Low thermal conductivity and high thermoelectric figure of merit in n-type BaxYbyCo4Sb12 double-filled skutterudites

Shi, Xun; Kong, Huijun; Li, C.-P.; Uher, Ctirad; Yang, Junjiao; Salvador, James R.; Wang, H.; Chen, Lidong; Zhang, W.

doi:10.1063/1.2920210

Cited by 377 publications

(258 citation statements)

References 22 publications

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“…As mentioned above, Yb is an indispensable filler for high-performance n-type skutterudites, as indicated for previously reported double-or triple-filled samples. 5,52 Yb-filled CoSb 3 actually possesses comparable κ L values to those of double-or triple-filled CoSb 3 considering the experimental error and different C p used for κ calculations, as shown in Supplementary Figure S4. The intrinsically low κ L of Yb-filled CoSb 3 can be well understood from the specific features of its phonon dispersion, as shown in Figure 6d.…”

Section: Te Transport Propertiesmentioning

confidence: 99%

High-performance n-type YbxCo4Sb12: from partially filled skutterudites towards composite thermoelectrics

et al. 2016

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The filling fraction limit (FFL) of skutterudites, that is, the complex balance of formation enthalpies among different species, is an intricate but crucial parameter for achieving high thermoelectric performance. In this work, we synthesized a series of Yb x Co 4 Sb 12 samples with x = 0.2-0.6 and systemically studied the FFL of Yb, which is still debated even though this system has been extensively investigated for decades. Our combined experimental efforts of X-ray diffraction, microstructural and quantitative compositional analyses clearly reveal a Yb FFL of~0.29 in CoSb 3 , which is consistent with previous theoretical calculations. The excess Yb in samples with x40.35 mainly form metallic YbSb 2 precipitates, significantly raising the Fermi level and thus increasing the electrical conductivity and decreasing the Seebeck coefficient. This result is further corroborated by the numerical calculations based on the Bergman's composite theory, which accurately reproduces the transport properties of the x40.35 samples based on nominal Yb 0.35 Co 4 Sb 12 and YbSb 2 composites. A maximum ZT of 1.5 at 850 K is achieved for Yb 0.3 Co 4 Sb 12 , which is the highest value for a single-element-filled CoSb 3 . The high ZT originates from the high-power factor (in excess of 50 μW cm-K − 2 ) and low lattice thermal conductivity (well below 1.0 W m-K − 1 ). More importantly, the large average ZTs, for example,~1.05 for 300-850 K and~1.27 for 500-850 K, are comparable to the best values for n-type skutterudites. The high thermoelectric and thermomechanical performances and the relatively low air and moisture sensitivities of Yb make Yb-filled CoSb 3 , a promising candidate for large-scale power generation applications.

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Section: Te Transport Propertiesmentioning

confidence: 99%

High-performance n-type YbxCo4Sb12: from partially filled skutterudites towards composite thermoelectrics

et al. 2016

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“…To achieve high ZT values in TE materials, a synergistic optimisation on both transport aspects is required. Armed with a deep understanding of transport phenomena, spectacular enhancements in the figure of merit ZT have been achieved in recent years across many families of TE materials, 22,31,38,54,69,104,109,124,132,150, as shown in Figure 10. Many traditional TE materials have doubled their ZT and new promising material systems have been identified and optimised.…”

Section: Synergistic Optimisation For High Ztsmentioning

confidence: 99%

“…Experimentally, the so-designed multiple-filled skutterudites do possess reduced κ L and enhanced ZT values, as shown in refs. 68,69,132,133. Resonant frequencies of fillers in p-type skutterudites were also calculated by Liu et al 134 and used to design high-performance p-type skutterudites.…”

Section: From the Conventional Phonon-phonon Interactions To Nanostrumentioning

confidence: 99%

“…In 2005, Shi et al concluded that the filling fraction limit in CoSb 3 -based skutterudites is determined by the competition between the Figure 10. The chronological evolution of ZT values in various thermoelectric materials, 22,31,38,54,69,104,109,124,132,150, and the three detailed examples (PbSe matrix with band aligned nanocomposites, 31 n-type filled skutterudites, 69 and superionic compound Cu 2 Se 150 ).…”

Section: Synergistic Optimisation For High Ztsmentioning

confidence: 99%

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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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“…Moreover, recently, filling two or more types of fillers into the voids in skutterudite have been shown to be able to further reduce lattice thermal conductivity and improve ZT to 1.4 in double-filled and 1.7 in multiple-filled n-type skutterudites. [17][18][19][20] Although there are a series of recent study reported with very high ZTs in n-type partially filled skutterudites, only a few literatures focusing on high temperature thermoelectric properties in p-type skutterudites have been published in the past decade. Furthermore, the ZT values in p-type filled skutterudites are confirmed in experiment around 1.0, much lower than n-type materials.…”

Section: Introductionmentioning

confidence: 99%

High-temperature electrical and thermal transport properties of fully filled skutterudites RFe4Sb12 (R = Ca, Sr, Ba, La, Ce, Pr, Nd, Eu, and Yb)

Qiu

Yang

Liu

et al. 2011

Journal of Applied Physics

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162

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Fully filled skutterudites RFe 4 Sb 12 (R ¼ Ca, Sr, Ba, La, Ce, Pr, Nd, Eu, and Yb) have been prepared and the high-temperature electrical and thermal transport properties are investigated systematically. Lattice constants of RFe 4 Sb 12 increase almost linearly with increasing the ionic radii of the fillers, while the lattice expansion in filled structure is weakly influenced by the filler valence charge states. Using simple charge counting, the hole concentration in RFe 4 Sb 12 with divalent fillers (R ¼ Ca, Sr, Ba, Eu, and Yb) is much higher than that in RFe 4 Sb 12 with trivalent fillers (R ¼ La, Ce, Pr, and Nd), resulting in relatively high electrical conductivity and low Seebeck coefficient. It is also found that RFe 4 Sb 12 filled skutterudites having similar filler valence charge states exhibit comparable electrical conductivity and Seebeck coefficient, and the behavior of the temperature dependence, thereby leading to comparable power factor values in the temperature range from 300 to 800 K. All RFe 4 Sb 12 samples possess low lattice thermal conductivity. The correlation between the lattice thermal resistivity W L and ionic radii of the fillers is discussed and a good relationship of W L $ (r cage Àr ion ) 3 is observed in lanthanide metal filled skutterudites. CeFe 4 Sb 12 , PrFe 4 Sb 12, and NdFe 4 Sb 12 show the highest thermoelectric figure of merit around 0.87 at 750 K among all the filled skutterudites studied in this work.

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Low thermal conductivity and high thermoelectric figure of merit in n-type BaxYbyCo4Sb12 double-filled skutterudites

Cited by 377 publications

References 22 publications

High-performance n-type YbxCo4Sb12: from partially filled skutterudites towards composite thermoelectrics

High-performance n-type YbxCo4Sb12: from partially filled skutterudites towards composite thermoelectrics

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

High-temperature electrical and thermal transport properties of fully filled skutterudites RFe4Sb12 (R = Ca, Sr, Ba, La, Ce, Pr, Nd, Eu, and Yb)

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