Graphene layers are fabricated from multiwalled carbon nanotubes (MWCNTs) with a high direct current pulse through a pulsed current sintering process. We confirm the transformation of the structure from MWCNTs to graphene layers. Graphene layers are analyzed by field emission scanning electron microscopy, high resolution transmission electron microscopy, high resolution Raman, and x-ray diffraction.
Phone: þ82 2 2220 0501, Fax: þ82 2 2291 7395Liquid-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 a-Fe 2 O 3 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, elemen-tal 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 (g-Fe 2 O 3 ) nanoparticles, while that in D.I. water yields amorphous hematite (a-Fe 2 O 3 ). Use of an iron oxide (a-Fe 2 O 3 ) 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.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.