Pressure-induced phase transition, metallization and superconductivity in ZrS2

Phys Chem Chem Phys. 2018 Sep 19;20(36):23656-23663. doi: 10.1039/c8cp04271c.

Abstract

Zirconium disulfide (ZrS2) is an exemplary case among layered materials that exhibit unusual electronic and vibrational properties, with applications in potential photovoltaic and single-layer transistor materials. Here, we examine the effect of pressure on the structural stability, phonon dispersion, electronic properties and electron-phonon coupling of ZrS2 using first-principles calculations. Our results unravel that ZrS2 undergoes several pressure-induced phase transformations from the ambient-pressure P3[combining macron]m1 structure to a monoclinic P21/m structure at 2.0 GPa, to an orthorhombic Immm structure at 5.6 GPa, and to a tetragonal I4/mmm structure at 25.0 GPa. The electronic band calculations indicate that the layered P3[combining macron]m1 and P21/m structures are narrow-gap semiconductors. The gaps of the above two phases, which are normal semiconductors, decrease with pressure. Our results show that ZrS2 reaches the metallic state by a P21/m → Immm phase transition and keeps its metallic state in the I4/mmm phase. A pressure-driven evolution of the topological Fermi surface has been uncovered. The electron-phonon coupling results identify superconducting states in both metallic Immm and I4/mmm structures. Our research shows that pressure is efficient in the modulation of the bonding states, crystal structures and electronic properties of ZrS2, which will stimulate further high-pressure structural and conductive measurements.