Person: ERDEM, MURAT
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ERDEM
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MURAT
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Publication Metadata only Effect of pressure and temperature on the white light produed by Ytterbium (III) doped and undoped Yttrium Silicate nanopowders excited by a laser diode(ELSEVIER SCIENCE BV, 2017) ERDEM, MURAT; Cinkaya, Hatun; Eryurek, Gonul; Bilir, Gokhan; Erdem, Murat; Di Bartolo, BaldassareIn the present study, we have directed our attention to yttrium silicate nanopowders undoped and with different ytterbium (III) dopant concentrations, systems that, when illuminated by a laser diode emit white light. We have investigated the effects that two physical parameters, pressure of the ambient and temperature of the powders have on the emission of the white light. We have observed that low pressure and high temperatures enhance the intensity of the emitted white light. At high pressure, the output from the nanopowder is represented by groups of sharp lines due to ytterbium cooperative emission and unwanted erbium impurities. As the pressure decreases to 0.01 mbar, the spectrum changes to a wide band resembling the white light spectrum. High temperatures of the nanopowders enhance the emission of white light. (C) 2016 Elsevier B.V. All rights reserved.Publication Metadata only Structural and spectroscopic properties of Nd3+:Y2Si2O7 phosphors(ELSEVIER SCI LTD, 2013) TAV, CUMALİ; Erdem, Murat; Ozen, Gonul; Tav, Cumali; Di Bartolo, BaldassarePhosphors of alpha-Y2Si2O7 doped with Nd3+ ions were prepared using the sol gel technique. Nano-sized crystalline phosphor powders were obtained by annealing the dried gels at 960 degrees C. The crystallization properties of the phosphor powders were determined from their XRD patterns. The alpha-Y2Si2O7 phase was the only phase observed in all compositions. As the amount of amorphous SiO2 in the composition was increased, the crystalline sizes and the widths of the size distribution curves were found to decrease from 17.8 nm to 10.6 nm and from 15.6 nm to 12.2 nm, respectively. The spectroscopic properties of the powders were studied by measuring the luminescence and the decay patterns of the F-4(3/2) -> I-4(9/2) and F-4(3/2) -> I-4(11/2) transitions between 50 K and 310 K. No appreciable effect of the crystallite sizes on the average lifetime of the F-4(3/2) level was observed at temperatures below 100 K. The effect of temperature, however, becomes relevant above 100 K as the size of alpha-Y2Si2O7 nano-crystal becomes smaller. (C) 2013 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Publication Metadata only White light emission from sol-gel derived gamma-Y2Si2O7 nanoparticles(ELSEVIER SCIENCE SA, 2015) ERDEM, MURAT; Erdem, Murat; Eryurek, Gonul; Di Bartolo, BaldassareWe report the generation of wideband white light with a spectrum ranging from 400 to 800 nm obtained from sol-gel derived gamma-Y2Si2O7 nano powders with average particle size under 100 nm when excited with the 803.5 nm emission of a laser diode. The white light intensity was found to increase with decreasing environment pressure and increasing laser pumping power. The International Commission on Illumination coordinates were found to be x = 0.3408 and y = 0.3100 under 803.5 nm excitation. These values lie in the yellowish region and correspond to color temperature values of 5030 K with a color rendering index of 85. The illuminance value was found to be 1456 lux. (C) 2015 Elsevier B.V. All rights reserved.Publication Metadata only Up conversion based white light emission from sol-gel derived alpha-Y2Si2O7 nanoparticles activated with Yb3+, Er3+ ions(ELSEVIER SCIENCE BV, 2015) ERDEM, MURAT; Erdem, Murat; Sitt, BryanWhite up conversion emission has been observed in sol-gel derived alpha-Y2Si2O7 nano powders activated with ytterbium and erbium ions when excited with the 950 nm emission of a laser diode. Measurements of the sample emission intensity dependence on the pumping power under atmospheric pressure condition were performed to provide possibly an explanation for the UC mechanism. The emission intensities of each Er3+ transition decreased when the pumping power was increased from 1.7 to 2.5 W with the observation of the bright wide band under atmospheric pressure condition. When the sample was subject to very low pressure at 0.03 mbar and the pumping power was set from 0.9 to 2.5W, the white emission brightness increased. The CIE coordinates (x, y) for YSYE were found to be (0.330, 0300 (1.7 W-0.3 mbar)) and (0.339, 0.304 (2.5 W-atmospheric pressure)) under the 950 nm laser diode excitation. (C) 2015 Elsevier B.V. All rights reserved.Publication Metadata only Pressure effects on the cooperative emission of Yb3+ : Y2Si2O7 nano-powders(ELSEVIER SCI LTD, 2016) ERDEM, MURAT; Erdem, Murat; Eryurek, Gonul; Mergen, Ayhan; Di Bartolo, BaldassareCooperative emission has been observed in sol-gel derived nano-powders doped with yitterbium ions when excited with the 950 nm emission of a laser diode. Measurements of the sample emission intensity dependence on the pumping power under atmospheric pressure condition were performed to provide possibly an explanation for the cooperative emission mechanism. The emission intensities of each nano-powder increased when the pressure was increased from 0.01 mbar to 1 atm with the observation of the bright blue emission. When the powders were subject to very low pressure at 0.01 mbar, the blue emission intensities decreased and green emission intensities increased. The CIE coordinates (x, y) for YSY1 were found to be (0.187, 0.196) under 1 atm. with a color rendering index (CRI) of 67 under the 950 nm laser diode excitation. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.Publication Open Access Spectral investigation of Yb3+/Ho3+/Tm3+:Y2Si2O7 upconverting nanophosphors for the usage of temperature sensing(2023-02-28) ERDEM, MURAT; ESMER, KADİR; ERDEM M., ESMER K., Eryürek G.© 2023, Turkish Chemical Society. All rights reserved.Rare earth (Yb3+, Ho3+, Tm3+) yttrium disilicate phosphors were produced by sol-gel technique and heated at 1050 °C temperature. The sizes of the phosphors vary between 20-30 nm according to the images obtained from the Transmission Electron Microscope. The up-conversion (UC) emissions of the nanopowders were measured in the range of 500–900 nm wavelength under 950 nm laser excitation. A linear increase with power was observed in the emission intensity ratio depending on the laser excitation power. Using the FIR technique, the phosphor’s temperature was determined by the heating effect caused by the laser pump power. Due to the change in intensity ratio versus temperature, the temperature sensitivity at 428 K was calculated as 0.781x10-2K-1 and it was suggested that it can be used as a promising temperature sensor probe in photonic devices.Publication Metadata only Bright white up-conversion emission from sol-gel derived Yb3+/Er3+/Tm3+: Y2SiO5 nanocrystalline powders(ELSEVIER SCI LTD, 2015) EKMEKÇİ, METE KAAN; Erdem, Murat; Erguzel, Olgun; Ekmekci, Mete K.; Orucu, Humeyra; Cinkaya, Hatun; Genc, Seval; Mergen, Ayhan; Eryurek, Gonul; Di Bartolo, BaldassareBright white up conversion emission has been observed in sol gel derived Yb3+/Er3+/Tm3+: Y2SiO5 nanocrystalline powders when excited with the 950 nm emission of a laser diode. Measurements of the sample emission intensity dependence on the pumping power were performed to explain the up conversion mechanism. The CIE chromaticity coordinates (x, y) for white emission in X-2-Y2SiO5 nanocrystalline form were found to be (0.334, 0.332) under 950 nm laser diode excitation. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.