Abstract
The high pressure evolution of silicon clathrates is studied at room temperature by x-ray diffraction up to 15 GPa. Remarkably, no transition towards the diamond structure is observed and the clathrate phase transforms directly into the -tin metallic phase at 11 GPa. Further, the bulk modulus is found to be , that is, only smaller than the one of the diamond phase. These results are in good agreement with ab initio calculations which predict further that carbon clathrates, if synthesized, should be less compressible than cubic BN.
- Received 19 May 1999
DOI:https://doi.org/10.1103/PhysRevLett.83.5290
©1999 American Physical Society