Laser-Assisted Synthesis of Colloidal FeW O and Fe/Fe O Nanoparticles in Water and Ethanol.

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