The goal of this project is to investigate the fundamental gas phase chemistry of silicon nanoparticle precursors. The work at Argonne is part of a joint project with Prof. Margaret Wooldridge at the University of Michigan. We have complementary experimental methods that allow a broader range of studies to be performed than could be achieved individually. Siloxanes and silanols are common precursors and in flames rapidly create silicon nanoparticles. These can be desirable or problematic. For example, flame synthesis is a major industrial process creating commodity and exotic silicon-based materials whereas traces of siloxanes and silanols in biogases lead to fouling of power generation equipment with silicon nanoparticles. The overarching goal is to develop a detailed understanding of the reaction paths involved in the early stages of the pyrolysis and oxidation of siloxanes and silanols at temperatures and pressures relevant to flame synthesis and power generation and understand the chemistry sufficiently well to guide the gas phase synthesis of nanoparticles with customized properties. This project is experimental in nature and utilizes unique shock tube facilities at Argonne to create the necessary reaction environments.
The experimental studies exploit our experience with gas phase hydrocarbon chemistry to investigating the gas phase chemistry of silicon containing species. There are few, if any, parallels between the C and Si chemistries but the experimental methods we have developed for carbonaceous systems are entirely applicable to Si systems.
- Unique shock tube methods provide well-defined high temperature reaction environments with pressures that can be varied over several orders of magnitude allowing detailed mechanisms to be developed.
- Optical and mass spectrometric detection methods provide complementary probes of the reaction environments.
- The project is broadening to include theoretical investigations of potential reaction pathways and theoretical calculations of key thermochemical properties.