Phonon conductivity of plastically deformed crystals: Role of stacking faults and dislocations

Singh, Benoy Kumar; Menon, V. J.; Sood, K. C.

doi:10.1103/physrevb.74.184302

Cited by 26 publications

(29 citation statements)

References 22 publications

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“…, consistent with the dynamic scattering results where the relaxation rate is independent of the Burgers vector b [16,19,36]. Eq.…”

supporting

confidence: 90%

“…All of the above DPI mechanisms dominate at very low temperature where anharmonic phonon-phonon interaction is weak. Dislocations may also reduce the thermal conductivity above the conductivity maximum temperature [13,16,36,37]. This is explained as contributions beyond the dislocation, such as dislocation dipoles [16] or stacking faults [36].…”

mentioning

confidence: 99%

“…Dislocations may also reduce the thermal conductivity above the conductivity maximum temperature [13,16,36,37]. This is explained as contributions beyond the dislocation, such as dislocation dipoles [16] or stacking faults [36]. In this case, the question whether this phenomenon is intrinsic (can be induced by dislocation itself) or extrinsic (such as stacking fault scattering) is not resolved.…”

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confidence: 99%

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Nonperturbative Quantum Nature of the Dislocation–Phonon Interaction

Ding

Meng

et al. 2017

Nano Lett.

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Despite the long history of dislocation-phonon interaction studies, there are many problems that have not been fully resolved during this development. These include an incompatibility between a perturbative approach and the long-range nature of a dislocation, the relation between static and dynamic scattering, and their capability of dealing with thermal transport phenomena for bulk material only. Here by utilizing a fully quantized dislocation field, which we called a "dislon", a phonon interacting with a dislocation is renormalized as a quasi-phonon, with shifted quasi-phonon energy, and accompanied by a finite quasi-phonon lifetime, which are reducible to classical results. A series of outstanding legacy issues including those above can be directly explained within this unified phonon renormalization approach. For instance, a renormalized phonon naturally resolves the decade-long debate between dynamic and static dislocation-phonon scattering approaches, as two limiting cases. In particular, at nanoscale, both the dynamic and static approaches break down, while the present renormalization approach remains valid by capturing the size effect, showing good agreement with lattice dynamics simulations.

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“…, consistent with the dynamic scattering results where the relaxation rate is independent of the Burgers vector b [16,19,36]. Eq.…”

supporting

confidence: 90%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Nonperturbative Quantum Nature of the Dislocation–Phonon Interaction

Ding

Meng

et al. 2017

Nano Lett.

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“…C in Equation ( 5) represents the phonon scattering parameter of stacking faults, which is in proportional to the number of stacking faults. [54,55] The resonant frequency of 1.48 THz, derived from the above C p analysis, is used for the fitting. The fitted κ L curve (red solid curve) agrees well with the experimental data (square symbols).…”

Section: Resultsmentioning

confidence: 99%

Ultralow Lattice Thermal Conductivity and Superhigh Thermoelectric Figure‐of‐Merit in (Mg, Bi) Co‐Doped GeTe

