Size effect on absorption edges of ultra-fine SnO2 nanoparticles

Aqueous sols containing nanocrystalline SnO2 Particles with sizes less than 2 nm were prepared by ultra-filtration from original acidic and alkaline s ols with SnO2 particles. The sizes of SnO2, nanocrystallines were determine d by dynamic light scattering, X-ray diffraction, and computer analysis of nanocrystalline images of transmission electron microscopy. Blue shifts of absorption edges of the nanocrystallines were observed in both the ultra-fi ltrated acidic and alkaline sols. The results show that the. blueshifts of the SnO2 nanocrystallines are mainly attributable to the size decrease for the same kind of nanocrystallines.