Effect of Sm(3+)and Mn2+ incorporation on the structure and luminescence characteristics of Zn2SiO4 phosphor

To evaluate the dopant effect precisely, X-ray diffraction (XRD) for structural, scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) analysis for morphological, photoluminescence (PL) and thermoluminescence (TL) characteristics of un-doped, 2.0 mol% Sm3+ doped and 2.0 mol% Sm3+;x mol% Mn2+ (x = 0.5, 1.0, 2.0, 4.0) doped Zn2SiO4 phosphors were tested. PL mechanisms of excitation and emission were discussed together with data on the structure and morphology of the samples. The beta doses from 0.1 to 500 Gy with various steps were applied to observe the glow curve readouts after 200 degrees C preheat at a linear heating rate of 2 degrees C/s from RT to 500 degrees C. Zn2SiO4:2.0%Sm3+;0.5%Mn2+ was chosen for further analysis due to having both the most PL and TL peak area. Various heating rate method was used to determine the kinetic parameters as well as initial rise with T-M-T-stop analysis and computerized glow curve deconvolution methods.Research Fund of Cukurova University, Turkey [FBA2019-11318, FAY-2015-435]All authors thank Dr. M. Ayvacikli and Prof. Dr. N. Can for their support on XRD and PL evaluations. Z.G. Portakal-Ucar would like to thank Dr. J.M. Kalita and Dr. G.S. Polymeris for the valuable discussions on the TL results. The current study is financially supported by the Research Fund of Cukurova University, Turkey (Project Numbers: FBA2019-11318 and FAY-2015-435)

UV effect on the cathodo- and thermoluminescence properties of a gem-quality Cr-rich diaspore (alpha-AlOOH)

WOS: 000449448300017PubMed ID: 30196246This work reports on the cathodoluminescence (CL) and thermoluminescence (TL) properties of gem-quality diaspore samples from Milas/Mugla (Turkey) after 100 h of ultraviolet-C (UVC) exposure. The UVC exposure induces significant changes in the intensity of the CL emission in the range of 400-800 nm that would be mainly associated with photo-oxidation processes of the impurities (Cr3+, Ti3+, Fe2+) that substitute for Al3+ in the diaspore (alpha-AlOOH) lattice. The UVC effect on the 400 nm-TL behavior of beta irradiated samples in the range of 0.1-8 Gy modifies the TL glow curves probably due to both photo-transfer process where electrons release from deeper to shallower traps and redox reactions involving, also, breakages-linkages of chemical bonds. Meanwhile, the 'as received' samples consist of three maxima centered at about 120, 180, and 234 degrees C, the 100 h UVC-irradiated samples display three maxima at 122, 220 and 270 degrees C. The physical trapping parameters (intensity and peak position, trap depth and pre-exponential factor) for each TL curve were estimated by using a computerized glow curve analysis program.Research Fund of the Cukurova University [FBI-2017-7569]; Consejeria de Educacion, Juventud y Deporte de la Comunidad de Madrid, Spain [152]; Fondo Social Europeo, Belgium [152, PEJ15/BIO/AI-0418]Dr. Mustafa Topaksu acknowledges support by the Research Fund of the Cukurova University through FBI-2017-7569 Project. Cecilia Boronat thanks to "Consejeria de Educacion, Juventud y Deporte de la Comunidad de Madrid, Spain" and "Fondo Social Europeo, Belgium" (PEJ15/BIO/AI-0418) for the support provided under the "Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)" program (B.O.C.M. Num.152. Orden 1880/2015, de 16 de junio del 2015). All authors gratefully acknowledge to "Milenyum Metal Madencilik A.S." for providing a gem-quality diaspore from Milas/Mugla

Feasibility of gel phantoms in MRI for the assessment of kurtosis for prostate brachytherapy

WOS: 000463117903196

UV effect on the cathodo- and thermoluminescence properties of a gem-quality Cr-rich diaspore (α-AlOOH)