et al. 2021

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zT = S 2 σT/κ, where S is the Seebeck coefficient, σ is the electrical conductivity, T is the absolute temperature, and κ is the thermal conductivity consisting of the lattice thermal conductivity (κ L ) and carrier thermal conductivity (κ c ). [3] Doping external elements is a routine but effective approach to improve zT because it can tune carrier concentration or band structure to optimize PF (S 2 σ) and introduce point defects to suppress κ L . [4][5][6][7][8] However, the application of this approach highly relies on the kind and solution limit of the external elements in the host lattice. Among the numerous TE materials reported so far, GeTe is a special one because its lattice can accommodate many external elements with relatively large solution limits. Typical dopants are Sb (≈10% at Ge-sites), Bi (≈10% at Ge-sites), Pb (≈10% at Ge-sites), and Mn (>50% at Ge-sites). [9][10][11][12][13][14] Upon introducing these dopants, the κ L of GeTe can be reduced from 3.0 to around 1.0 W m −1 K −1 at 300 K. Moreover, the lattice of GeTe can simultaneously accommodate two or multiple kinds of external elements with distinct atomic mass and radius, such as (Mn, Sb), (Mn, Bi), (Cu, Sb), (In, Sb), (In, Bi), (Cr, Sb), (Ti, Sb), (Pb, Sb), and (Pb, Bi), which can further reduce the κ L to as low as 0.5 W m −1 K −1 . [15][16][17][18][19][20][21][22][23][24][25] Combining the optimized electrical transport properties by these external elements, GeTe-based compounds demonstrate high zTs in the intermediate temperature range. Among the single-doped GeTe-based compounds, Ge 0.9 Sb 0.1 Te and Ge 0.9 Bi 0.06 Te demonstrate zTs above 1.5 at 700 K. [9,10] Among the double-or multiple-doped GeTe-based compounds, Ge 0.89 Sb 0.1 In 0.01 Te, Ge 0.89 Cu 0.06 Sb 0.08 Te, Ge 0.86 Pb 0.1 Bi 0.04 Te, and Ge 0.9 Cd 0.05 Bi 0.05 Te demonstrate high zTs exceeding the level of 2.0. [15][16][17]26] Currently, GeTe-based compounds are among the best TE materials in thermoelectrics.The κ L reduction in doped GeTe-based compounds are mainly caused by the strain field and mass fluctuations introduced by the dopants. Theoretically, κ L is given by [27,28] High-efficiency thermoelectric (TE) technology is determined by the performance of TE materials. Doping is a routine approach in TEs to achieve optimized electrical properties and lowered thermal conductivity. However, how to choose appropriate dopants with desirable solution content to realize high TE figure-of-merit (zT) is very tough work. In this study, via the use of large mass and strain field fluctuations as indicators for low lattice thermal conductivity, the combination of (Mg, Bi) in GeTe is screened as very effective dopants for potentially high zTs. In experiments, a series of (Mg, Bi) co-doped GeTe compounds are prepared and the electrical and thermal transport properties are systematically investigated. Ultralow lattice thermal conductivity, about 0.3 W m −1 K −1 at 600 K, is obtained in Ge 0.9 Mg 0.04 Bi 0.06 Te due to the introduced large mass and strain field fluctuations by (Mg, Bi)...

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“…Several strategies to enhance zT include i) enhancing the TE power factor PF ( = S 2 / ) via energy filtering of charge carriers, [9,10] or introduction of resonance levels in the valence or conduction band to improve S, [11] and/or reduce (= 1/ ) through bandstructure engineering [12,13] and modulation doping, [14] and ii) reducing lat through phonon engineering. This can be achieved by the incorporation of point defects, [15] stacking faults, [16] dislocations, [17,18] vacancies, [19] nanostructuring, [20,21] nanocomposites, [22] secondary phase precipitates, [23] and phase separation techniques, [24] all resulting in enhanced phonon scattering. Low intrinsic lat is also attributed to phonon anharmonicity in single-crystalline SnSe, and is responsible for its promising TE properties.…”

Section: Introductionmentioning

confidence: 99%

High zT and Its Origin in Sb‐doped GeTe Single Crystals

et al. 2020

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A record high zT of 2.2 at 740 K is reported in Ge0.92Sb0.08Te single crystals, with an optimal hole carrier concentration ≈4 × 1020 cm−3 that simultaneously maximizes the power factor (PF) ≈56 µW cm−1 K−2 and minimizes the thermal conductivity ≈1.9 Wm−1 K−1. In addition to the presence of herringbone domains and stacking faults, the Ge0.92Sb0.08Te exhibits significant modification to phonon dispersion with an extra phonon excitation around ≈5–6 meV at Γ point of the Brillouin zone as confirmed through inelastic neutron scattering (INS) measurements. Density functional theory (DFT) confirmed this phonon excitation, and predicted another higher energy phonon excitation ≈12–13 meV at W point. These phonon excitations collectively increase the number of phonon decay channels leading to softening of phonon frequencies such that a three‐phonon process is dominant in Ge0.92Sb0.08Te, in contrast to a dominant four‐phonon process in pristine GeTe, highlighting the importance of phonon engineering approaches to improving thermoelectric (TE) performance.

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Phonon conductivity of plastically deformed crystals: Role of stacking faults and dislocations

Cited by 26 publications

References 22 publications

Nonperturbative Quantum Nature of the Dislocation–Phonon Interaction

Nonperturbative Quantum Nature of the Dislocation–Phonon Interaction

Ultralow Lattice Thermal Conductivity and Superhigh Thermoelectric Figure‐of‐Merit in (Mg, Bi) Co‐Doped GeTe

High zT and Its Origin in Sb‐doped GeTe Single Crystals

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