Browsing by Author "Ayvacikli M."
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Item Optical properties of Cu implanted ZnO(2006) Cetin A.; Kibar R.; Ayvacikli M.; Can N.; Buchal Ch.; Townsend P.D.; Stepanov A.L.; Karali T.; Selvi S.Nanoparticles of Cu have been made in zinc oxide crystals by ion implantation. The Cu ions were implanted at 400 keV into the (0 0 0 1) face of a single crystal. After implantation and after post-irradiation annealing there are numerous changes in the luminescence responses which include a variety of green and yellow emission bands. Following annealing at temperatures up to 1000 °C a green luminescence near 525 nm was observed which has been associated with the isolated Cu ions. The changes between as implanted and annealed luminescence signals suggests that the implants generate clustering or nanoparticle formation of Cu but anneals dissociate them. © 2006 Elsevier B.V. All rights reserved.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 Radioluminescence of SrAl2O4:Ln3+ (Ln = Eu, Sm, Dy) phosphor ceramic(Elsevier B.V., 2011) Ayvacikli M.; Ege A.; Can N.Phosphors for radiation detection require efficient energy transfer from the ionization track to the luminescent centers. In this work, the radioluminescence (RL) spectra of SrAl2O4 phosphor ceramics doped with individual trivalent rare earth element (REE) ions (Sm, Eu and Dy) are reported at the room temperature. Although there is some intrinsic UV/blue emission from the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the REE2+ and REE3+ states. The shapes of the emission bands are different for each dopant. The sharp emission properties show that the SrAl2O 4 is a suitable host for rare-earth ion doped phosphor material. © 2011 Elsevier B.V. All rights reserved.Item Synthesis and optical properties of Er3 and Eu3 doped SrAl2O4 phosphor ceramic(2011) Ayvacikli M.; Ege A.; Yerci S.; Can N.We report, for the first time on luminescence from a Er3 doped SrAl2O4 phosphor. Effects of Eu3 doping were also studied. The influence of rare-earth doping in crystal structure and its optical properties were analysed by means of X-ray diffraction (XRD), Raman scattering, optical absorption, excitation and emission (PL) spectroscopy, thermally stimulated luminescence (TSL) and scanning electron microscope (SEM). Luminescence spectra and luminescence decay curves for Er3 transitions in the near infrared region were recorded. The PL maximum for Eu doped SrAl2O4 is obtained at 620 nm and corresponds to the orange region of the spectrum. Diffraction patterns reveal a dominant phase, characteristic of the monoclinic SrAl2O4 compound and the presence of dopants has no effect on the basic crystal structure of SrAl 2O4. The shapes of the glow curves are different for each dopant irradiated with either a 90Sr90Y beta source, or UV light at 311 nm, and in detail the TL signals differ somewhat between Er and Eu dopants. © 2011 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 Luminescence characterization of cerium doped yttrium gadolinium aluminate phosphors(Elsevier B.V., 2012) Uysal Satilmis S.; Ege A.; Ayvacikli M.; Khatab A.; Ekdal E.; Popovici E.J.; Henini M.; Can N.Yttrium gadolinium aluminate ((Y1-xGdx) 3Al5O12:Ce) doped cerium phosphors with the different yttrium and gadolinium concentration were prepared by a wet-chemical route via the reagent simultaneous addition technique (WCS-SimAdd). The phosphors were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL), radioluminescence (RL) of cerium doped yttrium gadolinium aluminate phosphors. With increasing Gd dopant concentration, the PL intensity was shifted to the red region. Preliminary RL measurements were performed to further evaluate these newly prepared materials. Intense RL was observed that is typical of Ce3+ doped structure. © 2012 Elsevier B.V. All rights reserved.Item Radioluminescence study of rare earth doped some yttrium based phosphors(Elsevier B.V., 2012) Ayvacikli M.; Ege A.; Ekdal E.; Popovici E.