Lattice dynamics and structure of GeTe, SnTe and PbTe

Pereira, P. Bauer; Sergueev, I.; Gorsse, Stéphane; Dadda, J.; Müller, Eckhard; Hermann, Raphaël P.

doi:10.1002/pssb.201248412

Cited by 170 publications

(133 citation statements)

References 63 publications

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“…The larger cation MSD was noted in Ref. 59 , but no clear origin for the effect was found. Our detailed DFT simulations actually reveal that these large MSD values for cations arise from the weaker on-site force-constants for cations, in good agreement with prior DFT investigations of the bonding and phonons in these materials [13][14][15][16]38 .…”

Section: Atomic Distributionsmentioning

confidence: 74%

“…29 The partial phonon densities of states (DOS) of Sn and Te were previously measured in rock-salt SnTe at 60 K using nuclear-resonant inelastic x-ray scattering, and it was found that the phonons are softer than similar materials in rhombohedral phase. 59 In addition, lattice dynamics study of SnTe using Mössbauer spectroscopy suggested the existence of low-temperature anharmonicity. 60 Our more detailed measurements of the temperaturedependent phonon dispersions and DOS provide further information about the phonon dynamics and anharmonicity, and also enable to clarify the origin of asymmetric PDF/RDF peaks observed in diffraction experiments.…”

Section: Lattice Dynamicsmentioning

confidence: 99%

“…The neutron-weighted phonon DOS agrees well with previous nuclear inelastic scattering measurement of Sn and Te at 115 and 60 K, respectively. 59 However, there are a few differences between INS and calculation. The experimental DOS for SnTe shows a higher intensity near 3∼4 meV at T = 100 K, which subsides at higher temperatures.…”

Section: Lattice Dynamicsmentioning

confidence: 99%

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Anharmonicity and atomic distribution of SnTe and PbTe thermoelectrics

Cao

et al. 2014

Phys. Rev. B

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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 (RDF) 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.

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Section: Atomic Distributionsmentioning

confidence: 74%

Section: Lattice Dynamicsmentioning

confidence: 99%

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Anharmonicity and atomic distribution of SnTe and PbTe thermoelectrics

Cao

et al. 2014

Phys. Rev. B

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“…Figure 2A shows the orthorhombic crystal structure for compounds such as SnSe, SnS, GeSe, and GeS in the Pnma-phase (#62) (Tritsaris et al, 2013;Ding et al, 2015;Guo et al, 2015;Wang et al, 2015), and Figure 2B shows the hexagonal crystal structure for compounds such as SnSe2 and SnS2 in the P3m1-phase (#164) (Sava et al, 2006;Bauer Pereira et al, 2013;Sun et al, 2015). For each simulation, only one layer was considered, where the number of atoms per primitive cell is 4 for the orthorhombic crystal structure and 3 for the hexagonal crystal structure.…”

Section: Computational Detailsmentioning

confidence: 99%

First-Principles Calculations of Thermoelectric Properties of IV–VI Chalcogenides 2D Materials

et al. 2017

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A first-principles study using density functional theory and Boltzmann transport theory has been performed to evaluate the thermoelectric (TE) properties of a series of single-layer 2D materials. The compounds studied are SnSe, SnS, GeS, GeSe, SnSe2, and SnS2, all of which belong to the IV-VI chalcogenides family. The first four compounds have orthorhombic crystal structures, and the last two have hexagonal crystal structures. Solving a semi-empirical Boltzmann transport model through the BoltzTraP software, we compute the electrical properties, including Seebeck coefficient, electrical conductivity, power factor, and the electronic thermal conductivity, at three doping levels corresponding to 300 K carrier concentrations of 10 . The spin orbit coupling effect on these properties is evaluated and is found not to influence the results significantly. First-principles lattice dynamics combined with the iterative solution of phonon Boltzmann transport equations are used to compute the lattice thermal conductivity of these materials. It is found that these materials have narrow band gaps in the range of 0.75-1.58 eV. Based on the highest values of figure-of-merit ZT of all the materials studied, we notice that the best TE material at the temperature range studied here (300-800 K) is SnSe.

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“…15 Since the experiments are performed in the transmission geometry, the observed dynamics is determined by the averaged contribution along the direction …”

Section: Transient Change Of Diffraction Intensity and Peak Positionmentioning

confidence: 99%

Transient Structures and Possible Limits of Data Recording in Phase-Change Materials

Vanacore

Yang

et al. 2015

ACS Nano

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Phase-change materials (PCMs) represent the leading candidates for universal data storage devices, which exploit the large difference in the physical properties of their transitional lattice structures. On a nanoscale, it is fundamental to determine their performance, which is ultimately controlled by the speed limit of transformation among the different structures involved. Here, we report observation with atomic-scale resolution of transient structures of nanofilms of crystalline germanium telluride, a prototypical PCM, using ultrafast electron crystallography. A nonthermal transformation from the initial rhombohedral phase to the cubic structure was found to occur in 12 ps. On a much longer time scale, hundreds of picoseconds, equilibrium heating of the nanofilm is reached, driving the system toward amorphization, provided that high excitation energy is invoked.These results elucidate the elementary steps defining the structural pathway in the transformation of crystalline-to-amorphous phase transitions and describe the essential atomic motions involved when driven by an ultrafast excitation. The establishment of the time scales of the different transient structures, as reported here, permits determination of the possible limit of performance, which is crucial for high-speed recording applications of PCMs.

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Lattice dynamics and structure of GeTe, SnTe and PbTe

Cited by 170 publications

References 63 publications

Anharmonicity and atomic distribution of SnTe and PbTe thermoelectrics

Anharmonicity and atomic distribution of SnTe and PbTe thermoelectrics

First-Principles Calculations of Thermoelectric Properties of IV–VI Chalcogenides 2D Materials

Transient Structures and Possible Limits of Data Recording in Phase-Change Materials

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