Assessment of thermally driven local structural phase changes in 1 T ′ − MoTe 2

The role of layer disorder is important in establishing the topological phases of {MoTe}₂ . A rich tapestry of atomic ordering influences the structural phase transitions (SPTs), but there is little understanding of the mechanistic details of the phase transition. An atomistic level study was conducted to investigate the local structure of the 1{T}^′ and {T}_d phases of {MoTe}₂ by using the pair distribution function (PDF) technique. While the average structure exhibits an SPT and coexistence of phases as a function of temperature, the local structure showed the suppression of SPT. The sample retained its monoclinic structure at all temperatures in short-range order. A sharp PDF peak observed at short distances indicated a strong atom-atom correlation between the Mo and Te atoms within the Mo octahedra. In addition, a large-box modeling of the PDF data indicated a preferential motion of Te atoms towards c axis at all temperatures. Structural defects, such as stacking faults, likely result in the coexistence of phases in the average structure and suppress the local SPT of {MoTe}₂ . These results are stepping stones to understand the long-debated origins of structural, vibrational, and electronic properties of {MoTe}₂ and similar transition metal dichalcogenides.