首页|(163109)Structure and luminescent properties of Dy~(3+) activated NaLa9(SiO_4)_6O_2 yellow-emitting phosphors for application in white LEDs
(163109)Structure and luminescent properties of Dy~(3+) activated NaLa9(SiO_4)_6O_2 yellow-emitting phosphors for application in white LEDs
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NSTL
Elsevier
A series of Dy~(3+)-doped sodium lanthanum orthosilicate oxyapatites, NaLa_(9-x)Dy_x(SiO_4)_6O_2 (NLSO:xDy, x = 0-0.3), were synthesized by the solid-state reaction method at 1100 °C, with the aim of developing yellow emitting phosphors for applications in w-LEDs. Their crystal structure, morphology and particle size distribution, electronic structure, Raman spectra, concentration- and temperature-dependent luminescent properties were investigated for the first time. The crystal structure was refined by the Rietveld method. Undoped NLSO is hexagonal (space group P6_3/m - C_(6h)~2) with lattice constants a = b = 9.6917(3) A and c = 7.1836(4) A. It is shown that Dy~(3+) ions substitute for the La~(3+) ones in two types of sites with C_3 and C_s point symmetries. The first-principle calculations for undoped NLSO revealed an indirect bandgap of 5.06 eV. The NLSO:0.2Dy phosphor exhibited intense yellow emission with CIE 1931 chromaticity coordinates of (0.469, 0.495) and a correlated color temperature of 3150 K owing to the hypersensitive electric-dipole transition ~4F_(9/2)→~6H_(13/2) (571 nm) dominating in the luminescence spectrum. Excellent thermal stability was found for this apatite phosphor (the activation energy is 0.23 ± 0.02 eV).
Universitat Rovira i Virgili (URV), Fisica i Cristal-lografia de Materials i Nanomaterials (FiCMA-FiCNA), Marcelli Domingo 1, 43007 Tarragona, Spain
Centre de Recherche sur les Ions, les Materiaux et la Photonique (CIMAP), UMR 6252 CEA-CNRS-ENSICAEN, Universite de Caen Normandie, 6 Boulevard Marechal ]uin, 14050 Caen Cedex 4, France
ITMO University, 49 Kronverkskiy Pr., 197101 St. Petersburg, Russia
NSTL
Elsevier
