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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.
Cathodoluminescence and Raman characteristics of CaSO4:Tm3+, Cu phosphor
(ELSEVIER SCIENCE BV, 2015) Ekdal, E.; Garcia Guinea, J.; Kelemen, A.; Ayvacikli, M.; Canimoglu, A.; Jorge, A.; 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 v(1)SO(4) 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 P-3(0) -> H-3(4), D-1(2) -> H-3(6), D-1(2) -> F-3(4) were clearly identified. The study is novel as no such CL-ESEM data are available for this doped compound. (C) 2015 Elsevier B.V. All rights reserved.
CATHODOLUMINESCENCE RESPONSE FROM RARE EARTH DOPED Bi4Ge3O12
(ELSEVIER SCIENCE BV, 2009) Kibar, R.; Cetin, A.; Tuncer, Y.; Uysal, S.; Townsend, P. D.; Canimoglu, A.; Can, N.; Boulon, G; Dujardin, C; Jurdyc, AM
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 Bi4Ge3O12 (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.
Cathodoluminescence Response From Sanidine Feldspar
(TAYLOR & FRANCIS INC, 2013) Karabulut, Y.; Canimoglu, A.; Can, N.
In the present study, cathodoluminescence (CL) providing information about surface rather than bulk material reveals blue and red emissions within the sanidine feldspar from the Eifel Mountains, Germany. The emission line occurring in the blue region at about 450nm reflects Al-O--Al structural defects, although distribution maps of the major elements, including Si, Al, and K, do not display a clear correlation with the CL properties of the sanidine feldspar. Dominant emission being in the longer-visible wavelength region (red region) approximate to 730nm is assumed to be caused by Fe3+ activation attributed to Fe3+-Al3+ substitution. Much less is known about the spectral characteristic of the feldspar CL emission, and the application of an older luminescence technique yields encouraging results for the practical application of the feldspar identification.
Catholuminescence properties of rare earth doped CaSnO3 phosphor
(PERGAMON-ELSEVIER SCIENCE 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 degrees C exhibits orthorhombic structure. The evidence and rationale for two strong broad emission bands appeared at 360 and 780 nm for undoped CaSnO3 are presented. The CL measurements exhibit that the 4f-4f emissions from D-5(4) -> F-7(5) (490 nm), D-5(4) -> F-7(5) (544 nm), D-5(4) -> F-7(4) (586 nm) and D-5(4) -> F-7(3) (622 nm), assigned to possible transitions of Tb3+ ions are seen. The strongest one, observed at 544 nm, due to its probability of both magnetic and electric transitions make the sample emission green. Emissions at 480, 574, 662 and 755 nm were detected for the CaSnO3:Dy3+ and attributed to the transitions from the F-4(9/2) to various energy levels H-6(15/2), H-6(13/2), H-6(11/2) and H-6(9/2)+F-6(11/12) of Dy3+, respectively. CL spectra of Eu doped CaSnO3 reveal that there is a strong emission peak appeared at 615 am due to the electric dipole transition D-5(0) -> F-7(2) (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. (C) 2015 Elsevier Ltd. All rights reserved.
Characterisation and luminescence studies of Tm and Na doped magnesium borate phosphors
(PERGAMON-ELSEVIER SCIENCE LTD, 2015) Ekdal, E.; Garcia Guinea, J.; Karabulut, Y.; Canimoglu, A.; Harmansah, C.; Jorge, A.; Can, N.
In this study, structural and luminescence properties of magnesium borate of the form MgB4O7 doped with Tm and Na were investigated by X-ray diffraction (XRD), Raman spectroscopy and cathodoluminescence (CL). The morphologies of the synthetised compounds exhibit clustered granules and road-like materials. As doping trivalent ions into a host with divalent cations requires charge compensation, this effect is discussed. The CL spectra of undoped MgB4O7 shows a broad band emission centred around 350 nm which is postulated to be produced by self-trapped excitons and some other defects. From the CL emission spectrum, main emission bands centred at 360, 455, 475 nm due to the respective transitions of D-1(2)-> H-3(6),D-1(2)-> F-3(4) and (1)G(4)-> H-3(6) suggest the presence of Tm3+ ion in MgB4O7 lattice site. CL mechanism was proposed to explain the observed phenomena which are valuable in possibility of the developing new luminescent materials for different applications. In addition, the experimental Raman spectrum of doped and undoped MgB4O7 were reported and discussed. (C) 2015 Elsevier Ltd. All rights reserved.
