Influence of octanoic acid on SmCo5 nanoflakes prepared by surfactant-assisted high-energy ball milling

High-energy ball milling (HEBM) of magnetically hard SmCo5 was conducted in heptane with octanoic acid as the surfactant. The effects of octanoic acid on the morphology and magnetic properties of the powders were investigated by scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry. The results show an interesting unexpected fact that the SmCo5 powders processed by octanoic acid-assisted HEBM were in form of nanoflakes with aspect-ratio of 10(2)-10(3) without the presence of nanoparticles. The thickness of nanoflakes decreases with increasing milling time. X-ray diffraction patterns did not show the sign of oxidation and the diffraction peaks of SmCo5 were getting broader with the increase of milling time. The nanoflakes were magnetically anisotropic and had a higher coercivity than the micro-particles prepared by HEBM without surfactant. The coercivity of SmCo5 increased initially with the milling time and then it decreased after reaching the maximum value of 15.2 kOe. High-resolution transmission electron microscopy image showed that the SmCo5 nanoflakes are nanocrystalline with an average crystallite size approximately 12 nm. (C) 2010 Elsevier B.V. All rights reserved.