Structural, optical and chemical characterizations of sol-gel grown tin oxide aerogels

Monolithic tin oxide aerogels synthesized using the epoxide technique were characterized with X-ray diffraction, diffusive reflectance spectroscopy, infrared spectroscopy, particle induced X-ray emission and photoluminescence. Our results indicate that the resulting aerogel is an electrical semi-insulator. This happens due to an incomplete chemical reaction that leaves chloride and hydroxide ions unreacted. These ions form complexes with oxygen vacancy sites producing electron trapping. Furthermore, ions of Cu, Zn and Fe were identified as naturally occurring impurities in the gel matrix, substituting Sn ^{+ 4} ions.