Evolution of the structure of ultrafine SiC-laser-formed powders with synthesis conditions
Abstract
Ultrafine SiC powders in the nanometre range (less than 100 nm) have been synthesized by laser-driven reactions. Mixtures of SiH 4 and C 2H 2 (eventually with He) have been irradiated by a high power continuous-wave CO 2 laser in a cross-flow configuration cell. By varying the reaction conditions (mainly flow rates of the reaction gases) amorphous to crystalline powders of various sizes were formed. The powders were investigated by 29Si solid state nuclear magnetic resonance. This technique, contrary to X-ray diffraction, is mainly sensitive to the local order of small regions of the materials. A comparison of the different spectra obtained provides information on the phase composition, α-SiC or β-SiC of the materials, which seems different for these small powders from what is usually observed.
- Publication:
-
Diamond and Related Materials
- Pub Date:
- 1993
- DOI:
- 10.1016/0925-9635(93)90105-B
- Bibcode:
- 1993DRM.....2..486T