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Nasser S. Alzayed

Professor

Professor of Physics

كلية العلوم
AA64, Ground Flooar, Building 4
publication
Journal Article
2012

Changes of fluorescent spectral features after successive rare earth doping of gadolinium oxide powders

Kityk, W. Kuznik, M.G. Brik, I. Cie´slik, A. Majchrowski, L. Jaroszewicz, N.S. AlZayed, A.M. El-Naggar, I. Sildos, S. Lange, V. Kiisk, I.V. . 2012

We present a complex fluorescence study of a series of gadolinium oxide polycrystalline powders singly, doubly and triply doped with trivalent rare earth ions (Er3+, Tb3+, and Dy3+), to explore a possibility of their use as materials for white light emitting diodes. The excitation and luminescence spectra along with the decay kinetics were measured in the temperature range from 6 to 300 K. The luminescence efficiency was studied within the visible spectral range, i.e. −400 nm to 750 nm under excitation by 355 nm third harmonic Nd:YAG laser pulses. Singly doped Er3+ sample gave stronger luminescence signals, but others showed significantly larger decay lifetimes. The successive rare earths doping leads to substantial changes of the spectral positions due to the up-conversion processes. In the singly (Er3+) doped sample, following the time resolved spectrum and decay curves, there are two different types of emissions: at 660 nm and at shorter wavelengths (below 640 nm) the red emission’s lifetime is ten times longer than at shorter wavelengths. The singly doped sample shows unclear temperature-dependence of luminescence with lifetime at 550 nm (the longest at 100 K, similarly at 6 K and 300 K) and achieved luminous efficacy 73.5 lm/W.

Issue Number
511
Magazine \ Newspaper
Journal of Alloys and Compounds
Pages
221– 225
more of publication
publications

We have used the pulsed laser deposition (PLD) technique followed by post-annealing process with magnesium vapor at 700 ◦C for 30 min to grow a high-quality CrO2/MgB2 bilayer prepared on Al2O3 (…

by N. S. Alzayed, S. Soltan, M. Shahabuddin, A. El-Naggar, I. V. Kityk, S. E. Qaid, Jafar M. Parakkandy, M. S. Shah, Niyaz Ahmad Madhar
2014
publications

We have discovered occurrence of strong narrow spectral lines in gold nanoparticles deposited on fluorine-doped tin oxide substrates at wavelengths 410, 440 and 550 nm under influence of 808 nm…

by E. Al-Harbi, M. A. Aziz, M. Oyama, A. M. El-Naggar, N. AlZayed, A. Wojciechowski, I. V. Kityk
2013
publications

We present a complex fluorescence study of a series of gadolinium oxide polycrystalline powders singly, doubly and triply doped with trivalent rare earth ions (Er3+, Tb3+, and Dy3+), to explore a…

by W. Kuznik, M.G. Brik, I. Cie´slik, A. Majchrowski, L. Jaroszewicz, N.S. AlZayed, A.M. El-Naggar, I. Sildos, S. Lange, V. Kiisk, I.V. Kityk
2012