Thermodynamically Controlled High-Pressure High-Temperature Synthesis of Crystalline Fluorinated sp³‑Carbon Networks

We report the feasibility of the thermodynamically controlled synthesis of crystalline sp³-carbon networks. We show that there is a critical pressure below which decomposition of the carbon network is favored and above which the carbon network is stable. Based on advanced, highly accurate quantum mechanical calculations using the all-electron full-potential linearized augmented plane-wave method (FP-LAPW) and the Birch–Murnaghan equation of state, this critical pressure is 26.5 GPa (viz. table of contents graphic). Such pressures are experimentally readily accessible and afford thermodynamic control for suppression of decomposition reactions. The present results further suggest that a general pattern of pressure-directed control exists for many isolobal conversions of sp² to sp³ allotropes, relating not only to fluorocarbon chemistry but also extending to inorganic and solid-state materials science.