Insulator-metal transition of highly compressed carbon disulfide

Abstract

We present integrated spectral, structural, resistance, and theoretical evidences for simple molecular CS${}_{2}$ transformations to an insulating black polymer with threefold carbon atoms at 9 GPa, then to a semiconducting polymer above 30 GPa, and finally to a metallic solid above 50 GPa. The metallic phase is a highly disordered three-dimensional network structure with fourfold carbon atoms at the carbon-sulfur distance of \ensuremath{\sim}1.70 \AA{}. Based on first-principles calculations, we present two plausible structures for the metallic phase: \ensuremath{\alpha}-chalcopyrite and tridymite, both of which exhibit metallic ground states and disordered diffraction features similar to that measured. We also present the phase and chemical transformation diagram for carbon disulfide, showing a large stability field of the metallic phase to 100 GPa and 800 K.