This work reports on the cathodoluminescence (CL) and thermoluminescence (TL) properties of gem-quality diaspore samples from Milas/Muğla (Turkey) after 100 h of ultraviolet-C (UVC) exposure. The UVC exposure induces significant changes in the intensity of the CL emission in the range of 400–800 nm that would be mainly associated with photo-oxidation processes of the impurities (Cr3+, Ti3+, Fe2+) that substitute for Al3+ in the diaspore (α-AlOOH) lattice. The UVC effect on the 400 nm-TL behavior of beta irradiated samples in the range of 0.1–8 Gy modifies the TL glow curves probably due to both photo-transfer process where electrons release from deeper to shallower traps and redox reactions involving, also, breakages-linkages of chemical bonds. Meanwhile, the ‘as received’ samples consist of three maxima centered at about 120, 180, and 234 °C, the 100 h UVC-irradiated samples display three maxima at 122, 220 and 270 °C. The physical trapping parameters (intensity and peak position, trap depth and pre-exponential factor) for each TL curve were estimated by using a computerized glow curve analysis program.Dr. Mustafa Topaksu acknowledges support by the Research Fund of the Çukurova University through FBI-2017-7569 Project. Cecilia Boronat thanks to “Consejería de Educación, Juventud y Deporte de la Comunidad de Madrid, Spain” and “Fondo Social Europeo, Belgium” (PEJ15/BIO/AI-0418) for the support provided under the “Operativo de Empleo Juvenil y la Iniciativa de Empleo Juvenil (YEI)” program (B.O.C.M. Núm.152. Orden 1880/2015, de 16 de junio del 2015

Comprehensive study of photoluminescence and cathodoluminescence of Eu and Tb doped Mg2SiO4 prepared via a solid-state reaction technique

We report narrow-band green-red emitting Mg2SiO4 phosphors successfully synthesized through solid-state reaction method, and the cathodoluminescence (CL) and photoluminescence (PL) properties of the samples were investigated in detail. Under electron beam and 275 nm excitation, Mg2SiO4 phosphors doped with various Eu3+ and Tb3+ concentrations in the range of 1 mol % up to 10 mol % exhibit typical green and red emissions, respectively. Tb doped samples were efficiently excited by a low voltage electron beam and UV light, yielding several emission peaks between 370 and 760 nm, and produced a bright green light peaking at 541 nm due to the D-5(4) -> F-7(5) transition. Eu3+ doped samples exhibited CL and PL emission spectra from D-5(0) to F-7(j) manifold transitions of Eu3+. A strong red-light emission peaking at 610 nm also supports the incorporation of Eu3+ ions. A concentration quenching effect was observed and discussed for both phosphors. The optimal doping concentration of Eu3+ and Tb3+ doped phosphors was 7 mol %. In view of the outstanding performance in the PL and CL, the Mg2SiO4:Eu3+, Tb3+ can be considered as a promising green and red phosphor in solid-state lighting applications

Thermoluminescence behaviour of europium doped magnesium silicate after beta exposure

This article presents a detailed analysis of beta ray exposed thermoluminescence response of a series of Eu3+ doped (0.5-10 mol%) Mg2SiO4 nanocrystalline samples successfully synthesized through solid state reaction method. Optimizing the doping concentration of Eu3+ ion in Mg2SiO4 phosphor was found as 3 mol%. Two main peaks were seen at 246 degrees C and 374 degrees C and also low temperature peak at 78 degrees C. The intensities of these peaks were increased linearly with increasing beta absorbed dose. T-m-T-stop method was used to reveal trap levels. Variable heating rate and computerized glow curve deconvolution methods were also used to evaluate the number of peaks and kinetic parameters, namely activation energy and frequency factor. The results of a series of experiments carried out to investigate some fading characteristics of Mg2SiO4:Eu3+ were also presented. The findings suggest that thermoluminescence properties of Mg2SiO4:Eu(3+ )makes this material suitable and promising dosimetric phosphor material for medical applications.Scientific Research Projects of Cukurova UniversityCukurova University [FAY 2015 435]The authors thank the financial support from Scientific Research Projects of Cukurova University FAY 2015 435 project

Doping Sm3+ into ZnB2O4 phosphors and their structural and cathodoluminescence properties

