Growth mechanism of silicon-based functional nanoparticles fabricated by inductively coupled thermal plasmas

Abstract

An experimental and computational study is conducted for the Si-based functional nanoparticle fabrication in an inductively coupled thermal plasma reactor. In the computational study, the improved multi-component co-condensation model with nodal discretization is proposed to clarify the nanoparticle growth mechanism in the consideration of coagulation and thermophoresis as well as simultaneous co-condensation. The nanoparticle growth by nucleation and co-condensation completes approximately in 12.6 ms for the Mo–Si system and in 5.0 ms for the Ti–Si system. Mo nanoparticles grow in advance, and then Si vapour condenses on the Mo nanoparticles in the Mo–Si system, while vapours of Si and Ti simultaneously co-condense following Si nucleation in the Ti–Si system. A smaller number of larger nanoparticles are created with an increase in the powder feed rate. When the silicon content in the feed powders is 66.7%, nanoparticles of MSi2 (M = Mo, Ti) are fabricated as the main product. Nanoparticles of Ti5Si3 are mainly synthesized in the case of the silicon content 33.0%. In the experiment, the nanoparticles are successfully fabricated and examined by x-ray diffractometry and transmission electron microscopy. The experimental and computational results show good agreement in the size distribution and the composition.