Magnetic cobalt nanocrystals organized in patches and chains

Co nanocrystals have been prepared via two different chemical preparation routes. Microstructural characterization has. been carried out by conventional and high-resolution transmission electron microscopy. Magnetic characterization reveals that Co nanocrystals with mean particle size distributions about 6 nm are ferromagnetic at room temperature. Superlattices of about 1 μm × 1 μm can be reproduced. For the second preparation route the formation of an ε-Co phase was detected by X-ray diffraction. Whereas the pure Co nanocrystals form domains with a mixture of simple cubic and hexagonal packing, FeCo alloyed nanoparticles form long chain-like structures.