Crystallization of Iron Nanostructures with Secondary-Laser-Assisted Pulsed Laser Ablation in Ethanol Solution

Abstract

In this paper, we have investigated the growth technique of graphite-coated nanomagnet particles to apply a sustainable environment technology by millisecond YAG pulsed laser ablation (PLA) method in ethanol solution using Fe bulk-target. To control crystallized forms and/or grain-size of nanomagnet-materials, laser diode (LD) beam was irradiated to the ablation plumes, which were generated by this PLA method. Additionally, magnetic field was applied to the ablation plumes, in order to separate a nanomagnet particle and a non-magnet one. Ablation plumes were observed by high-speed camera images, and they were re-excited by LD laser beam irradiation. In case of magnetic field assist, ablation plumes were attracted to the magnet. This suggested that growth nano-particles had magnetic property. Typical carbon-coated nano-particles, which grown by non-assisted PLA, were observed by TEM images, and these grain sizes were dependent on the pulsed width of PLA source. On the other hand, LD assisted samples showed there were rod-sharped nano-materials, and crystallization of these materials was β-Fe₃O₄, γ-Fe₂O₃ surmised by electron diffraction.