Iron is more preferable than cobalt in permanent magnet applications considering its low price plus that Fe has a larger magnetic moment than Co. By extending our work on Fe-Co-N based ternary system, Fe-Co-B has been investigated as rare-earth free magnets. Among them, Fe3CoB2 has been successfully synthesized by experiment, with K1 = 1.0 MJ/m3 and Js = 1.35 T at 300 K and K1 = 1.2 MJ/m3 and Js = 1.39 T at 10 K, in good agreement with calculated values of K1 = 1.34 MJ/m3 and Js = 1.40 T, respectively [1].
In the following table, the calculated magnetic polarization and MAE values are listed. The crystal structures of the listed configurations can be found by clicking the name of each composition.
[1] Weiyi Xia, Masahiro Sakurai, Balamurugan Balasubramanian, Timothy Liao, Renhai Wang, Chao Zhang, Huaijun Sun, Kai-Ming Ho, James R. Chelikowsky, David J. Sellmyer, and Cai-Zhuang Wang, Accelerating the discovery of novel magnetic materials using a machine learning–guided adaptive feedback, PNAS (in publication)
| Entry ID | Composition | Space group | Ehull (eV/atom) | Js (T) | MAE K1 (MJ/m3) | Easy axis | Estimated Tc (K) |
| aga1_312_2_02 |
Fe3CoB2 |
Cmmm |
22.8 |
1.40 |
1.34 | a | 1252 |
| aga1_111_4_30 |
FeCoB |
Pbcm |
26.7 |
1.34 |
1.07 | c | 928 |
| st2-0531 |
Fe2CoB |
Pnma |
66.7 |
1.55 |
1.32 | b | 881 |
| st2-2523 |
Fe3CoB3 |
C2/m |
72.2 |
1.08 |
1.12 | c | 643 |
| st2-2418 |
Fe2CoB2 |
Immm |
92.4 |
1.15 |
1.96 | b | 789 |
| aga1_212_2_45 |
Fe2CoB2 |
Pmmm |
92.4 |
1.25 |
1.24 | c | 997 |
| aga1_212_2_46 |
Fe2CoB2 |
P-4m2 |
92.9 |
1.22 |
1.48 | c | 870 |