Spark Plasma Sintering of Co80Ni20 nanopowders synthesized by polyol process and their magnetic and mechanical properties

Ouar, Nassima; Bousnina, Mohamed Ali; Schoenstein, Frédéric; Mercone, Silvana; Brinza, Ovidiu; Farhat, S.; Jouini, N.

doi:10.1016/j.jallcom.2014.01.058

Cited by 14 publications

(18 citation statements)

References 35 publications

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“…Moreover, each nanowire was terminated at both ends by a cone‐shaped structure with diameter D . EDX measurements performed on these nanowires revealed that the core of the nanowire was rich in cobalt, whereas the conical heads were rich in nickel . These results were confirmed by electron energy loss spectroscopy (EELS) …”

Section: Resultsmentioning

confidence: 57%

Magnetic nanowire synthesis: A chemical engineering approach

et al. 2014

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Bimetallic one-dimensional cobalt-nickel magnetic nanowires capped on both sides with conical heads were synthesized using the polyol process. Then, the process was scaled up to produce magnetic nanowires in sample aliquots of approximately 20 g. The scale-up strategy involved improving the mixing reagents using either axial or radial mixing configurations and was experimentally validated by comparing the structural and magnetic properties of the resulting nanowires. The results indicated a connection between the flow patterns and the size and shape of the nanowires. When a Rushton turbine was used, shorter nanowires with unconventional small heads were obtained. Because the demagnetizing field is strongly localized near or inside these heads, the coercive field was enhanced nearly twofold. These results were confirmed by micromagnetic simulations using isolated nanowires. In addition, the development of flow patterns at the small and pilot scales was predicted and compared using three-dimensional turbulent computational fluid dynamics simulations.

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Section: Resultsmentioning

confidence: 57%

Magnetic nanowire synthesis: A chemical engineering approach

et al. 2014

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“…11 Recently, several groups have worked on the bottom-up approach of permanent magnets prepared with magnetic nanorods and nanowires. 12,13,14,15 Permanent magnets are a special class of magnetic material that exhibits both high coercivity and high magnetization. 16,17 In particular, cobalt nanorods (Co NRs) with a hcp structure are interesting for this application because when their long axis is parallel to the hcp c axis, they exhibit both shape and magnetocrystalline anisotropies.…”

Section: Introductionmentioning

confidence: 99%

“…For an increase in the 4 particle mean size and/or loss of shape anisotropy, the coercivity decreases substantially, preventing permanent magnet applications. 15 Based on the results of previous studies, it is established that raw Co NRs undergo sintering and oxidation when they are heated at a temperature higher than 200°C. 22 Consolidation at the high pressures involved in the cold and hot compaction processes can produce the same effect.…”

Section: Introductionmentioning

confidence: 99%

“…(b) Evolution of the (0002) and (10-10) crystallite sizes of the hcp Co and (10-11),(10)(11)(12) and(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) crystallite sizes of the β-CoSb as a function of the Sb content.…”

mentioning

confidence: 99%

“…Crystallite size of the Co 50 @(Co 0.5 Sb 0.5 ) 50 particles measured after annealing under forming gas at different temperature for the Co hcp phase perpendicular and parallel to the c axis calculated from the (10-10) and (0002) line broadening, respectively, and for the (10-11),(10)(11)(12) and(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) reflections of the β-CoSb phase. The fit of the corresponding XRD patterns is provides in the supplementary materials(Fig.…”

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confidence: 99%

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Co@CoSb Core–Shell Nanorods: From Chemical Coating at the Nanoscale to Macroscopic Consolidation

et al. 2016

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Core-shell magnetic anisotropic particles were prepared by reduction of Sb acetate at the surface of cobalt nanorods dispersed in a solution consisting of 1,2 tetradecanediol in oleylamine. X-ray diffraction and local EDS analyses revealed a thin β-CoSb shell with a controlled thickness ranging from 5 to 15 nm that depended on the Sb/Co molar ratio and the reduction temperature. The shell completely coats the rod surface but does not alter the shape anisotropy or the hcp structure of the cobalt cores, and the hard magnetic properties are preserved after coating with a coercivity higher than 3 kOe. Consolidated nanostructured materials that exhibit properties of permanent magnets were prepared by compaction of the core-shell Co@CoSb nanorods. The thin CoSb shell was very efficient for preventing the cobalt anisotropic core from sintering at high temperatures (up to 300°C) and high pressures (up to 1.5 GPa). These results indicate that the bottom-up approach is very promising for preparation of nanostructured hard magnetic materials.

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