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

TL;DR

This study uses ab initio calculations to investigate the structural, energetic, and electronic properties of hypothetical lithium-doped carbon clathrates under pressure, assessing their synthesis feasibility and vibrational characteristics.

Contribution

It provides new insights into the pressure-induced behavior and synthesis conditions of Li-doped carbon clathrates through theoretical modeling.

Findings

Large negative pressure transitions compared to diamond.

A minimum energy barrier near 40 GPa suggests possible synthesis.

Pressure affects electronic band structure and Raman modes.

Abstract

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.