Characterization, room and low temperature photoluminescence of yttrium aluminium borate activated with Sm3+ions
(Pergamon-Elsevier Science Ltd, 2023) Madkhli, A. Y.; Kaynar, U. H.; Coban, M. B.; Ayvacikli, M.; Canimoglu, A.; Can, N.
In this study, the combustion method assisted by urea that is ideally suited to economic and time saving was used for the synthesizing of reddish orange emitting YAl3(BO3)4 phosphor samples doped with various Sm3+ ions (from 0.01 wt% to 7wt%). A detailed study of the structural and luminescence properties at room/low tem-perature of the synthesized samples was performed. XRD analysis revealed a rhombohedral structure with an R32 space group (155). The particle size was determined by the Scherrer's method to be 48 nm. The visible PL emission spectra upon excitation at 359 nm are recorded and four emission peaks around 564, 599, 646, and 707 nm with transitions 4G5/2 -> 6H5/2, 4G5/2 -> 6H7/2, 4G5/2 -> 6H9/2 and 4G5/2 -> 6H11/2 are observed. Concentration quenching was mainly caused by dipole-dipole interactions between neighbouring trivalent Sm3+ ions. Through the CIE chroma coordinates (0.606, 0.382), the optimized sample (x = 0.03) demonstrates admirable luminous performance. YAl3(BO3)4:Sm3+ can be a good candidate for use as a red component for lighting applications.
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.
Comparison of thermoluminescence characteristics of undoped and europium doped YAl3(BO3)4 phosphor synthesized by combustion method: Anomalous heating rate, dose response and kinetic analyses
(Pergamon-Elsevier Science Ltd, 2023) Kaynar, Umit H.; Oglakci, M.; Bulcar, K.; Benourdja, S.; Bakr, M.; Ayvacikli, M.; Canimoglu, A.
In this study, undoped and YAl3(BO3)(4) phosphors doped with Eu3+ at varying concentrations (x = 0.5 to 7 wt%) produced by a combustion process have been thoroughly examined by using the X-ray diffraction (XRD) and thermoluminescence (TL) techniques. The crystallized phosphors were confirmed by XRD analysis, and its crystal structure was examined. XRD analyses of the synthesized phosphor is in accordance with ICSD File No 96-152-6006. TL glow curve of undoped sample produced three glow peaks located at 80 degrees C, 240 degrees C, and 360 degrees C with a heating rate of 2 degrees Cs-1 whilst Eu3+ doped one appears at 90 degrees C, 230 degrees C, and 390 degrees C. The undoped example complied with the theory as expected, namely, as the heating rate increased, the TL glow curve shifted towards lower temperatures and decreased in intensity. However, an anomalous change was observed in the sample with Eu3+ additive. The experimental findings from the dose-response of YAl3(BO3)(4):0.5 wt%Eu3+ demonstrate that the intensity of TL provided by the total area under glow curves has an acceptable linearity (r(2):0.999) up to 100 Gy. The intensity of each maximum on the TL glow curve augments proportionally as the heating rate is augmented. Possible reasons of this behaviour are discussed. Various heating rate (VHR) methods (such as Hoogenstraaten's and Booth-Bohun-Parfianovitch) have also been used to estimate kinetic parameters (e.g., energy and frequency factor), which seem to be in good agreement with each other.
Integrating K plus into Eu and Tb doped GdCa 4O(BO3)3: A dual study on photoluminescence and structure
(Elsevier Science Sa, 2024) Altowyan, Abeer S.; Kaynar, U. H.; Hakami, Jabir; Coban, M. B.; Ayvacikli, M.; Aydin, H.; Canimoglu, A.
