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Synthesis of phase-controlled iron oxide nanoparticles by pulsed laser ablation in different liquid media



Liquid-phase pulsed laser ablation (LP-PLA) is a promising technique for the fabrication of various nanomaterials because this technique is very simple and it is easy to control the experimental parameters. This paper demonstrates the synthesis of phase-controlled iron oxide magnetic nanoparticles by laser ablation of a bulk α-Fe2O3 target in the following liquid media: ethanol, D.I. water and acetone. Absorption spectra of the nanocolloidal solutions are measured by UV–Vis spectrophotometer. As-synthesized nanoparticles, extracted from the colloidal solutions, are characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscope (TEM) equipped with X-ray energy dispersive spectrometry (EDX) and a vibrating sample magnetometer (VSM) to discover crystallinity, phase structure, morphology, elemental compositions and magnetic properties in detail. The experimental results showed that the type of target and the magnitude of laser power play important roles in controlling the uniformity of iron oxide phase in the final product nanoparticles. Laser ablation of the iron oxide target in ethanol and acetone yields crystalline maghemite (γ-Fe2O3) nanoparticles, while that in D.I. water yields amorphous hematite (α-Fe2O3). Use of an iron oxide (α-Fe2O3) target for PLA in all three solvents is able to prevent the formation of metal iron and wustite phases in the final product nanoparticles. Moreover, our nanoparticles obtained in all three solvents possess magnetic behaviour, particularly that obtained in acetone, which has better saturation magnetization than those in ethanol and D.I. water.