Student Author: Margaret Samuels  (Class of 2009)
Faculty Author:  Dr. Ali Bakhshai

The ball milling technique employs mechanical energy to reduce the particle size of reactants to a size small enough to cause defects in their lattice structures.  In exothermic reactions, self-heat propagating synthesis (SHS) has been known to occur, allowing a complete reaction via mechanical energy.  However, extracting silicon from silicon oxide using aluminum is endothermic, and therefore, milling does not complete the reaction.  This study sought to supplement the lattice defects with energy supplied by moderate heat treatment as a method of producing pure silicon.  The parameters tested were annealing temperature, milling time, and annealing time.  The relationship between annealing temperature and milling time was also investigated thoroughly.  X-ray diffraction, as well as some comparison with Atomic Force Microscopy, was used to determine the presence of products in samples.  The data confirmed that milling is necessary for the reaction to take place, and that even one minute of milling can change the products significantly.  The use of milling, combined with a moderate heat treatment, can produce silicon in a way that is more environmentally friendly than current methods, more cost-effective, and can be used at tonnage proportions for industrial purposes.