Effect of Carbon Shell on the Structural and Magnetic Properties of Fe3O4 Superparamagnetic Nanoparticles

Jafari, Atefeh; Boustani, Komail; Shayesteh, S. Farjami

doi:10.1007/s10948-013-2239-8

Cited by 34 publications

(13 citation statements)

References 36 publications

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“…This behavior, typical of systems with two different oxidation states, is indicative of electron delocalization phenomena, which are responsible for the intense color of the material in the visible region as well. A further confirmation of the iron-based oxide formation comes from FTIR spectra, where the intense absorption in the 550-500 cm −1 interval, has been assigned to Fe-O stretching mode of Fe 3 O 4 (Jafari et al, 2014) (Supplementary Figure 4, right panel). Notice that the intense absorption at about 38,000 cm −1 (black curve), before ascribed to π-π* transitions of sp 2 carbon sites inside the amorphous carbon phase, is quite completely eroded, although a redshift inside the complex envelope cannot be ruled out (blue curve).…”

Section: Optical Properties Of the Samplesmentioning

confidence: 85%

“…Furthermore, multilayered structures made by porous carbon microspheres with embedded magnetic nanoparticles are known to show an enhanced high surface area, large pore volume together with superior adsorption capability, a fast adsorption rate and facile separation (Lu et al, 2017). The stability of magnetic nanoparticles is also greatly enhanced when they are covered by carbon layers, in a core-shell structure, thus preventing the nanoparticles from agglomeration phenomena (Jafari et al, 2014). Hence, by combining the advantages of cheap activated carbon and the properties of the magnetic particles, it is possible to fabricate new adsorbents incorporating iron-based particles, being the high surface area, the suitable pore size and the separability the main goals to achieve (Yang et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

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From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies

et al. 2019

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The facile preparation of polymer waste-derived microporous carbon microspheres (S BET ∼800 m 2 /g) 100-300 µm in size, is reported at first. We have taken advantage of both, the crosslinked nature and the porous texture of the poly(4-ethylstyrene-co-divinylbenzene) microspheres, which allow the incoming anions and cations present in liquid media to enter and to remain segregated into the pores of the polymer microspheres as soon as the solvent is removed. Interestingly, the ZnCl 2 phase, when incorporated in the microporous molecular architecture of the polymer, prevents the collapsing of the pore structure of thermosetting polymer spheres during the pyrolysis occurring at 800 • C and acts as an activating agent of the carbon phase under formation, being responsible for the formation of an extended meso-and macroporosity (30-200 and 300-1,000 Å ranges). More interestingly, porous carbon microspheres with magnetic properties have been prepared from the ZnCl 2 -activated porous carbon spheres after impregnation with Fe nitrate solution and thermal treatment at 800 • C. A multi-technique methodology to characterize more extensively carbons at the micro/nanoscale is reported in the paper. More in detail, the morphology, structure, porous texture, and the surface properties of the carbon and of the magnetic carbon microspheres have been investigated by scanning and transmission electron microscopy, atomic force microscopy, X-ray diffraction, N 2 physisorption, diffuse reflectance UV-Vis, Raman and infrared spectroscopies. Furthermore, magnetic properties have been revealed at the nano-and at the macroscale by magnetic force microscopy and simple magnetically guided experiments by permanent magnets. The multi-technique methodology presented in the paper allows in elucidating more extensively about the different characteristics of activated carbons. Notwithstanding the huge amount of literature on activated carbons, the precise control of both the structure and the surface has, for the most part, hidden the relevance of other properties at the molecular scale of the assembled architectures. On the other hand, recent studies indicate that by molecular design, nanostructured, and porous carbonaceous materials could also be rationally proposed.

