Radial distribution function studies of Al2O3-La2O3 binary oxides prepared by sol-gel

The structure of Al2O3-xLa(2)O(3) (x = 0, 2, 6, 15, 25, 50 wt%) binary oxides prepared via the sol-gel preparation method was studied by means of radial distribution functions determined from X-ray diffraction patterns. At first neighbors, the binary oxides are characterized by Al-O bond distances typical of gamma-Al2O3. At second neighbors the binary oxides show La-O and O-O bond distances of La2O3. However, at higher coordination shells, these materials present bond distances corresponding to the mixed oxides with a perovskite-type structure. These structural differences of the binary oxides could be related to their differences in activity observed in the NO reduction with H-2. (C) 2004 Elsevier B.V. All rights reserved.