Browsing by Author "Çetin A."
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Item Optical properties of Tb implantation into ZnO(2007) Çetin A.; Kibar R.; Ayvacikli M.; Tuncer Y.; Buchal Ch.; Townsend P.D.; Karali T.; Selvi S.; Can N.ZnO [0001] single crystals were implanted at room temperature with 400 keV Tb+ ions at fluences in the range of 1 × 1016-2 × 1017 ions/cm2. Zinc oxide was chosen because of its potential for photonic applications as a semiconductor with high radiation resistance. After implantation and post-irradiation annealing, optical absorption was measured in a UV-VIS-NIR range and radioluminescence spectra were recorded at room temperature. Emission signals were generated by the Tb+ ion implants and intrinsic emission of the ZnO matrix were observed. The implant signal intensities were comparable with the host radioluminescence, even though the implants modify the surface of the crystal. It is suggested that the presence of Tb at high concentration generates stresses which influence the bulk material and also potentially forms precipitates or nanoparticles in the near surface region. Overall ion implantation of ZnO results in strongly modified luminescence. © 2007.Item Advanced oxidation protein products, ferrous oxidation in xylenol orange, and malondialdehyde levels in thyroid cancer(2007) Kosova F.; Çetin B.; Akinci M.; Aslan S.; Ari Z.; Sepici A.; Altan N.; Çetin A.Aims and Background: The oxidation of protein plays an essential role in the pathogenesis of an important number of degenerative and cancer diseases, which is now widely recognized. The aim is to examine advanced oxidation protein products (AOPPs), lipid peroxidation products malondialdehyde (MDA), and ferrous oxidation in xylenol orange (FOX) in blood samples of papillary thyroid cancer patients compared with healthy controls to determine the oxidation status and the change after thyroidectomy. Methods: Thirty-five female thyroid cancer patients who underwent total thyroidectomy and 39 female control subjects were included into this study. Prethyroidectomy and postthyroidectomy, AOPP, FOX, and MDA levels were studied. Results: Prethyroidectomy AOPP, FOX, and MDA levels were significantly higher compared to control (P < .05). In postthyroidectomy AOPP, FOX, and MDA levels were significantly decreased compared with prethyroidectomy levels (P < .05). However, postthyroidectomy levels on the 20th day were still significantly higher, compared to control subjects (P < .05). Conclusion: In conclusion, all of AOPP, FOX, and MDA levels that are markers of protein oxidation and lipid hyperoxidation may induce thyroid cancer development and begin to decrease after thyroidectomy. © 2007 Society of Surgical Oncology.Item Luminescent, optical and color properties of natural rose quartz(2007) Kibar R.; Garcia-Guinea J.; Çetin A.; Selvi S.; Karal T.; Can N.Rose quartz is an interesting mineral with numerous impurities that have been studied by scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD), cathodoluminescence (CL), ion beam luminescence (IBL), radioluminescence (RL), thermoluminescence (TL) and optical absorption (OA). After HF etching, rose quartz from Oliva de Plasencia (Caceres, Spain) shows under SEM the presence of other silicate phases such as dumortierite [Al6.5 - 7 (BO3) (SiO4)3 (O, OH)3]. The OA spectrum of rose quartz suggests that these inclusions are the cause of coloration of rose quartz. The luminescence (CL, IBL, RL, TL) spectra behavior, at both room temperature and lower, confirms that the ∼ 340 nm emission could be associated with Si-O strain structures, including non-bridging oxygen or silicon vacancy-hole centers; the observed ∼ 400 nm emission could be associated with recombination of a hole trapped adjacent to a substitutional, charge-compensated aluminum alkali ion center; the ∼ 500 nm emission could be associated with substitutional Al3 + and the ∼ 700 nm peak could be associated with Fe3 + point defects in Si4 + sites. These results suggest that, while defect properties of rose quartz are not greatly dissimilar to those of purer forms of quartz and silica, further research seems necessary to determine criteria for the evolution of the newly-formed self-organized microstructures in the rose quartz lattice under irradiation. © 2007 Elsevier Ltd. All rights reserved.Item A comparative study of single and duplex treatment of martensitic AISI 420 stainless steel using plasma nitriding and plasma nitriding-plus-nitrogen ion implantation techniques(2007) Çetin A.; Tek Z.; Öztarhan A.; Artunç N.Martensitic AISI 420 is a high chromium mold steel which is suitable for tools for molding corrosive plastics. In this study, micro-pulsed plasma nitriding