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Enhancement of upconversion emission of LaPO4 : Er@Yb core-shell nanoparticles/nanorods

Ghosh, Pushpal and Haldar, Krishna Kanta and Solis, David and Patra, Amitava and Oliva, Jorge and De la Rosa, Elder (2008) Enhancement of upconversion emission of LaPO4 : Er@Yb core-shell nanoparticles/nanorods. JOURNAL OF PHYSICAL CHEMISTRY C, 112 (26). pp. 9650-9658.

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Official URL: http://pubs.acs.org/doi/abs/10.1021/jp801978b

Abstract

We demonstrated the synthesis of LaPO4:Er:Yb-doped nanoparticles/nanorods and LaPO4:Er@Yb core-shell nanoparticles/nanorods by a solution-based technique. The mechanism related to morphology control of LaPO4: Er:Yb nanorods/nanoparticles is proposed and discussed. Bright-green (550 nm) and red (670 nm) emission were observed due to the transitions H-2(11/2) + S-4(3/2) -> I-4(15/2) and F-4(9/2) -> I-4(15/2), respectively. The experimental data for 550- and 670-nm emission bands of doped nanoparticle/nanorod and core-shell nanoparticles/nanorods have been fit with a straight line with a slope of similar to 2, which confirms the two-photon absorption process. The enhancement of upconversion emission of LaPO4:Er:Yb-doped nanoparticles and LaPO4:Er@Yb core-shell nanoparticles/nanorods are mainly due to modifications of surface-related effects. It is found that the tensile strain increases from +1.0% to +1.9% with changing the shape from nanoparticle to nanorod and reversal of the lattice strain (compressive) is obtained for coated nanoparticle/nanorod. It is worth mentioning that the lattice strain varies with changing the shape and surface coating on nanocrystals and the upconversion emission intensity increases with decreasing the tensile lattice strain and it increases with increasing compressive strain. Analysis suggests that the lattice strain plays an important role in modification of the upconversion properties of the rare-earth-doped nanocrystals.

Item Type:Article
Subjects:Material Science > Nanofabrication processes and tools
Material Science > Nanostructured materials
ID Code:1451
Deposited By:Farnush Anwar
Deposited On:12 Dec 2008 14:37
Last Modified:12 Dec 2008 14:37

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