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. Author manuscript; available in PMC: 2016 Oct 28.
Published in final edited form as: Nanoscale. 2015 Oct 28;7(40):16571–16577. doi: 10.1039/c5nr03411f

Figure 2. Monodisperse core-shell UCNPs with blue emission upon near-infrared excitation were synthesized.

Figure 2

(a) Transmission electron microscopy (TEM) image of core NaYF4:Yb3+/Tm3+ (30 / 0.2 mol%) nanoparticles (left, scale bar: 100 nm) and core@shell NaYF4:Yb3+/Tm3+ (30 / 0.2 mol%)@NaYF4 UCNPs (right, scale bar: 50 nm). (b) Photographic image of a cuvette with a suspension of UCNPs under laser excitation at 980-nm. (c) Upconversion emission spectrum of core-shell UCNPs in hexane solution (1 mg/mL) under near-infrared light excitation at 980-nm. (d) Powder X-ray diffraction (PXRD) patterns of the core-shell UCNPs, showing all peaks to be well-indexed in accordance with the β-hexagonal-phase NaYF4 crystal structure (Joint Committee on Powder Diffraction Standards file No. 16-0334).