High Effective Preparation of Amorphous-Like Si Nanoparticles Using Spark Erosion Followed by Bead Milling.

This work aims to prepare the silicon nanoparticles with the nanocrystal-embedded amorphous structure through spark erosion followed by bead milling. Spark erosion breaks up monocrystal silicon ingots into micro/nanoparticles, refines the crystal grains, makes the crystals randomly disordered, and increases isotropic character. Bead milling further refines the crystal grains to a few nanometers and increases the amorphous portion in the structure, eventually forming an amorphous structure with the nanocrystals embedded. Spark erosion saves much time and energy for bead milling. The crystallite size and the amount of amorphous phase could be controlled through varying pulse durations of spark discharge and bead milling time. The final particles could contain the nanocrystals as small as 4 nm and the content of amorphous phase as high as 84% and could be considered as amorphous-like Si nanoparticles. This processing route for Si nanoparticles greatly reduced the production time and the energy consumption and, more importantly, is structure-controllable and scalable for mass production of the products with higher purity.