Upconversion Nanoparticles Synthesized by Ultrashort Pulsed Laser Ablation in Liquid: Effect of the Stabilizing Environment

Abstract

The distinctive feature of upconverting compounds to absorb and emit light in the near-infrared region has made upconverting nanoparticles of great interest in various application fields. Nevertheless, these colloids show a highly hydrophobic behavior, and therefore, the use of a proper stabilizing agent is necessary in most cases. Although few chemical techniques for colloid stabilization are available, it is still difficult to achieve a fully reproducible synthesis method for stable upconverting nanoparticle colloids. In this work, upconversion 18 %Yb:1 %Er:NaYF nanoparticles were produced by ultrafast pulsed laser ablation in a water and 2-[2-(2-methoxyethoxy)- ethoxy]acetic acid (MEEAA) environment to assess the stabilization effect of the surfactant on the nanoparticle colloid properties. The effects of the laser fluence and MEEAA concentration on the nanoparticles' properties were investigated by TEM, EDS, and emission spectra analyses. The results show that ultrashort pulsed laser ablation in liquid allows generating highly spherical nanoparticles with conserved stoichiometry and optical properties. Moreover, it is possible to obtain colloids with significantly higher stability and preserved optical properties by one-step PLAL processes directly in the MEEAA environment.

Room‐Temperature Laser Synthesis in Liquid of Oxide, Metal‐Oxide Core‐Shells, and Doped Oxide Nanoparticles

“…[63] The same ligand has been used to stabilize lanthanide sesquioxides and yttrium aluminium garnet (YAG), [63] but also upconversion NPs NaYF 4 :Yb,Er. [183] N-(phosphonomethyl) iminodiacetic acid (PMIDA)h as been used to stabilize nanoaggregates of iron poly-oxo-clusters (Figure7C). [160] In LAL, the drastic size quenching observed with ligands [63,160] (see Figures 6B-C) suggestsa ne arly quenching of the particleg rowth, and thus an earlyp enetration of the ligands into the environment where NPs form.…”

Rare-earths doped-nanoparticles prepared by pulsed laser ablation in liquids

“…Among the wet chemical synthesis methods, PLAL is one of the best ways to prepare lanthanide-activated nanoparticles with high crystallinity and multi-element compositions. Lots of lanthanide-activated nanoparticles have been synthesized by PLAL, for instance, lanthanide-based down-conversation [64] and up-conversation nanoparticles [61,66]. Concerning the persistent phosphors, the number of works is very limited.…”

Preparation of rare-earth doped NaYF4 luminescent nanoparticles by a high-energy ball milling process

“…It involves production of nanoscale particles from bulk or microcrystalline powder via mechanical or laser-assisted treatment. [44][45][46][47] By combining impact and friction, mechanical milling can be used both for activation of solid-state reactions and formation of new compounds, as well as for milling of bulk materials to nanoscale. 48 Besides, this "green" and versatile approach is implemented under ambient conditions not requiring high temperatures and pressures.…”