Transparent NaGdF4:Nd3+ colloid prepared by femtosecond laser ablation as a liquid laser medium

By using femtosecond-pulsed laser to ablate the larger nanosized target in liquid, stable transparent NaGdF 4 :Nd 3+ colloid has been successfully fabricated. The X-ray diffraction (XRD) spectra reveal that the colloidal nanoparticles remain the hexagonal phase crystal structure of NaGdF 4 powder target. SEM and TEM images results indicate that the size of these colloidal nanoparticles decreases sharply. FT-IR results indicate that the number of O–H and C–H groups on the surface is decreased. The emission properties of the colloid have been investigated using 794   nm pulsed wave laser radiation , and it is found that the colloid exhibits near-infrared luminescent emissions in the spectral range of 850–1400   nm, and the decay time for 4 F 3/2 → 4 I 11/2 (1058   nm) Nd 3+ ion transitions is lengthened than that of powder target, these results are probably due to the reduced nonradiative relaxation assisted by high energy oscillators . The observed near-infrared emission of the stable transparent colloid makes it a good candidate for application in liquid laser .