In this study, we investigate the structural and photoluminescence (PL) properties of rare -earth -doped GdCa 4 O (BO 3 ) 3 (GdCOB) phosphors, specifically focusing on the spectral behaviour induced by doping with Eu 3 + and Tb 3 + ions. The powder X-ray diffraction (XRD) spectra confirm the formation of a monoclinic phase. The XRD data were also refined by a Rietveld refinement method. The existence of B, O, Ca, Gd, Tb, Eu and K elements was verified by EDS spectra. We introduce a detailed examination of the charge compensation process using Kro ger- Vink notation to clarify the mechanisms essential for tailoring the optical properties of the phosphors. The PL excitation spectrum of GdCOB:Eu 3 + , monitored at 611 nm, reveals sharp excitation peaks at 319, 361, 380, and 392 nm, corresponding to 7 F 0 -> 5 H 3 , 7 F 0 -> 5 D 4 , 7 F 0 -> 7 F 0 , and 7 F 0 -> 5 L 6 transitions, respectively. The PL spectrum under excitation of 392 nm exhibits that phosphors doped with Eu 3 + a significant red emission at 611 nm, which is attributed to the 5 D 0 -> 7 F 2 transition. This emission intensity is particularly enhanced at non-centrosymmetric sites of the Eu 3 + ions. Similarly, the PL excitation spectrum of GdCOB:Tb 3 + , monitored at 552 nm, displays distinct excitation peaks at 316, 341, 353, and 379 nm, which correspond to the transitions 7 F 6 -> 5 D 0, 7 F 6 -> 5 L 7, 7 F 6 -> 5 D 2, and 7 F 6 -> 5 D 3, respectively. Tb 3 +-doped phosphors display a bright green emission, with a dominant peak at 552 nm, resulting from the 5 D 4 -> 7 F 5 transition. Additionally, the introduction of K + ions as co-dopants results in modifications to the local environments of Eu 3 + and Tb 3 + ions. These changes allow for fine-tuning of the emission peaks, significantly enhancing the luminescent output of the phosphors. Optimal doping concentrations of 5 mol% for Eu 3 + and 1 mol% for Tb 3 + enhance luminescent intensity and prevent concentration quenching. This phenomenon, often resulting in reduced PL intensity at higher dopant levels, is primarily due to dipole -dipole interactions, consistent with Dexter's theory of energy transfer. Strategic modulation of doping concentrations, coupled with a deep understanding of energy transfer mechanisms are critical for the development of advanced luminescent materials Our analysis of the Commission de l ' Eclairage (CIE) chromaticity coordinates reveals enhanced energy transfer dynamics in rare -earth -doped borates, facilitating the tuning of luminescent properties. These results not only deepen our understanding of the fundamental physics governing such phosphors but also open pathways for the development of optoelectronic applications requiring consistent color output, such as LED technologies and solid-state lighting.
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).
Luminescence of dysprosium doped strontium aluminate phosphors by codoping with manganese ion
(ELSEVIER SCIENCE SA, 2014) Karabulut, Y.; Canimoglu, A.; Kotan, Z.; Akyuz, O.; Ekdal, E.
The authors report here the luminescence properties of strontium aluminate doped with dysprosium and manganese. The dysprosium, manganese co-doped powders were prepared by a solid state reaction at temperatures at 1600 degrees C under H-2 (15%)-Ar (85%) atmosphere. The dysprosium, manganese co-doped strontium aluminate phosphors have the monoclinic structure with lattice parameters a approximate to 8.440 angstrom, b approximate to 8.821 angstrom, c approximate to 5.157 angstrom and beta approximate to 93.4 degrees. The characteristic (4)F9/2 -> H-6(15/2) (blue), F-4(9/2) -> H-6(13/2) (yellow), F-4(9/2) -> H-6(11/2) (red) and F-4(9/2) -> H-6(9/2) (NIR) transitions of Dy3+ for different luminescence techniques (radioluminescence, photoluminescence and cathodoluminescence) were detected in the emission spectra at the room temperature. The luminescence of Mn2+ co-doped SrAl2O4:Dy3+ exhibits a broad greenorange emission band (T-4(1) -> (6)A(1) transition) 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. 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. (C) 2013 Elsevier B.V. All rights reserved.
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.
Luminescent, Structural, and Thermal Properties of the Unusual "Anatolian" Diaspore (Zultanite) from Turkey
(TAYLOR & FRANCIS INC, 2014) Canimoglu, A.; Garcia-Guinea, J.; Correcher, V.; Karabulut, Y.; Tuncer, Y.; Can, N.
Results are presented for the cathodoluminescence (CL) probe of an environmental scanning electron microscopy (ESEM) with an energy-dispersive spectrometry analyzer (EDS), thermoluminescence (TL), thermo X-ray diffraction in situ (TXRD), and simultaneous differential thermal analysis and thermogravimetric analysis (DTA/TGA) techniques of gem-quality zultanite samples collected from the Mugla region of southwest Turkey. Micro-Raman measurements were also performed on different zultanite orientations and preheated aliquots to study the spectral phase transition diaspore-corundum also detected by the other thermal techniques in the 450 degrees C-500 degrees C thermal range. The thermal phenomena of TL are synchronous with this dehydroxylation process, involving consecutive breaking-linking bonds of Al-O, Cr-O, Fe-O, Al-OH, Cr-OH, and Fe-OH, including the formation of hydrolyzed ions such , and and redox reactions. Assuming that zultanite oxygen atoms are distributed as a hexagonal close packed layer, the experimental spectrum CL of zultanite is characteristic of the E-2 ->(4)A(2) transitions of substitutional Cr3+ luminescent centers in positions of Al3+ in sixfold coordination.