and plasma nitriding + nitrogen ion implantation techniques have been used to improve the surface hardness and tribological properties of AISI 420 substrates. Firstly polished-AISI 420 samples are nitrided at 530 °C for 15 h at a pressure of 10 mbar. Then nitrided samples are implanted with nitrogen ions to a dose of 2 × 1017 ions/cm2. Mechanical characterization of both of the modified and unmodified samples has been carried out by means of nano-hardness, wear resistance, friction coefficient and surface roughness measurements. It is found that the nano-hardness, wear resistance, friction coefficient and surface roughness values improve 1.6, 3.5, 1.4 and 10 times for plasma nitrided samples, and 2.0, 4.6, 1.1 and 9 times for plasma nitrided-plus-N+ ion implanted samples, respectively, in comparison with unmodified AISI 420 samples. Both the plasma nitriding process and the plasma nitriding-plus-N+ ion implantation treatment sample results are also compared. The improvement of the samples modified using nitriding-plus-N+ ion implantation process is found to be better than that of samples modified by the nitriding process. © 2007 Elsevier B.V. All rights reserved.Item Oxidant/antioxidant balance in patients with thyroid cancer(2008) Akinci M.; Kosova F.; Çetin B.; Sepici A.; Altan N.; Aslan S.; Çetin A.Purpose: To compare the antioxidant enzyme activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and the levels of lipid peroxidation product malondialdehyde (MDA) in blood samples of thyroid cancer patients compared to healthy controls. Methods: 43 control subjects (mean age 44±13 years) and 43 patients (43±13 years) presented with multinodular goiter whose fine needle aspiration revealed malignant cytology were included into this study. The SOD, MDA and GSH-Px activities were measured in control subjects, and before/20 days after thyroidectomy in thyroid cancer patients. Results: SOD activities of pre-thyroidectomy, post-thyroidectomy and control groups were not different (p<0.05). Before thyroidectomy GSH-Px activities were lower (p<0.05) and MDA levels were higher (p<0.05) than the control group. In post- thyroidectomy, GSH-Px activity (p<0.05) increased, and MDA levels (p<0.05) decreased compared to prethyroidectomy levels. After thyroidectomy GSH-Px activity was significantly higher than the control group (p<0.05). Although post-thyroidectomy MDA levels significantly decreased, they were still higher than the control group (p<0.05). Conclusion: The superoxide dismutase does not seem to change with thyroid cancer and thyroidectomy but both antioxidant glutathione peroxidase and lipid peroxidation product malondialdehyde do. These preliminary findings may point out oxidant/antioxidant imbalance associated with thyroid cancer.Item Cathodoluminescence response from rare earth doped Bi4Ge 3O12(Elsevier B.V., 2009) Kibar R.; Çetin A.; Tuncer Y.; Uysal S.; Townsend P.D.; Canimoglu A.; Karali T.; Can N.Room and low temperature cathodoluminescence (CL) of rare earth doped Bi4Ge3O12 (BGO) has been recorded. Luminescence signals noted in the wavelength range (300 - 800 nm) include intrinsic broad emission bands and signals related to Eu3+, Nd3+, and Tm3+. CL measurements made on Bi4Ge3O 12 (BGO) doped with rare earth ions are reported for the temperature range 40 to 300 K with different CL excitation modulation frequencies. Dopant levels used in the present study are 1.1, 0.4, and 0.3 wt% Nd, 0.4 wt% Tm and 3 ppm Eu. All dopant levels exhibited different CL spectra with evidence for lines due to the rare-earth dopants intra-4f transitions. The temperature dependence of the intensity of the emission band is discussed.Item Effect of thermal treatment on linear optical properties of Cu nanoclusters(2009) Kibar R.; Çetin A.; Can N.Silica glass was implanted with 50 keV Cu+ ions at various fluences from 6×1015 to 8×1016 ions/cm2 and thermally-annealed in air between room temperature to 1200 °C. UV/visible spectroscopy measurements reveal absorption bands at characteristics surface plasmon resonance (SPR) frequencies, signifying the formation of copper colloids in silica, even without thermal treatments. Such copper nanoclusters can be attributed to the relatively high mobility of copper atoms, even at ambient conditions. Using the equation derived from the framework of free-electron theory, the average radii of the Cu particles were found to be in the range 2-4 nm from the experimental surface plasmon absorption peaks. Radioluminescence (RL) spectra exhibited broad bands at 410 and 530 nm, associated with the presence of Cu+ ions in the as-implanted samples. The effect of thermal annealing in air on absorption and emission spectra of these Cu-implanted