Dependence of Eu3+ luminescence dynamics on the structure of the combustion synthesized Sr5(PO4)3F host

Europium (Eu3+) activated strontium fluoropatite (Sr-5(PO4)(3)F) phosphor powders were prepared by a combustion method. The structure and luminescence properties of this potential red emitting phosphor are explored. In order to improve the luminescent properties the obtained powders were also annealed at 900 and 1200 degrees C. The X-ray diffraction (XRD) data indicated that the major crystalline phases from the as-prepared or annealed powder samples were identical to the hexagonal apatite structure of Sr-5(PO4)(3)F. The Eu3+ occupied two different sites (C-s (S1) and C-3 (S2)) of Sr in the Sr-5(PO4)(3)F host, giving rise to two emission sites, as inferred from the time resolved luminescence spectroscopy (TRES) data. The photoluminescence (PL) intensity of Eu3+ from the as prepared sample was found to be more intense than the annealed samples. In addition from the PL data it was evident that a reduction of the Eu3+ to Eu2+ occurred. (C) 2010 Elsevier B.V. All rights reserved.