Phonon scattering by nanoscale twin boundaries

Mao, Jun; Wang, Yumei; Liu, Zihang; Ge, Binghui; Ren, Zhifeng

doi:10.1016/j.nanoen.2016.12.026

Cited by 83 publications

(55 citation statements)

References 57 publications

(63 reference statements)

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“…Similar strategy has been applied to other high-performance TE materials such as CoSb 3 [19], Mg 2 Si [20], and PbTe [21]. In addition, it was observed that the phonon scatting induced by TBs can further decrease the lattice thermal conductivity [22]. Despite the important roles of TBs in material properties, their effects on the mechanical properties remain unknown.…”

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confidence: 94%

Enhanced Strength Through Nanotwinning in the Thermoelectric Semiconductor InSb

Morozov

Zhang

et al. 2017

Phys. Rev. Lett.

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The conversion efficiency (zT) of thermoelectric (TE) materials has been enhanced over the last two decades, but their engineering applications are hindered by the poor mechanical properties, especially the low strength at working conditions. Here we used density functional theory (DFT) to show a strength enhancement in the TE semiconductor InSb arising from the twin boundaries (TBs). This strengthening effect leads to an 11% enhancement of the ideal shear strength in flawless crystalline InSb where this theoretical strength is considered as an upper bound on the attainable strength for a realistic material. DFT calculations reveal that the directional covalent bond rearrangements at the TB accommodating the structural mismatch lead to the anisotropic resistance against the deformation combined with the enhanced TB rigidity. This produces a strong stress response in the nanotwinned InSb. This work provides a fundamental insight for understanding the deformation mechanism of nanotwinned TE semiconductors, which is beneficial for developing reliable TE devices.

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confidence: 94%

Enhanced Strength Through Nanotwinning in the Thermoelectric Semiconductor InSb

Morozov

Zhang

et al. 2017

Phys. Rev. Lett.

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“…Therefore, two basic approaches have been used to enhance the ZT via decreasing the relatively independent lattice thermal conductivity or increasing the power factor (i.e., S 2 σ). Phonon scattering via defect engineering [point defects (8)(9)(10)(11), dislocations (12)(13)(14)(15), and grain boundaries (16,17)] or nanostructuring (18) has led to a significant reduction in lattice thermal conductivity. On the other hand, power factors have also been enhanced via different approaches such as band engineering (19)(20)(21)(22), inducing resonant levels (23), the carrier filtering effect (24)(25)(26)(27), ionized impurity scattering (28), and modulation doping (29,30).…”

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confidence: 99%

Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg ₃ Sb ₂ -based materials

Mao

Shuai

Song

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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Achieving higher carrier mobility plays a pivotal role for obtaining potentially high thermoelectric performance. In principle, the carrier mobility is governed by the band structure as well as by the carrier scattering mechanism. Here, we demonstrate that by manipulating the carrier scattering mechanism in n-type MgSb-based materials, a substantial improvement in carrier mobility, and hence the power factor, can be achieved. In this work, Fe, Co, Hf, and Ta are doped on the Mg site of MgSbBiTe, where the ionized impurity scattering crosses over to mixed ionized impurity and acoustic phonon scattering. A significant improvement in Hall mobility from ∼16 to ∼81 cm⋅V⋅s is obtained, thus leading to a notably enhanced power factor of ∼13 μW⋅cm⋅K from ∼5 μW⋅cm⋅K A simultaneous reduction in thermal conductivity is also achieved. Collectively, a figure of merit () of ∼1.7 is obtained at 773 K in MgCoSbBiTe The concept of manipulating the carrier scattering mechanism to improve the mobility should also be applicable to other material systems.

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“…Twin boundaries (TBs), a thermodynamically stable planar defect, could provide another phonon scattering source to effectively suppress κ L [36][37][38] [38]. These findings suggest that TBs play significant roles in phonon scattering and κ L reduction without degrading electronic transport properties.…”

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confidence: 99%

Dramatically reduced lattice thermal conductivity of Mg2Si thermoelectric material from nanotwinning

et al. 2019

Acta Materialia

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Dramatically reduced lattice thermal conductivity of Mg 2 Si thermoelectric material from nanotwinning, Acta Materialia, https://doi. Abstract:Tuning phonon transport to reduce the lattice thermal conductivity (κ L ) is crucial for advancing thermoelectrics (TEs). Traditional strategies on κ L reduction focus on introducing scattering sources such as point defects, dislocations, and grain boundaries, that may degrade the electrical conductivity and Seebeck coefficient. We suggest here, a novel twin boundary (TB) strategy that can decrease the κ L of Mg 2 Si by ~90%, but which may not degrade the electrical properties significantly. We validate this suggestion using density functional theory (DFT). We attribute the mechanism of TB induced κ L reduction to (i) the lower phonon velocities and larger Grüneisen parameter, (ii) "rattling" of the Mg−Mg pair induced soft acoustic and optical modes, (iii) shorter phonon lifetime and higher phonon scattering rate. We predict that the size of nanotwinned structure should be controlled between 3 nm and 100 nm in the Mg 2 Si matrix for the most effective κ L reduction. These results should be applicable for other TE or non TE energy materials with desired low thermal conductivity, suggesting rational designs of high-performance Mg 2 Si TE materials with low κ L for the energy conversion applications. Functional Theory 0.4 W m −1 K −1 and a zT of 1.5 at 1000 K [21]. In SnSe single crystals, The lattice anharmonicity leads to an exceptionally low κ L of 0.23 ± 0.03 W m −1 K −1 and an unprecedented zT of 2.6 ± 0.03 at 923 K [22,23]. In such TE materials as MgAgSb [24], Ag 5-δ Te 3 [25], and Ag 8 SnSe 6 [26], the complex crystal structure or weak chemical bonds leads to low heat capacity or low speed of sound, well explaining the low intrinsic κ L of < 0.5 W m −1 K [24-26]. Introducing phonon scattering sources such as point defects [27-29], dislocations [30-32], grain boundaries [33-35], can effectively shorten phonon relaxation time, giving rise to reduction in κ L . Multiple fillers inCoSb 3 can achieve broad-frequency phonon scattering, reducing κ L to the glass limit value of 0.2 W m −1 K −1 , and leading to an extremely high zT of 1.7 at 850 K [29]. Full-spectrum phonon scattering, which was achieved through grain boundary, dense dislocation arrays, and point defect,

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Phonon scattering by nanoscale twin boundaries

Cited by 83 publications

References 57 publications

Enhanced Strength Through Nanotwinning in the Thermoelectric Semiconductor InSb

Enhanced Strength Through Nanotwinning in the Thermoelectric Semiconductor InSb

Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg ₃ Sb ₂ -based materials

Dramatically reduced lattice thermal conductivity of Mg2Si thermoelectric material from nanotwinning

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Phonon scattering by nanoscale twin boundaries

Cited by 83 publications

References 57 publications

Enhanced Strength Through Nanotwinning in the Thermoelectric Semiconductor InSb

Enhanced Strength Through Nanotwinning in the Thermoelectric Semiconductor InSb

Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg 3 Sb 2 -based materials

Dramatically reduced lattice thermal conductivity of Mg2Si thermoelectric material from nanotwinning

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Manipulation of ionized impurity scattering for achieving high thermoelectric performance in n-type Mg ₃ Sb ₂ -based materials