Ruddlesden-Popper chalcogenides push the limit of mechanical stiffness and glass-like thermal conductivity in single crystals

Md Shafkat Hoque, Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA.
Eric R. Hoglund, Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA, USA.
Boyang Zhao, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA.
De-Liang Bao, Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA.
Hao Zhou, Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA.
Sandip Thakur, University of Rhode Island
Eric Osei-Agyemang, Department of Materials Design and Innovation, University at Buffalo, The State University of New York, Buffalo, NY, USA.
Khalid Hattar, Nuclear Engineering, University of Tennessee, Knoxville, TN, USA.
Ethan A. Scott, Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA.
Mythili Surendran, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA.
John A. Tomko, Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA.
John T. Gaskins, Laser thermal analysis, Charlottesville, VA, USA.
Kiumars Aryana, Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA.
Sara Makarem, Department of Materials Science and Engineering, University of Virginia, Charlottesville, VA, USA.
Adie Alwen, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA.
Andrea M. Hodge, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA.
Ganesh Balasubramanian, Department of Mechanical and Industrial Engineering, University of New Haven, West Haven, CT, USA.
Ashutosh Giri, University of Rhode Island
Tianli Feng, Department of Mechanical Engineering, University of Utah, Salt Lake City, UT, USA.
Jordan A. Hachtel, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN, USA.
Jayakanth Ravichandran, Mork Family Department of Chemical Engineering and Materials Science, University of Southern California, Los Angeles, CA, USA. j.ravichandran@usc.edu.
Sokrates T. Pantelides, Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA. pantelides@vanderbilt.edu.
Patrick E. Hopkins, Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, VA, USA. phopkins@virginia.edu.

Document Type

Article

Date of Original Version

7-2-2025

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 BaZrS, n = 2, 3, which are derivatives of BaZrS. 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".

Publication Title, e.g., Journal

Nature communications

Volume

16

Issue

1

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