Commensurate Stacking Phase Transitions in an Intercalated Transition Metal Dichalcogenide.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34871466.
- Also identified by DOI 10.1002/adma.202108550.
- No licence information is recorded for this record.
- Because redistribution is not established, this page shows the abstract only. Follow the links below for the full text.
Abstract
Intercalation and stacking-order modulation are two active ways in manipulating the interlayer interaction of transition metal dichalcogenides (TMDCs), which lead to a variety of emergent phases and allow for engineering material properties. Herein, the growth of Pb-intercalated TMDCs-Pb(Ta<sub>1+x</sub> Se<sub>2</sub> )<sub>2</sub> , the first 124-phase, is reported. Pb(Ta<sub>1+x</sub> Se<sub>2</sub> )<sub>2</sub> exhibits a unique two-step first-order structural phase transition at around 230 K. The transitions are solely associated with the stacking degree of freedom, evolving from a high-temperature (high-T) phase with ABC stacking and R3m symmetry to an intermediate phase with AB stacking and P3m1, and finally to a low-temperature (low-T) phase again with R3msymmetry, but with ACB stacking. Each step involves a rigid slide of building blocks by a vector [1/3, 2/3, 0]. Intriguingly, gigantic lattice contractions occur at the transitions on warming. At low-T, bulk superconductivity with T<sub>c</sub> ≈ 1.8 K is observed. The underlying physics of the structural phase transitions are discussed from first-principle calculations. The symmetry analysis reveals topological nodal lines in the band structure. The results demonstrate the possibility of realizing higher-order metal-intercalated phases of TMDCs and advance the knowledge of polymorphic transitions, and may inspire stacking-order engineering in TMDCs and beyond.