Lattice dynamics and elasticity in thermoelectric 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi>Mg</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi>Si</mml:mi><mml:mrow><mml:mn>1</mml:mn><mml:mo>−</mml:mo><mml:mi>x</mml:mi></mml:mrow></mml:msub><mml:msub><mml:mi>Sn</mml:mi><mml:mi>x</mml:mi></mml:msub></mml:mrow></mml:math>

Klobes, Benedikt; Boor, Johannes de; Alataş, Ahmet; Hu, Michael Y.; Simon, Ronnie; Hermann, Raphaël P.

doi:10.1103/physrevmaterials.3.025404

Cited by 10 publications

(12 citation statements)

References 48 publications

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“…The examples depicted of Si isotope scattering and Mg 2 Si 1-x Sn x shown in Figure 2 both show excellent correspondence between the first principles methods and the Klemens model. Since both materials disagree with the Debye model dispersion implicitly assumed in Klemens theory, the suitability is surprising 55,56 .…”

Section: Dispersion Relation Sensitivitymentioning

confidence: 97%

Analytical Models of Phonon–Point-Defect Scattering

et al. 2020

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Point defects exist widely in engineering materials and are known to scatter vibrational modes to reduce thermal conductivity. The Klemens description of point defect scattering is the most prolific analytical model for this effect. This work reviews the essential physics of the model and compares its predictions to first principles results for isotope and alloy scattering, demonstrating the model as a useful materials design metric. A treatment of the scattering parameter (Γ) for a multiatomic lattice is recommended and compared to other treatments presented in literature, which have been at times misused to yield incomplete conclusions about the system's scattering mechanisms. Additionally, we demonstrate a reduced sensitivity of the model to the full phonon dispersion and discuss its origin. Finally, a simplified treatment of scattering in alloy systems with vacancies and interstitial defects is demonstrated to suitably describe the potent scattering strength of these off-stoichiometric defects.26. Carrete, J. et al. almaBTE: A solver of the space-time dependent Boltzmann transport equation for phonons in structured materials.

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Section: Dispersion Relation Sensitivitymentioning

confidence: 97%

Analytical Models of Phonon–Point-Defect Scattering

et al. 2020

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“…[101] In stark contrast, there are also compounds with high shear and Young's moduli, such as (GeTe) 17 Sb 2 Te 3 , which were reported for lattice "hardening" effects. [102] Mössbauer spectroscopy, which can enlighten more on the correlation between elastic moduli, the speed of sound, and the Debye temperature, [103] makes a strong case for potential future work. [56] κ latt = Aν s T -1 .…”

Section: Analogies From Elastic Properties-shear and Young's Moduli Versus Phonon Anharmonicitymentioning

confidence: 99%

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

Muchtar

Srinivasan

Tonquesse

et al. 2021

Advanced Energy Materials

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Most of the best known SnTe‐based materials exhibit an attractive thermoelectric figure of merit (zT) only at the high‐temperature regime, but their performance at the low‐mid temperature ranges is quite uninspiring, and this discordance necessitates a large temperature gradient (∆T ≥ 550 K) to effectuate a reasonable efficiency, η. Here, the transition elements, Ti and Zr, that have not been used in the past are tried as dopants for SnTe and an enhanced device/average zT and/or η are reported with a lower ∆T ≈ 400 K and without the requisite for a stupendous peak/maximum zT. This notable performance emanates from—i) improved weighted mobility by optimally balancing between effective mass, carrier concentration, and mobility, ii) coupling of charge carriers with magnetic entropy, and the paramount factor being the iii) weakening of the chemical bonds (lattice softening). The thermal damping caused by lattice softening affects the phonon group velocity and the elastic properties, and the resultant increase in the degree of anharmonicity and the high density of internal strain‐fields, along with the phonon scattering effects, play an active role in tuning the overall thermoelectric performance. This work also excavates/opens up the discussion of applying the Heikes’ equation to qualitatively compare the trend of charge carriers for a given thermoelectric material system.

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“…This variation in turn is within the same range as the precision of the measurement presented. Mechanical properties are heavily influenced by the nature of the bonding between atoms and hence the composition, in this case the Si:Sn ratio, is known to have an effect on the Young's modulus [24,53].…”

Section: Discussionmentioning

confidence: 99%

Impact of the Dopant Species on the Thermomechanical Material Properties of Thermoelectric Mg2Si0.3Sn0.7

2022

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Thermoelectric generators are an excellent option for waste heat reuse. Materials for such devices have seen their thermoelectric properties improving constantly. The functioning of a generator, however, does not only depend on thermoelectric properties. Thermal and mechanical properties play a decisive role in the feasibility of any thermoelectric generator. To shed light on the properties exhibited by thermoelectric materials, we present the temperature dependent characterization of Young’s modulus and coefficient of thermal expansion for Mg2Si0.3Sn0.7. Comparing undoped to Bi-doped n-type and Li-doped p-type material, we investigated the influence of doping in the relevant temperature regime and found the influences to be minor, proving similar properties for n- and p-type. We found a Young’s modulus of 84 GPa for the p-type and 83 GPa for the n-type, similar to that of the undoped compound with 85 GPa. The thermal expansion coefficients of undoped, as well as n- and p-type were equally similar with values ranging from 16.5 to 17.5 × 10−6 1/K. A phase analysis was performed to further compare the two materials, finding a similar phase distribution and microstructure. Finally, using the gathered data, estimations on the possible thermally induced stresses under a temperature difference are provided to evaluate the relevance of knowing temperature dependent thermal and mechanical properties.

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Lattice dynamics and elasticity in thermoelectric Mg2Si1−xSnx

Cited by 10 publications

References 48 publications

Analytical Models of Phonon–Point-Defect Scattering

Analytical Models of Phonon–Point-Defect Scattering

Physical Insights on the Lattice Softening Driven Mid‐Temperature Range Thermoelectrics of Ti/Zr‐Inserted SnTe—An Outlook Beyond the Horizons of Conventional Phonon Scattering and Excavation of Heikes’ Equation for Estimating Carrier Properties

Impact of the Dopant Species on the Thermomechanical Material Properties of Thermoelectric Mg2Si0.3Sn0.7

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