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Research Article Issue
Continuous synthesis of ultrasmall core–shell upconversion nanoparticles via a flow chemistry method
Nano Research 2022, 15 (2): 1199-1204
Published: 20 October 2021
Downloads:90

A continuous synthesis method for the less than 10 nm core–shell upconversion nanoparticles was developed via coiled tube embedded flask reactors and a flow solvothermal co-participation reaction up to 300 ℃. Fast nucleation of hexagonal nanocrystals in less than 9 min residence time was achieved owing to the excellent heating ability of the reactors, and a two-step reaction strategy was created for the synthesis of β-NaYF4: Gd, Yb, Er/Ho/Tm@NaYF4 particles without intermediate purification.

Research Article Issue
Efficient synthesis of lithium rare-earth tetrafluoride nanocrystals via a continuous flow method
Nano Research 2020, 13 (10): 2837-2846
Published: 05 October 2020
Downloads:13

As an important upconversion illuminant material, LiREF4 nanocrystals were efficiently synthesized in a continuous reactor with the assistant of a new precursor solution. The employed trioctylamine solvent in the solution had a strong interaction with HF, and helped to avoid the generation of unnecessary solid components as LiF and NH4REF4 during the reaction. A silicon carbide reactor was developed to carry out the synthesis reaction, where LiYF4:Yb,Er/Ho/Tm quickly nucleated in 5 min at 300 °C. The reaction time to successfully prepare 15 nm sized nanocrystals was less than 30 min, and the space-time yield of the flow synthesis method was 14.8 times that of a control group batch reaction. The prepared nanocrystals had a strong illuminant ability, which could find its use in the area of security mark printing.

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