Preparation of Anisotropic Sm–Co Particles Using Calcination Process and Addition of Ca(ac)₂ · H₂O

Mechanochemical processes, including mechanical alloying by high-energy ball milling and subsequent reduction diffusion (RD) steps, have been widely used to fabricate particles with rare earth-transition metal compounds. However, a new process is required to synthesize magnetically alignable particles for enhancing the anisotropic properties of rare earth-transition metal hard magnetic compounds. In this study, commercial Sm
₂
O
₃
and CoO powders were used as precursors to obtain Sm
₂
Co
₁₇
or SmCo
₅
phases, and Ca(ac)
₂

$\cdot$
H
₂
O powders were added for inhibition of particle growth and enhancement of particle distribution. In addition, pre-treatment conditions before the RD process have been investigated to obtain alignable particles. As a result, the average size of Sm–Co particles was able to be reduced to 300 nm according to the amount of the Ca(ac)
₂

$\cdot$
H
₂
O powders and SmCo
₅
particles showed a maximum energy product of 18 MGOe with a squareness of 0.99.