Surfactant-free synthesis of magnetic cobalt particles with hierarchical nanostructures

Magnetic cobalt particles with various novel morphologies were prepared via a simple polyol route with a single step and without the assistance of a surfactant. Polyhedral microspheres, bumpy surface microspheres, and unique microspheres with hierarchical nanorod growth on top were synthesized and reported for the first time. Both face centered cubic and hexagonal closed packed phases of cobalt coexisted in these samples, where face centered cubic was the dominant phase. Cobalt microspheres covered with nanorods showed enhanced coercivity compared to their bulk cobalt counterpart most possibly is attributed to shape anisotropy. A possible formation mechanism of the cobalt particles was proposed. © 2016, Inst Materials Physics. All right reserved.