CHARACTERIZATION OF MULTIPHASE AEROGELS BY CONTRAST-MARCHING SANS

Contrast-matching small-angle neutron scattering (SANS) has been used to independently characterize the structures of two-phase aerogels con sisting of a metal oxide supported on silica aerogel. Ru oxide was for med on silica aerogel by oxidation at 400 degrees C of ruthenocene, im pregnated from the vapor phase, or Ru(III)acetylacetonate, impregnated via an acetone solution. Fe oxide was formed by vapor-phase impregnat ion of ferrocene, followed by reduction at 400 degrees C and exposure to ambient air. The Ru oxide forms particles several tens of nanometer s in diameter in the aerogel mesopores. The Fe oxide forms a coating w hich mimics the structure of the support. The silica aerogel structure is not affected by the deposition and heat treatment processes. (C) 1 998 Elsevier Science B.V. All rights reserved.