Magnetic properties of acicular Fe1−xREx (RE = Nd, Sm, Eu, Tb; x = 0, 0.05, 0.10) metallic nanoparticles

Varanda, Laudemir Carlos; Morales, M.P.; Goya, Gerardo F.; Imaizumi, Momotaro; Serna, Carlos J.; Jafelicci, Miguel

doi:10.1016/j.mseb.2004.05.030

Cited by 16 publications

(7 citation statements)

References 16 publications

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“…This composition is not completely normal or inverse. Such a type of behaviour is also observed in other rare earth substituted spinel ferrites [14][15][16]. Also, a very small amount of impurity phase such as DyFeO 3 is observed in XRD patterns at x = 0.075 & 0.1 Dy content.…”

Section: X-ray Diffraction and Rietveld Analysissupporting

confidence: 64%

Compositional variation of structural, electrical and magnetic properties of Dy substituted Ni–Co spinel ferrite

Kadam

Rajpure

2016

J Mater Sci: Mater Electron

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In the present work nanocrystalline dysprosium substituted Ni 0.8 Co 0.2 Fe 2-x Dy x O 4 (x = 0.00, 0.025, 0.050, 0.075 & 0.1) ferrite system was synthesized by the solution combustion method. The phase formation has been confirmed by Reitveld analysis of XRD patterns, which is a characteristic of spinel ferrite with most intense (311) peak. The bond lengths and site radii of tetrahedral and octahedral sites are found to increase with increase in Dy content. IR measurements showed two prominent bands which are common characteristics of spinel ferrite. The surface morphology shows spherical grains of increasing size with increase in Dy content. The dielectric measurements show the usual dielectric dispersion due to space charge polarization. The electrical resistivity of Ni-Co ferrites is found to increase with Dy content. This can be explained on the basis of formation of DyFeO 3 secondary phase along with spinel lattice. Complex impedance spectra show incomplete semicircles due to the high resistance values at low frequency. Magnetic measurements reveal low coercive field with increase in Dy content. Low coercive fields suggest the use of these materials in data storage and magnetic shielding devices.

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Section: X-ray Diffraction and Rietveld Analysissupporting

confidence: 64%

Compositional variation of structural, electrical and magnetic properties of Dy substituted Ni–Co spinel ferrite

Kadam

Rajpure

2016

J Mater Sci: Mater Electron

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“…This is the opposite behaviour compared to the case of J d = 30 K, J d < J b . The second case, where J d > J b , could explain the experimentally obtained increase in H c and M r by the substitution of doping ions, such as Pt in Fe-Pt [50], rare earths (Nd, Sm, Eu, Tb) in Fe nanoparticles [51], Pr in Pr-Fe-B-type [52] nanocomposite magnets.…”

Section: Numerical Results and Discussionmentioning

confidence: 95%

Size, anisotropy and doping effects on the coercive field of ferromagnetic nanoparticles

Wesselinowa¹,

Apostolova²

2007

J. Phys.: Condens. Matter

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The influence of size, anisotropy and doping effects on the hysteresis loop of ferromagnetic nanoparticles is studied, based on the modified Heisenberg model. A Green's function technique in real space allows the calculation of the dependence of the magnetization on the temperature, magnetic field, anisotropy, defects and particle size. It is demonstrated that the coercive field H(c) is very sensitive to the surface single-ion anisotropy, and to the exchange interaction constant on the surface J(s) and in the defect shells J(d). With respect to the strong surface single-site anisotropy D(s), we observe at small particle size, N = 4 shells, a maximum in the size dependence of the coercive field, whereas for the small surface anisotropy there is no maximum. Taking into account that J can be different in the defect shells compared to the case without defects, we have obtained for the first time that the coercive field H(c), the permanent magnetization M(r) and the Curie temperature T(C) can increase or decrease for different kinds of doping ions. The dependence on the particle size is discussed, too. The results are in accordance with the experimental data.

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“…Structural, magnetic, electronic, and catalytic properties of many materials are strongly size-dependent at the nanometer scale, and the preparation of high-quality nanocrystals of desired size is of great fundamental and technological interest. − The synthesis of metal colloids has been studied for more than a century, yet the number of preparations yielding a size series of monodisperse metal nanocrystals is surprisingly small. ,, Control of nanocrystal size and composition is key in the formation of two- and three-dimensional self-assembled structures where the individual nanocrystals play the role of building-blocks  artificial atoms in the next level of material hierarchy. ,,, Moreover, in the past decades, magnetic recording technology has made tremendous gains in data storage density, partially by scaling down the grain size of thin-film media. ,, In this direction, one of the Chemistry Highlights of 2000 was reported bySun and co-workers 7 at IBM, regarding the synthesis, self-assembly, and magnetic recording performance of FePt nanoparticles. , …”

Section: Introductionmentioning

confidence: 99%

Self-Assembled FePt Nanocrystals with Large Coercivity: Reduction of the fcc-to-L1₀ Ordering Temperature

Varanda

Jafelicci

2006

J. Am. Chem. Soc.

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Herein we report the synthesis and properties of Fe(55)Pt(45) nanoparticles, both monodisperse and self-assembled into hexagonal close-packed and cubic arrays of 4.0 +/- 0.2 nm size in an L1(0) structure, obtained by a modified polyol process. The new synthetic route improved the control over the particle composition, thereby reducing the temperature required to convert from face-centered cubic (fcc) to face-centered tetragonal (fct) phase by some 30-50 degrees C without additives. Annealing at 550 degrees C for 30 min converts the self-assembled nanoparticles into ferromagnetic nanocrystals with large coercivity, H(C) = 11.1 kOe. Reducing the fcc-to-fct (L1(0)) ordering temperature avoided particle coalescence and decreased the loss in particle positional order without compromising the magnetic properties, as is generally observed when additives are used.

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Magnetic properties of acicular Fe1−xREx (RE = Nd, Sm, Eu, Tb; x = 0, 0.05, 0.10) metallic nanoparticles

Cited by 16 publications

References 16 publications

Compositional variation of structural, electrical and magnetic properties of Dy substituted Ni–Co spinel ferrite

Compositional variation of structural, electrical and magnetic properties of Dy substituted Ni–Co spinel ferrite

Size, anisotropy and doping effects on the coercive field of ferromagnetic nanoparticles

Self-Assembled FePt Nanocrystals with Large Coercivity: Reduction of the fcc-to-L1₀ Ordering Temperature

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Magnetic properties of acicular Fe1−xREx (RE = Nd, Sm, Eu, Tb; x = 0, 0.05, 0.10) metallic nanoparticles

Cited by 16 publications

References 16 publications

Compositional variation of structural, electrical and magnetic properties of Dy substituted Ni–Co spinel ferrite

Compositional variation of structural, electrical and magnetic properties of Dy substituted Ni–Co spinel ferrite

Size, anisotropy and doping effects on the coercive field of ferromagnetic nanoparticles

Self-Assembled FePt Nanocrystals with Large Coercivity: Reduction of the fcc-to-L10 Ordering Temperature

Contact Info

Product

Resources

About

Self-Assembled FePt Nanocrystals with Large Coercivity: Reduction of the fcc-to-L1₀ Ordering Temperature