MAGNETIC-PROPERTIES OF SINGLE-DOMAIN SAMARIUM-COBALT NANOPARTICLES

Samarium cobalt nanoparticles were prepared by ball milling under argo n, both with and without a surfactant. X-ray diffraction indicated a s ingle SmCo5 phase, with an average size of 25 nm from Debye-Scherrer a nalysis of the peak widths, but a broad size distribution based on TEM . SQUID magnetometry yielded the coercivity as a function of temperatu re between 4 and 300 K. Large coercivities (H-c = 2.1 T at 10 K) were observed in the bare particles, but the values were significantly redu ced (H-c = 0.12 T at 5 K) for those coated with surfactant, indicating probable surface oxidation.