New High-Pressure Phases of MoSe$_2$ and MoTe$_2$

Oto Kohulák; Roman Martoňák

doi:10.1103/PhysRevB.95.054105

paper

New High-Pressure Phases of MoSe $_{2}$ and MoTe $_{2}$

arXiv:1611.07757 · doi:10.1103/PhysRevB.95.054105

Abstract

Three Mo-based transition metal dichalcogenides MoS $_{2}$ , MoSe $_{2}$ and MoTe $_{2}$ share at ambient conditions the same structure 2H $_{c}$ , consisting of layers where Mo atoms are surrounded by six chalcogen atoms in trigonal prism coordination. The knowledge of their high-pressure behaviour is, however, limited, particularly in case of MoSe $_{2}$ and MoTe $_{2}$ . The latter materials do not undergo a layer-sliding transition 2H $_{c}$ $\to$ 2H $_{a}$ known in MoS $_{2}$ and currently no other stable phase besides 2H $_{c}$ is known in these systems at room temperature. Employing evolutionary crystal structure prediction in combination with \textit{ab initio} calculations we study the zero-temperature phase diagram of both materials up to Mbar pressures. We find a tetragonal phase with space group \textit{P4/mmm}, previously predicted in MoS $_{2}$ , to become stable in MoSe $_{2}$ at 118 GPa. In MoTe $_{2}$ we predict at 50 GPa a transition to a new layered tetragonal structure with space group \textit{I4/mmm}, similar to CaC $_{2}$ , where Mo atoms are surrounded by eight Te atoms. The phase is metallic already at the transition pressure and becomes a good metal beyond 1 Mbar. We discuss chemical trends in the family of Mo-based transition metal dichalcogenides and suggest that MoTe $_{2}$ likely offers the easiest route towards the post-2H phases.

arXiv comment6 pages, 9 figures

New High-Pressure Phases of MoSe2​ and MoTe2​

Abstract

References in corpus (10)

New High-Pressure Phases of MoSe $_{2}$ and MoTe $_{2}$