Unifying first-principles theoretical predictions and experimental measurements of size effects in thermal transport in SiGe alloys
Author(s)Huberman, Samuel C.; Chiloyan, Vazrik; Duncan, Ryan Andrew; Zeng, Lingping; Jia, Roger Qingfeng; Maznev, Alexei; Fitzgerald, Eugene A; Nelson, Keith Adam; Chen, Gang; ... Show more Show less
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We demonstrate the agreement between first-principles calculations and experimental measurements of size effects in thermal transport in SiGe alloys without fitting parameters. Transient thermal grating (TTG) is used to measure the effect of the grating period on the temperature decay. The virtual crystal approximation under the density-functional-theory framework combined with impurity scattering is used to determine the phonon properties for the exact alloy composition of the measured samples. With these properties, classical size effects are calculated for the experimental geometry of reflection mode TTG using the recently developed variational solution to the phonon Boltzmann transport equation, which is verified against established Monte Carlo simulations. We find agreement between theoretical predictions and experimental measurements in the reduction of thermal conductivity (as much as fourfold of the bulk value) across grating periods spanning one order of magnitude. This paper provides a framework for the study of size effects in thermal transport in opaque materials.
DepartmentMassachusetts Institute of Technology. Center for Materials Science and Engineering; Massachusetts Institute of Technology. Department of Chemistry; Massachusetts Institute of Technology. Department of Mechanical Engineering
Physical Review Materials
American Physical Society
Huberman, Samuel et al. “Unifying First-Principles Theoretical Predictions and Experimental Measurements of Size Effects in Thermal Transport in SiGe Alloys.” Physical Review Materials 1, 5 (October 2017): 054601 © 2017 American Physical Society