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|Type:||Artigo de evento|
|Title:||Photon Upconversion, Structural, And Magnetic Properties Of Rare Earth-doped Nayf4 Nanoparticles|
|Abstract:||Magnetic, structural, and optical investigations of rare-earths (R) co-doped nanoparticles (NPs) of Nay1-x-yRx 1Ry 2F4 with Rx 1. = Yb0.20/Ry 2 = Er0.02 and R.J. = Yb0.30/Ry 2 = Tm0.005 and single doped (y = 0) with Rx 1. = Yb0.20 and Rx1. = Er0.02 are reported. The visible green and blue upconversion emitted lights of Yb/Er and Yb/Tm co-doped NaYF4 NPs were observed with naked eye and no filters when excited with a 980 nm laser diode. The NPs are mixture of both phases, α (cubic nanospheres: 15-25 nm) and β (hexagonal nanoplates: ~230 nm). From the observed electron spin resonance (ESR) signals and Curie-Weiss fits of the temperature dependence of the magnetization, we obtained the oxidation states to be trivalent ions, i.e., Yb3+ (4f13, J = 7/2) and Er3+ (4f11, J = 15/2). As expected for NPs with mixture of α- and β-phases, the ESR spectra broaden toward higher magnetic fields due to the anisotropic contribution of the crystal electric field to the Kramer ground state g-values.|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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