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Phys. Rev. Lett. 83, 5290–5293 (1999)

High Pressure Behavior of Silicon Clathrates: A New Class of Low Compressibility Materials

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A. San-Miguel1, P. Kéghélian1, X. Blase1, P. Mélinon1, A. Perez1, J. P. Itié2, A. Polian2, E. Reny3, C. Cros3, and M. Pouchard3
11 Département de Physique des Matériaux, Université Claude Bernard-Lyon 1 and CNRS (UMR 5586), Bâtiment 203, 43 Boulevard 11 Novembre 1918, 69622 Villeurbanne, France
2Laboratoire de physique des milieux condensés, Université Paris VI, 4 Place Jussieu, T13, 75252 Paris Cedex 05, France
3Institut de Chimie de la Matière Condensée de Bordeaux, Université Bordeaux I, 33608 Pessac, France

Received 19 May 1999; published in the issue dated 20 December 1999

See accompanying Physics Focus

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 β-tin metallic phase at 11 GPa. Further, the bulk modulus is found to be 90±5 GPa, that is, only (8±5)% 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.

© 1999 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.83.5290
DOI:
10.1103/PhysRevLett.83.5290
PACS:
61.50.-f, 64.70.Kb, 71.15.Nc, 81.40.Vw