Relative kinetics of nucleation and condensation of silane pyrolysis in a helium atmosphere provide mechanistic insight in the initial stages of particle formation and growth

Abstract

Chemical nucleation for the synthesis of solid nanoparticles from gas phase precursor is a fundamental process of technological relevance, yet, not well understood. In this work, a silane pyrolysis system was built to obtain insights in particle formation and growth. Primary particle analysis was used to determine the relative condensation and nucleation rates in the aerosol process of silane pyrolysis. TEM, XRD and SMPS allow the comparison between primary particle and agglomerate dynamics. The analysis reveals that nucleation is correlated to silane concentration to the power of 2/3. This relationship and other observations are used to assess the impact of magnetic interactions in classical Brownian agglomeration in the initial stages of primary particle dynamics in silane pyrolysis. Furthermore, this mechanism is consistent with key observations reported in the literature regarding nanoparticles of various materials, suggesting the proposed mechanism could be valid for more materials and deserves further attention.