Evolution of Nd2Fe14B nanoparticles magnetism during surfactant-assisted ball-milling

The aim of this work was the fabrication of Nd2Fe14B nanoparticles, through a “top-down” technique like surfactant-assisted high-energy ball-milling, and the monitoring of the milling-process stages with respect to the structure and magnetism. The ball-milling of a 40 μm powder under Ar atmosphere, in an organic solution of oleic acid/oleylamine, resulted in 15 nm isolated nanoparticles after 20 h, presenting improved magnetocrystalline anisotropy compared to the initial material. By extending the mechanical process up to 100 h a gradual formation of elongated nanoparticles followed by structural amorphization was observed.