Abstract
We examine the lattice thermal conductivities (κl) of Li2X(X=O,S,Se,Te) using a first-principles Peierls-Boltzmann transport methodology. We find low κl values ranging between 12 and 30 Wm-1K-1 despite light Li atoms, a large mass difference between constituent atoms, and tightly bunched acoustic branches, all features that give high κl in other materials including BeSe (630 Wm-1K-1), BeTe (370 Wm-1K-1), and cubic BAs (3170 Wm-1K-1). Together these results suggest a missing ingredient in the basic guidelines commonly used to understand and predict κl. Unlike typical simple systems (e.g., Si, GaAs, SiC), the dominant resistance to heat-carrying acoustic phonons in Li2Se and Li2Te comes from interactions of these modes with two optic phonons. These interactions require significant bandwidth and dispersion of the optic branches, both present in Li2X materials. These considerations are important for the discovery and design of new materials for thermal management applications and give a more comprehensive understanding of thermal transport in crystalline solids.
| Original language | English |
|---|---|
| Article number | 224301 |
| Journal | Physical Review B |
| Volume | 93 |
| Issue number | 22 |
| DOIs | |
| State | Published - Jun 7 2016 |
Funding
S. M., L. L., and D. P. acknowledge support from the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division and 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. We thank Craig Bridges for many useful discussions.