Synthesis of YbyCo4Sb12∕Yb2O3 composites and their thermoelectric properties

Zhao, Xueying; Shi, Xun; Chen, Lidong; Zhang, W. Q.; Bai, Shengqiang; Pei, Yanzhong; Li, X. Y.; Goto, Takashi

doi:10.1063/1.2345249

Cited by 186 publications

(121 citation statements)

References 11 publications

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“…16 Even further reductions have been reported in multi-filled compounds where two or more elements are used as rattler atoms. 7,[17][18][19][20][21][22][23][24] The larger reductions in the thermal conductivity in the thermal conductivity of multi-compared to single-filled materials is attributed to the scattering of a broader range of host lattice phonon frequencies due to the rattlers of the different elements vibrating at different frequencies. In a recent contribution 25 on the study of rattling in the Al-doped β-pyrochlores, AAl0.33W1.67O6 (A = K, Rb, Cs), we reported the discovery of novel rattling of K atoms in KAl0.33W1.67O6 involving both vibrations at a broad range of frequencies as well as local diffusion.…”

Section: Introductionmentioning

confidence: 99%

Novel K rattling: A new route to thermoelectric materials?

Shoko

Kearley

Peterson

et al. 2014

Journal of Applied Physics

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We have performed ab initio molecular dynamics (MD) simulations to study the alkali-metal dynamics in the Al-doped (KAl0.33W1.67O6 and RbAl0.33W1.67O6) and undoped (KW2O6 and RbW2O6) defect pyrochlore tungstates. The K atoms exhibit novel rattling dynamics in both the doped and undoped tungstates while the Rb atoms do not. The KAl0.33W1.67O6 experimental thermal conductivity curve shows an unusual depression between ~ 50 K and ~ 250 K, coinciding with two crossovers in the K dynamics: the first at ~ 50 K, from oscillatory to diffusive, and the second at ~ 250 K, from diffusive back to oscillatory. We found that the low-temperature crossover is a result of the system transitioning below the activation energy of the diffusive dynamics whereas the high-temperature crossover is driven by a complex reconstruction of the local potential around the K atoms due to the cage dynamics.This leads to a hardening of the K potential with increasing temperature. This unusual reconstruction of the potential may have important implications for the interpretation of finite-temperature dynamics based on zero-temperature potentials in similar materials. The key result is that the novel K rattling, involving local diffusion, leads to a significant reduction in the thermal conductivity. We suggest that this may open a new route in the phonon engineering of cage compounds for thermoelectric materials where the rattlers are specifically selected to reduce the lattice thermal conductivity by the mechanism of local diffusion. a)

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Section: Introductionmentioning

confidence: 99%

Novel K rattling: A new route to thermoelectric materials?

Shoko

Kearley

Peterson

et al. 2014

Journal of Applied Physics

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“…Most recently, Tang et al 22 studied the Yb-Co-Sb ternary phase diagram and argued that Yb FFL is a thermodynamic parameter that depends on the annealing temperature and nominal composition, which could possibly account for some of the FFL discrepancies. In addition, only a few studies have been devoted to the role of excess Yb (e.g., Yb 2 O 3 ) and its effects on the TE transport properties while exceeding the FFL, 23,24 particularly in light of the fact that such excess Yb may form the electrically insulating Yb 2 O 3 or other impurity phases such as metallic YbSb or YbSb 2 .…”

Section: Introductionmentioning

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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“…6,7 Recently, a series of compounds AgPb m SbTe m+2 (LAST-m) 8,9 were characterized as an interesting kind of nanocomposite in which Ag-Sb-rich nanosized regions are dispersed in a Pb-rich matrix, and the n-type compound with optimized composition was reported to have a very high ZT value of 2.1 at 800 K. 8 AgPb m SbTe m+2 compounds possess an NaCl-type lattice structure in which Ag, Pb, and Sb atoms sit at the Na sublattice, showing +1, +2, and +3 valence, respectively, while Te atoms sit at the Cl sublattice, showing À2 valence. These compounds can be obtained through isoelectronic substitution of Ag + and Sb 3+ pairs for Pb 2+ ions in the PbTe lattice.…”

Section: Introductionmentioning

confidence: 98%

Preparation and Thermoelectric Properties of Ag0.5In0.5−x Pb5Sn4Te10

Yan

Tang

Liu

et al. 2009

Journal of Elec Materi

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A series of compounds with composition Ag 0.5 In 0.5Àx Pb 5 Sn 4 Te 10 (x = 0.05 to 0.20) were prepared by slowly cooling the melts of the corresponding elements, and the effect of In content on the thermoelectric transport properties of these compounds has been investigated. Results indicate that the compoundsÕ electronic structure is sensitive to In content, and that the carrier concentration of these compounds at room temperature increases from 4.86 9 10 18 cm À3 to 3.85 9 10 21 cm À3 as x increases from 0.05 to 0.20. For these compounds, electrical conductivity decreases and Seebeck coefficient increases with increasing In content. Ag 0.05 In 0.03 Pb 0.5 Sn 0.4 Te 10 shows very low lattice thermal conductivity, and has a maximum dimensionless figure of merit ZT of 1.2 at 800 K.

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Synthesis of YbyCo4Sb12∕Yb2O3 composites and their thermoelectric properties

Cited by 186 publications

References 11 publications

Novel K rattling: A new route to thermoelectric materials?

Novel K rattling: A new route to thermoelectric materials?

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

Preparation and Thermoelectric Properties of Ag0.5In0.5−x Pb5Sn4Te10

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