Experimental evidence of structural evolution in ultrafine cobalt particles stabilized in different polymers—From a polytetrahedral arrangement to the hexagonal structure

Ultrafine cobalt particles have been reproducibly synthesized by decomposition of an organometallic precursor in the presence of a stabilizing polymer. The size of the stable monodisperse colloids thus obtained is seen to strongly depend on the nature of the polymer: around 4.2 nm diameter in polyph...

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Bibliographic Details
Published in:The Journal of chemical physics 2000-05, Vol.112 (18), p.8137-8145
Main Authors: Dassenoy, F., Casanove, M.-J., Lecante, P., Verelst, M., Snoeck, E., Mosset, A., Ely, T. Ould, Amiens, C., Chaudret, B.
Format: Article
Language:English
Subjects:
Condensed Matter
Materials Science
Physics
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Summary:Ultrafine cobalt particles have been reproducibly synthesized by decomposition of an organometallic precursor in the presence of a stabilizing polymer. The size of the stable monodisperse colloids thus obtained is seen to strongly depend on the nature of the polymer: around 4.2 nm diameter in polyphenylenoxide (PPO) and around 1.4 nm diameter in polyvinylpyrrolidone (PVP). Investigations by wide angle x-ray scattering (WAXS) and high-resolution transmission electron microscopy (HRTEM) give evidence for a size dependence of the structural organization, and hence for a close relationship between structure and synthesis conditions. Co/PPO particles exhibit a hexagonal compact structure with the metal–metal bond length of the bulk material while Co/PVP ones display an original structure. We show that the unusual features of the experimental data in Co/PVP clearly point to a nonperiodic polytetrahedral structure. Successful simulations of the HRTEM and WAXS results have been obtained using models built on the basis of a polytetrahedral arrangement.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.481414