samples, as well as the formation of copper nanoclusters from original Cu+ ions, is discussed. © 2008 Elsevier B.V. All rights reserved.Item An experimental study on the linear differential scattering coefficients of the GaAs, n- and p-type Si(Elsevier, 2009) Içelli O.; Çankaya G.; Çetin A.The linear differential scattering coefficients at 60 keV have been measured for GaAs, p-Si and n-Si semiconductors at seven angles ranging from 60° to 120° at intervals of 10°. The results have been compared with relativistic and non-relativistic theoretical values. The objective of this work is to seek evidence whether there is a relationship between the LDSC and the scattering angle. The LDSCs have been measured with energy-dispersive X-ray fluorescence spectroscopy (EDXRF) for wafers as GaAs, n- and p-type Si. This is the first time the LDSCs have been measured at <100 keV energies, so there is no comparable findings reported in the literature. © 2009 Elsevier B.V. All rights reserved.Item Amethyst and morion quartz gemstone raw materials from Turkey: Color saturation and enhancement by gamma, neutron and beta irradiation(2010) Hatipoǧlu M.; Helvac C.; Kibar R.; Çetin A.; Tuncer Y.; Can N.Color-enhancement investigations without using heating treatment from dull or pale to ideal saturation and/or changes to the formation of the rarer attractive colors are widely conducted to revalue abandoned gem material sources in the world. Such an investigation is carried out on pale or dull purple-colored amethyst and smoky-colored morion samples, which are two important gem species of the crystalline quartz (SiO2) mineral that are currently abandoned in natural deposits in Turkey because of their unattractive coloration. The results of color enhancements observed on these samples, after irradiation with artificial gamma, neutron and beta beams, were examined by comparing with samples with the ideal color saturation and also with colorless samples, using optical absorption (OA) and radioluminescence (RL) spectroscopy. The ICP-AES analyses reveal that the main impurity elements of over 100ppm in abundance in these quartz species are aluminum, iron and titanium for amethyst, and aluminum, iron, titanium and manganese for morion. The OA spectra indicate that vivid purple coloration of amethyst is due to the transmittance at about 395-420nm band gap as a result of absorbance peaks at 375, 480 and 530nm. These absorbances may be related to the unusual oxidized small proportions of certain impurity ions, after being exposed mainly to gamma irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Fe(IV) from the total iron, respectively. However, the RL spectroscopy of amethyst samples before and after they were exposed to artificial gamma, neutron and beta radiation beams demonstrates that the ions most affected by irradiation are Fe(IV) first and Al(IV) and Ti(V) second, and these ions represent the RL peaks at 600, 720 and 495nm, respectively. The OA spectra indicate that dark smoky coloration in morion is due to a lack of transmittance at the visible region as a result of the absorbance peaks at 375, 450-490, 620 and 730nm. These absorbances also may be related to the unusual oxidized small proportions of certain impurity ions by irradiation, such as Al(IV) from the total aluminum, Ti(V) from the total titanium and Mn(III) from the total manganese, respectively. In addition, the buoyancies of these absorbance peaks in the visible region produce the color hues between light smoky and dark smoky colorations in morion samples. These oxidized ion states are more resistant and stable against environmental destructive conditions in comparison with amethyst. Thus, the dark smoky coloration of morion becomes dull or pale after relatively longer periods. But, the RL spectroscopy of morion before and after being exposed to gamma, neutron and beta irradiation beams demonstrates that the most induced ions from the irradiation are Mn(III) and Al(IV) first and Ti(V) second. These ions represent the RL peaks at about 400, 720 and about 500nm, respectively. © 2010 Taylor & Francis.Item Thermal properties of gem-quality moganite-rich blue chalcedony(2010) Hatipoǧlu M.; Tuncer Y.; Kibar R.; Çetin A.; Karal T.; Can N.In this study, thermal properties and thermal decompositions of dehydration behaviour of gem-quality translucent blue chalcedonies, without banding or crystalline centre structure, from the Sarcakaya-Eskiehir region in Turkey were studied by means of X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometry (ICP-AES), Fourier transform infrared (FT-IR), thermoluminescence (TL), and simultaneously two thermal analyses of (DTA/TGA) spectroscopy. X-ray diffraction patterns of the blue