Synthesis and characterization of graphite-encapsulated iron nanoparticles from ball milling-assisted low-pressure chemical vapor deposition

Abstract

Graphite-encapsulated Fe nanoparticles were synthesized using a combined method of high-energy ball milling and low-pressure chemical vapor deposition (LPCVD). Fe2O3 and graphite powders were milled to increase their surface areas and obtain a more homogeneous distribution. LPCVD was performed at a pressure of ~0.57 Torr in a tube furnace under a CH4/H2 atmosphere at 1050°C for 1 and 3 h. As-synthesized samples were purified in a 2 M HF solution. Characterization was performed using X-ray diffractometry (XRD), scanning and transmission electron microscopy (SEM and TEM) and alternating gradient magnetometry (AGM). XRD revealed the presence of body centered cubic (BCC) and face centered cubic (FCC) Fe phases without residual iron oxides. SEM confirmed the powders were better mixed and smaller after ball milling compared to mortar and pestle milled powders. High resolution TEM showed all nanoparticles had at least four and on average 16 graphitic layers, around an Fe core ranging from 20–300 nm. Magnetic measurements indicated that nanoparticles exhibit soft ferromagnetic behavior with low saturation magnetization (17–21 emu/g) and coercivity (110 Oe). A chemical stability test performed in a 2 M HCl solution showed that graphitic shells did not degrade, nor was there evidence of core dissolution or shell discontinuity.

Synthesis and Characterization of Flower-like Carbon-encapsulated Fe-C Nanoparticles for Application as Adsorbing Material

“…76-1877) based on their positions and relative intensities. The characteristic peaks belonging to the crystalline graphite phase are not observed because of the low content and crystallinity of the deposited graphite phase in these samples, which is consistent with the literature [ 20 , 24 ]. For Sample 2, the diffraction peaks of Fe at 44.7° and 82.3° become weakened obviously.…”

Carbon-coated Fe3O4core–shell super-paramagnetic nanoparticle-based ferrofluid for heat transfer applications

“…The saturation magnetization was found to be much lower in case of core-shell NPs. The low value of the magnetic saturation may be attributed to the carbon coating over Fe 3 O 4 NPs as the carbon materials are diamagnetic in nature [54]. A low coercive field was also observed in both cases of NPs which indicate the spherical shape of NPs [55].…”

Multilayer Graphene Encapsulation on the Fe Nanoparticles Starting from Fe Chloride Precursors

“…The interest of the magnetic nanoparticles has increased due to their various application fields [1,2]. Magnetic iron nanoparticles were used as drug or gene delivery agents at cancer treatments like hyperthermia, diseases detections and imaging studies such as magnetic resonance imaging [1,3,4]. Not only biomedical applications, but also iron based magnetic nanoparticles are desired materials for catalytic applications, waste water treatment and electronic utilizations (supercapacitors, batteries etc.)…”

“…[5]. Graphene encapsulation protects the magnetic core materials against corrosion and also increases the surface area and reduce the agglomerations of the particles [3,5]. Solvothermal method, sol-gel method, combustion synthesis, plasma, electrophoretic deposition method and chemical vapor deposition (CVD) method are used to synthesize graphene coated nanoparticles [6,7].…”