Structural\nPhase Transitions and Metallization in\nZirconium Disulfide (ZrS<sub>2</sub>) under High Pressure

The high-pressure study on zirconium disulfide (ZrS<sub>2</sub>) has been conducted up to ∼33.9 GPa by using <i>in-situ</i> synchrotron X-ray diffraction at room temperature\nand electrical\ntransport measurements, aiming to investigate the pressure-induced\nstructural phase transitions and the metallization of the material.\nThe experiments indicated that a progressive structural evolution\noccurs as the sequence below: hexagonal (space group (SG): <i>P</i>3̅<i>m1</i>) → monoclinic (SG: <i>P2</i><sub><i>1</i></sub><i>/m</i>) started\nat 2.8 GPa → orthorhombic (SG: <i>Immm</i>) started\nat 9.9 GPa → tetragonal (SG: <i>I4/mmm</i>) started\nat 30.4 GPa. The lattice parameters and bulk modulus of the phases\nat high pressure are calculated. The decompression results demonstrate\nthe coexistence of ZrS<sub>2</sub> stability in monoclinic (SG: <i>P2</i><sub><i>1</i></sub><i>/m</i>) and\northorhombic (SG: <i>Immm</i>) structures. The electrical\ntransport results demonstrate a significant enhancement in the conductivity\nof ZrS<sub>2</sub> at 8 GPa, and metallization occurs at ∼29.8\nGPa. Combined with XRD results, the metallization is coincident with\nthe phase transition to the tetragonal (SG: <i>I4/mmm</i>) structure. Our study presents a more precise phase transition sequence,\ncalculates the cell parameters and bulk modulus of ZrS<sub>2</sub> under high-pressure conditions based on experimental results, and\nconfirms that metallization is induced by the structural phase transition.\nThese findings provide an experimental basis for the further utilization\nof transition metal sulfides (TMDs) under high pressure.