Effects of particle size and composition on coercivity of Sm-Co nanoparticles prepared by surfactant-assisted ball milling

The SmCox (x=3.5, 4, 5, 6, 8.5, and 10) magnetic nanoparticles with different composition have been prepared by surfactant-assisted ball milling technique. By controlling the settle-down time and the centrifugation conditions, the SmCox nanoparticles with different particle size and narrow size distribution were successfully obtained. It was observed that the SmCo nanoparticles become unstable with increasing Sm content. It was also observed that the coercivity of the SmCox nanoparticles increases with Co content and particle size, indicating a complex effect of the particle size and composition on magnetic hardening of the hard magnetic nanoparticles. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3334460]