-J.; Can N.This paper reports the luminescence emission spectra of Y(Ta,Nb)O 4 activated by rare earth ions such as Eu3+ and Tb 3+. The influence of these rare earth ions on the radioluminescence (RL) of yttrium niobate and tantalate phosphors was investigated. The luminescent properties were studied under X-ray and preliminary RL measurements to further evaluate prepared materials. The emission centers of the rare earth activators (Eu3+, Tb3+) were found to contribute efficiently to the total luminescence. With their various luminescence chromaticities, these rare earth activated phosphors are promising materials for solid-state lighting applications as well as for X-ray intensifying screens in medical diagnosis, providing the broad band variation of visible RL from blue to red. © 2012 Elsevier B.V. All rights reserved.Item Solid state synthesis, characterization and optical properties of Tb doped SrSnO3 phosphor(Elsevier Ltd, 2013) Kotan Z.; Ayvacikli M.; Karabulut Y.; Garcia-Guinea J.; Tormo L.; Canimoglu A.; Karali T.; Can N.In the present study, the structural and optical properties of SrSnO 3 doped with Tb ions are reported. Novel SrSnO3:Tb3+ phosphors were conventionally synthesized using a solid state reaction process under a mildly reduced atmosphere (5%H2 and 95%N2). The crystal structures, morphologies and optical properties of the resultant materials have been characterised by experimental techniques such as X-ray Diffraction (XRD), Raman spectroscopy (RS), Photoluminescence (PL), Radioluminescence (RL) and Cathodoluminescence coupled to an ESEM (ESEM-CL). The new phosphor material has good crystallization without any impurity phases, which matches with the standard JCPDS files (No. 22-1442) from XRD analysis. The PL, RL and CL measurements taken at room temperature showed that the transitions of 5D4 to 7FJ (j = 6, 5, 4, 3) corresponding to the typical 4f?4f dipole forbidden intra-configurational transitions of Tb3+ are largely independent of the host material. The green emissions of the 5D4?7F5 magnetic dipole transition at 540 nm are predominant for three types of luminescence. PL emission spectra recorded in the temperature range from 10 K to 300 K were influenced by temperature. We report anomalies in the PL spectra of SrSnO3:Tb3+ compatible with a structural phase transition at 260 K while simultaneously exciting and cooling the sample. This work clearly confirms the existence of a phase transition discovered by Singh et al. in SrSnO3 at 270 K. © 2013 Elsevier B.V. All rights reserved.Item Solid state synthesis of SrAl2O4:Mn2+ co-doped with Nd3+ phosphor and its optical properties(2013) Ayvacikli M.; Kotan Z.; Ekdal E.; Karabulut Y.; Canimoglu A.; Garcia Guinea J.; Khatab A.; Henini M.; Can N.The optical properties of alkaline earth aluminates doped with rare earth ions have received much attention in the last years and this is due to their chemical stability, long-afterglow (LAG) phosphorescence and high quantum efficiency. However, there is a lack of understanding about the nature of the rare earth ion trapping sites and the mechanisms which could activate and improve the emission centers in these materials. Therefore a new phosphor material composition, SrAl2O4:Mn2+, co-doped with Nd3+ was synthesized by a traditional solid-state reaction method. The influence of transition metal and rare earth doping on crystal structure and its luminescence properties have been investigated by using X-ray diffraction (XRD), Raman scattering, Photoluminescence (PL) and Radioluminescence (RL). Analysis of the related diffraction patterns has revealed a major phase characteristic of the monoclinic SrAl2O 4 compound. Small amounts of the dopants MnCO3 and Nd 2O3 have almost no effect on the crsytalline phase composition. Characteristic absorption bands from Nd3+ 4f-4f transitions in the spectra can be assigned to the transitions from the ground state 4I9/2 to the excited states. The luminescence of Mn2+ activated SrAl2O4 exhibits a broad green emission band from the synthesized phosphor particles under different excitation sources. This corresponds to the spin-forbidden transition of the d-orbital electron associated with the Mn2+ ion. In photo- and radio-luminescence