Magnetization temperature dependence in iron nanoparticles

Zhang, Dajie; Klabunde, Kenneth J.; Sorensen, C. M.; Hadjipanayis, G. C.

doi:10.1103/physrevb.58.14167

Cited by 161 publications

(112 citation statements)

References 10 publications

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“…6(b). This is because the surface modified or not modified nanoparticles reinforced the composites successfully (Zhang, et al, 1998). The Fe 2 O 3 particles did not make the remarkable difference in tensile modulus at a lower given particle content.…”

mentioning

confidence: 68%

“…The interfacial interactions between fillers and polymer matrix play a crucial role in determining the quality and properties of the nanocomposites (Rancourt and Taylor, 2008;Sawada et al, 2008;Chiang, et al, 2003). The poor bonding linkage between the fillers and the polymer matrix such as the composites made by simple mixing (Hsu, et al, 2003;Liu, et al, 1999;Park, et al, 2003;Sorensen, 2001;Zhang, et al, 1998) will introduce artificial defects, which consequently result in a adverse effect on the mechanical properties of the nanocomposites. Introducing good linkages between the fillers and the polymer matrix is still a challenge for specific composite fabrication.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and Characterization of Iron Oxide Nanoparticles Reinforced Polyester/Nanocomposites

Kumar¹,

Reddy

2015

ILCPA

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ABSTRACT. We report on synthesis of two highly disperse nanoparticles viz. Fe 2 O 3 & f-Fe 2 O 3 using chemical reduction method. Reaction was initiated to mix solution A (i.e. Fecl 3 6H 2 o) into solution B (i.e. Fecl 2 4H 2 o) together under the presence of ammonium to develop nanoparticles. Mechanical properties of above mentioned nanoparticles filled with polyester polymer nanocomposites were fabricated to assess the possibility of using this filler as a new material. Methacryloxypropyl was used as a functionalization agent to prepare f-Fe 2 O 3 nanoparticles. Mechanical properties of f-Fe 2 O 3 nanocomposites were improved with the help of functionalization when compared with Fe 2 O 3 nanocomposites. A functionalization of nanoparticles favours the composite fabrication with a lower curing temperature as compared to the as-synthesised nanoparticles filled polyester nanocomposites. Thermogravimetric analysis showed an increased thermo-stability of f-Fe 2 O 3 nanoparticles filled polyester nanocomposites as compared to the Fe 2 O 3 nanoparticles filled counterparts. Mechanical and thermal properties were increased due to the homogeneous particle dispersion and chemical bonding between nanoparticles and polyester matrix. The nanoparticles become magnetically harder after incorporation into the polyester resin matrix.

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mentioning

confidence: 68%

Section: Introductionmentioning

confidence: 99%

Synthesis and Characterization of Iron Oxide Nanoparticles Reinforced Polyester/Nanocomposites

Kumar¹,

Reddy

2015

ILCPA

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“…In the pure cobalt islands the Curie temperature is lowered compared to the bulk value due to the island's dimensionality. 24 This lowering is expected to be be more pronounced for the oxidized islands due to the disorder induced by the oxygen impurities.…”

Section: Magnetismmentioning

confidence: 99%

Oxidation Induced Enhanced Magnetic Susceptibility of Co Islands on Pt(111)

