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Novel Nanostructured Rare-Earth-Free Magnetic Materials With High Energy Products, Bhaskar Das Aug 2013

Novel Nanostructured Rare-Earth-Free Magnetic Materials With High Energy Products, Bhaskar Das

B. Das

Novel nanostructured Zr2Co11-based magnetic materials are fabricated in a single step process using cluster-deposition method. The composition, atomic ordering, and spin structure are precisely controlled to achieve a substantial magnetic remanence and coercivity, as well as the highest energy product for non-rare-earth and Pt-free permanent-magnet alloys.


Hfco7-Based Rare-Earth-Free Permanent-Magnet Alloys, Bhaskar Das Jun 2013

Hfco7-Based Rare-Earth-Free Permanent-Magnet Alloys, Bhaskar Das

B. Das

This study presents the structural and magnetic properties of melt-spun HfCo7,HfCo7-xFex (0.25 ≤ × ≤ 1) and HfCo7Six(0.2 ≤ × ≤1.2) alloys. Appreciable permanent-magnet properties with a magnetocrystalline anisotropy of about 9.6-16.5 Mergs/cm3, a magnetic polarization Js ≈ 7.2-10.6 kG, and coercivities Hc = 0.5-3.0 kOe were obtained by varying the composition of these alloys. Structural analysis reveals that the positions of x-ray diffraction peaks of HfCo7 show good agreement with those corresponding to an orthorhombic structure having lattice parameters of about α = 4.719 Å, b = 4.278 Å, and c = 8.070 Å. Based on these results, a …


Assembly Of Uniaxially Aligned Rare-Earth-Free Nanomagnets, B. Balamurugan, B. Das, V. R. Shah, Ralph Skomski, X. Z. Li, David Sellmyer Jun 2013

Assembly Of Uniaxially Aligned Rare-Earth-Free Nanomagnets, B. Balamurugan, B. Das, V. R. Shah, Ralph Skomski, X. Z. Li, David Sellmyer

B. Das

We report HfCo7 nanoparticles with appreciable permanent-magnet properties (magnetocrystalline anisotropy K1≈10 Mergs/cm3, coercivity Hc ≈ 4.4 kOe, and magnetic polarization Js≈10.9 kG at 300 K) deposited by a single-step cluster-deposition method. The direct crystalline-ordering of nanoparticles during the gas-aggregation process, without the requirement of a high-temperature thermal annealing, provides an unique opportunity to align their easy axes uniaxially by applying a magnetic field of about 5 kOe prior to deposition, and subsequently to fabricate exchange-coupled nanocomposites having Js as high as 16.6 kG by co-depositing soft magnetic Fe-Co. This study suggests HfCo7 as a promising rare-earth-free permanent-magnet alloy, which is …