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Lamiri L.,University of Abderrahmane Mira de Bejaia | Guerbous L.,Boulevard Frantz Fanon | Samah M.,University of Abderrahmane Mira de Bejaia | Boukerika A.,Boulevard Frantz Fanon | Ouhenia S.,University of Abderrahmane Mira de Bejaia
Luminescence | Year: 2015

Europium trivalent (Eu3+)-doped Y2O3 nanopowders of different concentrations (0.5, 2.5, 5 or 7 at.%) were synthesized by the sol-gel method, at different pH values (pH 2, 5 or 8) and annealing temperatures (600°C, 800°C or 1000°C). The nanopowders samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and steady state photoluminescence spectroscopy. The effect of pH of solution and annealing temperatures on structural, morphological and photoluminescence properties of Eu3+-doped Y2O3 were studied and are discussed. It was found that the average crystallite size of the nanopowders increased with increasing pH and annealing temperature values. The Y2O3:Eu3+ material presented different morphology and its evolution depended on the pH value and the annealing temperature. Activation energies at different pH values were determined and are discussed. Under ultraviolet (UV) light excitation, Y2O3:Eu3+ showed narrow emission peaks corresponding to the 5D0- 7FJ (J = 0, 1, 2 and 3) transitions of the Eu3+ ion, with the most intense red emission at 611 assigned to forced electric dipole 5D0→7F2. The emission intensity became more intense with increasing annealing temperature and pH values, related to the improvement of crystalline quality. For the 1000°C annealing temperature, the emission intensity presented a maximum at pH 5 related to the uniform cubic-shaped particles. It was found that for lower annealing temperatures (small crystallite size) the CTB (charge transfer band) position presented a red shift. © 2015 John Wiley & Sons, Ltd. Source


Lamiri L.,Boulevard Frantz Fanon | Lamiri L.,University of Abderrahmane Mira de Bejaia | Guerbous L.,Boulevard Frantz Fanon | Samah M.,University of Abderrahmane Mira de Bejaia | And 2 more authors.
Luminescence | Year: 2015

Europium trivalent (Eu3+)-doped Y2O3 nanopowders of different concentrations (0.5, 2.5, 5 or 7 at.%) were synthesized by the sol-gel method, at different pH values (pH 2, 5 or 8) and annealing temperatures (600 C, 800 C or 1000 C). The nanopowders samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectroscopy (FT-IR) and steady state photoluminescence spectroscopy. The effect of pH of solution and annealing temperatures on structural, morphological and photoluminescence properties of Eu3+-doped Y2O3 were studied and are discussed. It was found that the average crystallite size of the nanopowders increased with increasing pH and annealing temperature values. The Y2O3:Eu3+ material presented different morphology and its evolution depended on the pH value and the annealing temperature. Activation energies at different pH values were determined and are discussed. Under ultraviolet (UV) light excitation, Y2O3:Eu3+ showed narrow emission peaks corresponding to the 5D0- 7FJ (J = 0, 1, 2 and 3) transitions of the Eu3+ ion, with the most intense red emission at 611 assigned to forced electric dipole 5D0→7F2. The emission intensity became more intense with increasing annealing temperature and pH values, related to the improvement of crystalline quality. For the 1000 C annealing temperature, the emission intensity presented a maximum at pH 5 related to the uniform cubic-shaped particles. It was found that for lower annealing temperatures (small crystallite size) the CTB (charge transfer band) position presented a red shift. Copyright © 2015 John Wiley & Sons, Ltd. Source

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