Microwave-assisted one-pot synthesis of water-soluble rare-earth doped fluoride luminescent nanoparticles with tunable colors

Abstract

Polyethyleneimine (PEI) functionalized multicolor luminescent LaF(3) nanoparticles were synthesized via a novel microwave-assisted method, which can achieve fast and uniform heating under eco-friendly and energy efficient conditions. The as-prepared nanoparticles possess a pure hexagonal structure with an average size of about 12 nm. When doped with different ions (Tb(3+) and Eu(3+)), the morphology and structure of the nanoparticles were not changed, whereas the optical properties varied with doped ions and their molar ratio, and as a result emission of four different colors (green, yellow, orange and red) were achieved by simply switching the types of doping ions (Eu(3+) versus Tb(3) +) and the molar ratio of the two doping ions.

Fig. 1

TEM (a), SAED (b) and XRD (c) patterns of the as-prepared LaF₃:Ce,Tb nanoparticles.

Fig. 2

Size distribution the as-prepared LaF₃:Ce,Tb nanoparticles.

Fig. 3

TEM (a), SAED (b) and XRD (c) patterns of the as-prepared LaF₃:Eu nanoparticles.

Fig. 4

The excitation (a) and emission (b) spectra of as-prepared LaF₃:Ce,Tb nanoparticles.

Fig. 5

The excitation (a) and emission (b) spectra of as-prepared LaF₃:Eu nanoparticles.

Fig. 6

Multicolor luminescent photograph of LaF₃ nanoparticles doped with (a) 15 mol% Tb, (b) 25 mol% Tb, 5 mol% Eu, (c) 15 mol% Tb, 5 mol% Eu and (d) 30 mol% Eu.

Fig. 7

TEM image (a) and IR spectrum (b) of LaF₃:Ce,Tb nanoparticles one-pot synthesized and modified with PEI.

Scheme 1

Diagram illustrating the formation of PEI modified LaF₃ nanoparticles.