spectra, Nd3+ 4f-4f transition peaks were observed. The emitted radiations for different luminescence techniques were dominated by 560, 870, 1057 and 1335 nm peaks in the visible and NIR regions as a result of 4I9/2→4G7/2 and 4F3/2→4IJ (J=9/2, 11/2 and 13/2) transitions of Nd3+ ions, respectively. Multiple emission lines observed at each of these techniques are due to the crystal field splitting of the ground state of the emitting ions. The nature of the emission lines is discussed. © 2013 Elsevier B.V.Item Spectral emission of rare earth (Tb, Eu, Dy) doped Y2Sn 2O7 phosphors(2013) Ege A.; Ayvacikli M.; Dinçer O.; Satilmiş S.U.Radioluminescence (RL) characterization of the yttrium stannate (Y 2Sn2O7) phosphors doped with 1 mol% Tb, Eu and Dy was carried out and significant electronic transitions corresponding to doped rare earth ions were observed. It was seen that all parts of these rare earth ions are included in the phosphor material in their trivalent state. The RL measurement indicates that the series of the emission-state 5D 4→7F6, 5D4→ 7F4, 5D4→7F 3, corresponding to the characteristic 4f→4f intra-configuration forbidden transitions of Tb3+are appeared and that main emission peak occurs at about 542 nm. There are in fact multiple emission lines at each of these due to the crystal field splitting of the ground state of the emitting ions. Eu-doped Y2Sn2O7 sample displayed intense and predominant emission peaks located at 580-650 nm corresponding to the 5D0→7Fj (j=l, 2, 3 and 4) transitions. Red emission coming from the hypersensitive Dy doped phosphor presented luminescence emissions with dominating transitions at 4F9/2→6Hj (j=9/2, 11/2, 13/2 and 15/2). The sharp emission properties show that the Y2Sn 2O7 is a suitable host for rare-earth ion doped phosphor material. © 2013 Elsevier B.V.Item Synthesis and luminescence properties of trivalent rare-earth element-doped calcium stannate phosphors(Taylor and Francis Inc., 2014) Karabulut Y.; Ayvacikli M.; Canimoglu A.; Guinea J.G.; Kotan Z.; Ekdal E.; Akyuz O.; Can N.The phosphors of calcium stannate activated with individual trivalent rare-earth element (REE) ions (Neodymium III, Europium III, Terbium III, Dysprosium III, and Samarium III) were synthesized by high-temperature solid-state reaction (SSR), and their characterization and luminescent properties were investigated. The crystal structures and morphologies of the resultant materials were well characterized by experimental techniques such as X-ray powder diffraction (XRD) and environmental scanning electron microscopy (ESEM). The XRD results display that the rare-earths substitution of Calcium II does not change the structure of calcium stannate host. Obviously, the ESEM image exhibits that phosphors aggregate and their particles with irregular shape exist. The calcined powders of the Europium III, Neodymium III, Samarium III, Dysprosium III, and Terbium III ions doped in calcium stannate exhibits bright red, reddish orange, yellowish, orange white, and green light, respectively. Although there is some intrinsic emission ranging from UV to near-infrared (NIR) due to the host lattice, the dominant signals are from the rare-earth sites, with signals characteristic of the trivalent rare-earth states. The emission spectrum from undoped-calcium stannate phosphor is characterized by two broad bands centered at ∼800 and ∼950 nm. The shapes of the emission bands are different for each dopant. The sharp emission properties show that the calcium stannate is a suitable host for rare-earth ion-doped phosphor material. Furthermore the influence of different rare-earth dopants, that is, Europium III, Neodymium III, Samarium III, Dysprosium III, and Terbium III, on thermally stimulated luminescence (TSL) of calcium stannate phosphor under the beta irradiation was discussed. Among these trivalent rare-earth-doped phosphors samarium-doped material showed maximum TSL sensitivity with favorable glow curve shape. © 2014 Copyright Taylor & Francis Group, LLC.Item Radioluminescence and photoluminescence characterization of Eu and Tb doped barium stannate phosphor