Phonon self-energy and origin of anomalous neutron scattering spectra in SnTe and PbTe thermoelectrics

Journal Article · Wed Jan 01 00:00:00 EST 2014 · Physical Review Letters

DOI:https://doi.org/10.1103/PhysRevLett.112.175501· OSTI ID:1131510

Li, Chen ^[1]; Ma, Jie ^[1]; May, Andrew F ^[1]; Cao, Huibo ^[1]; Christianson, Andrew D ^[1]; Ehlers, Georg ^[1]; Singh, David J ^[1]; Sales, Brian C ^[1]; Delaire, Olivier A ^[1]

---

1. ORNL

The anharmonic lattice dynamics of rock-salt thermoelectric compounds SnTe and PbTe are investigated with inelastic neutron scattering (INS) and first-principles calculations. The experiments show that, surprisingly, although SnTe is closer to the ferroelectric instability, phonon spectra in PbTe exhibit a more anharmonic character. This behavior is reproduced in first-principles calculations of the temperature-dependent phonon self-energy. Our simulations reveal how the nesting of phonon dispersions induces prominent features in the self-energy, which account for the measured INS spectra and their temperature dependence. We establish that the phase-space for three-phonon scattering processes, rather than just the proximity to the lattice instability, is the mechanism determining the complex spectrum of the transverse-optical ferroelectric mode.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). High Temperature Materials Lab. (HTML); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Spallation Neutron Source (SNS)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1131510
• Journal Information: Physical Review Letters, Vol. 112, Issue 17; ISSN 0031--9007
• Country of Publication: United States
• Language: English

Related Subjects

phonon
thermoelectrics
thermal conductivity
neutron scattering
first-principles simulations