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Experimental evidence of structural evolution in ultrafine cobalt particles stabilized in different polymers—From a polytetrahedral arrangement to the hexagonal structure (2000)

Dassenoy, F. ; Casanove, M.-J. ; Lecante, P. ; [weitere]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 112 (2000), S. 8137-8145

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Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: 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. © 2000 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.481414

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Digitale Medien

Short range ordering in amorphous In-Se films by wide-angle X-ray scattering (2000)

Burian, A. ; Burian, A. M. ; Weszka, J. ; [weitere]

Springer

Journal of materials science 35 (2000), S. 3121-3126

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Details

ISSN: 1573-4803

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract Wide-angle X-ray scattering studies were performed on In-Se amorphous films, obtained by thermal evaporation, with selenium content of 60 and 66 at.%. The intensities were recorded in the scattering vector range between 3 and 160 nm−1. Structural information about the local structure of the amorphous In-Se films has been derived from the radial distribution function using the curve-fitting method. The experimental results have been compared with model based simulations. The obtained structural parameters indicate that for In40Se60 In-In, In-Se and Se-Se contributions are involved in the near-neighbour coordination sphere. As the Se content is increased, the number of In-In bonds is reduced to zero, within the precision of the method. For both amorphous films In is tetrahedrally coordinated while Se has three near neighbours on the average.