Laser-Assisted Synthesis of Colloidal FeWx Oy and Fe/Fex Oy Nanoparticles in Water and Ethanol

Abstract

Homogeneous polycrystalline Fe_x O_y nanoparticles were generated by ablation of iron targets in water by nanosecond laser pulses at 532 nm. In ethanol, crystalline core-shell Fe/Fe_x O_y structures with size medians around 20 nm were produced. The ablation of FeW_x O_y targets in water resulted in crystalline hollow shells and homogeneous FeW_x O_y nanoparticles. In contrast, amorphous core-shell FeW_x O_y nanoparticles with a median size of 17 nm were produced in ethanol. The size distribution of both the Fe_x O_y and the FeW_x O_y particles showed a slight dependence on fluence and pulse number. This may be related to primary and secondary ablation and modification mechanisms.

Keywords: colloids; core-shell structure; iron; laser ablation synthesis in solution (LASiS); nanoparticles.