ceramics(2014) Ayvacikli M.; Canimoglu A.; Karabulut Y.; Kotan Z.; Herval L.K.S.; De Godoy M.P.F.; Galvão Gobato Y.; Henini M.; Can N.In this paper, we report on structural and optical properties of terbium and europium doped barium stannate phosphors (BaSnO3) synthesised by conventional solid state reaction method. We have studied those materials by using X-ray diffraction (XRD), radioluminescence (RL) and photoluminescence (PL) techniques. XRD patterns confirm that the BaSnO3 sintered at 1400 C exhibit orthorhombic structure and that the Tb3+ and Eu3+ substitution of Ba2+ does not change the structure of the BaSnO 3 host. The optical emission spectrum is characterized a broad band centered at 897 nm (1.38 eV), with a high-energy tail approximately 750 nm from the host lattice. Other emission signals that are characteristic of the 3 + oxidation state of rare earth elements were generated by Eu and Tb doping. Luminescence measurements show that the series of emission states 5D4 → 7F6, 5D 4 → 7F5, 5D4 → 7F4 and 5D4 → 7F3 corresponding to the typical 4f → 4f infra-configuration forbidden transitions of Tb3+ are appeared and the major emission peak at 540 nm is due to 5D4 → 7F5 transitions of Tb3+. On the other hand, the emission spectrum of Eu doped BaSnO3 phosphor exhibits a series of emission bands, which are attributed to the 5D0 → 7Fj (j = 0-4) transitions of Eu3+ ions. The dominant emission of Eu3+ corresponding to the electric dipole transition 5D0 → 7F2 is located at 613 nm. The sharp emission properties exhibited demonstrate that the BaSnO3 is a suitable host for rare-earth ion doped phosphor material. This work clearly confirms the unusual near infrared (NIR) PL discovered by H. Mizoguchi et al. in BaSnO3 at room temperature. © 2014 Elsevier B.V. All rights reserved.Item Characterization of a green-emitting copper-doped barium aluminate phosphor(Taylor and Francis Inc., 2014) Ayvacikli M.A novel green-emitting phosphor copper-doped barium aluminate was synthesized by the conventional ceramic method. The crystallographic phase and microstructure identification were performed by powder X-ray diffraction and scanning electron microscopy. The X-ray diffraction pattern of the sample confirms the formation of the phosphor, and the scanning electron microscope image was recorded to observe the surface morphology. Differential thermal analysis results show that the initiatory decomposition temperature of barium carbonate starts at about 728°C. Cathodoluminescence studies have been undertaken to ensure the successful incorporation of copper ions in the barium aluminate host lattice. Under the excitation of the electron beam, the phosphor can efficiently display a broad green emission centered at 490 nm, corresponding to the transition from the conduction band edge to the excited state of copper in the barium aluminate host. However, there are no data available on copper luminescence in barium aluminate. New results on 3d activators of copper emission in the barium aluminate host are reported in this article, thus extending the list of copper-activated phosphors. These results strongly indicate that the copper-activated barium aluminate is a potential material used as a new high-brightness green phosphor for ultraviolet light-emitting diode and display devices. © 2014 Copyright Taylor & Francis Group, LLC.Item Cathodoluminescence and Raman characteristics of CaSO4:Tm3+, Cu phosphor(Elsevier, 2015) Ekdal E.; Guinea J.G.; Kelemen A.; Ayvacikli M.; Canimoglu A.; Jorge A.; Karali T.; Can N.The physical characterization and phosphor emission spectra are presented for CaSO4 doped with Tm and Cu. All spectral wavelengths are related to electronic transitions of Tm3+ ions. The powder X-ray diffraction pattern showed that the compound exhibits orthorhombic structure and all reflections were indexed without any other secondary impurity phases. Chemical and structural properties of the samples have been characterized by means of Raman spectroscopy and environmental scanning electron microscope (ESEM) with an attached X-ray energy dispersive system (EDS). Group frequencies