F. Papadimitrakopoulos et al., MECHANICALLY ATTRITED SILICON FOR HIGH REFRACTIVE-INDEX NANOCOMPOSITES, Chemistry of materials, 9(12), 1997, pp. 2928-2933
High-energy milling provides an effective and environmentally consciou
s method for nanosizing silicon. Colloidal suspensions of nanosized si
licon are presently demonstrated and utilized for the fabrication of h
igh refractive index nanocomposites. Si nanoparticles with average siz
es of 20-40 nm and size distributions of about 25% have been separated
from milled powder via sonication and centrifugation. These nanoparti
cles were analyzed using transmission electron microscopy, dynamic lig
ht scattering, X-ray diffraction and UV-vis/FTIR spectroscopy. Formati
on of stable colloids is in part attributed to a thin surface-oxide la
yer. The decrease in the average particle size causes a blue shift in
their absorption spectrum, thus increasing transparency in the red par
t of the visible region. These Si nanoparticles were used to fabricate
high refractive index nanocomposites, with refractive indexes up to 3
.2, when dispersed in gelatin.