Phonon engineering through crystal chemistry

Toberer, Eric S.; Zevalkink, Alex; Snyder, G. Jeffrey

doi:10.1039/c1jm11754h

Cited by 806 publications

(695 citation statements)

References 81 publications

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“…Because the unit cell size and average speed of sound of Sr 5 Al 2 Sb 6 (52 atoms, 2610 m s −1 ) are comparable to that of Sr 3 AlSb 3 (56 atoms, 2590 m s −1 ), κ L should be very similar in these two materials, despite their different structure types. 4 Indeed, at high temperature, κ L is nearly identical in Sr 5 Al 2 Sb 6 and Sr 3 AlSb 3 , reaching values of 0.54 W mK −1 and 0.60 W mK −1 , respectively. However, at 300 K, κ L of Sr 5 Al 2 Sb 6 is significantly lower than Sr 3 AlSb 3 , suggesting that an additional scattering mechanism such as boundary or point defect scattering is also present.…”

Section: Thermal Transportmentioning

confidence: 89%

“…4 In Sr 5 Al 2 Sb 6 , a single unit cell contains 52 atoms, meaning that much of the heat capacity is trapped in flat, low velocity optical modes, thus suppressing κ L . The thermal conductivity of Sr 5 Al 2 Sb 6 , shown in Fig.…”

Section: Thermal Transportmentioning

confidence: 99%

“…A repeat distance of four tetrahedra leads to a larger unit cell (4 formula units, or 52 atoms, per cell) than found in the other two A 5 M 2 Sb 6 structure types. In the original report of the Sr 5 Al 2 Sb 6 structure type, 21 Cordier et al argue that this unique structure results from a combination of the relatively large cation (Sr) and small triel element (Al) 4 ].…”

Section: Introductionmentioning

confidence: 99%

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Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr₃AlSb₃

et al. 2013

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The Zintl phase Sr 5 Al 2 Sb 6 has a large, complex unit cell and is composed of relatively earth-abundant and non-toxic elements, making it an attractive candidate for thermoelectric applications. The structure of Sr 5 Al 2 Sb 6 is characterized by infinite oscillating chains of AlSb 4 tetrahedra. It is distinct from the structure type of the previously studied Ca 5 M 2 Sb 6 compounds (M = Al, Ga or In), all of which have been shown to have promising thermoelectric performance. The lattice thermal conductivity of Sr 5 Al 2 Sb 6 (∼0.55 W mK −1 at 1000 K) was found to be lower than that of the related Ca 5 M 2 Sb 6 compounds due to its larger unit cell (54 atoms per primitive cell). Density functional theory predicts a relatively large band gap in Sr 5 Al 2 Sb 6 , in agreement with the experimentally determined band gap of E g ∼ 0.5 eV. High temperature electronic transport measurements reveal high resistivity and high Seebeck coefficients in Sr 5 Al 2 Sb 6 , consistent with the large band gap and valence-precise structure. Doping with Zn 2+ on the Al 3+ site was attempted, but did not lead to the expected increase in carrier concentration. The low lattice thermal conductivity and large band gap in Sr 5 Al 2 Sb 6 suggest that, if the carrier concentration can be increased, thermoelectric performance comparable to that of Ca 5 Al 2 Sb 6 could be achieved in this system.

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Section: Thermal Transportmentioning

confidence: 89%

Section: Thermal Transportmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr₃AlSb₃

et al. 2013

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“…1,88,89 Solid solutions are another time honored approach to enhance point defect scattering. [90][91][92][93][94][95] PPIs, as the intrinsic mechanism and basically the dominant one at high temperatures, have offered limited opportunities for regulation.…”

Section: From the Conventional Phonon-phonon Interactions To Nanostrumentioning

confidence: 99%

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

et al. 2016

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During the last two decades, we have witnessed great progress in research on thermoelectrics. There are two primary focuses. One is the fundamental understanding of electrical and thermal transport, enabled by the interplay of theory and experiment; the other is the substantial enhancement of the performance of various thermoelectric materials, through synergistic optimisation of those intercorrelated transport parameters. Here we review some of the successful strategies for tuning electrical and thermal transport. For electrical transport, we start from the classical but still very active strategy of tuning band degeneracy (or band convergence), then discuss the engineering of carrier scattering, and finally address the concept of conduction channels and conductive networks that emerge in complex thermoelectric materials. For thermal transport, we summarise the approaches for studying thermal transport based on phonon-phonon interactions valid for conventional solids, as well as some quantitative efforts for nanostructures. We also discuss the thermal transport in complex materials with chemical-bond hierarchy, in which a portion of the atoms (or subunits) are weakly bonded to the rest of the structure, leading to an intrinsic manifestation of part-crystalline part-liquid state at elevated temperatures. In this review, we provide a summary of achievements made in recent studies of thermoelectric transport properties, and demonstrate how they have led to improvements in thermoelectric performance by the integration of modern theory and experiment, and point out some challenges and possible directions. INTRODUCTION Thermoelectric (TE) materials are materials that can generate useful electric potentials when subjected to a temperature gradient (known as the Seebeck effect). Conversely, they also transfer heat against the temperature gradient when a current is driven against this potential (known as the Peltier effect). They are promising energy materials with many applications, such as waste heat harvesting, radioisotope TE power generation, and solid state Peltier refrigeration, all of which are driving growing research interest. A key challenge is to improve the TE properties in order to obtain more efficient energy conversion and in turn enable new practical applications. Good TE materials must have excellent electrical transport properties, measured by the TE power factor ( = S 2 σ, where S is the Seebeck coefficient and σ is the electrical conductivity), and also a very low thermal conductivity κ (composed of the electronic contribution κ e , the lattice contribution κ L , and the bipolar contribution κ bi ). Combining the two aspects gives us the dimensionless figure of merit ZT,

