Miguel Castro-Colin

From Average to Local Structure: A Rietveld and an Atomic Pair Distribution Function (PDF) Study of Selenium Clusters in Zeolite-NdY

The structure of Se particles in the approximately 13 A diameter alpha-cages of zeolite NdY has been determined by Rietveld refinement and pair distribution function (PDF) analysis of X-ray data. With the diffuse scattering subtracted an average structure comprised of an undistorted framework containing nanoclusters of 20 Se atoms is observed. The intracluster correlations and the cluster-framework correlations which give rise to diffuse scattering were modeled by using PDF analysis.

Diffraction Studies of Glasses, Liquids and Nanoclusters

Amorphous SiO{sub 2} is classically understood as a continuous random network forming glass. Typically amorphous materials possess no translational symmetry, which is the signature of a crystal. Our interest in investigating SiO{sub 2}, grown as a thin film (100, 500 {angstrom}) on Si(001), is to observe how this particular amorphous phase is able to couple to the crystalline substrate and reflect a peculiar degree of order.