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    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.
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    Novel Dy incorporated Ca3Y2B4O12 phosphor: Insights into the structure, broadband emission, photoluminescence and cathodoluminescence characteristics
    (Pergamon-Elsevier Science Ltd, 2022) Qaisi, Aziza H.; Kaynar, U. H.; Ayvacikli, M.; Garcia-Guinea, J.; Alajlani, Y.; Topaksu, M.; Can, N.
    This study reports cathodoluminescence (CL) and photoluminescence (PL) properties of undoped borate Ca3Y2B4O12 and Ca3Y2B4O12:x Dy3+ (x = 0.5, 1, 2, 3, 5, and 7) synthesized by gel combustion method. Micro-X-Ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), CL and PL under electron beam and 359 nm pulse laser excitation, respectively were used to investigate characterization and luminescence studies of synthesized samples in the visible wavelength. As-prepared samples match the standard Ca3Y2BO4 phase that belongs to the orthorhombic system with space group Pnma (62) based on XRD results. Under electron beam excitation, this borate host shows a broad band emission from about 250 to 450 nm, peaked at 370 nm which is attributed to NBHOC. All as-prepared phosphors exhibited the characteristic PL and CL emissions of Dy3+ ions corresponding to F-4(9/2)-> H-6(J) transitions when excited with laser at 359 nm. The CL emission spectra of phosphors were identical to those of the PL spectra. Concentration quenching occurred when the doping concentration was 1 mol% in both the CL and PL spectra. The underlying reason for the concentration quenching phenomena observed in the discrete orange-yellow emission peaked at 574 nm of Dy3+ ion-doped Ca3Y2B4O12 phosphor is also discussed. According to these data, we can infer that this new borate can be used as a yellow emitting phosphor in solid-state illumination.
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    Samarium doped Ca(3)Y2B(4)O(12) phosphor prepared by combustion method: Anomalous heating rate effect, dosimetric features, and TL kinetic analyses
    (Elsevier, 2022) Hakami, J.; Oglakci, M.; Portakal-Ucar, Z. G.; Sonsuz, M.; Kaynar, U. H.; Ayvacikli, M.; Topaksu, M.
    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.
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    Thermoluminescence glow curve analysis of Ca3Y2B4O12 phosphor prepared using combustion method
    (Pergamon-Elsevier Science Ltd, 2022) Hakami, J.; Sonsuz, M.; Kaynar, U. H.; Ayvacikli, M.; Oglakci, M.; Yueksel, M.; Topaksu, M.
    Ca3Y2B4O12 (CBYO) phosphor was synthesized using a gel combustion method. X-ray diffraction (XRD) measurement confirmed a single-phase structure (space group Pnma (62)) of synthesized compound. TL measurements were conducted between room temperature (RT) and 450 degrees C at a heating rate of 2 degrees Cs-1. Significant glow peaks were observed at 64, 116, and 242 degrees C in CYBO phosphor sample exposed to different beta doses. In the range of 0.1-100 Gy, the TL intensity of the glow peak displayed good linearity. Different methods were employed to determine the number of peaks, the trap structure, and the kinetic parameters of the thermoluminescence glow curve of CBYO; the Hoogenstraaten method, various heating rates (VHR), and glow curve deconvolution method (CGCD) implemented through tgcd:An R package. Currently available findings confirm that CYBO host is a promising candidate for environmental studies because one exhibits adequate TL dose response coupled with a good sensitivity and linearity.