Packing fraction dependence of the coercivity and the energy product in nanowire based permanent magnets

Panagiotopoulos, I.; Fang, Weiqing; Ott, F.; Boué, François; Aït-Atmane, K.; Piquemal, Jean‐Yves; Viau, Guillaume

doi:10.1063/1.4824381

Cited by 25 publications

(20 citation statements)

References 16 publications

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“…3 the energy product of the aligned nanowires in epoxy is estimated based on a 100 percent volume fraction of closely packed Co nanowires using the theoretical density of 8.92 g/cm 3 containing closely packed nanowires and have obtained a (BH) max value up to 44 MGOe. Although this result does not reflect any effects that can potentially reduce the energy density of a bulk magnet such as packing factor, demagnetization or dipolar interactions22, the Co nanowires of this type can potentially be ideal building blocks for high performance bonded magnets, consolidated magnets as well as thin film magnets with both isotropic and anisotropic magnetic structures.…”

Section: Resultsmentioning

confidence: 88%

High Energy Product Developed from Cobalt Nanowires

Gandha

Elkins

Poudyal

et al. 2014

Sci Rep

154

114

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Cobalt nanowires with high aspect ratio have been synthesized via a solvothermal chemical process. Based on the shape anisotropy and orientation of the nanowire assemblies, a record high room-temperature coercivity of 10.6 kOe has been measured in Co nanowires with a diameter of about 15 nm and a mean length of 200 nm. As a result, energy product of the wires reaches 44 MGOe. It is discovered that the morphology uniformity of the nanowires is the key to achieving the high coercivity and high energy density. Nanowires of this type are ideal building blocks for future bonded, consolidated and thin film magnets with high energy density and high thermal stability.

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Section: Resultsmentioning

confidence: 88%

High Energy Product Developed from Cobalt Nanowires

Gandha

Elkins

Poudyal

et al. 2014

Sci Rep

154

114

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“…Nevertheless, since the rod coalescence was discarded by SANS measurements, the decrease of coercivity observed with densification may be due to increasing dipolar interactions. [37,38] Finally, the energy products (BH)max. were found between 20 and 65 kJ.…”

Section: Magnetic and Structural Properties Of The Consolidated Matermentioning

confidence: 99%

Consolidation of cobalt nanorods: A new route for rare-earth free nanostructured permanent magnets

et al. 2018

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Rare-earth free permanent magnets were produced by consolidation of cobalt nanorods synthesized by the polyol process exhibiting a mean diameter in the range 10 to 30 nm. Compactions of magnetically prealigned rod assemblies at various pressures and temperatures were carried out to make dense materials. Bulk magnets exhibiting a very good mechanical strength and an energy product as high as 65 kJ.m-3 were obtained. The best results were obtained when the compaction conditions were soft enough to preserve the morphology and alignment of the rods in the final material, as revealed by X-ray diffraction and neutron scattering. For the first time the bottom-up approach is convincingly reported to produce bulk magnets without the addition of any matrix, the obtained nanostructured materials exhibit coercivity much higher than the AlNiCo magnets and can fill the performance "gap" between hexaferrites and rare-earth based magnets.

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“…(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.…”

mentioning

confidence: 99%

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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Packing fraction dependence of the coercivity and the energy product in nanowire based permanent magnets

Cited by 25 publications

References 16 publications

High Energy Product Developed from Cobalt Nanowires

High Energy Product Developed from Cobalt Nanowires

Consolidation of cobalt nanorods: A new route for rare-earth free nanostructured permanent magnets

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

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