et al. 2004

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We have studied the evolution of the magnetic properties of monolayer-high cobalt islands on a Pt(111) surface as function of their exposure to oxygen. We observe a sequential quenching of magnetic anisotropy and magnetic moment. For minute exposures to oxygen this leads to an enhancement of the maximum susceptibility of up to 66% for ′′. We show that the reason for the reduction of the anisotropy before the one of the moment is due to preferential oxygen adsorption at the island edges, which are the main source of magnetic anisotropy. Our example shows how the enhanced chemical reactivity, combined with the enhanced anisotropy of low coordinated atoms, leads to surprising changes of magnetic properties upon exposure to oxygen. IntroductionDue to their reduced dimensions, small metallic magnetic particles created by metal epitaxy at surfaces are very sensitive to pollution, in particular to oxidation. The effect of oxidation on magnetic properties can be quite complex. Therefore partial oxidation may provide helpful insight into the origin of magnetic properties, such as magneto-crystalline anisotropy. Generally, oxidation degrades the magnetic properties; for instance, it reduces the anisotropy. 1 However, in some particular systems it may dramatically increase the anisotropy, e.g., due to exchange coupling with an antiferromagnetic CoO shell. 2 One of the major questions coming up when dealing with very small nanoparticles is the influence of their shape and interfaces on the anisotropy. 3-7 For supported cobalt chains, 8 and for very small cobalt islands, 9 the anisotropy per atom K is increased with respect to bulk or thin film values. In the limit of single adatoms this increase is more than 2 orders of magnitude. 10 Due to the reduced atomic coordination the atoms recover part of their gas phase properties; e.g., their orbital moment is significantly larger than in bulk, where it is almost entirely quenched due to crystal field and delocalization effects. The higher orbital moments are related to a larger anisotropy of orbital moments, which in turn causes by spin-orbit coupling a higher magneto-crystalline anisotropy energy. 6 As a consequence of this strong coordination effect, the anisotropy of twodimensional cobalt islands grown on Pt (111) is principally determined by the edge atoms. 6 On the other hand, the overall magnetic moment of an island is determined by all atoms approximately to equal parts because the spin moment is largely independent of coordination and it overwhelms the orbital moment. As the anisotropy is strongly dependent on the particular structure of the islands, the effect of oxidation on K should strongly depend on the island dimensionality. In particular, monolayer-high islands should be very sensitive to pollution because all atoms are interfacial. There are two interfaces to be considered, the two-dimensional (2D) island and it's one-dimensional (1D) perimeter. It is the scope of this paper to study how these different interfaces are affected by oxidation and what the consequenc...

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“…[1][2][3][4] When the size of the magnetic particles decreases to a few nanometers, magnetic particles become single domain in contrast with the bulk magnetic materials and exhibit a number of outstanding physical properties such as superparamagnetism (SPM), 5 super-spin-glass, 6 surface spin-glass, and quantum tunneling of the magnetization. 7,8 In nanoscale magnetic materials, the symmetry breaking at the surface results in a surface anisotropy.…”

Section: Introductionmentioning

confidence: 99%

Surface spin-glass, large surface anisotropy, and depression of magnetocaloric effect in La0.8Ca0.2MnO3 nanoparticles

Xi¹,

Lu²,

Wu³

et al. 2012

Journal of Applied Physics

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The surface magnetic behavior of La 0.8 Ca 0.2 MnO 3 nanoparticles was investigated. We observed irreversibility in high magnetic field. The surface spin-glass behavior as well as the high-field irreversibility is suppressed by increasing particle size while the freezing temperature T F does not change with particle size. The enhanced coercivity has been observed in the particles and we attributed it to the large surface anisotropy. We have disclosed a clear relationship between the particle size, the thickness of the shell, and the saturation magnetization of the particles. The large reduction of the saturation magnetization of the samples is found to be induced by the increase of nonmagnetic surface large since the thickness of the spin-disordered surface layer increases with a decrease in the particle size. Due to the reduction of the magnetization, the magnetocaloric effect (MCE) has been reduced by the decreased particle size since the nonmagnetic surface contributes little to the MCE. Based on the core-shell structure, large relative cooling powers RCP(s) of 180 J/kg and 471 J/kg were predicted for a field change of 2.0 T and 4.5 T, respectively, in the small particles with thin spin-glass layer. V C 2012 American Institute of Physics. [http://dx

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Magnetization temperature dependence in iron nanoparticles

Cited by 161 publications

References 10 publications

Synthesis and Characterization of Iron Oxide Nanoparticles Reinforced Polyester/Nanocomposites

Synthesis and Characterization of Iron Oxide Nanoparticles Reinforced Polyester/Nanocomposites

Oxidation Induced Enhanced Magnetic Susceptibility of Co Islands on Pt(111)

Surface spin-glass, large surface anisotropy, and depression of magnetocaloric effect in La0.8Ca0.2MnO3 nanoparticles

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