The effect of particle size on coercivity and crystallinity of SmCo5

It is observed a turning point in the particle size for which the coercivity H-ci of a Sm-Co alloy reaches a peak. Using a broad size range from 20 nm to 5 mm, the turning point of the flake thickness for SmCo5 nanoflakes is determined in the range of 100-180 nm with H-ci peak at similar to 20 kOe. A lower coercivity at a particle size well below the turning point is likely related to a more detailed nanoscale morphology that controls coercivity. The effect of particle size on crystallinity for high energy milled powder is also discussed with four observations. (C) 2011 American Institute of Physics. [doi:10.1063/1.3607958]