Structural study of silica xerogel composites containing Pd aggregates

Composites containing Pd aggregates dispersed in amorphous silica are of interest from both a fundamental and applied point of view because of their attractive catalytic properties. The silica powders added with palladium, prepared by the sol-gel method, were studied using X-ray diffraction, and IR- and UV-Vis-spectrophotometry. Silica xerogel samples were prepared using a ethanol/H2O/TEOS molar ratio of 4:11.6:1 and loaded with sodium tetrachloropalladate. The silica xerogel microstructure of the powders was studied as a function of annealing temperature. Attention was paid to the evolution of the glass matrix as well as the palladium aggregates in the SiO2 matrix. We found in our samples partial crystallization of the glass matrix in form of quartz and cristobalite phases with palladium oxide and metallic palladium phase at 1000°C. The Rietveld refinement method was used in order to determine the percentage of the phase contents. © 2005 Springer Science %2b Business Media, Inc.

Composites; Rietveld; Sol-gel; X-ray Aggregates; Amorphous materials; Catalysis; Crystal structure; Crystallization; Ethanol; Glass; Infrared spectroscopy; Microstructure; Palladium; Silica gel; Sol-gels; Ultraviolet spectrophotometers; X ray diffraction analysis; Glass matrix; Partial crystallization; Rietveld; Sol-gel chemistry; Composite materials

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