Abstract
Solids with ultralow thermal conductivity are of great interest as thermal barrier coatings for insulation or thermoelectrics for energy conversion. However, the theoretical limits of lattice thermal conductivity (k) are unclear. In typical crystals a phonon picture is valid, whereas lowest k values occur in highly disordered materials where this picture fails and heat is supposedly carried by random walk among uncorrelated oscillators. Here we identify a simple crystal, Tl3VSe4, with a calculated phonon k [0.16 Watts per meter-Kelvin (W/m-K)] one-half that of our measured k (0.30 W/m-K) at 300 K, approaching disorder k values, although Raman spectra, specific heat, and temperature dependence of k reveal typical phonon characteristics. Adding a transport component based on uncorrelated oscillators explains the measured k and suggests that a two-channel model is necessary for crystals with ultralow k.
| Original language | English |
|---|---|
| Pages (from-to) | 1455-1458 |
| Number of pages | 4 |
| Journal | Science |
| Volume | 360 |
| Issue number | 6396 |
| DOIs | |
| State | Published - Jun 29 2018 |
Funding
We acknowledge helpful discussion with D. Cahill, D. Broido, P. Allen, and D. Mandrus. This work was supported by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. S.M. was in part supported by the NRC-NRL Research Associateship Program for supplemental calculations of structural and thermal properties. This work used computational resources from the National Energy Research Scientific Computing Center (NERSC), 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. Raman spectroscopy measurements were conducted as a user proposal at the Center for Nanophase Materials Sciences (CNMS), which is a DOE Office of Science User Facility.