Study of nanoparticle production from yttrium oxide by pulse-periodic radiation of ytterbium fibre laser

The paper was devoted to investigation of Nd:Y2O3 nanopowder production by laser evaporation. The main attention is paid to investigating the features of evaporation and ablation of target by a ytterbium fibre laser radiation: formation of irregularities on a target surface, low relative yield of nanopowder, a long-term ablation in the form of drops, and the regime of ablation. With a high-speed camera it was shown that the transfer from vapour to drop ablation at the radiation power density of 0.46 ÷ 1.4 MW/cm2 occurs in 150 ÷ 200 µs after the start of laser action on a target. It is possible to substantially reduce spattering of drops and increase the relative yield of nanopowder to 30% of target weight by choosing the laser pulse duration shorter then this value. The optimal conditions have been found for producing nanopowder in the regime of pulse-periodic radiation with a peak laser power of 600 W, in which enrichment of nanopowder by neodimium does not exceed 12% of its contents in the target. The obtained nanopowders are weakly agglomerated, nanoparticles have a spherical shape, monoclinic phase, and their average diameter is 8.5 nm.