SUPERCRITICAL DRYING PREPARATION AND FRACTAL STRUCTURE OF BLUE LUMINESCENT SILICA AEROGEL

A blue luminescent silica monolithic aerogel was prepared by a sol-gel process followed supercritical drying. The as-prepared silica aerogel s are transparent and exhibit blue luminescence excited by a near UV l ight of 365 nm wavelength. Scanning electron microscopy (SEM) and tran smission electron microscopy (TEM) revealed that the monolithic aeroge l had micropores and nanopores. Small angle X-ray scattering analysis showed that our aerogel had a fractal dimension of 1.96, which is cons istent with that calculated by chemically limited cluster-cluster aggr egation from a monodispersed particle system. The luminescent mechanis ms are also discussed.