Hexagonal CoSe formation in mechanical alloyed Co75Se25 mixture

Campos, Carlos Eduardo Maduro de; Lima, J.C. de; Grandi, T.A.; Machado, K.D.; Drago, Valderes; Pizani, P. S.

doi:10.1016/j.ssc.2004.03.044

Cited by 45 publications

(27 citation statements)

References 31 publications

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“…From the experimentally measured positions of the (0 0 2), (0 0 3), (0 0 4) peaks we have determined the lattice constant c=5.54 ( A, which was in agreement with the data published by other author [15]. According to Ref.…”

Section: Resultssupporting

confidence: 89%

High oriented FeSe thin film on GaAs(100) substrate prepared by low-pressure metalorganic chemical vapor deposition

Feng

Shen

Zhang

et al. 2004

Journal of Magnetism and Magnetic Materials

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Section: Resultssupporting

confidence: 89%

High oriented FeSe thin film on GaAs(100) substrate prepared by low-pressure metalorganic chemical vapor deposition

Feng

Shen

Zhang

et al. 2004

Journal of Magnetism and Magnetic Materials

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“…The spectrum of the sample milled for 3 h was fitted by one sextet with relative absorption area of 62%, which maintained the same BCC Fe parameter, a couple of sextets with relative absorption area of approximately 10% each, indicating the presence of both A and B sites of iron magnetite (Fe 3 O 4 ), and two doublets that were successfully set with parameters of the FeSe and FeSe 2 phases [17][18][19][20]. The relative absorption areas of the doublets were 10% (FeSe) and 6% (FeSe 2 ).…”

Section: Ms Measurementsmentioning

confidence: 99%

XRD, DSC, MS and RS studies of Fe75Se25 iron selenide prepared by mechano-synthesis

Campos

Lima

Grandi

et al. 2004

Journal of Magnetism and Magnetic Materials

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“…[14] In addition, X-ray fluorescence (XRF) analysis indicates that the ratio of Co:Se in the sample is approximately 1:1.80, which suggests that other cobalt selenide phases (for example, CoSe and Co 3 Se 4 ) may be present in small amounts. [15] Additional TEM analysis of the dispersion of cobalt nanocrystals prior to the addition of selenium showed that the cobalt nanocrystals assemble into wires (see Supporting Information), which are similar to the assemblies of hollow CoSe 2 nanocrystals. We also observed a small amount of necklace structures in both the samples of cobalt nanocrystals and hollow CoSe 2 nanocrystals (see Supporting Information).…”

mentioning

confidence: 94%

Magnetic‐Dipolar‐Interaction‐Induced Self‐Assembly Affords Wires of Hollow Nanocrystals of Cobalt Selenide

et al. 2006

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Self-assembly, an attractive and practical methodology, allows the formation of a wide range of nanostructures for promising applications-for example, nanoparticle arrays for new optical band-gap materials [1] or high-density magnetic recording media, [2] self-assembled monolayers (SAM) for nanometerthick films on a variety of substrates, [3] and nanofibers of selforganized small molecules or oligopeptides for drug delivery and tissue engineering.[4] Hydrogen bonding and/or van der Waals interactions are usually the driving forces that result in self-assembly at the nanoscale.[5] Despite extensive investigation, it is still difficult to control and predict the nanostructures resulting from these two types of forces. Although several recent reports have shown that magnetic dipolar interactions induce rather predictable nanoassemblies, [6,7] methods for maintaining these assemblies when the magnetic force decreases or vanishes have been less thoroughly investigated. Therefore, we decided to use the magnetic dipoles inherently associated with magnetic nanoparticles [8] to form 1D assemblies of hollow nanocrystals of semiconductors. [9] We chose to make wires of hollow nanocrystals of CoSe 2 to demonstrate the concept, because 1) the isolation of a nanonecklace of cobalt nanocrystals on a substrate from a dispersion after removal of the solvent [7] indicated that magnetic dipolar interactions are sufficient to maintain 1D assemblies of nanocrystals in solution; 2) the recently reported formation of hollow CoSe nanocrystals from cobalt nanocrystals through the Kirkendall effect [10] suggested that a similar process could be used to generate hollow CoSe 2 nanocrystals from 1D assemblies of cobalt nanocrystals; 3) hollow nanostructures have received considerable attention because they exhibit properties that differ from their solid counterparts; [11] and 4) nanowires of hollow nanocrystals of CoSe 2 are unknown. Herein, we show that when their sizes reach approximately 20 nm cobalt nanocrystals self-assemble into wires in solution at temperatures as high as 455 K. Through the nanoscale Kirkendall effect, [10,12] wires of hollow CoSe 2 nanocrystals form without loss of the preassembled nanostructure induced by the magnetic dipolar interactions of the cobalt nanocrystals. In control experiments, when the size of the cobalt nanocrystals is 6 nm, or when 20-nm cobalt nanocrystals are in an alternating magnetic field, no wires of hollow CoSe 2 nanocrystals form. These observations confirm that the magnetic interaction plays a key role in the formation of the nanowires of hollow CoSe 2 crystals. Several types of ferromagnetic metallic nanocrystals (iron, cobalt, nickel, FePt, or CoPt) can be prepared readily, and their selfassembly depends on the magnetic dipolar interactions of particles of a certain size. Therefore, the method shown herein should be a general route to 1D assemblies of hollow nanocrystals.The synthesis of wires of hollow CoSe 2 nanocrystals is easy and straightforward. Cobalt nanocrystals of approximatel...

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Hexagonal CoSe formation in mechanical alloyed Co75Se25 mixture

Cited by 45 publications

References 31 publications

High oriented FeSe thin film on GaAs(100) substrate prepared by low-pressure metalorganic chemical vapor deposition

High oriented FeSe thin film on GaAs(100) substrate prepared by low-pressure metalorganic chemical vapor deposition

XRD, DSC, MS and RS studies of Fe75Se25 iron selenide prepared by mechano-synthesis

Magnetic‐Dipolar‐Interaction‐Induced Self‐Assembly Affords Wires of Hollow Nanocrystals of Cobalt Selenide

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