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Section: Optical Properties Of the Samplesmentioning

confidence: 85%

Section: Introductionmentioning

confidence: 99%

From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies

et al. 2019

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“…Interestingly, in spite of smaller iron cores, the multi-iron cores nanoparticles (N100 sample) exhibit higher saturation magnetization than single oval shape nanoparticles in N75 sample. Jafari et al studied the effect of carbon shell on the structural and magnetic properties of Fe 3 O 4 and concluded that the magnetization of Fe 3 O 4 nanoparticles was reduced after coating with carbon [63]. Bittova et al carried out a research study on the effects of coating on dipolar interparticle interactions and showed the reduction of saturation magnetization after coating as well [64].…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Carbon Encapsulated Mono‐ and Multi‐Iron Nanoparticles

Sanaee

Bertran

2015

Journal of Nanomaterials

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Core–shell nanostructures of carbon encapsulated iron nanoparticles (CEINPs) show unique properties and technological applications, because carbon shell provides extreme chemical stability and protects pure iron core against oxidation without impairing the possibility of functionalization of the carbon surface. Enhancing iron core magnetic properties and, in parallel, improving carbon shell sealing are the two major challenges in the synthesis of CEINPs. Here, we present the synthesis of both CEINPs and a new carbon encapsulated multi-iron nanoparticle by a new modified arc discharge reactor. The nanoparticle size, composition, and crystallinity and the magnetic properties have been studied. The morphological properties were observed by scanning electron microscopy and transmission electron microscopy. In order to evaluate carbon shell protection, the iron cores were characterized by selected area diffraction and fast Fourier transform techniques as well as by electron energy loss and energy dispersive X-ray spectroscopies. Afterward, the magnetic properties were investigated using a superconducting quantum interference device. As main results, spherical, oval, and multi-iron cores were controllably synthesized by this new modified arc discharge method. The carbon shell with high crystallinity exhibited sufficient protection against oxidation of pure iron cores. The presented results also provided new elements for understanding the growth mechanism of iron core and carbon shell.

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“…The peaks in the range of 1000 cm −1 to 1400 cm −1 and 1630 cm −1 to 1650 cm −1 , can be assigned to the bending modes vibration of O-H and H-O-H, respectively [17,18]. The peaks in the range of 3400 cm −1 to 3850 cm −1 are related to stretching vibrations of OH [19]. As it is shown in the figure, increasing substrate temperature caused a decrease in absorption band related to OH vibrations.…”

Section: Ft-ir Spectroscopymentioning

confidence: 96%

Optical and structural properties of nanostructured copper oxide thin films as solar selective coating prepared by spray pyrolysis method

Asadi-Aghbolaghi

Rozati

2017

Materials Science-Poland

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Copper (II) oxide thin films were prepared by spray pyrolysis method on soda-lime glass substrates using copper acetate precursor solution. Influence of substrate temperature on structural and optical properties was investigated. Structural analysis of these layers were carried out by X-ray diffraction (XRD). Single phase nature and high crystallinity of CuO nanostructures were observed on XRD patterns. The general appearance of the films was uniform and black in color. FT-IR transmittance spectra confirmed the results from the XRD study. Selective solar absorber coatings of copper oxide (CuO) on stainless steel substrates was prepared by spray pyrolysis method. Effect of deposition temperature on optical properties of thin films was investigated. Optical parameters, absorbance (α) and emittance ( ) were evaluated from reflectance data. It can be deduced that the porous structure, such as a light traps, can greatly enhance absorbance, while the composition, thickness and roughness of thin films can greatly influence the emissivity. Single phase nature and high crystallinity of CuO nanostructures were observed by XRD patterns. Solar absorbance of thin films were in the range of 85 % to 92 %.

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Effect of Carbon Shell on the Structural and Magnetic Properties of Fe3O4 Superparamagnetic Nanoparticles

Cited by 34 publications

References 36 publications

From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies

From Polymer to Magnetic Porous Carbon Spheres: Combined Microscopy, Spectroscopy, and Porosity Studies

Synthesis of Carbon Encapsulated Mono‐ and Multi‐Iron Nanoparticles

Optical and structural properties of nanostructured copper oxide thin films as solar selective coating prepared by spray pyrolysis method

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