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Synthesis of Si Clathrate using Si nanoparticles

We have demonstrated that using silicon
nanoparticles as a starting point significantly improves the kinetics of
silicon clathrate
formation.  Removal of sodium from the
final clathrate
phase is also accelerated with the nanoparticle precursor.This becomes an attractive route to large
scale synthesis of a novel allotrope of silicon.

Synthesis of Si Clathrate using Si nanoparticles_1Synthesis of Si Clathrate using Si nanoparticles_3Synthesis of Si Clathrate using Si nanoparticles_2

Inorganic type II clathrates are
low density, semiconducting allotropes of group IV elements with the potential
for optoelectronic applications. Si clathrate
is routinely synthesized by passing from diamond silicon to sodium filled
silicon clathrate
using a sodium silicide intermediate.
Here we synthesize
NaSi by
using Si nanoparticles and reacting it with NaH. We find that the NaSi
quickly converts to clathrate upon
heating and the Na removal process is much faster in this synthesis when
compared to the clathrate
synthesis using bulk Si as Si source.

Si nanoparticles are grown by using a RF
plasma synthesis. We are able to tune the particles sizes between 4 nm to 10