Structure and magnetic properties of nanoparticles encapsulated in carbon shells

Leonowicz, M.; Woźniak, Michał; Shul’ga, Yu. M.; Muradyan, V. E.; Liu, Zhongwu; Davies, H.A.; Kaszuwara, W.; Grabski, J.

doi:10.1016/j.jmmm.2005.03.054

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…The specimens pyrolyzed at two lower temperatures showed J H C and M R close to zero, indicating the lack of magnetic anisotropy and domination of superparamagnetic ordering, whereas the material pyrolyzed at 873 K shows ferromagnetic interactions. Moreover, a quite high coercivity may indicate some dissolution of carbon in the nickel lattice, as was previously found for Ni nanocrystallites processed by arc discharge [12].…”

Section: Structure and Magnetic Propertiessupporting

confidence: 61%

Thermophysical and Magnetic Properties of Carbon Beads Containing Nickel Nanocrystallites

et al. 2011

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Ferromagnetic and superparamagnetic nickel nanocrystallites, stabilized in a carbon matrix, were prepared by a three-step procedure including formation of a Ni acrylamide complex, followed by frontal polymerization and pyrolysis of the polymer at various temperatures. It was found that the procedure applied enables fabrication of magnetic beads containing metallic nanocrystallites embedded in a carbon matrix. The size of the crystallites, their morphology, volume fraction, and magnetic properties can be tailored by the pyrolysis temperature. The size of the crystallites affects their behavior in an external magnetic field, i.e., a heating process is the most effective for a sample pyrolyzed at 873 K. The revealed H n -type dependence of the temperature increase rate, (dT /dt) t=0 , on the amplitude of the magnetic field indicates the presence of both superparamagnetic and ferromagnetic particles in all the samples studied since n > 2. For the superparamagnetic particles, the heating mechanism is associated with Néel relaxation. For the lower values of the magnetic field amplitude, H < H 0 , the relaxation losses dominate whereas for the opposite case, H > H 0 , the magnetic hysteresis is the main source of thermal energy losses. The composites containing magnetic Ni nanocrystallites entrapped in a carbon matrix can be potentially applied for hyperthermia treatment.

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Section: Structure and Magnetic Propertiessupporting

confidence: 61%

Thermophysical and Magnetic Properties of Carbon Beads Containing Nickel Nanocrystallites

et al. 2011

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“…Different notable materials including metals, , polymer, ,, silica, and carbon ,,,, have been reported to protect the nanoparticles from oxidation. Compared to polymer and silica shells, carbon shells exhibit much higher stability in harsh physical environments such as strong acid. , Different polymers such as vinyl ester resin and polyurethane have been used as carbon precursors to protect the metal nanoparticles from oxidation.…”

Section: Introductionmentioning

confidence: 99%

“…25,27 However, the easy agglomeration, oxidation/corrosion, and flammable properties under ambient conditions and at room temperature are challenges for practical applications of iron nanoparticles. 28,29 Different notable materials including metals, 30,31 polymer, 13,17,26 silica, 28 and carbon 23,26,27,32,33 have been reported to protect the nanoparticles from oxidation. Compared to polymer and silica shells, carbon shells exhibit much higher stability in harsh physical environments such as strong acid.…”

Section: Introductionmentioning

confidence: 99%

Magnetic and Magnetoresistance Behaviors of Solvent Extracted Particulate Iron/Polyacrylonitrile Nanocomposites