chalcedony indicate the presence of two important chalcedonic silica phases with overlapped peaks at 4.26, 3.34, 2.28, 2.13, 1.82, 1.54, 1.38, and 137 . During heating from the room temperature to 300 °C, the thermoluminescence pattern of the blue chalcedony shows a characteristic peak at 210 °C. This peak may be due to unusually high traces of the impurities S, Th, Tl, U, and W. During heating from the room temperature to 1400 °C, the TGA pattern of the blue chalcedony indicates that the weight loss is due to the silanol water loss only, and that this loss occurs in a wide temperature range between about 170 and 954 °C. In addition, after making some corrections concerning the artefact mass gain, being due to the drift with buoyancy effect of the atmosphere in its TGA curve, the moganite-rich blue chalcedony shows a relatively lower mass loss of 0.202%. The DTA pattern of the blue chalcedony displays both endothermic and exothermic behaviours because of silica phase transformations. There are one distinctive sharp endotherm and three weaker endotherms at 806 °C. In addition, there is one distinctive sharp exotherm and one weaker exotherm at 1270 °C. © 2010 Elsevier B.V. All rights reserved.Item Absorption and cathodoluminescence properties of Cu implanted SrTiO3(2010) Kibar R.; Çetin A.; Selvi S.; Can N.Single crystal of SrTiO3 (STO) has been implanted at room temperature with 200 and 400 keV Cu ions to doses ranging from 1×1016 to 1×1017 ions/cm2. The temperature cathodoluminescence (CL) of Cu implanted SrTiO3 has been studied in order to clarify the role of them in luminescence. Therefore CL measurements made on SrTiO3 implanted with metal ions are reported at 300 K with different excitation modulation frequencies. Room temperature ion implantation into surface layer changes low temperature CL signals both in terms of their relative intensities and also modifying the emission spectra. For such a large ion dose the unusual aspect is that the signals are still recognisable. The details of such changes and modifications of emission spectra are reported and discussed. A particularly important result is that the CL demonstrates that the implants cause bulk relaxations of the material that are apparent via the rear face CL. © 2009 Elsevier B.V. All rights reserved.Item Luminescence behavior and Raman characterization of jade from Turkey(2011) Tuncer Arslanlar Y.; Garcia-Guinea J.; Kibar R.; Çetin A.; Ayvacikli M.; Can N.Results are presented for the cathodoluminescence (CL), radioluminescence (RL) and thermoluminescence (TL) of jade from Turkey. Jade samples show broad band luminescence from green to red, which, using lifetime-resolved CL, reveals seven overlapping emissions, of which two are dominant. Green emission obtained using spatially resolved CL was associated with Mn2+ and emission bands centered near at 480 and 530nm were attributed to 3P0-3H4 and 1D2-3H4 transitions of Pr3+, respectively. Different shifts of the peak-wavelengths for 326 and 565nm were observed with varying jade compositions. The incorporation of the larger K ion causes non-linear variations of the cell dimensions and therefore changes in the Fe-O band distance. We suggest that stress of the jade structure can be linked to the luminescence emission at 326nm. Raman spectra have also been recorded in order to provide an unequivocal identification of the type of jade. The mechanism for the luminescence of the jade is considered. © 2011 Elsevier Ltd.Item Spectral, electron microscopic and chemical investigations of gamma-induced purple color zonings in amethyst crystals from the Dursunbey-Balkesir region of Turkey(2011) Hatipoǧlu M.; Kibar R.; Çetin A.; Can N.; Helvac C.; Derin H.Amethyst crystals on matrix specimens from the Dursunbey-Balkesir region in Turkey have five representative purple color zonings: dark purple, light purple, lilac, orchid, and violet. The purple color zonings have been analyzed with optical absorption spectra in the visible wavelength region, chemical full trace element analyses (inductively coupled plasma-atomic emission spectroscopy and inductively coupled plasma-mass spectroscopy), and scanning electron microscopic images with high magnification. It can be proposed that the production of the purple color in amethyst crystals is due to three dominant absorption bands centered at 375, 530, and 675nm, respectively. In addition, the purple color zonings are also due to four minor absorption bands centered at 435, 480, 620, and 760nm. X-ray diffraction graphics of the investigated amethyst crystals indicate that these crystals are composed of a nearly pure alpha-quartz phase and do not include any moganite silica phase and/or other mineral implications. Trace