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Lattice contraction in nanosized silicon particles produced by laser pyrolysis of silane (1999)

Hofmeister, H. ; Huisken, F. ; Kohn, B.

Springer

The European physical journal 9 (1999), S. 137-140

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ISSN: 1434-6079

Keywords: PACS: 61.16.-d Electron, ion, and scanning probe microscopy – 61.46.+w Clusters, nanoparticles, and nanocrystalline materials – 81.05.-t Specific materials: fabrication, treatment, testing and analysis

Source: Springer Online Journal Archives 1860-2000

Topics: Physics

Notes: Abstract. We used laser-induced decomposition of silane for the fabrication of nanosized Si particles and studied in detail their structural characteristics by conventional and high resolution electron microscopy. The silane gas flow reactor incorporated in a molecular beam apparatus was operated without size selection to achieve a broad size distribution. Deposition at low energy on carbon substrates yielded single crystalline, spherical Si particles almost completely free of planar lattice defects. The particles, covered by thin amorphous oxide shells, are not agglomerated into larger aggregates. The lattice of diamond cubic type exhibits deviations from the bulk spacing which vary from distinct contraction to dilatation as with decreasing particle size the oxide shell thickness is reduced. This effect is discussed in terms of the strong Si/oxide interfacial interaction and compressive stresses arising upon oxidation. A negative interface stress, as determined from the size dependence of the lattice spacing, limits the curvature of the interface, i.e., at small sizes Si oxidation must be considered as a self-limiting process.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s100530050413

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Crystallization of nanosized silicon powder prepared by plasma-induced clustering reactions (1997)

Dutta, J. ; Hofmann, H. ; Houriet, R. ; [et al.]

Hoboken, NJ : Wiley-Blackwell

AIChE Journal 43 (1997), S. 2610-2615

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ISSN: 0001-1541

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology

Notes: Nanosized silicon powders were prepared by gas-phase cluster agglomeration reactions in a low-pressure silane plasma. The formation and agglomeration of clusters leading to the growth of primary particles of powder were studied by in-situ techniques including mass spectroscopy and laser light-scattering experiments. These powders, generally amorphous and crystallized in a reducing atmosphere, were studied in detail by Raman spectroscopy and high-resolution electron microscopy, which revealed a very rough surface of as-prepared single powder particles with structures of 1 to 2 nm. Upon 1-h annealing at temperatures between 300 and 600°C, circular contrast features, 1.5 to 2.5 nm in size, are observed in the amorphous particles, which show medium-range order. A distinct onset of crystallization is observed at 700°C with structures ranging from very small crystalline ordered regions of 2.5-3.5 nm in size to fast-grown multipletwinned crystallites. The crystallization behavior is influenced by the clusters that form primary particles. Observed sintering behavior cannot be explained by a classical approach; hence, theoretical models need to be adapted to nanosized powders.

Additional Material: 7 Ill.