Abstract
Insulating materials featuring ultralow thermal conductivity for diverse applications also require robust mechanical properties. Conventional thinking, however, which correlates strong bonding with high atomic-vibration-mediated heat conduction, led to diverse weakly bonded materials that feature ultralow thermal conductivity and low elastic moduli. One must, therefore, search for strongly-bonded single crystals in which heat transport is impeded by other means. Here, we report intrinsic, glass-like, ultralow thermal conductivity and ultrahigh elastic-modulus/thermal-conductivity ratio in single-crystalline Ruddlesden-Popper Ban+1ZrnS3n+1, n = 2, 3, which are derivatives of BaZrS3. Their key features are strong anharmonicity and intra-unit-cell rock-salt blocks. The latter produce strongly bonded intrinsic superlattices, impeding heat conduction by broadband reduction of phonon velocities and mean free paths and concomitant strong phonon localization. The present study initiates a paradigm of “mechanically stiff phonon glasses”.
| Original language | English |
|---|---|
| Article number | 6104 |
| Journal | Nature Communications |
| Volume | 16 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 2025 |
Funding
We thank Kevin Ye and Rafael Jaramillo from Department of Materials Science and Engineering of Massachusetts Institute of Technology for their help with the sample preparation. M.S.B.H., E.A.S., J.A.T., S.M., K.A. and P.E.H. appreciate support from the Office of Naval Research Grant No. N0014-23-1-2630. E.R.H. and J.A.H. acknowledge that vibrational EELS experiments were supported by the U.S. Department of Energy, Office of Basic Energy Sciences (DOE-BES), Division of Materials Sciences and Engineering under contract ERKCS8 and was performed at the Center for Nanophase Materials Sciences, (CNMS), which is a DOE Office of Science User Facility using instrumentation within ORNL’s Materials Characterization Core provided by UT-Battelle, LLC, under Contract No. DE-AC05- 00OR22725 with the DOE and sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy. D.-L.B. and S.T.P. acknowledge support by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Science and Technology Division Grant No. DE-FG02-09ER46554 and by the McMinn Endowment at Vanderbilt University. Computations were performed at the National Energy Research Scientific Computer Center (a U.S. Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under contract no. DE-AC02-05CH11231. B.Z., M.S., and J.R. acknowledge support from an ARO MURI program (W911NF-21-1-0327), an ARO grant (W911NF-19-1-0137), and National Science Foundation (DMR-2122071). H.Z. and T.F. acknowledge support from National Science Foundation (NSF) (award number: CBET 2212830). H.Z. and T.F. used the computational resource of Bridges-2 at Pittsburgh Supercomputing Center through allocation PHY220002 from the Advanced Cyber infrastructure Coordination Ecosystem: Services & Support (ACCESS) program, which is supported by National Science Foundation grants #2138259, #2138286, #2138307, #2137603, and #2138296, National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 using NERSC award BES-ERCAP0022132, and Center for High Performance Computing (CHPC) at the University of Utah. G.B. thanks NSF award CMMI 2436601 that supported the work, in part. A.G. and S.T. acknowledge support from the Office of Naval Research Grant No. N00014-24-1-2419. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International, Inc., for the U.S. DOE’s National Nuclear Security Administration under contract DE-NA-0003525. The views expressed in the article do not necessarily represent the views of the U.S. DOE or the United States Government.