element analyses of the amethyst crystals show five representative purple color zonings, suggesting that the absorption bands can be mainly attributed to extrinsic defects (chemical impurities). However, another important factor that influences all structural defects in amethyst is likely to be the gamma irradiation that exists during amethyst crystallization and its inclusion in host materials. This gamma irradiation originates from the large underlying intrusive granitoid body in the region of amethyst formation. Irradiation modifies the valence values of the impurity elements in the amethyst crystals. It is observed that the violet-colored amethyst crystals have the most stable and the least reversible coloration when exposed to strong light sources. This situation can be related to the higher impurity content of Fe (2.50ppm), Co (3.1ppm), Ni (38ppm), Cu (17.9ppm), Zn (10ppm), Zr (3.9ppm), and Mo (21.8ppm). © 2011 Taylor & Francis.Item Luminescence behaviour of beryl (aquamarine variety) from Turkey(2012) Kati M.I.; Türemis M.; Keskin I.C.; Tastekin B.; Kibar R.; Çetin A.; Can N.Natural blue-green beryl from Turkey has been investigated using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and Cathodoluminescence (CL). Beryl has the chemical formula Be 3Al 2Si 6O 18 and is hexagonal with space group P6/mcc. Chemical analyses of the beryl sample utilised inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for major oxides and trace elements. It shows that the beryl sample is rich in Cs (531 ppm) and contains low concentrations of transition-metal ions, in total 2.29 wt.% Fe, 269 ppm Mn, V<5 ppm and Cr 20 ppm. Ideas on the origin of the green colour of this mineral are presented. The CL spectrum of the bulk sample display intense broad band emission from ∼360 to ∼800 nm. © 2012 Elsevier B.V. All rights reserved.Item Radioluminescence properties of copper-and terbium-implanted strontium titanate(2013) Arslanlar Y.T.; Kibar R.; Çetin A.; Canmoǧlu A.In this study, the effects of Cu and Tb implantation on the radioluminescence (RL) properties of unimplanted and Cu-and Tb-implanted SrTiO3 (STO) crystals were investigated. The changes induced by heavy ion implants of the surface clearly modify the initial strong RL signals seen near 400-750 nm. During heating there are step increases in intensity at the RL spectrum near 60, 40, and 82 K for unimplanted and Cu-and Tb-implanted samples, respectively. © 2013 Taylor and Francis Group, LLC.Item Electrical and optical properties of chalcedony and striped chalcedony(2013) Çetin A.; Okutan M.; Içelli O.; Yalçin Z.; San S.E.; Kibar R.; Pesen E.The electrical and optical properties of chalcedony (SiO2) and striped chalcedony are determined by the impedance and optical absorption spectroscopy techniques. The capacitance, impedance, dissipation factor and the complex dielectric constants are measured by the parallel plate technique in the voltage frequency range 100 to 10 MHz. The dissipation factor is measured as 1.2 and 0.7 for chalcedony and striped chalcedony respectively around 10 kHz. It is found that the striped chalcedony has a major complex broad band with two absorption bands that are centered at 225 and 275 nm. The chalcedony however, has a minor absorption band which is centered at 210 nm. © 2013 Elsevier Ltd. All rights reserved.Item Microstructure and Electrical Conductivity of ZnO Addition on the Properties of (Bi0.92Ho0.03Er0.05)2O3(Springer New York LLC, 2016) Ermiş I.; Çorumlu V.; Sertkol M.; Öztürk M.; Kaleli M.; Çetin A.; Turemiş M.; Arı M.The solid electrolyte is one of the most important components for a solid oxide fuel cell (SOFC). The various divalent or trivalent metal ion-doped bismuth-based materials exhibit good ionic conductivity. Therefore, these materials are used as electrolytes in the SOFC. In this paper, the samples of (Bi0.92−xHo0.03Er0.05)2O3 + (ZnO)x solutions with a 0 ≤ x ≤ 0.2 molar ratio are synthesized by the solid state reaction method. The detailed structural and electrical characterizations are investigated by using x-ray diffraction (XRD), alternating current electrochemical impedance spectroscopy, and scanning electron microscopy (SEM). The XRD patterns of all samples are indexed on a monoclinic symmetry with a P21/c space group. In addition, the rietveld parameters are determined by using the FullProf software program. The impedance measurements of the samples are obtained at the 1 Hz to 20 MHz frequency range. The impedance value of the pellets increases with temperature. Based on the impedance results, it is found that the contribution of grain (bulk) is more than a grain boundary in terms of conductivity, which permits the attribution of a grain boundary. The ionic conductivity decreases with an increasing amount of Zn contribution. The value of highest electrical conductivity among all samples is calculated as 0.358 S cm−1 at 800°C for undoped (Bi0.92Ho0.03Er0.05)2O3. © 2016, The Minerals, Metals & Materials Society.Item The radioluminescence and optical behaviour of nanocomposites with CdSeS quantum dot(Elsevier B.V., 2017) Keskin İ.