Novel Tb3+-Doped LaAl2 B4 O10 phosphors: Structural analysis, luminescent properties, and energy transfer mechanism
(Pergamon-Elsevier Science Ltd, 2024) Kaynar, U. H.; Aydin, H.; Hakami, Jabir; Altowyan, Abeer S.; Coban, M. B.; Ayvacikli, M.; Canimoglu, A.
This study explores the structural and luminescent properties of terbium (Tb3+)-doped lanthanum aluminium borate (LaAl2B4O,0, abbreviated as LAB) phosphors, a novel host lattice for Tb3+ doping. LAB:Tb3+ phosphors, with varying dopant concentrations, were synthesized using a microwave-assisted combustion synthesis approach and characterized using X-ray diffraction (XRD), Rietveld refinement, and photoluminescence spectroscopy at both room and low temperatures. The structural analysis confirmed the hexagonal crystal structure of LAB and revealed successful incorporation of Tb3+ ions without altering the fundamental lattice. Luminescence studies demonstrated that the LAB:Tb3+ phosphors show strong green emission primarily attributed to the 5D4 -> 7F5 transition of Tb3+. The optimal doping concentration was determined to be 5 wt% Tb3+, which provided maximum luminescence efficiency. This concentration also allowed for a critical study of energy transfer mechanisms within the phosphor, revealing dipole-dipole interactions with a critical distance of 9.80 & Aring; between Tb3+ ions. Additionally, the CIE chromaticity coordinates of LAB:0.05 Tb3+ were precisely determined to be (0.289, 0.4460), indicating the potential for high-quality green emission suitable for solid-state lighting and display technologies. This work not only demonstrates the potential of LAB:Tb3+ as a highly efficient green luminescent material, but also sheds light on the mechanisms responsible for energy transfer and concentration quenching.
Optical spectroscopy of the Ce-doped multicomponent garnets
(PERGAMON-ELSEVIER SCIENCE LTD, 2016) Canimoglu, A.; Karabulut, Y.; Ayvacikli, M.; Muresan, L. E.; Perhaita, I.; Barbu-Tudoran, L.; Can, N.
Here, we report our results referring to the preparation of Ce doped Y2.22MgGa2Al2SiO12, Y1.93MgAl4SiO12 and Y2.22Gd0.75Ga2Al3O12 using solid state reaction at high temperature. Several complementary methods (i.e. powder x-ray diffraction (XRPD), energy dispersive analysis of X-rays (EDX), scanning electron microscopy (SEM) and Fourier transforms infrared spectroscopy (FTIR)) were studied to examine the effects of the synthesis procedure on the morphology and structure. XRD analyses revealed that all compounds include yttrium aluminate phase with garnet structure. Cathodoluminescence (CL), radioluminescence (RL) and photoluminescence (PL) measurements were carried out for clarification of relationship between host lattice defects and the spectral luminescence emissions. Luminescence emission of phosphors is peaked at 530 nm assigned to 5d-4f transitions of the dopant Ce3+ ions with a broad emission band in 400-700 nm range. Under electron irradiation, the emission spectrum of Ce doped (YGd)(3)Ga2Al3O12 is well defined and has a characteristic fairly narrow and sharp emission band peaking at 312 nm and 624 nm corresponding to transition of P-6(7/2) -> S-8(7/2) and (6)G(J) -> P-6(J) (Gd3+), respectively. We suggest some of phosphors might be excellent phototherapy phosphor materials under electron excitation. (C) 2016 Elsevier Ltd. All rights reserved.
Preparation and characterization of Yttrium based luminescence phosphors
(Elsevier Science Bv, 2017) Muresan, L. E.; Ayvacikli, M.; Garcia Guinea, J.; Canimoglu, A.; Karabulut, Y.; Can, N.
