Electron-phonon coupling and thermal transport in the thermoelectric compound Mo3Sb7–xTex
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
Phonon properties of Mo3Sb7–xTex (x = 0, 1.5, 1.7), a potential high-temperature thermoelectric material, have been studied with inelastic neutron and x-ray scattering, and with first-principles simulations. The substitution of Te for Sb leads to pronounced changes in the electronic struc- ture, local bonding, phonon density of states (DOS), dispersions, and phonon lifetimes. Alloying with tellurium shifts the Fermi level upward, near the top of the valence band, resulting in a strong suppression of electron-phonon screening, and a large overall stiffening of interatomic force- constants. The suppression in electron-phonon coupling concomitantly increases group velocities and suppresses phonon scattering rates, surpassing the effects of alloy-disorder scattering, and re- sulting in a surprising increased lattice thermal conductivity in the alloy. We also identify that the local bonding environment changes non-uniformly around different atoms, leading to variable perturbation strengths for different optical phonon branches. The respective roles of changes in phonon group velocities and phonon lifetimes on the lattice thermal conductivity are quantified. Lastly, our results highlight the importance of the electron-phonon coupling on phonon mean-free-paths in this compound, and also estimates the contributions from boundary scattering, umklapp scattering, and point-defect scattering.
- Research Organization:
- Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States); Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES)
- Grant/Contract Number:
- AC05-00OR22725; AC02-06CH11357; AC02-05CH11231
- OSTI ID:
- 1238024
- Alternate ID(s):
- OSTI ID: 1228414; OSTI ID: 1245023
- Journal Information:
- Physical Review. B, Condensed Matter and Materials Physics, Vol. 92, Issue 21; ISSN 1098-0121
- Publisher:
- American Physical Society (APS)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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