Rare earth-cobalt permanent magnets

Scalable parallel micromagnetic solvers for magnetic nanostructures

“…Precipitation hardened Sm(Co,Fe,Cu,Zr) 7.5−8 magnets are classified as "pinning controlled" [81,82] and their behavior arises from the cellular precipitation structure, which is observed in transmission electron micrographs. The cellular precipitation structure is formed during a lengthy production process with sophisticated heat treatment, which includes sintering, homogenizing, quenching, isothermal aging, and annealing [12].…”

First principles calculations, neutron, and x-ray diffraction investigation of Y3Ni13B2, Y3Co13B2, and Y3Ni10Co3B2

“…in the magnetic anisotropy energy, excepting the larger difference, of 0.6 meV/f.u., in the case of the supercell calculations at the experimental lattice parameters; a denser grid should be used for the disordered compound, but the computational effort is substantial, (ii) in-plane magnetic anisotropy is predicted for Y 3 5 , using the same formalism and code, (iv) the magnetocrystalline anisotropy energy of the mixed compound, at the equilibrium structure, is considerable, having in view the moderate substitution rate (23 at.% Co); a comparison between the MAE values (in MJ/m 3 ) calculated at the experimental volume and at equilibrium volume reveals the strong dependence on V u.c. : an increase by 7.47% in volume determines an increase by about 93% in MAE, and (v) the MAE of YCo 5 calculated in this work is overestimated with respect to the experimental value, 9 3.8 meV, which may be associated with the effect of the empirical OPC used.…”

“…: an increase by 7.47% in volume determines an increase by about 93% in MAE, and (v) the MAE of YCo 5 calculated in this work is overestimated with respect to the experimental value, 9 3.8 meV, which may be associated with the effect of the empirical OPC used. 45 The in-plane magnetic anisotropy predicted for Y 3 19 An examination of the total DOS plots displayed in Figs. 3(a), 4(a), and 6(a) reveals that the T-3d band edge in the majority band is close, at about 0.1-0.2 eV below the Fermi energy, similarly to the Co-3d band edge in YCo 5 , see Fig.…”

“…3,4 Thus, SmCo z (z ¼ 5-8.5) based magnets still set the reference for high temperature applications, see, for example, Refs. 5-8.…”

Enhanced energy product in Y-Co-Fe magnets intermediate between Nd-Fe-B and ferrite

“…3 Bulk crystals have very strong uniaxial anisotropy with remanence B r ¼ 1.06 T, Curie temperature T c ¼ 630 C, anisotropy constant K 1 ¼ 5.7 MJ/m 3 , and anisotropy field l 0 H a ¼ 13.0 T. The theoretical maximum energy product (BH) MAX ¼ 1 4 l 0 M 2 s ¼ 224 kJ/m 3 at room temperature. [4][5][6] The magnetocrystalline anisotropy energy of YCo 5 comes mainly from the orbital moment of cobalt atoms in the structurally distorted 2c (Co I ) sites, which lie in the same plane as Y. Yttrium has no 4f electrons, but contributes to the anisotropy via its 4d electron which hybridizes with the 3d electrons of Fe or Co. [7][8][9][10] The calculated magnetic anisotropy constant K 1 in YCo 5Àx Fe x increases with Fe doping from x ¼ 0 to x ¼ 0.5 and drops for larger x. 11 Experimental results confirm that K 1 first increases by 20% for x ¼ 0.2 and then decreases.…”