Iron nanoparticles coated with boron nitride nanolayers synthesized by a solid phase reaction

The authors have developed a new technique to synthesize Fe nanoparticles encapsulated by boron nitride (BN) nanolayers. Starting materials-Hematite (/spl alpha/-Fe/sub 2/O/sub 3/) and boron (B) powders-are annealed at 1273-1473 K for 2 h in a nitrogen (N/sub 2/) atmosphere. Hematite is reduced during annealing and Fe particles coated with BN are synthesized. It is revealed that the average diameter of the particles is 320 nm and the thickness of the coating layers is several nanometers from the observation using a high-resolution transmission electron microscope. The nanoparticles exhibit soft magnetic properties and the saturation magnetization depends on the weight ratio of hematite to boron in the starting materials.