Generation of metal-oxide nanoparticles using continuous-wave fibre laser ablation in liquid

In recent years, laser ablation in liquid has become an increasingly important technique for the fabrication of nanoparticles (NPs). To date, only pulsed lasers have been used. This paper reports our recent studies on the generation of Ti-oxide and Ni-oxide NPs by the ablation of metal targets in aqueous environments using a high-power, high-brightness continuous-wave (cw) fibre laser at a wavelength of 1070 nm. Owing to the high and uniform irradiation, the fibre laser provides an alternative approach for NP generation with well-controlled phase, size and size distribution, along with high production rate. Characterization of the NPs, in terms of morphology, size and size distribution, chemical composition and phase structure, by means of high-resolution transmission electron microscopy (HRTEM), high-angle annular dark field (HAADF) in scanning-transmission (STEM) mode, energy-dispersive x-ray spectroscopy (EDS) and x-ray diffraction (XRD), has been presented. In addition, limitations of the cw fibre laser process have been discussed in comparison with pulsed laser process.