Synthesis Of Carbon-encapsulated Magnetic Nanoparticles Research Articles

Inspired by efficient cellulose-dissolving system: Facile one-pot synthesis of biomass-based hydrothermal magnetic carbonaceous materials

The core-shell structure of carbon encapsulated magnetic nanoparticles (CEMNs) displays unique properties. Enhancing the magnetization of iron core, in parallel, improving the encapsulation of carbon shell are the two major challenges in the synthesis of CEMNs. Inspired by efficient cellulose-dissolving system, carbon encapsulated magnetic nano-Fe3O4 particles (Fe3O4@C) with ∼10.0nm Fe3O4 cores and 1.9-3.3nm carbon shell, were successfully one-pot synthesized via a novel hydrothermal carbonization (HTC) process. The dissolving process in ionic liquids ([Emim]Ac and [Amim]Cl) completely cleaved the intra- and intermolecular H-bonds in cellulose, and favored the incorporation of Fe3O4 nanoparticles into the cellulose H-bonds systems during the regeneration process. Some stable linkages were formed in Fe3O4@C, taking Fe3O4 nanoparticles as a structure guiding agent. The morphology and properties of Fe3O4@C depended strongly on the type of carbon precursors and pyrolysis temperature. Well encapsulated nanostructure was obtained at HTC temperature 280°C, when [Emim]Ac-treated holocellulose was used as the carbon source. Meanwhile, the thickness of the amorphous shell and magnetization increased with HTC temperature. More importantly, a novel elements for understanding the growth mechanism for the Fe3O4@C composite under HTC conditions was proposed.

Self-sustaining high-temperature synthesis of carbon-encapsulated magnetic nanoparticles from organic and inorganic metal precursors

Self-sustaining high-temperature synthesis of carbon-encapsulated magnetic nanoparticles from organic and inorganic metal precursors

Self-sustaining high-temperature synthesis of carbon-encapsulated magnetic nanoparticles from organic and inorganic metal precursors

Abstract A systematic study on the synthesis of carbon-encapsulated magnetic nanoparticles by self-sustaining high-temperature synthesis (SHS) is presented. The SHS was carried out using NaN 3 as a reducer; and poly(tetrafluoroethene) (C 2 F 4 ) n , hexachloroethane (C 2 Cl 6 ) and hexachlorobenzene (C 6 Cl 6 ) as three various oxidizers. The effect of metal precursor, (Fe(CO) 5 or K 3 [Fe(CN) 6 ]) on the yield, reaction heat, morphology, structure and magnetic properties of the products was investigated. The highest product yield with best magnetic characteristics was obtained from the organometallic iron precursor and C 2 Cl 6 oxidizer.

Continuous synthesis of carbon-encapsulated magnetic nanoparticles with a minimum production of amorphous carbon

Abstract The continuous synthesis of carbon-encapsulated magnetic nanoparticles is described using an inductively coupled radio frequency thermal plasma torch. The synthesis uses the simultaneous vaporization of iron powder and a liquid carbon source in the plasma jet. It was found that the process parameters could be adjusted to minimize the amorphous carbon content in the product. It could be achieved using either aliphatic alcohols (processed in Ar plasma) or hydrocarbons (processed in Ar–O2 plasma). In such circumstances the oxygen etches any amorphous carbon particles produced. Complete reduction of amorphous carbon was achieved when ethanol was used as a carbon feedstock.

Synthesis of carbon-encapsulated magnetic nanoparticles by pulsed laser irradiation of solution

Abstract A method for synthesizing carbon-encapsulated magnetic nanoparticles (CEMNPs) is reported. In the proposed method, a solution containing various metalocenes dissolved in xylene is irradiated with a nanosecond pulsed ultraviolet laser at room temperature and atmospheric pressure. Upon the completion of irradiation, CEMNPs (Fe–C, Ni–C, Co–C) with diameters ranging from a few nanometers to about 300 nm are produced in the solution. The material characteristics of these nanoparticles are then examined with electron microscopy, Raman spectroscopy, X-ray diffraction (XRD) and superconducting quantum interference device (SQUID) magnetometry. It was found that the magnetic nanoparticles coated with graphitic shells exhibit good stability in a high concentration HCl (10 mol) solution. The possible growth mechanisms of CEMNPs under the pulsed laser irradiation of the solution are then discussed.

Large scale continuous synthesis of carbon-encapsulated magnetic nanoparticles

Fe, Fe3C and NdC2 nanoparticles, encapsulated within carbon cages, were continuouslyproduced during the induction thermal plasma processing ofFe14Nd2B, in the presence of methane or acetylene. The product morphology was studied by means ofSEM. Further structural details were obtained from TEM, HRTEM, Raman spectroscopyand x-ray powder diffraction studies. The so-produced nanostructures have core–shellstructure, with inner cavity diameters varying between 10 and 30 nm. The carbon coatingswere composed of between 5 and 25 graphene layers. The carbon cages were built fromsp2 carbon atoms, which protected the encapsulated nanoparticles from both oxidation andagglomeration. The plasma generated products were ferromagnetic, with maximumvalues of coercivity field of 600 G s, and saturation magnetization values of up to40 emu g−1.

Synthesis of carbon-encapsulated magnetic nanoparticles by spray pyrolysis of iron carbonyl and ethanol

Synthesis of carbon-encapsulated magnetic nanoparticles by spray pyrolysis of iron carbonyl and ethanol

Synthesis of carbon-encapsulated magnetic nanoparticles by a grain-boundary-reaction

AbstractCarbon-encapsulated ferric magnetic nanoparticles were prepared by the grain-boundary-reaction of ultrafine goethite particles. The mechanism of the grain-boundary-reaction was studied with high-resolution transmission electronic microscope, X-ray diffraction and thermo gravimetric analysis. The magnetic properties are measured with a vibrating sample magnetometer. The diameter of carbon-encapsulated ferric magnetic nanoparticles is 30~60 nm, and the coercive force and saturate magnetization are 315 Oe and 30 emu /(g powder), respectively. These composite particles are very stable in air.