Structural evolution and phase transition mechanism of [Formula: see text] under high pressure.
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ABSTRACT: [Formula: see text] is a layered transition-metal dichalcogenide (TMD) with outstanding electronic and optical properties, which is widely used in field-effect transistor (FET). Here the structural evolution and phase transition of [Formula: see text] under high pressure are systematically studied by CALYPSO structural search method and first-principles calculations. The structural evolutions of [Formula: see text] show that the ground state structure under ambient pressure is the experimentally observed P6[Formula: see text]/mmc phase, which transfers to R3m phase at 1.9 GPa. The trigonal R3m phase of [Formula: see text] is stable up to 72.1 GPa, then, it transforms into a new P6[Formula: see text]/mmc phase with different atomic coordinates of Se atoms. This phase is extremely robust under ultrahigh pressure and finally changes to another trigonal R-3m phase under 491.1 GPa. The elastic constants and phonon dispersion curves indicate that the ambient pressure phase and three new high-pressure phases are all stable. The electronic band structure and projected density of states analyses reveal a pressure induced semiconducting to metallic transition under 72.1 GPa. These results offer a detailed structural evolution and phase diagram of [Formula: see text] under high pressure, which may also provide insights for exploration other TMDs under ultrahigh pressure.
SUBMITTER: Xiao Y
PROVIDER: S-EPMC8586237 | biostudies-literature |
REPOSITORIES: biostudies-literature
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