Structural and Transport Properties of 1T-VSe2 Single Crystal Under High Pressures

Two-dimensional transition metal dichalcogenide 1T-VSe2 exhibits a unique three-dimensional charge density wave (CDW) order below similar to 110 K at ambient pressure, which shows unusual evolution under pressure. Here we report on the high-pressure structural and transport properties of 1T-VSe2 by extending the pressure up to 57.8 GPa, through electrical transport, synchrotron X-ray diffraction (XRD) and Raman scattering measurements, which unravel two critical pressure points. The CDW transition is found to be enhanced under compression at a rate of 16.5 K/GPa up to the first critical pressure P (C1) similar to 12 GPa, at which a structural phase transition from hexagonal P-3m1 to monoclinic C2/m phase takes place. The second critical pressure P (C2) similar to 33 GPa corresponds to another structural transition from monoclinic C2/m to P2(1)/m phase. These findings extend the phase diagram of pressurized 1T-VSe2 and may help to understand pressure tuning of structures in transition metal dichalcogenides.