Using First Principles Thermal Transport to Aid in Energy Recovery and Conservation

Derek Stewart
Cornell University

Given the substantial amount of energy lost in the form of heat, any developments that improve energy recovery or reduce heat generation would have broad impacts. Heat in non-metals is carried primarily by lattice vibrations (a.k.a. phonons). In order to improve energy capture and conservation, new materials with tailored phonon properties are required for applications ranging from heat conduits to thermoelectrics. In this talk, I will present a first principle framework for thermal transport that offers a unique window into phonon scattering mechanisms and that provides accurate predictions for thermal conductivity [1,2,3]. This approach links first principles interatomic force constants (harmonic and anharmonic) to an iterative solution of the phonon Boltzmann Transport Equation. Predicted thermal conductivities are in excellent agreement with experiment for a number of materials. I will highlight our recent work on non-toxic thermoelectric alloys (e.g. SiGe, Mg2SixSn1-x ) and examine routes to modify thermal conductivity via embedded nanoparticles[4] and size effects in nanowires[5,6]. I will also discuss our current effort on thermal transport in large unit-cell crystals and some of the materials informatics challenges in the field. This research has been done in collaboration with the groups of David Broido (Boston College) and Natalio Mingo (CEA-Grenoble). This work is supported in part by NSF Grants CBET-1066406, CBET-1066634, and by a European Union IRG Grant. [1] D. A. Broido et al, Appl. Phys. Lett., 91, 231922 (2007) [2] A. Ward et al, Phys. Rev. B, 80, 125203 (2009) [3] N. Mingo et al., “Ab Initio Thermal Transport” in Length-Scale Dependent Phonon Interactions, editors: S. L. Shinde and G. P. Srivastava, Springer-Verlag (2013) [4] A. Kundu et al, Phys. Rev. B, 84, 125426 (2011) [5] W. Li et al, Phys. Rev. B, 86, 174307 (2012) [6] W. Li et al. Phys. Rev. B, 85, 195436 (2012)

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