Development of Co-lean (Sm,Y)(Fe,Co,Ti)₁₂ compounds with large saturation magnetization

Abstract

Large saturation magnetization in the SmFe12-based compounds is realized by substitution of scarce Co for Fe site. However, reduction of Co is necessary for their potential practical applications. In this work, we successfully decreases the concentration of Co, from 17.3 at.% to 8.7 at.% while maintaining large µ0Ms of 1.41 T at 300 K in Ti reduced Sm0.8Y0.2(Fe0.9Co0.1)11.25Ti0.75 compound. In addition, we report the highest µ0Ms for bulk Sm0.8Y0.2(Fe0.8Co0.2)11.25Ti0.75 with µ0Ms = 1.49 T, µ0Ha = 9.14 T at 300 K and Tc = 831 K. We demonstrate (Sm0.8Y0.2)Fe12-based compounds exhibit superior intrinsic magnetic properties than Nd2Fe14B above 473 K.

Intrinsically High Magnetic Performance in Core–Shell Structural (Sm,Y)Fe12‐Based Permanent Magnets

“…Tozman et al also reported an abnormal increase for the anisotropy field (9.14 T) in Sm 0.82 Y 0.18 (Fe 0.8 Co 0.2 ) 11.26 Ti 0.74 alloy, but they assumed that a further increase of Y content would reduce the anisotropy field. [ 23 ] Our present results provided an unexpected optimization that the formation of core–shell structure, as increasing the Y content, is more beneficial, thus achieving the combined merits of μ 0 H a = 9.24 T, μ 0 M s = 1.45 T, and T c = 788 K in the Sm 0.75 Y 0.25 (Fe 0.8 Co 0.2 ) 11.25 Ti 0.75 alloy.…”

“…[ 20,21 ] The optimized Y‐substituted (Sm 1− x Y x )(Fe 1− y Co y ) 12− z Ti z alloys exhibit desirable phase stability and μ 0 M s , but it results in a rapid decrease for the anisotropy field and the coercivity because of the low anisotropy field of YFe 12 phase. [ 22,23 ]…”

“…[20,21] The optimized Y-substituted (Sm 1−x Y x ) (Fe 1−y Co y ) 12−z Ti z alloys exhibit desirable phase stability and μ 0 M s , but it results in a rapid decrease for the anisotropy field and the coercivity because of the low anisotropy field of YFe 12 phase. [22,23] The core-shell structure has been recognized as the most effective way to optimize permanent magnets ascribed to the ThMn 12 -type SmFe 12 -based permanent magnets have exhibited great potential in advanced magnet motors because of their high temperature stability of magnetic properties. However, the applications could be seriously limited due to the trade-off between phase stability and intrinsic magnetic properties.…”

Thermodynamics and Magnetism of SmFe12 Compound Doped with Zr, Ce, Co and Ni: An Ab Initio Study

“…Rare earth-based magnets that exhibit the ThMn 12 -type structure have garnered interest as hard magnetic materials. Specifically, the tetragonal REFe 12 -based compound, which RE describes as a rare-earth metal, is studied because of its significant saturation magnetization (µ 0 M s ), significant anisotropy field (µ 0 H a ), and significant Curie temperature (T c ) [1][2][3][4][5][6][7][8]. An REFe 12 magnet has a lower RE concentration (7.7 at.%) in contrast to the extensively used Nd 2 Fe 14 B 1 magnet, or so-called Neomax, (11.8 at.%).…”