First-principles study of lithium-doped carbon clathrates under pressure

Nicolas Rey (1) , Alfonso Munoz (2) , Placida Rodriguez-Hernandez (2) , Alfonso San Miguel (1)

1 LPMCN - Laboratoire de Physique de la Matière Condensée et Nanostructures
2 Departamento de Fisica Fundamental II

We present a theoretical study on the behavior under pressure of the two hypothetical C$_{46}$ and Li$_8$C$_{46}$ type-I carbon clathrates in order to bring new informations concerning their synthesis. Using \textit{ab initio} calculations, we have explored the energetic and structural properties under pressure of these two carbon based cage-like materials. These low-density meta-stable phases show large negative pressure transitions compared to diamond which represent a serious obstacle for their synthesis. However, we evidence that a minimum energy barrier can be reached close to 40~GPa, suggesting that the synthesis of the Li-clathrate under extreme conditions of pressure and temperature may be possible. Electronic band structure with related density of states behavior under pressure as well as the dependence of the active Raman modes with pressure are also examined.

Mots clés: ab initio calculations; carbon clathrates

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Nicolas Rey, Alfonso Munoz, Placida Rodriguez-Hernandez, Alfonso San Miguel. First-principles study of lithium-doped carbon clathrates under pressure. 2007. ⟨hal-00187773⟩