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Oxyapatite Ca2Gd8(SiO4)6O2 (CGS) nanostructures with nanorod bundle-like morphology are prepared by mixed solvothermal and hydrothermal reaction methods. Detailed structural and morphological studies are performed using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and transmission electron microscopy measurements. CGS nanorod bundles are formed by crystal splitting, and the growth mechanism as a function of reaction time is discussed. The size and crystal splitting of the nanorod bundles are controlled by varying the concentration of 2-propanol. The annealing temperature does not have any effect on the morphology of CGS nanorod bundles, and the bundles can sustain high temperatures, which confirms the crystal splitting of nanorod bundles. Photoluminescence and cathodoluminescent studies are carried out by activating the Eu3+ ions in the CGS host lattice as a function of annealing temperature. The corresponding CIE chromaticity coordinates are in close proximity to the commercial red emitting phosphor chromaticity coordinates.

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The solvothermal synthesis and structural characterization of silicate based oxyapatite Tb 3+ activated Ca 2 Gd 8 Si 6 O 26 ͑CGS͒ nanophosphors have been reported. The structure of these phosphors was elucidated by the powder x-ray diffraction ͑XRD͒ and further characterized by scanning electron microscopy. The XRD results revealed that the obtained Tb 3+ :CGS shows the characteristic peaks of oxyapatite in a hexagonal lattice structure. The photoluminescence ͑PL͒ properties were studied with variations of Tb 3+ concentration and sintering temperature. Under 275 nm excitation, both Tb 3+ ͑ 5 D 3,4 → 7 F J=6,5,4,3 ͒ and Gd 3+ ͑ 6 P 7/2 → 8 S 7/2 ͒ characteristic emissions associated with 4f-4f transitions have been observed, and when the concentration of Tb 3+ increases above 1 mol % the 5 D 3 emission intensity decreases due to cross relaxation. The Gd 3+ emission intensity decreases with increasing Tb 3+ concentration and the PL intensity of Tb 3+ at 378 nm excitation was much weaker than the obtained intensity with excitation at 275 nm, suggesting that the efficient energy transfer occurred from Gd 3+ to Tb 3+ ions in CGS host lattice. The decay curves of the 5 D 4 level show that the lifetime decreases with increasing crystallite size and concentration of Tb 3+ ions. These luminescent powders are expected to find potential applications such as white light emitting diodes and optical display systems.

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