Kinetic data and product studies are reported for the silane pyrolysis in the presence of olefins and acetylene. The kinetics of silane loss in the presence of acetylene was found to be identical to the initial gas phase silane decomposition step (SiH4 + M + SiH, + H2 + M) when corrected for pressur
Kinetics and mechanism of the silane decomposition
โ Scribed by C. G. Newman; H. E. O'neal; M. A. Ring; F. Leska; N. Shipley
- Publisher
- John Wiley and Sons
- Year
- 1979
- Tongue
- English
- Weight
- 871 KB
- Volume
- 11
- Category
- Article
- ISSN
- 0538-8066
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โฆ Synopsis
The homogeneous gas-phase decomposition kinetics of silane has been investigated using the single-pulse shock tube comparative rate technique (T = 1035-1184ยฐK, P ~d = 4000 Torr).
The initial reaction of the decomposition SiH4 ! + SiHz + H2 is a unimolecular process in its pressure fall-off regime with experimental Arrhenius parameters of logkl (sec-I) = 13.33 f 0.28-52,700 f 1400/2.303RT. The decomposition has also been studied at lower temperatures by conventional methods. The results confirm the total pressure effect, indicate a small but not negligible extent of induced reaction, and show that the decomposition is first order in silane at constant total pressures. RRKM-pressure fall-off calculations for four different transition-state models are reported, and good agreement with all the data is obtained with a model whose high-pressure parameters are logAl (sec-') = 15.5, El(,) = 56.9 kcal, and AE;;, = 55.9 kcal. The mechanism of the decomposition is discussed, and it is concluded that hydrogen atoms are not involved. It is further suggested that silylene in the pure silane pyrolysis ultimately reacts with itself to give hydrogen: 2SiH2 -(SiZHd)* -(SiH3SiH)* -SizHz
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