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Title: Interface-Driven Structural Distortions and Composition Segregation in Two-Dimensional Heterostructures

The discovery of emergent phenomena in 2D materials has sparked substantial research efforts in the materials community. A significant experimental challenge for this field is exerting atomistic control over the structure and composition of the constituent 2D layers and understanding how the interactions between layers drive both structure and properties. While no segregation for single bilayers was observed, segregation of Pb to the surface of three bilayer thick PbSe–SnSe alloy layers was discovered within [(Pb xSn 1–xSe) 1+δ] n(TiSe 2) 1 heterostructures using electron microscopy. This segregation is thermodynamically favored to occur when Pb xSn 1–xSe layers are interdigitated with TiSe 2 monolayers. DFT calculations indicate that the observed segregation depends on what is adjacent to the Pb xSn 1–xSe layers. As a result, the interplay between interface- and volume-free energies controls both the structure and composition of the constituent layers, which can be tuned using layer thickness.
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  1. Univ. of Oregon, Eugene, OR (United States)
  2. Univ. of Florida, Gainesville, FL (United States)
  3. Sandia National Lab. (SNL-CA), Livermore, CA (United States)
  4. Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1433-7851; 657273
Grant/Contract Number:
AC04-94AL85000; AC05-76RL01830; DMR-1266217; DMR-1729613; 00095176; NA0003525
Accepted Manuscript
Journal Name:
Angewandte Chemie (International Edition)
Additional Journal Information:
Journal Name: Angewandte Chemie (International Edition); Journal Volume: 56; Journal Issue: 46; Journal ID: ISSN 1433-7851
Research Org:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); National Institute of Standards and Technology (NIST)
Country of Publication:
United States
36 MATERIALS SCIENCE; 2D materials; heterostructures; monolayers; surface segregation; transition metal dichalcogenides
OSTI Identifier: