Thermal stability and structure of acicular Fe–Co metal particles

Tetsukawa, Hiroki; Inoue, Makoto; Kondo, Hirofumi

doi:10.1016/s0304-8853(03)00654-1

Cited by 3 publications

(2 citation statements)

References 6 publications

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“…XRD revealed similar patterns for the two reduced samples, which correspond to a body-centred-cubic structure assigned to α-Fe (figure 3). The presence of the iron oxide passivation layer in the samples was confirmed by the positions observed for the Fe 2p 3/2 (710.3 eV) and Fe 2p 1/2 (724.0 eV) XPS peaks which, as illustrated for the Fe(Y) 5 sample (figure 4), were consistent with the presence of oxidized iron [20]. Such an oxide phase could not be detected by means of XRD due to a low oxide content and/or to the fact that it normally appears in the form of nanocrystals about 2 nm in size (with a grain size lower than ∼2 nm, diffraction effects are diffuse and close to the background noise).…”

Section: Formation Of Metallic Nanoparticlessupporting

confidence: 57%

The influence of protective coatings on the magnetic properties of acicular iron nanoparticles

Pozas¹,

Ocaña²,

Morales³

et al. 2006

Nanotechnology

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Core–shell acicular nanoparticles of ∼90 nm length and ∼5 axial ratio consisting of an iron core coated with an oxidized layer of different composition have been obtained by thermal reduction with hydrogen of coated goethite precursors. Uniform goethite particles were prepared by oxidation in air of FeSO4 solutions previously precipitated with Na2CO3. Al or Y oxide layers were deposited on the goethite particle surface by heterocoagulation. The efficiencies of both compounds as protecting agents for preventing particle sintering and corrosion and their effects on the magnetic properties of the final α-Fe nanoparticles have been evaluated. Yttrium oxide coating was found to be more effective than alumina coating, giving rise to iron nanoparticles with larger coercivity and higher corrosion resistance. This behaviour is mainly discussed in terms of the observed differences in location of the two sintering prevention agents during the transformation from iron oxide to metal, which give rise to different particle microstructures.

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Section: Formation Of Metallic Nanoparticlessupporting

confidence: 57%

The influence of protective coatings on the magnetic properties of acicular iron nanoparticles

Pozas¹,

Ocaña²,

Morales³

et al. 2006

Nanotechnology

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“…Co alloy (mol%) Fe oxid (mol%) the Fe 2p 3/2 (710.3 eV) and Fe 2p 1/2 (724.0 eV) XPS peak positions observed for all samples were consistent with the presence of oxidized iron in the particle outer layers [21]. The XPS spectra also indicated the presence of oxidized Co(II) in these layers by two broad main peaks at 780.0 and 795.6 eV due to Co 2p 3/2 and Co 2p 1/2 levels, respectively, and two strong associated satellites located at the high binding energy side of the main peaks [22,23].…”

Section: Co Xrf (Mol%)supporting

confidence: 55%

Improving Co distribution in acicular Fe–Co nanoparticles and its effect on their magnetic properties

et al. 2007

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We report on a procedure for increasing the Co content in acicular Fe–Co nanoparticles (70 nm length and ∼5 axial ratio) obtained by thermal reduction of Co-doped goethite nanoparticles coated with Co(OH)2 layers. It has been found that the diffusion of Co cations located onto the particle surface of the precursor to the inner part can be promoted by separating reduction in two steps, first from the precursor to Co-doped magnetite and, finally, from this phase to metal. Furthermore, the uniformity in the Co distribution in the final metallic alloy could be improved by annealing the Co-doped magnetite obtained from the first reduction step, resulting in an important increase of coercivity. The enhancement of the magnetic properties is mainly discussed in terms of the reversal magnetization mechanism into the metallic alloy. The hard magnetic properties resulting from the higher Co content and its homogeneous distribution in the final Fe–Co alloy, along with the reduction in the particle size, make our acicular Fe–Co nanoparticles suitable for high-density magnetic recording applications.

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Cr-free Fe-based metal oxide catalysts for high temperature water gas shift reaction of fuel processor using LPG

Lee

et al. 2009

Catalysis Today

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Thermal stability and structure of acicular Fe–Co metal particles

Cited by 3 publications

References 6 publications

The influence of protective coatings on the magnetic properties of acicular iron nanoparticles

The influence of protective coatings on the magnetic properties of acicular iron nanoparticles

Improving Co distribution in acicular Fe–Co nanoparticles and its effect on their magnetic properties

Cr-free Fe-based metal oxide catalysts for high temperature water gas shift reaction of fuel processor using LPG

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