Chemical Synthesis of Cobalt Nanochains

Cobalt nanochains of elongated and equiaxed nanoparticles were made by a simple and facile thermal decomposition of chemically synthesized cobalt oxalate nanorods. Such magnetic chains are relevant to high-density data storage applications. The kinetics of chain formation from the rods were in reasonable agreement with the Rayleigh criterion, when the additional factor of magnetostatic interaction was taken into account. The rods were transformed into chains by the ovulation mechanism proposed by Nichols. Both hexagonal close-packed and face-centered cubic phases were obtained in the chains. The Co nanochains exhibited enhanced coercivity compared to bulk Co or randomly dispersed nanoparticles. The magnetic coercivity of the chains of elongated nanoparticles was greater than the coercivity of chains of equiaxed nanoparticles due to shape anisotropy. A similar approach may be used to produce nanostructures of other metal and metal oxide materials for applications, such as bioengineering, catalysis, and imaging.