Ce doped Yttrium aluminate modified by replacing different molar part of aluminium or gallium (Y(3)Al(5-x)GaxO(12)) and Yttrium silicate phosphors activated with Ce and Tb (Y2SiO5:Ce3+,Tb3+) were synthesized by solid state reaction and a gel combustion method, respectively. X-ray diffraction and Scanning electron microscope (SEM) techniques are used to identify their structures and morphologies. Luminescence characteristics are measured and spectroscopic data confirm that Y2SiO5:Ce3+, Tb3+ phosphors can be effectively excited upon UV excitation light and X-ray irradiation, resulting in intense blue and green emissions, respectively. This energy transfer takes place by means of a non-radiative process inside Ce3+-Tb3+ clusters formed in the host matrix. Tb3+ doped Y2SiO5 yields both blue emission D-5(3) -> F-7(j) (j = 3,4,5,6) and green emission D-5(4) -> F-7(J) (J = 3,4,5,6) of Tb3+. Y(3)Al(5-x)GaxO(12):Ce3+ phosphors exhibit a broad blue emission band originating from allowed 5d-4f transition of the Ce3+ ions under different excitation sources but the broad emission band shifts with increasing of Ga3+ content. This work presents a quantitative understanding of host material's on dopant's luminescence properties and thereby provides an optimization guideline, which is extremely demanding for the development of new luminescent materials. (C) 2017 Elsevier B.V. All rights reserved.
Radioluminescence and photoluminescence characterization of Eu and Tb doped barium stannate phosphor ceramics
(ELSEVIER SCIENCE SA, 2014) Ayvacikli, M.; Canimoglu, A.; Karabulut, Y.; Kotan, Z.; Herval, L. K. S.; de Godoy, M. P. F.; 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 degrees C exhibit orthorhombic structure and that the Tb3+ and Eu3+ substitution of Ba2+ does not change the structure of the BaSnO3 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 D-5(4) -> F-7(6), D-5(4) -> F-7(5), D-5(4) -> F-7(4) and D-5(4) -> F-7(3) corresponding to the typical (4)f -> (4)f infra-configuration forbidden transitions of Tb3+ are appeared and the major emission peak at 540 nm is due to D-5(4) -> F-7(5) 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 D-5(0) -> F-7(j) (j = 0-4) transitions of Eu3+ ions. The dominant emission of Eu3+ corresponding to the electric dipole transition D-5(0) -> F-7(2) 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. (C) 2013 Elsevier B.V. All rights reserved.
Rare Earth Photoluminescence in Bismuth-Germanate Crystals
(TAYLOR & FRANCIS INC, 2013) Arslanlar, Y. Tuncer; Kotan, Z.; Kibar, R.; Canimoglu, A.; Can, N.
In the present work, the photoluminescence (PL) spectra of bismuth germanate (BGO) doped with trivalent rare earth element (REE) ions with different doping concentrations (0.03wt% Eu, 0.4wt% Tm, and 1.1wt% Nd) are reported in the temperature range from 10 to 300K using different detectors, namely, photomultiplier tube (PMT), InGaAs (IGA), and Si. The luminescence in the NIR region was also measured at room temperature. Two broad emission bands attributed to undoped BGO were found at circa 1350 and 1800nm, respectively. The broad-band emissions are replaced by narrow-band line emissions defined by the trivalent rare earth dopants. The emission spectra from rare earth ion-doped BGO extend from 500 to 2000nm. Rare earth ions act as the dominant recombination centers and define the emission spectra. This is interpreted as resulting from direct charge transfer from intrinsic defect traps to rare earth recombination centers. The temperature-dependent luminescence of BGO doped with 0.4wt% Tm is also presented.
Room and Low Temperature Luminescence Properties of CaSO4:Dy,Tm Codoped with Li
(ELSEVIER SCIENCE BV, 2009) Can, N.; Karali, T.; Wang, Y.; Townsend, P. D.; Prokic, M.; Canimoglu, A.; Boulon, G; Dujardin, C; Jurdyc, AM
Rare earths, especially Dy or Tm doped CaSO4 phosphors are actively studied. They have high sensitivity, a large dynamic range, thermal stability and ease of preparation. Nevertheless, they can be enhanced by inclusion of lithium and this study reports some effects of lithium co-dopant on the TL and radioluminescence (RL) emissions of two TL phosphors. Addition of Li as a co-dopant ion was made either during chemical preparation of the phosphors, or as a binder component mixed with the basic phosphors matrix during the process of pressing and sintering the TLD pellets.

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