Efficient multicolor tunability of ultrasmall ternary-doped LaF3 nanoparticles: energy conversion and magnetic behavior
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2017
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Physical Chemistry Chemical Physics
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Luminescence-tunable multicolored LaF3: xCe(3+), xGd(3+), yEu(3+) (x = 5; y = 1, 5, 10, and 15 mol%) nanoparticles have been synthesized via a low cost polyol method. Powder X-ray diffraction and high-resolution transmission electron microscopy studies confirm the hexagonal phase of the LaF3: xCe(3+), xGd(3+), yEu(3+) nanophosphors with average sizes (oval shape) ranging from 5 to 7 nm. Energy-dispersive X-ray spectroscopy analyses show the uniform distribution of Ce3+, Gd3+, and Eu3+ dopants in the LaF3 host matrix. The photoluminescence spectra and electron paramagnetic resonance measurements guarantee the presence of Eu2+, corroborated through DC susceptibility measurements of the samples displaying paramagnetic behavior at 300 K, whereas weak ferromagnetic ordering is shown at 2 K. The non-radiative energy transfer processes from the 4f(F-2(5/2)) -> 5d state (Ce3+) to the intraconfigurational 4f excited levels of rare earth ions and simultaneous emissions in the visible region from the 4f(6)5d(1) (Eu2+) and D-5(0) (Eu3+) emitting levels, leading to overlapped broad and narrow emission bands, have been proclaimed. The energy transfer mechanism proposes involvement of the Gd3+ ion sub-lattice as the bridge and finally trapping by Eu2+/3+, upon excitation of the Ce3+ ion. The calculation of experimental intensity parameters (Omega(2,4)) has been discussed and the highest emission quantum efficiency (eta = 85%) of the Eu3+ ion for the y = 10 mol% sample is reported. The advantageous existence of the Eu2+/Eu3+ ratio along with variously doped nanomaterials described in this work, results in tunable emission color in the blue-white-red regions, highlighting the potential application of the samples in solid-state lighting devices, scintillation devices, and multiplex detection.
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SHRIVASTAVA, NAVADEEP; KHAN, L.U.; VARGAS, J.M.; OSPINA, CARLOS; COAQUIRA, J.A.Q.; ZOPPELLARO, GIORGIO; BRITO, H.F.; JAVED, YASIR; SHUKLA, D.K.; FELINTO, M.C.F.C.; SHARMA, SURENDER K. Efficient multicolor tunability of ultrasmall ternary-doped LaF3 nanoparticles: energy conversion and magnetic behavior. Physical Chemistry Chemical Physics, v. 19, n. 28, p. 18660-18670, 2017. DOI: 10.1039/c7cp02235b. Disponível em: http://repositorio.ipen.br/handle/123456789/27895. Acesso em: 02 Jul 2024.
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