Abstract
At elevated temperatures SnSe is reported to undergo a structural transition from the low symmetry orthorhombic GeS-type to a higher symmetry orthorhombic TlI-type. Although increasing symmetry should likewise increase lattice thermal conductivity, many experiments on single crystals and polycrystalline materials indicate that this is not the case. Here we present temperature dependent analysis of time-of-flight (TOF) neutron total scattering data in combination with theoretical modeling to probe the local to long-range evolution of the structure. We report that while SnSe is well characterized on average within the high symmetry space group above the transition, over length scales of a few unit cells SnSe remains better characterized in the low symmetry GeS-type space group. Our finding from robust modeling provides further insight into the curious case of a dynamic order-disorder phase transition in SnSe, a model consistent with the soft-phonon picture of the high thermoelectric power above the phase transition.
| Original language | English |
|---|---|
| Article number | 3211 |
| Journal | Nature Communications |
| Volume | 14 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2023 |
Funding
Structure analysis, including work by B.J., D.O., and K.P. was primarily supported by the Basic Energy Sciences Office of Science Early Career Award: Exploiting Small Signatures: Quantifying Nanoscale Structure and Behavior. This work was supported by the “investments for the future” project ISITE-BFC (contract ANR-15-IDEX-0003). The computing resources were made available through the VirtuES project as well as the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract no. DE-AC05-00OR22725. This research made use of the NOMAD instrument at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. J.N. and T.S. acknowledge support from the National Science Foundation, grant DMR-1606952. Work by J.N. and T.S. was carried out at the NHMFL, which is supported by the National Science Foundation under grant DMR-1644779 and the State of Florida. Structure analysis, including work by B.J., D.O., and K.P. was primarily supported by the Basic Energy Sciences Office of Science Early Career Award: Exploiting Small Signatures: Quantifying Nanoscale Structure and Behavior. This work was supported by the “investments for the future” project ISITE-BFC (contract ANR-15-IDEX-0003). The computing resources were made available through the VirtuES project as well as the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract no. DE-AC05-00OR22725. This research made use of the NOMAD instrument at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory. J.N. and T.S. acknowledge support from the National Science Foundation, grant DMR-1606952. Work by J.N. and T.S. was carried out at the NHMFL, which is supported by the National Science Foundation under grant DMR-1644779 and the State of Florida.