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“…value is distinctly lower than that of isostructural SrBiS2F (l  2.7 Wm −1 K −1 ), 17) which is attributed to the lower speed of sound resulting from the heavier atomic mass of the Eu ions than that of Sr ions. 18) Notably, the relative density of the sample in this study is 90%.…”

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confidence: 68%

Electrical and Thermal Transport of Layered Bismuth-Sulfide EuBiS₂F at Temperatures between 300 and 623 K

et al. 2015

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We demonstrate the electrical and thermal transport of the layered bismuth-based sulfide EuBiS2F from 300 to 623 K. Although significant hybridization between Eu 4f and Bi 6p electrons was reported previously, the carrier transport of the compound is similar to that of F-doped LaBiS2O, at least above 300 K. The lattice thermal conductivity is lower than that of isostructural SrBiS2F, which is attributed to the heavier atomic mass of Eu ions than that of Sr ions.Searching for novel thermoelectric materials is the most fundamental issue for the development of thermoelectrics because the maximum conversion efficiency of a thermoelectric device is primarily determined by the material's dimensionless figure of merit, ZT = S 2 T −1  −1 , where T, S, , and  denote the temperature, Seebeck coefficient, electrical resistivity, and thermal conductivity, respectively. 1) Bismuth telluride (Bi2Te3) and its related compounds have been the state-of-the-art thermoelectric materials at around room temperature since the 1950s with a ZT value as high as 1.4 in a nanocrystalline bulk specimen. 2) Compared with tellurides and selenides, little attention has been paid to the thermoelectric properties of bismuth-based sulfides because of their low ZT value. However, recent studies on sulfide systems have clearly shown that sulfides also exhibit attractive thermoelectric properties. 3) Aside from thermoelectricity, the superconductivity of layered bismuth sulfides, such as Bi4S3O4 4) and LaBiS2O1xFx 5) , has led to novel studies on superconductivity (the chemical formula is written according to standard nomenclature 6) ). The crystallographic structures of these compounds are basically composed of alternate stacks of BiS2 and oxide/fluoride layers, as shown in the inset of Fig. 1. The conduction band near the Fermi level is primarily composed of in-plane Bi 6p orbitals. The thermoelectric properties of LaBiS2O are suppressed by F substitution, 7) whereas they are improved by Se substitution. 8) Recently, EuBiS2F has been reported as a possible compound that exhibits charge-density-wave-like order below 280 K and superconductivity below 0.3 K without element substitution. 9) Specific heat measurement showed significant hybridization between Eu 4f and Bi 6p electrons, while density functional theory (DFT) calculation indicates that the valence band maximum consists of Eu 4f orbitals. 9) Given the results shown in the previous study, it was controversial from the viewpoint of thermoelectricity, whether Eu 4f and Bi 6p hybridized orbitals are effective in modulating the Fermi surface and enhancing S, 10) or reducing S owing to the coexistence of electrons and holes, i.e., mixed conduction. In this study, we demonstrate the electrical and thermal transport of EuBiS2F at temperatures between 300 and 623 K.Polycrystalline EuBiS2F was prepared by a solid-state reaction using a sealed silica tube, following the method reported by Zhai et al. 9) The relative density of the sample was calculated to be 90%. The sample purity was examined by ...

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Phonon engineering through crystal chemistry

Cited by 806 publications

References 81 publications

Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr₃AlSb₃

Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr₃AlSb₃

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

Electrical and Thermal Transport of Layered Bismuth-Sulfide EuBiS₂F at Temperatures between 300 and 623 K

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Phonon engineering through crystal chemistry

Cited by 806 publications

References 81 publications

Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr3AlSb3

Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr3AlSb3

On the tuning of electrical and thermal transport in thermoelectrics: an integrated theory–experiment perspective

Electrical and Thermal Transport of Layered Bismuth-Sulfide EuBiS2F at Temperatures between 300 and 623 K

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Product

Resources

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Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr₃AlSb₃

Thermoelectric Properties and Electronic Structure of the Zintl‐Phase Sr₃AlSb₃

Electrical and Thermal Transport of Layered Bismuth-Sulfide EuBiS₂F at Temperatures between 300 and 623 K