Abstract
A model for the thermal conductivity of bulk solids is proposed in the limit of diffusive transport mediated by diffusons as opposed to phonons. This diffusive thermal conductivity, κdiff, is determined by the average energy of the vibrational density of states, ωavg, and the number density of atoms, n. Furthermore, κdiff is suggested as an appropriate estimate of the minimum thermal conductivity for complex materials, such that (at high temperatures):. A heuristic finding of this study is that the experimental ωavg is highly correlated with the Debye temperature, allowing κdiff to be estimated from the longitudinal and transverse speeds of sound: . Using this equation to estimate κmin gives values 37% lower than the widely-used Cahill result and 18% lower than the Clarke model for κmin, on average. This model of diffuson-mediated thermal conductivity may thus help explain experimental results of ultralow thermal conductivity.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 609-616 |
| Number of pages | 8 |
| Journal | Energy and Environmental Science |
| Volume | 11 |
| Issue number | 3 |
| DOIs | |
| State | Published - Mar 2018 |
Funding
The authors would like to thank Olivier Delaire, David Singh, David Clarke, Yanzhong Pei, John Ketterson, and David Cahill for useful discussions about minimum thermal conductivity. The contributions of M. T. A. and R. H. are supported as part of the Solid-State Solar-Thermal Energy Conversion Center (S3TEC) an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science, Basic Energy Sciences (BES), under Award # DE-SC0001299/DE-FG02-09ER46577. G. J. S. acknowledges NSF DMREF 1729487.
ASJC Scopus subject areas
- Environmental Chemistry
- Renewable Energy, Sustainability and the Environment
- Nuclear Energy and Engineering
- Pollution
