Magnetic Properties of Iron Particles Embedded in Multiwall Carbon Nanotubes

Arya, Ved Prakash; Prasad, G. Durga; Kumar, P. S. Anil

doi:10.1166/jnn.2009.1165

Cited by 11 publications

(8 citation statements)

References 9 publications

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“…In addition, diffraction pattern shows less intense peaks corresponding to Fe 3 C, α-Fe and γ-Fe phase; Fe 3 C peak probably originates from the junction between outer surfaces of Fe NPs with inner-most wall of CNT, whereas α-Fe peak mainly arises from the encapsulated Fe NPs. The diffraction pattern of MWCNT is well in agreement with the earlier reports [26,27]. Fig.…”

Section: Resultssupporting

confidence: 92%

Low temperature magnetoresistance and magnetization studies of iron encapsulated multiwall carbon nanotube/polyvinyl chloride composites

Vasanthkumar

Sameera

Bhatia

et al. 2015

Solid State Communications

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Section: Resultssupporting

confidence: 92%

Low temperature magnetoresistance and magnetization studies of iron encapsulated multiwall carbon nanotube/polyvinyl chloride composites

Vasanthkumar

Sameera

Bhatia

et al. 2015

Solid State Communications

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“…The MWCNT mats were prepared by thermally assisted chemical vapor deposition at 980 • C using a single hot-zone horizontal quartz reactor, taking benzene as a carbon source and ferrocene as a catalyst [10]. The sample's morphology was studied using a Quanta 200 scanning electron microscope (SEM) and a high-resolution FEI Technai F30 transmission electron microscope (TEM).…”

Section: Methodsmentioning

confidence: 99%

Effect of magnetic field on Mott’s variable-range hopping parameters in multiwall carbon nanotube mat

Arya¹,

Prasad²,

Kumar³

2012

J. Phys.: Condens. Matter

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We report the temperature and magnetic field dependence of the conductivity of multiwall carbon nanotube mat in the temperature range 1.4-150 K and in magnetic fields up to 10 T. It is observed that charge transport in this system is governed by Mott’s variable-range hopping of three-dimensional type in the higher temperature range and two-dimensional type in the lower temperature range. Mott’s various parameters, such as localization length, hopping length, hopping energy and density of states at the Fermi level are deduced from the variable-range hopping fit. The resistance of the sample decreases with the magnetic field applied in the direction of tube axis of the nanotubes. The magnetic field gives rise to delocalization of states with the well-known consequence of a decrease in Mott’s T0 parameter in variable-range hopping. The application of magnetic field lowers the crossover temperature at which three-dimensional variable-range hopping turns to two-dimensional variable-range hopping. The conductivity on the lower temperature side is governed by the weak localization giving rise to positive magnetoconductance. Finally, a magnetic field-temperature diagram is proposed showing different regions for different kinds of transport mechanism.

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“…H c reached values up to ∼0.29 kOe slightly higher than those found for α-Fe or Fe 3 C nanoparticles inside multiwalled carbon nanotubes. 58−60 Previous results on the magnetic properties of carbon nanotubes with Fe 2 O 3 (maghemite) and Fe 3 C (cementite) inside reported an M s of 5 emu/g and an H c of ∼500 Oe. 61 The ferromagnetism displayed by N-CNSs could be useful for several applications such as magnetic sensor devices, stem cell transplantation, and magnetic fluid hyperthermia.…”

Section: Resultsmentioning

confidence: 99%

Oxygenated Surface of Carbon Nanotube Sponges: Electroactivity and Magnetic Studies

2019

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We report the synthesis of nitrogen-doped carbon nanotube sponges (N-CNSs) by pyrolysis of solutions of benzylamine, ferrocene, thiophene, and isopropanol-based mixture at 1020 °C for 4 h using an aerosol-assisted chemical vapor deposition system. The precursors were transported through a quartz tube using a dynamic flow of H2/Ar. We characterized the N-CNSs by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis. We found that isopropanol, isopropanol–ethanol, and isopropanol–acetone as precursors promote the formation of complex-entangled carbon fibers making knots and junctions. The N-CNSs displayed an outstanding oxygen concentration reaching a value of 9.2% for those synthesized with only isopropanol. We identified oxygen and nitrogen functional groups; in particular, the carbon fibers produced using only isopropanol exhibited a high concentration of ether groups (C–O bonds). This fact suggests the presence of phenols, carboxyl, methoxy, ethoxy, epoxy, and more complex functional groups. Usually, the functionalization of graphitic materials is carried out through aggressive acid treatments; here, we offer an alternative route to produce a superoxygenated surface. The understanding of the chemical surface of these novel materials represents a huge challenge and offers an opportunity to study complex oxygen functional groups different from the conventional quinone, carboxyl, phenols, carbonyl, methoxy, ethoxy, among others. The cyclic voltammetry measurements confirmed the importance of oxygen in N-CNSs, showing that with high oxygen concentration, the highest anodic and cathodic currents are displayed. N-CNSs displayed ferromagnetic behavior with an outstanding saturation magnetization. We envisage that our sponges are promising for anodes in lithium-ion batteries and magnetic sensor devices.

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Magnetic Properties of Iron Particles Embedded in Multiwall Carbon Nanotubes

Cited by 11 publications

References 9 publications

Low temperature magnetoresistance and magnetization studies of iron encapsulated multiwall carbon nanotube/polyvinyl chloride composites

Low temperature magnetoresistance and magnetization studies of iron encapsulated multiwall carbon nanotube/polyvinyl chloride composites

Effect of magnetic field on Mott’s variable-range hopping parameters in multiwall carbon nanotube mat

Oxygenated Surface of Carbon Nanotube Sponges: Electroactivity and Magnetic Studies

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