SiOx Nanoparticles Synthesized by an Evaporation and Condensation Process Using Induction Melting of Silicon and Gas Injection

SiOx nanoparticles were synthesized using a specially designed induction melting system equipped with a segmented graphite crucible. The graphite crucible with the segmented wall was the key to enhancing the evaporation rate due to the increase of the evaporation area and convection of the silicon melt. Injection of the gas mixture of oxygen (O-2) and argon (Ar) on silicon (Si) melt caused the formation of SiOx nanoparticles. The evaporated SiOx nanoparticles were then cooled and condensed in a process chamber. The effects of the O-2/Ar ratio in the injection gas on the microstructures of the SiOx nanoparticles were then investigated. Synthesized SiOx nanoparticles were proven to be of a homogeneous amorphous phase with average diameters of 30 similar to 35 nm. The microstructures were independent from the O-2/Ar ratio of the injected gas. However, x increased from 1.36 to 1.84 as the O-2/Ar ratio increased. The purity of the synthesized nanoparticles was about 99.9%. SiOx nanoparticles could be applied as the active anode material in a lithium (Li) ion secondary battery.