Raman study of semiconductor clathrates under high pressure

Abstract

In order to gain an insight into the mechanism of the isostructural phase transition observed previously for Ba8Si46 compound, the high pressure Raman experiments have been performed for clathrate compounds of Ba8Au6Si40 and Ba8Ge 3Si43 derivative from Ba8Si46 by substituting Si with other atoms. The Ba8Ge3Si 43 clathrate indicated the occurrence of the phase transition at the same pressure as Ba8Si46 but, the Ba8Au 6Si40 did not show up to 27 GPa. The present results suggest that a particular crystal site (6c site) plays an important role for the phase transition of the clathrate compounds. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA.