Abstract
This article shows the recent Raman studies for type I silicon clathrates doped with Ba, K, and I atoms under high pressure at room temperature. The obtained Raman spectra indicate vibrational signals related with guest atoms encaged in the Si cages in a frequency region lower than 100 cm-1. In order to explore the pressure-induced phase transition, the Raman spectra were measured for the Si clathrates under high pressures using a diamond anvil cell. The spectral changes associated with the phase transition were observed, and the mechanisms of the phase transition were discussed on the basis of the spectral changes.
