Lattice Softening Significantly Reduces Thermal Conductivity and Leads to High Thermoelectric Efficiency

Riley Hanus, Matthias T. Agne, Alexander J.E. Rettie, Zhiwei Chen, Gangjian Tan, Duck Young Chung, Mercouri G Kanatzidis, Yanzhong Pei, Peter W. Voorhees, G. Jeffrey Snyder

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The influence of micro/nanostructure on thermal conductivity is a topic of great scientific interest, particularly to thermoelectrics. The current understanding is that structural defects decrease thermal conductivity through phonon scattering where the phonon dispersion and speed of sound are assumed to remain constant. Experimental work on a PbTe model system is presented, which shows that the speed of sound linearly decreases with increased internal strain. This softening of the materials lattice completely accounts for the reduction in lattice thermal conductivity, without the introduction of additional phonon scattering mechanisms. Additionally, it is shown that a major contribution to the improvement in the thermoelectric figure of merit (zT > 2) of high-efficiency Na-doped PbTe can be attributed to lattice softening. While inhomogeneous internal strain fields are known to introduce phonon scattering centers, this study demonstrates that internal strain can modify phonon propagation speed as well. This presents new avenues to control lattice thermal conductivity, beyond phonon scattering. In practice, many engineering materials will exhibit both softening and scattering effects, as is shown in silicon. This work shines new light on studies of thermal conductivity in fields of energy materials, microelectronics, and nanoscale heat transfer.

Original languageEnglish
Article number1900108
JournalAdvanced Materials
DOIs
Publication statusPublished - Jan 1 2019

Fingerprint

Phonon scattering
Thermal conductivity
Acoustic wave velocity
Silicon
Microelectronics
Nanostructures
Scattering
Heat transfer
Defects

Keywords

  • lattice dynamics
  • thermal conductivity
  • thermoelectrics

ASJC Scopus subject areas

  • Materials Science(all)
  • Mechanics of Materials
  • Mechanical Engineering

Cite this

Hanus, R., Agne, M. T., Rettie, A. J. E., Chen, Z., Tan, G., Chung, D. Y., ... Snyder, G. J. (2019). Lattice Softening Significantly Reduces Thermal Conductivity and Leads to High Thermoelectric Efficiency. Advanced Materials, [1900108]. https://doi.org/10.1002/adma.201900108

Lattice Softening Significantly Reduces Thermal Conductivity and Leads to High Thermoelectric Efficiency. / Hanus, Riley; Agne, Matthias T.; Rettie, Alexander J.E.; Chen, Zhiwei; Tan, Gangjian; Chung, Duck Young; Kanatzidis, Mercouri G; Pei, Yanzhong; Voorhees, Peter W.; Snyder, G. Jeffrey.

In: Advanced Materials, 01.01.2019.

Research output: Contribution to journalArticle

Hanus, Riley ; Agne, Matthias T. ; Rettie, Alexander J.E. ; Chen, Zhiwei ; Tan, Gangjian ; Chung, Duck Young ; Kanatzidis, Mercouri G ; Pei, Yanzhong ; Voorhees, Peter W. ; Snyder, G. Jeffrey. / Lattice Softening Significantly Reduces Thermal Conductivity and Leads to High Thermoelectric Efficiency. In: Advanced Materials. 2019.
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