Anharmonicity and atomic distribution of SnTe and PbTe thermoelectrics

Article

关键词: IV-VI COMPOUNDS;    PERFORMANCE BULK THERMOELECTRICS;    TOTAL-ENERGY CALCULATIONS;    WAVE BASIS-SET;    CARRIER-CONCENTRATION;    THERMAL-CONDUCTIVITY;    LEAD CHALCOGENIDES;    CRYSTAL-STRUCTURE;    LATTICE-DYNAMICS;    PHASE-TRANSITION;   

DOI  :  10.1103/PhysRevB.90.214303

来源: SCIE

【 摘 要 】

The structure and lattice dynamics of rock-salt thermoelectric materials SnTe and PbTe are investigated with single-crystal and powder neutron diffraction, inelastic neutron scattering (INS), and first-principles simulations. Our first-principles calculations of the radial distribution function in both SnTe and PbTe show a clear asymmetry in the first nearest-neighbor (1NN) peak, which increases with temperature, in agreement with recent experimental reports. We show that this peak asymmetry for the 1NN Sn-Te or Pb-Te bond results from large-amplitude anharmonic vibrations (phonons). No atomic off centering is found in our simulations. In addition, the atomic mean-square displacements derived from our diffraction data reveal stiffer bonding at the anion site, in good agreement with the partial phonon densities of states from INS and first-principles calculations. These results provide clear evidence for large-amplitude anharmonic phonons associated with the resonant bonding leading to the ferroelectric instability.

【 授权许可】

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