Materials Science Group
The Materials Science team operates the Powder Diffraction and the Surface Diffraction stations at the SLS and is active in research utilizing hard x-ray scattering and diffraction for structural and dynamical investigations of crystalline materials.
Atoms at or near the surface of a crystalline material in general experience different electrostatic forces than atoms located deeper down in the bulk of the material, primarily because some of the electrons that would, for "bulk" atoms, be involved in forming a bond with neighbouring atoms are now left "dangling" at the surface. They inevitably reconfigure their distribution in order to minimize the surface energy, which leads to the surface atoms rearranging themselves. The physical properties of the surface (defined as the region down to which atomic positions differ "significantly" from bulk values) can therefore be quite distinct from the same material's bulk properties. On the one hand, this can limit the minimum thickness of a material, below which its bulk properties no longer apply, or conversely, the surface of a crystal may have new and unexpected properties that can be exploited in nanostructural design. At the SD station of the Materials Science beamline, we are especially interested in investigating the surface structure of complex metal oxides, in particular the perovskites, as these are known to change their properties radically as a result of subtle structural modifications.