Magnetic properties of iron oxide nanoparticles prepared by seeded-growth route

Espinosa, Ana; Muñoz-Noval, Á.; Garcı́a-Hernández, M.; Serrano, Aída; Morena, J. Jiménez de la; Figuerola, Albert; Quarta, Alessandra; Pellegrino, Teresa; Wilhelm, Claire; García, M. A.

doi:10.1007/s11051-013-1514-8

Cited by 24 publications

(21 citation statements)

References 45 publications

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“…27 Nevertheless one has to be aware that the anisotropy constant of a single particle changes with the reduction of its size, and also magnetic inter-particle interactions lead to an enhancement of the magnetic anisotropy of the system. 28 Using the experimental measured values of T B for the four iron oxide particle sizes, 4, 5, 8 and 10 nm infiltrated within SiNTs (assuming that they do not interact), one can estimate K 1 values as follows: for 10 nm particles (T B = 30 K) K 1 = 1.98 × 10 4 J m −3 , 8 nm particles (T B = 20 K) K 1 = 2.5 × 10 4 J m −3 , 5 nm particles (T B = 15 K) K 1 = 7.9 × 10 4 J m −3 and for 4 nm particles (T B = 12 K) K 1 = 1.2 × 10 5 J m −3 . These values deviate from the bulk-value and they are also higher than those reported by Luo et al which deals with a frozen ferrofluid, 29 where magnetic interactions can be neglected.…”

Section: Magnetic Propertiesmentioning

confidence: 99%

The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles

et al. 2015

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The purpose of this work is a detailed comparison of the fundamental magnetic properties of nanocomposite systems consisting of Fe3O4 nanoparticle-loaded porous silicon as well as silicon nanotubes. Such composite structures are of potential merit in the area of magnetically guided drug delivery. For magnetic systems to be utilized in biomedical applications, there are certain magnetic properties that must be fulfilled. Therefore magnetic properties of embedded Fe3O4-nanoparticles in these nanostructured silicon host matrices, porous silicon and silicon nanotubes, are investigated. Temperature-dependent magnetic investigations have been carried out for four types of iron oxide particle sizes (4, 5, 8 and 10 nm). The silicon host, in interplay with the iron oxide nanoparticle size, plays a sensitive role. It is shown that Fe3O4 loaded porous silicon and SiNTs differ significantly in their magnetic behavior, especially the transition between superparamagnetic behavior and blocked state, due to host morphology-dependent magnetic interactions. Importantly, it is found that all investigated samples meet the magnetic precondition of possible biomedical applications of exhibiting a negligible magnetic remanence at room temperature.

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Section: Magnetic Propertiesmentioning

confidence: 99%

The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles

et al. 2015

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“…The magnetic nanocrystals are an appealing subject of study because they exhibit a vastly different physical behavior from that in their bulk counterparts [8]. Magnetism is a quantum mechanical property, and as such, nanoscale size and shape particle modifications can lead to its evolution in an unexpected way [9,10]. For these reasons, a variety of methodologies have been utilized, but among them, the surfactant-assisted chemical approaches hold a prominent place.…”

Section: Introductionmentioning

confidence: 99%

Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

Κωστοπούλου

Lappas

2015

Nanotechnology Reviews

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Magnetic particles of optimized nanoscale dimensions can be utilized as building blocks to generate colloidal nanocrystal assemblies with controlled size, well-defined morphology, and tailored properties. Recent advances in the state-of-the-art surfactant-assisted approaches for the directed aggregation of inorganic nanocrystals into cluster-like entities are discussed, and the synthesis parameters that determine their geometrical arrangement are highlighted. This review pays attention to the enhanced physical properties of iron oxide nanoclusters, while it also points to their emerging collective magnetic response. The current progress in experiment and theory for evaluating the strength and the role of intra-and inter-cluster interactions is analyzed in view of the spatial arrangement of the component nanocrystals. Numerous approaches have been proposed for the critical role of dipole-dipole and exchange interactions in establishing the nature of the nanoclusters' cooperative magnetic behavior (be it ferromagnetic or spin-glass like). Finally, we point out why the purposeful engineering of the nanoclusters' magnetic characteristics, including their surface functionality, may facilitate their use in diverse technological sectors ranging from nanomedicine and photonics to catalysis.

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“…This is because their complex structure may attain collective properties 22 due to the coupling mechanisms established across the interfaced or strongly coupled material nanodomains 5,23,24 . In addition, the magnetic behavior of these complex systems may be affected by microscopic phenomena associated with the surface coordination environment, such as, canted surface spins 25 , intraand inter-particle interactions (dipolar or exchange, involving surface spins among different particles) 3,26,27 and even increased surface anisotropy 28 . Understanding of such effects is a key in the exploitation of these systems in applications strongly related to their magnetization, such as, magnetic resonance imaging (MRI) contrast enhancement 7,14,20,29 , magnetic hyperthermia 30,31 and even targeted drug delivery 9,32,33 .…”

Section: Introductionmentioning

confidence: 99%

Assembly-mediated interplay of dipolar interactions and surface spin disorder in colloidal maghemite nanoclusters

et al. 2014

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Controlled assembly of single-crystal, colloidal maghemite nanoparticles is facilitated via a high-temperature polyol-based pathway. Structural characterization shows that size-tunable nanoclusters of 50 and 86 nm diameters (D), with high dispersibility in aqueous media, are composed of ~13 nm (d) crystallographically oriented nanoparticles. The interaction effects are examined against the increasing volume fraction, φ, of the inorganic magnetic phase that goes from individual colloidal nanoparticles (φ= 0.47) to clusters (φ= 0.72). The frozen-liquid dispersions of the latter exhibit weak ferrimagnetic behavior at 300 K. Comparative Mössbauer spectroscopic studies imply that intra-cluster interactions come into play. A new insight emerges from the clusters' temperature-dependent ac susceptibility that displays two maxima in χ''(T), with strong frequency dispersion. Scaling-law analysis, together with the observed memory effects suggest that a superspin glass state settles-in at T B~ 160-200 K, while at lowertemperatures, surface spin-glass freezing is established at T f~ 40-70 K. In such nanoparticleassembled systems, with increased φ, Monte Carlo simulations corroborate the role of the inter-particle dipolar interactions and that of the constituent nanoparticles' surface spin disorder in the emerging spin-glass dynamics.

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Magnetic properties of iron oxide nanoparticles prepared by seeded-growth route

Cited by 24 publications

References 45 publications

The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles

The effect of nanocrystalline silicon host on magnetic properties of encapsulated iron oxide nanoparticles

Colloidal magnetic nanocrystal clusters: variable length-scale interaction mechanisms, synergetic functionalities and technological advantages

Assembly-mediated interplay of dipolar interactions and surface spin disorder in colloidal maghemite nanoclusters

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