Chemical synthesis of hard magnetic SmCo nanoparticles

We report a facile synthesis of ferromagnetic SmCo nanoparticles (NPs) via a controlled reduction of SmCo–O NPs. The SmCo–O NPs were prepared by co-precipitation of Co(II) and Sm(III) acetates with hexadecyl-trimethylammonium hydroxide and were embedded in a CaO matrix. The 7 nm SmCo3.6–O NPs were reduced by Ca at 960 °C and converted into ferromagnetic 6 nm SmCo5 NPs with their coercivities reaching 7.2 kOe. The synthesis provides a viable route to ferromagnetic SmCo NPs with controlled compositions and magnetism for high performance permanent magnetic applications.