The effect of doping on the combustion and reaction kinetics of silicon reactives

The influence of low levels of lattice doping in silicon on the combustion and reaction kinetics of silicon based reactives was investigated. Doped silicon powders were produced by ball milling intrinsic, As-, and B-doped silicon wafers. After morphological and physical characterization of the doped silicon powders, energetic composites consisting of silicon and polytetrafluoroethylene (PTFE) powder were produced and characterized by thermal analysis and combustion rate measurements. The apparent activation energy decreased from 283 ± 3 to 243 ± 25 kJ/mol as dopant concentration was increased, and burning rates increased from 1.94 ± 0.05 mm/s to 3.04 ± 0.10 mm/s. This appears to be caused by inclusion of the dopant atoms in the Si lattice as no burning rate change was observed for Si reactive mixtures with the same dopant element added as a bulk powder at the same atomic proportions. The ability to modify combustion behavior through low levels of doping is an intriguing observation, with implications in general burning rate modification and tuning, and the emerging study of silicon based integrated nanoenergetics.