12-15 July 2011
Saint George Hotel
Africa/Johannesburg timezone
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Synthesis and photoluminescence properties of CaxSiyOz:Tb3+ nanophosphors prepared using solution-combustion method.

Presented by Prof. Francis DEJENE on 13 Jul 2011 from 17:00 to 19:00
Type: Poster Presentation
Session: Poster1
Track: Track A - Condensed Matter Physics and Material Science


<p>Tb3+-activated calcium silicate (CaxSyyOz:Tb3+) nanophosphors have been synthesized by means of simple and low temperatures (500°C) using the solution-combustion of corresponding metal nitrate, TEOS and urea solution mixtures. The structural evolution of the phosphor was studied by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and the luminescence properties of the phosphor powders investigated as a function of terbium concentration. The XRD study indicates that new peaks appear as the terbium concentration increase results in phase changes from CaSiO3 to Ca3Si2O7. The later phase may be favored as a result of some Si sites substituted by the Tb ions as the concentration of Tb was changed from 1 to 4 mol. %. The CaxSiyOz:Tb phosphor powders show the characteristic emission of Tb3+ under UV excitation, with the emission transitions of (5D4→7F3,4,5,6) with excitation 257nm have been measured. Particularly, the green emission transition at 545nm has been found to be more prominent and intense which is due to an electronic transition of 5D4-7F5. The decay curves implied that these phosphors contain fast, medium and slow-decay process. The oxygen vacancies trap levels may be considered to be responsible for the long afterglow phosphorescence at room temperature. Such green strong emission displaying powder phosphor will find applications in the development of coated screens in certain electronic systems.

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Room: Asteria

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