Super Compliant and Soft (CH<sub>3</sub>NH<sub>3</sub>)<sub>3</sub>Bi<sub>2</sub>I<sub>9 </sub>Crystals with Ultralow Thermal Conductivity

ORAL

Abstract

In this work, we show the phonon dispersion of (CH3NH3)3Bi2I9 single crystals at 300 K measured by inelastic x-ray scattering. The frequencies of acoustic phonons are among the lowest of crystals. Nanoindentation measurements verified that these crystals are very compliant and considerably soft. The frequency overlap between acoustic and optical phonons results in strong acoustic-optical scattering. All these features lead to an ultralow thermal conductivity, as validated by the laser flash method. The fundamental knowledge obtained from this study will accelerate the design of novel hybrid materials for energy applications. This work has been published in Phys. Rev. Lett. 123, 155901 (2019).

*This work was funded by Z.T.’s NSF CAREER Award (CBET-1839384). This work was supported by the Molecular Foundry at Lawrence Berkeley National Laboratory, a user facility supported by the Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy (DOE) under Contract No. DE-AC02-05CH11231. This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

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Presenters

  • Zhiting Tian

    • Cornell University

Authors

  • Hao Ma

    • Cornell University

  • Chen Li

    • Cornell University

  • Yunwei Ma

    • Virginia Tech

  • Heng Wang

    • Illinois Institute of Technology

  • Zachary Rouse

    • Cornell University

  • Zhuolei Zhang

    • Lawrence Berkeley National Laboratory

  • Carla Slebodnick

    • Virginia Tech

  • Ahmet Alatas

    • Argonne National Laboratory

  • Shefford Baker

    • Cornell University

  • Jeffrey Urban

    • Lawrence Berkeley National Laboratory

  • Zhiting Tian

    • Cornell University