Structural Phase Transitions and Metallization in Zirconium Disulfide (ZrS₂) under High Pressure

The high-pressure study on zirconium disulfide (ZrS₂) has been conducted up to ∼33.9 GPa by using <i>in-situ</i> synchrotron X-ray diffraction at room temperature and electrical transport measurements, aiming to investigate the pressure-induced structural phase transitions and the metallization of the material. The experiments indicated that a progressive structural evolution occurs as the sequence below: hexagonal (space group (SG): <i>P</i>3̅<i>m1</i>) → monoclinic (SG: <i>P2</i>_<i>1</i><i>/m</i>) started at 2.8 GPa → orthorhombic (SG: <i>Immm</i>) started at 9.9 GPa → tetragonal (SG: <i>I4/mmm</i>) started at 30.4 GPa. The lattice parameters and bulk modulus of the phases at high pressure are calculated. The decompression results demonstrate the coexistence of ZrS₂ stability in monoclinic (SG: <i>P2</i>_<i>1</i><i>/m</i>) and orthorhombic (SG: <i>Immm</i>) structures. The electrical transport results demonstrate a significant enhancement in the conductivity of ZrS₂ at 8 GPa, and metallization occurs at ∼29.8 GPa. Combined with XRD results, the metallization is coincident with the phase transition to the tetragonal (SG: <i>I4/mmm</i>) structure. Our study presents a more precise phase transition sequence, calculates the cell parameters and bulk modulus of ZrS₂ under high-pressure conditions based on experimental results, and confirms that metallization is induced by the structural phase transition. These findings provide an experimental basis for the further utilization of transition metal sulfides (TMDs) under high pressure.