Ç.; Türemiş M.; Katı M.İ.; Kibar R.; Şirin K.; Çipiloğlu M.A.; Kuş M.; Büyükçelebi S.; Çetin A.In this work, highly luminescent alloyed CdSeS QDs are successfully synthesized by two phase route method by using oleic acid (OA) as a surfactant. OA capped CdSeS QDs prepared in two different synthesis duration were compared in terms of luminescence and optical properties. The nanocomposites blended with CdSeS QDs which have highly luminescent efficiency in different ratios by Low Density Polyethylene (LDPE) and these nanocomposites were mainly investigated radioluminescence (RL) and optical properties (UV/VIS absorption). Structural, morphological, thermal properties of the nanocrystal and nanocomposites were examined using; XRD, FT-IR, TEM, SEM, TG-DTA techniques. OA capped CdSeS and also nanocomposites were showed two RL spectrum peaks in green and red region at around 528 nm and 710 nm respectively. Also, it is seen that the radioluminescence intensity changes linearly with the particle size of the QDs and about 12% size change of quantum dot led to a threefold increase in RL intensity. The luminescence glow curves are in compliance with absorption and fluorescence spectra. The absorption bands showed a significant blue shift for the nanocomposites as compare to powder CdSeS. The optical band gap of the OA capped CdSeS calculated as 1.77 eV. It was observed that the optical band gap of LDPE was decreased by the adding ratio of CdSeS from 3.71 eV to 2.25 eV. © 2017 Elsevier B.V.Item X-ray irradiated thermo- and radioluminescence, structural and thermal characterization of septarian (powder&bulk) from Madagascar(Elsevier B.V., 2018) Keskin İ.; Katı M.İ.; Türemiş M.; Gültekin S.; Üstün S.; Çetin A.; Kibar R.The luminescence properties of septarian have been investigated for the first time in this study, which has been the subject of many studies in both geological and geophysical fields. This sediment with a calcium carbonate structure exhibited high luminescence properties with X-ray excitation. The radioluminescence (RL) and thermoluminescence (TL) properties were investigated as well as their structural (FT-IR, XRD), morphological (SEM), thermal (TG-DTA) and absorption (UV-Vis-NIR) properties of this sediment. The broad RL peak of septarian was observed at 640 nm. There was a significant increase in the RL intensities of the sifted samples compared with the bulk sample. The TL glow curves of septarian irradiated with X-rays exhibited intense main TL glow peak having the maximum temperatures at 116 °C and about 390 °C with a heating rate of 2 °C/s. Also; the TL kinetic parameters were reported; activation energy (E), frequency factor (s) and the order of kinetics (b) of the first peak have been determined in detail by using peak shape (PS) and Computerized Glow Curve Deconvolution (CGCD) methods. SEM and EDS analysis were performed for the two different layers of septarian. The light colored side with the amorphous structure of the sample has more impurities (such as Fe, Al, Zr, K) than the crystallized and darker side. © 2018 Elsevier B.V.Item Determination of thermoluminescence kinetic parameters of white and blue chalcedony exposed to X-ray irradiation(Elsevier Ltd, 2018) Keskin İ.Ç.; Katı M.İ.; Türemiş M.; Çetin A.; Arslanlar Y.T.; Kibar R.The study reveals the thermoluminescence (TL) properties of white and blue chalcedony minerals which this mineral mined two different regions (Edirne and Eskişehir, respectively) of Turkey. With the help of various characterization techniques (such as X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR)), the gem-quality of the samples was tested. The TL glow curves of the samples irradiated with X-rays show intense main TL glow peak having the maximum temperatures at 100 °C and 121 °C with a heating rate of 2 °C/s, respectively. The TL kinetic parameters of the samples are reported here for the first time. Activation energy (E), frequency factor (s) and the order of kinetics (b) of these peaks have been determined in detail by using various heating rates (VHR) and peak shape (PS) methods and verified by Computerized Glow Curve Deconvolution (CGCD). The CGCD method was used to determine the number of peaks associated with the TL glow curves. The values of E calculated with these three methods are a good agreement. © 2018 Elsevier Ltd