Main content area

Pressure-induced metallization in MoSe₂ under different pressure conditions

Yang, Linfei, Dai, Lidong, Li, Heping, Hu, Haiying, Liu, Kaixiang, Pu, Chang, Hong, Meiling, Liu, Pengfei
RSC advances 2019 v.9 no.10 pp. 5794-5803
Raman spectroscopy, atomic force microscopy, electrical conductivity, molybdenum, phase transition, shear stress, transmission electron microscopy, van der Waals forces
In this study, the vibrational and electrical transport properties of molybdenum diselenide were investigated under both non-hydrostatic and hydrostatic conditions up to ∼40.2 GPa using the diamond anvil cell in conjunction with Raman spectroscopy, electrical conductivity, high-resolution transmission electron microscopy, atomic force microscopy, and first-principles theoretical calculations. The results obtained indicated that the semiconductor-to-metal electronic phase transition of MoSe₂ can be extrapolated by some characteristic parameters including abrupt changes in the full width at half maximum of Raman modes, electrical conductivity and calculated bandgap. Under the non-hydrostatic condition, metallization occurred at ∼26.1 GPa and it was irreversible. However, reversible metallization occurred at ∼29.4 GPa under the hydrostatic condition. In addition, the pressure-induced metallization reversibility of MoSe₂ can be revealed by high-resolution transmission electron and atomic force microscopy of the recovered samples under different hydrostatic conditions. This discrepancy in the metallization phenomenon of MoSe₂ in different hydrostatic environments was attributed to the mitigated interlayer van der Waals coupling and shear stress caused by the insertion of pressure medium into the layers.