Silicon halide--alkali metal flames as a source of solar grade silicon
This program is designed to demonstrate the feasibility of using alkali metal-silicon halide diffusion flames to produce solar-cell-grade silicon in large quantities at low cost. Prior work has demonstrated that high purity silicon (metallic impurities < 5 ppm) can be produced using Na + SiCl/sub 4/ and Na + SiF/sub 4/ flames. Much lower flame temperatres were observed in the latter case as well as low silicon yields due to Na/sub 2/SiF/sub 6/ formation. Work performed during the current reporting period has shown that reactor wall temperaure of approximately 1000 K are sufficient to prevent formation of Na/sub 2/SiF/sub 6/. Silicon produced from SiF/sub 4/ appears identical in form and purity to that from SiCl/sub 4/ although product collection and separation are less thermo-chemically favored in the fluoride system. To separate the silicon from the byproduct salt in an efficient and continuous manner, higher temeratures are necessary. Resistively heated thin-walled graphite tubular reactors have been used to achieve these temperatures (> 1700 K), and successful product separation has been experimentally demonstrated using a Na + SiCl/sub 4/ flame. Keys to this success appear to be sustaining high reaction temperatures and not using a diluent gas in the recent flows.
- Research Organization:
- Aerochem Research Labs., Inc., Princeton, NJ (USA)
- DOE Contract Number:
- NAS-7-100-954777
- OSTI ID:
- 5953524
- Report Number(s):
- DOE/JPL/954777-5; AeroChem-TN-199
- Country of Publication:
- United States
- Language:
- English
Similar Records
Silicon halide-alkali metal flames as a source of solar grade silicon. Third quarterly report
Silicon halide--alkali metal flames as a source of solar grade silicon. Fourth quarterly report, March 1--May 31, 1978
Related Subjects
140501* -- Solar Energy Conversion-- Photovoltaic Conversion
36 MATERIALS SCIENCE
360601 -- Other Materials-- Preparation & Manufacture
ALKALI METALS
CHEMICAL REACTORS
CHLORIDES
CHLORINE COMPOUNDS
DIRECT ENERGY CONVERTERS
ELEMENTS
FEASIBILITY STUDIES
FLAMES
FLUORIDES
FLUORINE COMPOUNDS
HALIDES
HALOGEN COMPOUNDS
METALS
PHOTOELECTRIC CELLS
PHOTOVOLTAIC CELLS
PRODUCTION
PURIFICATION
RESEARCH PROGRAMS
SEMIMETALS
SILICON
SILICON CHLORIDES
SILICON COMPOUNDS
SILICON FLUORIDES
SILICON SOLAR CELLS
SODIUM
SOLAR CELLS