concept is essential point to the interpretation of the bands due to the main SO4 vibrational units and these displayed main characteristic intensive Raman bands including typical strong intensity at 1016 cm-1 that corresponds to ν1SO4 vibrational mode. From the spatially-resolved cathodoluminescence (CL) spectrum, main emission bands of Tm3+ centered at 346, 362, and 452 nm, due to the respective transitions of 3P0→3H4, 1D2→3H6, 1D2→3F4 were clearly identified. The study is novel as no such CL-ESEM data are available for this doped compound. © 2015 Elsevier B.V. All rights reserved.Item Visible to infrared low temperature luminescence of Er3+, Nd3+ and Sm3+ in CaSnO3 phosphors(Elsevier Ltd, 2015) Orsi Gordo V.; Tuncer Arslanli Y.; Canimoglu A.; Ayvacikli M.; Galvão Gobato Y.; Henini M.; Can N.Novel stannate phosphor, orthorhombic CaSnO3 phosphors doped with Er3+, Nd3+ and Sm3+ have been synthesized by a conventional solid-state method under N2+H2 gas flow. Visible and near-infrared photoluminescence (PL) properties were investigated as function of laser power and temperature. It was observed that all dopant ions are well incorporated in CaSnO3 and are responsible for the optical emission in the temperature range of 10-300K. PL peaks at 490, 546, 656, 696, 894, 1065, and 1344nm were observed for the CaSnO3:Nd3+ phosphor and associated to f-f transition of Nd3+ ion. Emissions at 564, 600-607, 646-656 and 714nm were detected for the CaSnO3:Sm3+. The strongest one, observed at 600nm, was associated to 4G5/2→6H7/2 of Sm3. Emission lines at 528, 548, 662 at 852nm were also seen for CaSnO3:Er3+ and correspond to Er3+ intra-4fn shell transitions. In addition, at low temperatures, a stark splitting of the 4f electron energy levels of the Er3+ ions were observed in infrared region (1520-1558nm) and assigned to the transition between the 4I13/2 state and the 4I15/2 state. Finally, our results show that the rare earth doped CaSnO3 has remarkable potential for applications as optical material since it exhibits efficient and sharp emissions due to rare earth ions. © 2015 Elsevier Ltd.Item Catholuminescence properties of rare earth doped CaSnO3 phosphor(Elsevier Ltd, 2015) Canimoglu A.; Garcia-Guinea J.; Karabulut Y.; Ayvacikli M.; Jorge A.; Can N.The present study describes cathodoluminescence (CL) properties of CaSnO3 phosphors doped with Eu3+, Tb3+ and Dy3+ synthesized by a solid-state method. X-ray diffraction (XRD) patterns confirm that CaSnO3 sintered at 1200°C exhibits orthorhombic structure. The evidence and rationale for two strong broad emission bands appeared at 360 and 780nm for undoped CaSnO3 are presented. The CL measurements exhibit that the 4f-4f emissions from 5D4→7F6 (490nm), 5D4 →7F5 (544nm), 5D4 →7F4 (586nm) and 5D4 →7F3 (622nm), assigned to possible transitions of Tb3+ ions are seen. The strongest one, observed at 544nm, due to its probability of both magnetic and electric transitions make the sample emission green. Emissions at 480, 574, 662 and 755nm were detected for the CaSnO3:Dy3+ and attributed to the transitions from the 4F9/2 to various energy levels 6H15/2, 6H13/2, 6H11/2 and 6H9/2+6F11/2 of Dy3+, respectively. CL spectra of Eu doped CaSnO3 reveal that there is a strong emission peak appeared at 615nm due to the electric dipole transition 5D0→7F2 (red). Finally, our results show that the rare earth doped CaSnO3 have remarkable potential for applications as optical materials since it exhibits efficient and sharp emission due to rare earth ions. © 2015 Elsevier Ltd.Item Studies on luminescence from a cerium-doped strontium stannate phosphor(John Wiley and Sons Ltd, 2015) Karabulut Y.; Ayvacikli M.; Canimoglu A.; Garcia Guinea J.; Can N.The crystal structure and morphology of Ce3+-doped SrSnO3 materials prepared using the solid-state reaction method were extensively characterized using experimental techniques. X-Ray diffraction results show that the cerium substitution of strontium does not change the structure of the strontium stannate. Raman spectroscopy was used to investigate the microstructures and lattice vibrations. Environmental