Pressure-induced homothetic volume collapse in silicon clathrates. - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue EPL - Europhysics Letters Année : 2005

Pressure-induced homothetic volume collapse in silicon clathrates.

Résumé

The high-pressure properties of the \ensuremath {{\rm Ba}}-doped silicon clathrate \ensuremath {{\rm Ba_8Si_{46}}} have been investigated combining X-ray diffraction and X-ray absorption spectroscopy. A pressure-induced isostructural phase transition associated with an important volume collapse takes place at 11.5-14 \ensuremath{{\rm ~GPa}}. This transformation is characterized by the homothetic contraction of the silicon cages containing the \ensuremath {{\rm Ba}} atoms. This transition is preceded by a change in the electronic structure at 5 \ensuremath{{\rm ~GPa}}in good agreement with Raman spectroscopy observations (T. KUME et al., Phys. Rev. Lett., 90 (2003) 155503) that it is also of isostructural nature. The cage structure is preserved through the phase transitions allowing to obtain tetrahedral silicon with record interatomic distances as low as 2.13 \ensuremath{{\rm ~Å}}. At the highest studied pressure of 49 \ensuremath{{\rm ~GPa}}, the structure becomes irreversibly amorphous. The physical origin of the homothetic isostructural transitions is discussed.

Dates et versions

hal-00021564 , version 1 (22-03-2006)

Identifiants

Citer

A. San Miguel, A. Merlen, Pierre Toulemonde, T. Kume, S. Le Floch, et al.. Pressure-induced homothetic volume collapse in silicon clathrates.. EPL - Europhysics Letters, 2005, 69, pp.556-562. ⟨10.1209/epl/i2004-10387-x⟩. ⟨hal-00021564⟩
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