Gd3+ Sensitization Effect on the Luminescence Properties of Tb3+ Activated Calcium Gadolinium Oxyapatite Nanophosphors

The solvothermal synthesis and structural characterization of silicate based oxyapatite Tb3+ activated Ca2Gd8Si6O26 (CGS) nanophosphors have been reported. The structure of these phosphors was elucidated by the powder x-ray diffraction (XRD) and further characterized by scanning electron microscopy. The XRD results revealed that the obtained Tb3+:CGS shows the characteristic peaks of oxyapatite in a hexagonal lattice structure. The photoluminescence (PL) properties were studied with variations of Tb3+ concentration and sintering temperature. Under 275 nm excitation, both Tb3+ (D-5(3,4) -> F-7(J=6,5,4,3)) and Gd3+ (P-6(7/2) -> S-8(7/2)) characteristic emissions associated with 4f-4f transitions have been observed, and when the concentration of Tb3+ increases above 1 mol % the D-5(3) emission intensity decreases due to cross relaxation. The Gd3+ emission intensity decreases with increasing Tb3+ concentration and the PL intensity of Tb3+ at 378 nm excitation was much weaker than the obtained intensity with excitation at 275 nm, suggesting that the efficient energy transfer occurred from Gd3+ to Tb3+ ions in CGS host lattice. The decay curves of the D-5(4) level show that the lifetime decreases with increasing crystallite size and concentration of Tb3+ ions. These luminescent powders are expected to find potential applications such as white light emitting diodes and optical display systems. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3511786] All rights reserved.