Nature of low dimensional structural modulations and relative phase stability in Re_xMo(W)_1-xS₂ transition metal dichalcogenide alloys

Abstract

We report on the various types of Peierls like two dimensional structural modulations and relative phase stability of 2H and 1T poly-types in the Re_xMo_1-xS₂ and Re_xW_1-xS₂ alloy system. Theoretical calculation predicts a polytype phase transition cross over at ∼50 at. % of Mo and W in ReS₂ in both monolayer and bulk form, respectively. Experimentally, two different types of structural modulations at 50% and a modulation corresponding to trimerization at 75% alloy composition are observed for Re_xW_1-xS₂ and only one type of modulation is observed at the 50% Re_xW_1-xS₂ alloy system. The 50% alloy system is found to be a suitable monolithic candidate for metal semiconductor transition with minute external perturbation. ReS₂ is known to be in the 2D Peierls distorted 1T_d structure and forms a chain like superstructure. Incorporation of Mo and W atoms into the ReS₂ lattice modifies the metal-metal hybridization between the cations and influences the structural modulation and electronic properties of the system. The results offer yet another effective way to tune the electronic structure and poly-type phases of this class of materials other than intercalation, strain, and vertical stacking arrangement.