Synchrotron studies on silicon clathrates: Highly stable nanostructured materials

We have pushed the limits of X-ray absorption spectroscopy under high pressure in order to study the stability of the Ba intercalated silicon clathrate. EXAFS experiments at the Ba K-edge have been performed in the step by step mode up to a pressure of 14.5 GPa using the Paris-Edinburgh cell with sintered diamond anvils. XANES experiments at the Ba L-III edge were done in an energy dispersive set-up using hollowed diamond anvil cells up to a pressure of 20 GPa. Combining the obtained results with high pressure X-ray diffraction we demonstrate the high stability of the Ba intercalated silicon clathrates. Our conclusions could be extended to other clathrate systems.