Magnetocrystalline anisotropy of (NdxSm(1-x))2(Co0.7Fe0.3)17

The magnetic property which limits permanent magnet application of rare earth-transition metal compounds of the R
2
TM
17
type is the relatively low coercivity compared with that of the RCo
5
compounds. Of the plentiful, light rare earths, neodymium most strongly promotes undesirable planar magnetic anisotropy in both type magnets; but in RCo
5
, Nd substituted to ∼ 20% of the rare earth content has been reported to strongly enhance coercivity[6]. In anticipation of a similar effect in R
2
TM
17
compounds, the intrinsic property, magnetocrystalline anisotropy upon which coercivity depends, was measured as a function of Nd in the series (Nd
x
Sm
1-x
)
2
(Co
0.7
Fe
0.3
)
17
for x=0, 0.25, 0.5, 0.75, and 1.0 over the temperature range 100K < T < 350K. More than 50% of the Sm can be replaced by Nd before the uniaxial anisotropy reverts to planar. Therefore, the greater natural abundance of Nd and the liklihood of coercivity enhancement makes this rare earth a good candidate for substitution in 2:17 type permanent magnets.