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  • Silica-coated upconversion lanthanide nanoparticles: The effect of crystal design on morphology, structure and optical properties.

Silica-coated upconversion lanthanide nanoparticles: The effect of crystal design on morphology, structure and optical properties.

Beilstein journal of nanotechnology (2016-01-07)
Uliana Kostiv, Miroslav Šlouf, Hana Macková, Alexander Zhigunov, Hana Engstová, Katarína Smolková, Petr Ježek, Daniel Horák
ABSTRACT

NaYF4:Yb(3+)/Er(3+) nanoparticles were synthesized by thermal decomposition of lanthanide trifluoroacetates using oleylamine (OM) as both solvent and surface binding ligand. The effect of reaction temperature and time on the properties of the particles was investigated. The nanoparticles were characterized by transmission electron microscopy (TEM), electron diffraction (ED), energy dispersive spectroscopy (EDX), dynamic light scattering (DLS), thermogravimetric analysis (TGA), elemental analysis and X-ray diffraction (XRD) to determine morphology, size, polydispersity, crystal structure and elemental composition of the nanocrystals. TEM microscopy revealed that the morphology of the nanoparticles could be fine-tuned by modifying of the synthetic conditions. A cubic-to-hexagonal phase transition of the NaYF4:Yb(3+)/Er(3+) nanoparticles at temperatures above 300 °C was confirmed by both ED and XRD. Upconversion luminescence under excitation at 980 nm was observed in the luminescence spectra of OM-NaYF4:Yb(3+)/Er(3+) nanoparticles. Finally, the OM-NaYF4:Yb(3+)/Er(3+) nanoparticles were coated with a silica shell to enable further functionalization and increase biocompatibility and stability in aqueous media, preventing particle aggregation.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Ammonia-14N, 99.99 atom % 14N
Sigma-Aldrich
Ammonia, anhydrous, ≥99.98%
Sigma-Aldrich
Ammonia solution, 0.4 M in THF
Sigma-Aldrich
Ammonia solution, 4 M in methanol
Sigma-Aldrich
Ammonia solution, 7 N in methanol
Sigma-Aldrich
Ammonia solution, 0.4 M in dioxane
Sigma-Aldrich
Ammonia solution, 2.0 M in methanol
Sigma-Aldrich
Ammonia solution, 2.0 M in isopropanol
Sigma-Aldrich
Ammonia solution, 2.0 M in ethanol
Sigma-Aldrich
Ytterbium(III) chloride hexahydrate, 99.998% trace metals basis
Sigma-Aldrich
Ytterbium(III) chloride hexahydrate, 99.9% trace metals basis
Sigma-Aldrich
Oleylamine, technical grade, 70%
SAFC
Oleylamine, ≥98% (primary amine)