David B. Mitzi
Journal of Materials Chemistry
General synthetic routes to monodisperse e-cobalt (β-Mn type phase) nanocrystals (e-Co) and controlled assembly of these nanocrystals are presented in this paper. The e-Co particles are obtained by superhydride reduction of cobalt chloride (anhydrous or hexahydrate) in a high temperature solution phase (200°C) in the presence of a combination of long chain diol, oleic acid and trialkylphosphine. Monodisperse nanocrystals are isolated by size selective precipitation. As synthesized cobalt particles are each a single crystal with a complex cubic structure related to the beta phase of elemental manganese (β-Mn). Self-assembly of these uniform cobalt particles on solid substrates is induced by evaporation of the carrier solvent producing 2-D and 3-D magnetic superlattices. Annealing of assembled e-Co nanocrystal arrays converts them to the hep cobalt crystal arrays. The inter-particle distance can be adjusted by selected thermal treatments or by chemical ligand exchange. This control over particle dimensions, crystallinity and assembly offers a model system for the study of ultra-high density recording media. re 1999 Materials Research Society.
David B. Mitzi
Journal of Materials Chemistry
Daniel J. Coady, Amanda C. Engler, et al.
ACS Macro Letters
J.V. Harzer, B. Hillebrands, et al.
Journal of Magnetism and Magnetic Materials
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Synthetic Metals