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Öğe Cathodoluminescence and photoluminescence properties of Dy doped La2CaB10O19 phosphor(Elsevier, 2020) Ayvacıklı, M.; Kaynar, Ümit H.; Karabulut, Y.; Guinea, J. Garcia; Doğan, T.; Can, N.In this study, we report a detailed analysis of the photoluminescence (PL) and cathodoluminescence (CL) properties of La2CaB10O19 (LCB) doped with Dy ion. Dy doped LCB materials were successfully synthesized using a sol-gel combustion method. Dy doped LCB has the monoclinic structure with lattice parameters a = 11.02067 angstrom, b = 6.55755 angstrom, c = 9.10541 angstrom and alpha = gamma = 90.00, and 13 = 91.49?. Under the excitation by a low voltage electron beam and pulse laser at 349 nm, the LCB:Dy3+ phosphor produces the characteristic emission bands of Dy3+ due to intra-configuration transitions of F-4(9/2) -> H-6(15/2) (480 nm, blue), F-4(9/2) -> H-6(13/2) (574 nm, yellow), F-4(9/2) -> H-6(11/2) (662 nm, red) and F-4(9/2) -> H-6(9/2) (752 nm, red). The concentration quenching phenomenon was observed in both CL and PL measurements and optimum doping concentration was estimated to be 2%. We suggest that the concentration quenching mechanism of intense yellow emission at 574 nm was attributed to dipole-dipole interaction for both CL and PL.Öğe Cathodoluminescence properties of La2MoO6:Ln3+ (Ln: Eu, Dy, and Sm) phosphors(Elsevier Ltd, 2020) Ayvacıklı, M.; Kaynar, Ümit H.; Karabulut, Y.; Guinea, J.G.; Bulcar, K.; Can, N.La2MoO6 orange-red phosphors with high efficiency incorporated with Eu, Dy and Sm have been synthesized through a gel combustion method. The influences of rare earth doping in synthesized samples were analysed by X-ray diffraction (XRD), scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS), and cathodoluminescence. Rare earth doped La2MoO6 samples show strong emission bands in the range of 400–750 nm and optimal doping concentration for all samples was 2 mol%. La2MoO6 host doped Eu ion showed intense and predominant emission peaks in 450–750 nm range. The electrical multipolar interaction contributed to the non-radiative energy transfer between Eu3+ ions in La2MoO6 host matrix. Sm doped La2MoO6 host exhibited orange-red CL emission peaks at 564, 608, 652 and 708 nm La2MoO6:Dy3+ phosphor displayed emissions at 484, 574 and 670 nm, respectively. The observed intense and sharp emission peaks indicate that La2MoO6 is promising host for lanthanides doped phosphor materials in the applications of optoelectronic. © 2020 Elsevier LtdÖğe Influence of laser excitation power on temperature-dependent luminescence behaviour of Ce- and Tb-incorporated BaMgAl10O17 phosphors(Pergamon-Elsevier Science Ltd, 2020) Kaynar, Ümit H.; Kaynar, S. Cam; Ayvacıklı, M.; Karabulut, Y.; Souadi, G. O.; Can, N.BaMgAl10O17 (BAM) is a highly suitable host lattice for various rare earth ions with excellent luminescence properties in different spectral regions, including a strong photoluminescence (PL) emission from the visible spectral region. A new Ce- and Tb-incorporated BaMgAl10O17 phase was synthesized successfully using a wet combustion method and it was studied as a function of the temperature and laser excitation power. We further characterize the obtained phosphors with X-ray diffraction at room temperature. Different fuel/oxidant (f/o) ratios were introduced to investigate the optimum synthesis conditions for the BAM phosphors and optimum ratio was found out to be 8. The photoluminescence (PL) spectra were collected under the excitation light generated by a Nd:YLF pulse laser at 349 nm as the temperature was increased from 10 K to 300 K. A strong green emission of Tb3+ was observed in the green region of the spectrum due to the D-5(4)-> F-7(J) transition. We also observed a wide emission band from the Ce3+ ion in the wavelength range of 350-650 nm. The luminescence intensities of all phosphors exhibited different patterns with an increase in the temperature. We also evaluated how the PL spectrum of the rare earth-activated BAM host matrix shifts under various laser excitation powers. The PL intensity of Ce-activated BAM significantly shifted (similar to 30 A) to the blue region of the spectrum with an increase in the laser excitation power, however we did observed no shift forTb(3+) activated BAM. The present findings suggest that Tb-incorporated BaMgAl10O17 can be effective as a green phosphor candidate material with a wide range of applications.Öğe Synthesis and competitive luminescence quenching mechanism of Ca(3)Al(2)O(6)Ln(3+)(Ln: Dy and Sm) phosphors(Pergamon-Elsevier Science Ltd, 2020) Bakr, M.; Kaynar, Ümit H.; Ayvacıklı, M.; Benourdja, S.; Karabulut, Y.; Hammoudeh, A.; Can, N.Sm3+ and Dy3+ activated Ca3Al2O6 phosphors were produced through a gel combustion method using Urea + beta-Alanine, Urea, and Urea + Glycine as fuels. The crystal structure and the phase purity of the obtained materials were characterized by X-ray powder diffraction (XRD). Ca3Al2O6 :Sm3+ phosphor shows characteristic emission lines (565 nm, 602 nm, 649 nm, and 714 nm) in the orange red region assigned to (4)G(5/2) -> H- 6(J) (J = 5/2, 7/2, 9/2, 11/2) transitions of Sm3+. The strongest peak is located at 602 nm. Emission spectra of Ca3Al2O6 :Dy3+ show that there are two dominant peaks centered at 480 nm and 573 nm emitting blue and yellow light. Optimum doping concentrations of Sm(NO3)(3) and Dy(NO3)(3) are 0.01 % and 0.03 %, respectively. The concentration quenching mechanism is verified to be a dipole-dipole interaction as the type of energy transfer among Sm3+-Sm3+ and Dy3+-Dy3+ ions. The critical distance is also calculated to be 24.19 angstrom and 16.77 angstrom, respectively.Öğe Synthesis and photoluminescence characteristics of Dy incorporated MoO3 phosphor: Suppression concentration quenching(Elsevier Ltd, 2020) Ayvacıklı, M.; Kaynar, Ümit H.; Karabulut, Y.; Canımoğlu, A.; Bakr, M.; Akça, S.; Can, N.A series of MoO3:Dy3+ phosphors have been synthesized via the gel-combustion method. The X-ray and photoluminescence (PL) emission spectra were employed to characterize the obtained phosphors. The prepared samples were characterized through XRD measurements and exhibited that Dy3+ ions can be successfully incorporated into the host material. The PL emission bands of Dy3+ doped MoO3 were observed at 486 nm, 574 nm and 666 nm which are assigned to the transitions of 4F9/2 ? 6H15/2, 4F9/2 ? 6H13/2 and 4F9/2 ? 6H11/2, respectively. Concentration quenching were largely taken into consideration as one of the crucial aspects limiting the application range of phosphors in today's modern world. An abnormal thermal quenching dependence was reported when Dy3+ ions were incorporated into MoO3 host matrix. In order to understand the origin of this beneficial behaviour, energy transfer processes occurring via radiative and nonradiative mechanisms were investigated to elucidate this suppression of the concentration quenching. © 2020 Elsevier Ltd