scanning electron microscopy images showed that phosphors aggregate and their particles form irregular shapes. SrSnO3 exhibits an intense green emission with a broad band originating from the 5d1 → 4f1 transition of cerium. It was observed that, after exposure to beta-irradiation, the glow curve of this material has two broad thermoluminescence peaks, one centered at ∼ 127C and the other at ∼ 245C for a heating rate of 5 K/s. The kinetic parameters, which include the frequency factor and the activation energy of the material, were calculated using Chen's method, after beta-irradiation. The fading and reusability of the phosphor were also studied and it was found that the phosphor is suitable for radiation dosimetry. Copyright © 2014 John Wiley & Sons, Ltd. Copyright © 2014 John Wiley & Sons, Ltd.Item Enhancement of the luminescence intensity by co-doping Mn2+ into Er3+-doped SrAl2O4(Elsevier, 2015) De Herval L.K.S.; Tuncer Arslanlar Y.; Ayvacikli M.; Iikawa F.; Nobrega J.A.; Pizani P.S.; Galvão Gobato Y.; Can N.; Henini M.; De Godoy M.P.F.Structural and optical properties of erbium- and manganese-doped strontium aluminates (SrAl2O4) phosphor materials synthesized by a solid state reaction were investigated. The samples presented the fundamental optical transitions due to Er3+ and Mn2+ which are typical features of the well-diluted doping process. A significant enhancement of the Er3+ optical emission band at 1530 nm was observed when the matrix is co-doped with Mn. Photoluminescence intensity under ultraviolet excitation was three times larger as compared to samples without Mn content. A model of energy transfer mechanism from Mn2+ to Er3+ ions due to optical energy matching is proposed to explain the experimental results. This result, presented first time, can be applied as useful tool for developments in optical communications. © 2015 Elsevier B.V. All rights reserved.Item Removal of thorium (IV) ions from aqueous solution by a novel nanoporous ZnO: Isotherms, kinetic and thermodynamic studies(Elsevier Ltd, 2015) Kaynar U.H.; Ayvacikli M.; Hiçsönmez U.; Çam Kaynar S.The adsorption of thorium (IV) from aqueous solutions onto a novel nanoporous ZnO particles prepared by microwave assisted combustion was studied using batch methods under different experimental conditions. The effect of contact time, solution pH, initial concentration and temperature on adsorption process was studied. The ability of this material to remove Th (IV) from aqueous solution was characterises by Langmuir, Freunlinch and Temkin adsorption isotherms. The adsorption percent and distribution coefficient for nanoporous ZnO powders in optimum conditions were 97% ± 1.02; 8080 L kg-1for Th (IV), respectively. Based on the Langmuir model, the maximum adsorption capacity of nanoporous ZnO for Th (IV) was found to be 1500 g kg-1. Thermodynamic parameters were determined and discussed. The results indicated that nanoporous ZnO was suitable as sorbent material for recovery and adsorption of Th (IV) ions from aqueous solutions. The radioactive Th (VI) in surface water, sea water and waste waters from technologies producing nuclear fuels, mining (uranium and thorium) and laboratories working with radioactive materials (uranium and thorium) can be removed with this nanoporous ZnO. © 2015 Elsevier Ltd.Item Thermoluminescence studies of Nd doped Bi4Ge3O12 crystals irradiated by UV and beta sources(Elsevier Ltd, 2016) Karabulut Y.; Canimoglu A.; Ekdal E.; Ayvacikli M.; Can N.; Karali T.Thermoluminescence (TL) glow curves of pure and rare earth doped bismuth germanate (BGO) were investigated under UV and beta radiation. The glow curves of pure BGO crystal present different patterns for both kinds of radiation. The TL glow curves of BGO crystals doped with Nd ions are similar to that of pure BGO under UV radiation. The kinetic parameters, kinetic order (b), activation energy (E) and frequency factor (s) of the TL glow curves of pure BGO crystal have been determined by peak shape method. Activation energies of 3 peaks obtained by PS were found to be 1.81, 1.15 and 1.78, respectively. © 2016 Elsevier Ltd.