et al. 2009

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Iron nanoparticle reinforced polyacrylonitrile (PAN) nanocomposites are fabricated by a facile and environmentally benign solvent extraction method. Fourier transform infrared (FT-IR), thermal gravimetric analysis (TGA), and differential scanning calorimetry (DSC) results indicate a strong interaction between the iron nanoparticles and the polymer matrix for the as-prepared polymer nanocomposites. The heat treatment induces the carbonization of the polymer matrix. High-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD) analysis show a protecting carbon shell surrounding the iron nanoparticles within the carbon matrix against the particle oxidation. The magnetic properties, electrical conductivity, and magnetic field dependent resistivity of heat-treated nanocomposites with different particle loadings are carried out in a physical properties measurement system by Quantum Design and by a standard four probe method. The saturation magnetization increases and the coercivity decreases with an increase of the nanoparticle loading. The heat-treated nanocomposites possess a room temperature magnetoresistance (MR) of 5.1% at a field of 90 kOe. The nanoparticle loading has a significant effect on the resistivity of nanocomposites. The heat-treated nanocomposites show a particle loading dependent transport mechanism. A transition from semiconductive to metallic conduction was observed with an increase of the nanoparticle loading.

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“…It has already been proven that the composition of ferromagnetic nanoparticles, their size (5-30 nm) and size distribution as well as the thickness of a stabilizing polymer shell can be controlled at the stage of nanocomposite synthesis [10][11][12][13][14][15]. Previous studies have shown that nanocomposites of this type exhibit ferromagnetic properties at room temperature, with the coercive force depending on the pretreatment conditions.…”

Section: Issn: 2577-7920mentioning

confidence: 99%

The Influence of Magnetic Field on Synthesis of Iron Nanoparticles

Ualkhanova¹,

Ay²,

Ag³

et al. 2017

Journal of Nanoscience and Nanotechnology Applications

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One of today's tasks is the development of new strategies for the synthesis of ferromagnetic, superparamagnetic nanoparticles immobilized in a polymer or carbon nanostructured matrix, and studying of the possibility of influencing their structure and magnetic properties.When the critical parameter that determines certain phenomena (the size of magnetic domains, the characteristic length of exchange interactions, the length of magnetostatic interactions, etc.) becomes comparable to the particle size, nanoscale magnetic materials exhibit sharp (dramatic) variability of magnetic properties. Therefore, there is a need to develop new methods of synthesis, protection and certification of such nanosystems to synthesize promising magnetic materials using technologically controlled processes.The encapsulation of metal nanoparticles into carbon chemically inert graphite like shells allows the synthesis of new generation materials to begin. Magnetic nanoparticles occupy an important place among these materials and such nanoparticles, which can be technologically important magnetic materials, will be investigated in this paper.The formation of nanocomposites, the production of nanoparticles of the same size and, accordingly, with reproducible properties, is one of the main technological tasks of this research. Methods of obtaining, which allow us to precisely control the size of particles are continuously improved. Magnetic nanostructured materials with unique electrical, mechanical, catalytic, optical and, moreover, specific magnetic properties, make it possible to constantly expand their fields of application in computer science, catalysis, for sensors production, in medicine and in biology.The correlation between nanostructure and magnetic properties allows us to offer different types of magnetic nanostructures: (1) systems with isolated particles, whose unique magnetic properties derive from decreasing sizes of components; (2) ultrafine particles with a cortical structure; (3) materials in which magnetic interaction is the dominant property; (4) nanocomposites, which consist of magnetic particles encapsulated in a chemically inert matrix. The magnetic properties in this case are determined by the ratio of volume fractions of magnetic particles and the matrix.In this work, we studied the effect of an external magnetic field on the formation and phase composition of iron particles synthesized in an arc discharge in a liquid phase. These products can be technologically important magnetic materials.

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Structure and magnetic properties of nanoparticles encapsulated in carbon shells

Cited by 6 publications

References 3 publications

Thermophysical and Magnetic Properties of Carbon Beads Containing Nickel Nanocrystallites

Thermophysical and Magnetic Properties of Carbon Beads Containing Nickel Nanocrystallites

Magnetic and Magnetoresistance Behaviors of Solvent Extracted Particulate Iron/Polyacrylonitrile Nanocomposites

The Influence of Magnetic Field on Synthesis of Iron Nanoparticles

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