WOS: 000429838900032In this study, ZnB2O4:xSm(3+) (0.01 H-6(7/2) located at 606 nm can occur as hypersensitive transition having the selection rule Delta J = +/- 1. The observed peaks are in the region of yellow reddish light of Sm3+. Experimental results verify that the optimum Sm3+ content in terms of intense luminescence for this series of phosphors was 2%. Beyond 2% of Sm3+ ions concentration, luminescence quenching occurs due to an enhanced probability of the energy transfer from one Sm3+ to another that matches in energy via cross-relaxation and dipole-dipole interactions according to Dexter theory. A suitable energy transfer model between two adjacent Sm3+ ions in the ZnB2O4 phosphors was accomplished by the electric dipole-dipole interaction. The critical transfer distance (R-c) for non-radiative energy transfer was found to be 21.52 angstrom at 2 mol % Sm3+ doped ZnB2O4. Additionally, thermoluminescence (TL) glow curves of undoped and Sm activated ZnB2O4 under beta irradiation of 10 Gy are also discussed here. (C) 2018 Elsevier B.V. All rights reserved.Commission of Scientific Research Projects of Uludag University [OUAP(F)-2015/31]; Cukurova University, Turkey [FAY-2015-4735, FDK-2017-7905]This work was supported by the Commission of Scientific Research Projects of Uludag University, Project number OUAP(F)-2015/31 and the Research Fund of the Cukurova University, Turkey (Project Number: FAY-2015-4735 and FDK-2017-7905)

Thermoluminescence study and evaluation of trapping parameters of samarium doped barium silicate phosphor

We report the detailed analysis of thermoluminescence (TL) glow curves and the evaluation of kinetic parameters of Sm3+-incorporated BaSi(2)O(5.)The effect of various heating rates on TL kinetics and glow peak temperatures of Sm3+-doped BaSi2O5 phosphors exposed to beta particle irradiation at room temperature are investigated. The glow curve of the phosphor exposed to beta-irradiation consists of two main peaks with maxima at about 91 degrees C and 193 degrees C and exhibits good linearity between 1 and 10 Gy. The activation energies and frequency factors of trap centers involved in the TL emission were calculated from the TL glow curve of the sample by means of variable heating rate (VHR), repeated initial rise (RIR), and computerized glow-curve deconvolution (CGCD). Analysis of the main dosimetric peak techniques indicate that activation energies (E) and pre-exponential factor (s) vary between 0.93 and 1.72 eV, 10(10) and 10(13) s(-1). It is found that the temperature of the glow peaks shifts toward the higher temperatures and the TL intensity smoothly decreases as the heating rate increases. The behavior of the TL intensities and glow peak temperatures as a function of the heating rate are discussed with regards to thermal quenching.Jazan University [W41-032]This work was supported by the Jazan University [W41-032]

Thermoluminescence properties of beta particle irradiated Ca3Al2O6 phosphor relative to environmental dosimetry

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

Samarium doped Ca(3)Y2B(4)O(12) phosphor prepared by combustion method: Anomalous heating rate effect, dosimetric features, and TL kinetic analyses

The structural and thermoluminescence characteristics of samarium doped Ca3Y2B4O12 samples at various concentrations are presented. The samples were synthesized via the combustion method. The thermolumines-cence (TL) glow curves for Ca(3)Y2B(4)O(12):Sm3+ depict strong peaks at 97 and 410 C. Ca(3)Y2B(4)O(12):Sm3+ exhibited completely opposite behavior, contrary to expectations, in that the luminescence intensity of both the total and individual glow peaks increased with the heating rate throughout the TL experiments. This unusual TL glow peak pattern was discussed via the Mandowski model of semi-localized transitions. The kinetic characteristics of both prominent glow peaks were established using various analysis techniques, including variable heating rate, initial rise (IR) by using the TM-Tstop method and the fractional glow technique (FGT), and computerized glow curve deconvolution (GCD). The dose response of the high temperature peak at 410 C is linear between 0.1 and 5 Gy, and then sublinear at higher doses. In addition, the repeatability and fading results of 410 C TL peak also yielded very favorable results. These findings suggest that Ca(3)Y2B(4)O(12):Sm(3+ )has great potential in the development of high temperature dosimetric materials for beta irradiation