We have synthesized powder samples of Dy3+ doped zinc borates by nitric acid method. X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) techniques were utilized to examine the structure and morphological observation of the samples. Luminescence characteristics of the samples were investigated using room temperature (RT) cathodoluminescence (CL) and radioluminescence (RL) measurements under excitation with electron beam and X-rays, respectively. The presence of small amounts of Dy3+ incorporated in the host lattice does not affect the structure of the prepared samples remarkably. The CL and RL spectra showed the characteristic emissions of Dy3+ (magnetic dipole transition of F-4(9/2) -> H-6(11/2) Blue; forced electric dipole transition of F-4(9/2) > H-6(13/2) Yellow; F-4(9/2) -> H-6(1/2) Red; F-4(9/2) -> (H-6(9/2) + H-6(11/2)) infrared). Thermoluminescence (TL) method was also conducted to determine the effects of various concentrations of Dy3+ on the TL properties of ZnB2O4. The TL glow peak of beta irradiated ZnB2O4:Dy3+ phosphors is a well-defined and centered at around 96 degrees C with a constant heating rate of 2 degrees C/s. Initial rise method was employed to observed main TL glow curve for determining the activation energy (E-a) and the frequency factor (s).Öğe Thermoluminescence properties of Tb doped Mg2SiO4 after beta irradiation(Elsevier, 2019) Akca, S.; Portakal, Z. G.; Dogan, T.; Kucuk, N.; Canimoglu, A.; Topaksu, M.; Can, N.In this study, we performed Thermoluminescence (TL) experiments to extract the trapping parameters and dosimetric properties of Tb-doped Mg2SiO4 phosphors. Glow peaks located at 193, 270, and 350 degrees C were observed in the glow curve but the peak at 193 degrees C was especially investigated as a dosimetric peak in this study. We also observed an anomalous heating rate effect in which the maximum TL intensity of the glow curve augmented with an increasing heating rate. The computerized glow curve deconvolution (CGCD) method, initial rise (IR) and Hoogenstraaten's method were used to determine the activation energies of associated trapping centers for both BSL-TL 365 nm and IRSL-TL wideband blue filters. The TL characteristics of this phosphor indicate that Mg2SiO4:Tb3+ could be a promising material for dosimetric applications. Efforts should be made to improve the fading behaviour by adding other activators as co-dopants.
