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Effective thermal conductivity of polycrystalline materials with randomly oriented superlattice grains

Yang, Fan and Ikeda, Teruyuki and Snyder, G. Jeffrey and Dames, Chris (2010) Effective thermal conductivity of polycrystalline materials with randomly oriented superlattice grains. Journal of Applied Physics, 108 (3). 034310 . ISSN 0021-8979.

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A model has been established for the effective thermal conductivity of a bulk polycrystal made of randomly oriented superlattice grains with anisotropic thermal conductivity. The in-plane and cross-plane thermal conductivities of each superlattice grain are combined using an analytical averaging rule that is verified using finite element methods. The superlattice conductivities are calculated using frequency dependent solutions of the Boltzmann transport equation, which capture greater thermal conductivity reductions as compared to the simpler gray medium approximation. The model is applied to a PbTe/Sb_2Te_3 nanobulk material to investigate the effects of period, specularity, and temperature. The calculations show that the effective thermal conductivity of the polycrystal is most sensitive to the in-plane conductivity of each superlattice grain, which is generally four to five times larger than the cross-plane conductivity of a grain. The model is compared to experimental measurements of the same system for periods ranging from 287 to 1590 nm and temperatures from 300 to 500 K. The comparison suggests that the effective specularity increases with increasing annealing temperature and shows that these samples are in a mixed regime where both Umklapp and boundary scattering are important.

Item Type:Article
Related URLs:
URLURL TypeDescription
Ikeda, Teruyuki0000-0001-7076-6958
Snyder, G. Jeffrey0000-0003-1414-8682
Additional Information:© 2010 American Institute of Physics. Received 29 April 2010; accepted 29 May 2010; published online 5 August 2010. This work is supported in part by the DARPA/DSO NMP program Grant No. W911NF-08-C-0058 and the PRESTO program of Japan Science and Technology Agency. The views, opinions, and/or findings contained in this article are those of the authors and should not be interpreted as representing the official views or policies, either expressed or implied, of the Defense Advanced Research Projects Agency or the Department of Defense. Approved for Public Release, Distribution Unlimited.
Funding AgencyGrant Number
Defense Advanced Research Projects Agency (DARPA)/DSO NMP programW911NF-08-C-0058
Japan Science and Technology AgencyUNSPECIFIED
Subject Keywords:annealing; antimony alloys; Boltzmann equation; finite element analysis; lead alloys; nanostructured materials; superlattices; tellurium alloys; thermal conductivity; umklapp process
Issue or Number:3
Classification Code:PACS: 72.15.Eb; 81.40.Gh; 63.22.Kn; 63.22.Np
Record Number:CaltechAUTHORS:20100908-113300905
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19834
Deposited By: Jason Perez
Deposited On:08 Sep 2010 21:37
Last Modified:03 Oct 2019 02:02

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