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Öğe 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 Science Sa, 2019) Dogan, T.; Akca, S.; Yuksel, M.; Kucuk, N.; Ayvacikli, M.; Karabulut, Y.; Canimoglu, A.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 degrees C and 192 degrees C were monitored at a heating rate of 2 degrees Cs-1. We observed anomalous heating rate effect for the peak centered at 192 degrees C whilst TL intensity of the peak at 81 degrees 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 T-max - T-stop 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. (C) 2019 Elsevier B.V. All rights reserved.Öğe Luminescence studies of zinc borates activated with different concentrations of Ce and La under x-ray and electron excitation(Pergamon-Elsevier Science Ltd, 2017) Kucuk, N.; Ayvacikli, M.; Akca, S.; Yuksel, M.; Garcia Guinea, J.; Karabulut, Y.; Canimoglu, A.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.Öğe Structural and spectroscopic properties of LaAlBO3 doped with Eu3+ ions(Pergamon-Elsevier Science Ltd, 2019) Halefoglu, Yusuf Ziya; Oglakci, M.; Yuksel, M.; Canimoglu, A.; Topaksu, M.; Can, N.In this study, we performed X-ray diffraction (XRD) and environmental scanning electron microscope (ESEM) techniques to examine the structure and morphological observation of the samples and thermoluminescence (TL) experiments to extract the trapping parameters and dosimetric properties of LaAlBO3 phosphors doped with Eu at various doping concentrations. Diffraction patterns of obtained sample were well consistent JCPDS card No 98-009-7945, indicating the formation of pure phase. The TL kinetic parameters were estimated by CGCD software. TL glow curves of LaAlBO3:Eu3+ consist of 12 trap levels and exhibited dominantly first order kinetics. Photoluminescence (PL) emission was observed in the range 400-800 nm for LaAlBO3 phosphor doped with Eu3+. The dominant emission of Eu3+ corresponding to the electric dipole transition D-5(0) -> F-7(2) is located at 616 nm. The sharp emission properties exhibited demonstrate that the LaAlBO3 is a suitable host for rare-earth ion doped phosphor material. It is observed that for the variable concentration of Eu3+ on PL studies, the PL intensity augments with increase in the dopant concentration and the concentration quenching was found after 1 mass% of Eu3+. The PL experimental results reveal that LaAlBO3:Eu3+ phosphor as an red emitting phosphor may be promising luminescence materials for the optoelectronic applications.Öğe Thermoluminescence properties of beta particle irradiated Ca3Al2O6 phosphor relative to environmental dosimetry(Elsevier, 2020) Bakr, M.; Portakal-Ucar, Z. G.; Yuksel, M.; Kaynar, U. H.; Ayvacikli, M.; Benourdja, S.; Canimoglu, A.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 degrees C in the heating rate of 2 degrees C/s. The glow curves of Ca3Al2O6 sample exposed to different beta doses (0-200 Gy) exhibited a significant glow peak at about 184 degrees 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.
