Anisotropic SmCo5 nanoflakes by surfactant-assisted high energy ball milling

Abstract

Crystallographically anisotropic SmCo5 nanoflakes were fabricated directly by one-step surfactant-assisted high energy ball milling (HEBM) of Sm17Co83 ingot powders for 5 h in heptane and oleic acid (OA) without preprocessing or further annealing. The SmCo5 nanoflakes have a strong [001] out-of-plane texture. The thickness of nanoflakes is in the range of 8–80 nm while their length is 0.5–8 μm. The surfactant OA plays an important role in the formation of SmCo5 nanoflakes. HEBM of SmCo5 ingots in heptane without OA resulted in the formation of magnetically isotropic more or less equiaxed SmCo5 particles with a size of 2–30 μm. Closely packed “kebablike” SmCo5 nanoflakes were formed by HEBM in heptane with 15 wt % OA. HEBM in 150 wt % OA led to well-separated nanoflakes instead of the closely packed kebablike nanostructure. This resulted in the enhanced [001] out-of-plane texture. In-plane transmission electron microscope examination showed that the SmCo5 nanoflakes were composed of grains with sizes in the range of 4–8 nm. Coercivities of about 18.0 kOe were obtained for the anisotropic SmCo5 nanoflakes.