Synthesis and evaluation of the size and the morphology of SIO [indice inférieur 2] nanoparticles in ICP RF plasma reactors

The synthesis of SiO[indice inférieur 2] nanoparticles in radio frequency (RF) plasma reactors is studied.The effect of feed rate, quench gas injection and reactor configuration, on the final size distribution and morphology of the prepared nanoparticles, are investigated.The laser scattering is used as a technique complementary to scanning electron microscopy (SEM) and the nitrogen absorption (BET) techniques, to determine the morphology, size and aggregation level of the resulting nanopowders. It is demonstrated that the quench gas configuration and reactor geometry can now be designed to control the morphology and size of the nanoparticles in these reactors. Depending on the preparation conditions and the reactor configuration chosen, various nanostructured products have been synthesised: i.e. highly aggregated nanostructured, partially sintered nanospheres and spherical nanoparticles with very low levels of aggregation. These nanostructures have their primary particles sized between 10 and 200 nm, while the aggregates sizes can lie in the range of between hundreds of nanometer to several micrometers. Computational fluid dynamics (CFD) modelling, using Fluent 6.2.16, and the fine particle model (FPM) are further employed to better understand the time-temperature history of the generated particles.The results are utilised to describe the effects of the above mentioned parameters on the formation (nucleation and growth) of the nanoparticles and clusters by various mechanisms. By combining the experimental measurements with the numerical results, the critical parameters that should be considered for a large scale production process are identified as: establishing the proper quench gas configuration, the extension of high temperature regions and the reduction of fluid circulations within the reactor