RADIOLYTIC PREPARATION OF NANOPHASE CUBIC COBALT METAL PARTICLES

Cobalt nanoparticles have been prepared by gamma-radiolysis in three d ifferent forms, namely, aqueous sol, self-supporting powder, and dispe rsed on the surface of Al2O3, and characterized for their particle siz e distribution and metallic characteristics, using a variety of techni ques. Air-stable ferromagnetic cobalt particles were found to possess the face-centered cubic structure with an average crystallite size of 5-6 nm. Magnetization studies carried out on frozen cobalt sol at 5 K also showed ferromagnetic behavior. The agglomeration of these crystal lites produced particles in the range of congruent to 100 nm. (C) 1998 Elsevier Science Ltd.