Preparation and thermoelectric properties of sintered type-II clathrates (K,Ba)24(Al,Sn)136

Utsunomiya, Satoshi; Kishimoto, Kenji; Koda, Shota; Akai, Koji; Fujita, Ryo; Asada, Hironori; Koyanagi, T.

doi:10.1016/j.jallcom.2016.09.231

Cited by 9 publications

(17 citation statements)

References 17 publications

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“…Extending this line of thinking into the corresponding A-Ba-Al-Sn (A = Na, K, Rb, and Cs) system, however, proved challenging. Despite repeated attempts, type-II clathrates between these elements remained elusive for us, although Utsunomiya et al (2017) Computer programs: SMART (Bruker, 2014), SAINT (Bruker, 2014), SHELXS97 (Sheldrick, 2008), SHELXL2018 (Sheldrick, 2015), DIAMOND (Brandenburg, 2014) and publCIF (Westrip, 2010).…”

Section: Resultsmentioning

confidence: 99%

Synthesis and structural characterization of the type-I clathrates K₈Al_xSn_46–xand Rb₈Al_xSn_46–x(x≃ 6.4–9.7)

2019

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Exploratory studies in the systems A–Al–Sn (A = K and Rb) yielded the clathrates K8Al x Sn46–x (potassium aluminium stannide) and Rb8Al x Sn46–x (rubidium aluminium stannide), both with the cubic type-I structure (space group Pm\overline{3}n, No. 223; a ≃ 12.0 Å). The Al:Sn ratio is close to the idealized A 8Al8Sn38 composition and it is shown that it can be varied slightly, in the range of ca ±1.5, depending on the experimental conditions. Both the (Sn,Al)20 and the (Sn,Al)24 cages in the structure are fully occupied by the guest alkali metal atoms, i.e. K or Rb. The A 8Al8Sn38 formula has a valence electron count that obeys the valence rules and represents an intrinsic semiconductor, while the experimentally determined compositions A 8Al8±x Sn38∓x suggest the synthesized materials to be nearly charge-balanced Zintl phases, i.e. they are likely to behave as heavily doped p- or n-type semiconductors.

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Section: Resultsmentioning

confidence: 99%

Synthesis and structural characterization of the type-I clathrates K₈Al_xSn_46–xand Rb₈Al_xSn_46–x(x≃ 6.4–9.7)

2019

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“…Figure 6 shows the temperature dependences of the thermoelectric properties S, σ, S 2 σ, κ, and ZT for the Cs 8 Ba 16 Ga 40 Sn 96 samples and the related clathrate samples. 16,17) A maximum ZT value of Cs 8 Ba 16 Ga 40 Sn 96 was 0.87 at 740 K, which is smaller than that, 1.19, of (K, Ba) 24 (Ga, Sn) 136 . Both clathrates had comparable high-temperature power factors S 2 σ [Fig.…”

Section: Thermoelectric Propertiesmentioning

confidence: 82%

“…15,16) (Al, Sn) 136 are also listed for comparison. 16,17) The Cs 8 Ba 16 Ga 40 Sn 96 samples exhibited almost the type-II clathrate structure. For example, the XRD pattern of the sample ACS31 is plotted in Fig.…”

Section: Sample Preparation and Crystal Structurementioning

confidence: 99%

“…Type-II clathrates ( Fd m 3 ) were not a thermoelectric material for over a decade 8,13) before Mano et al recently synthesized semiconducting (K, Ba) 24 (Ga, Sn) 136 . 14) Subsequently, the ZT values of 1.19 and 0.82 were obtained for (K, Ba) 24 (Ga, Sn) 136 15,16) and (K, Ba) 24 (Al, Sn) 136 , 17) respectively. Sn-based type-II clathrates were found to be a good thermoelectric material, but they have not been studied much.…”

Section: Introductionmentioning

confidence: 94%

“…5(d)] damage the band as discussed in a previous paper. 17) The band energy at the Γ point depends on which of Cs or K atoms are in the guest sites. The K atoms lower its band edge energy.…”

Section: Sample Preparation and Crystal Structurementioning

confidence: 99%

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Thermoelectric and transport properties of sintered type-II clathrate Cs₈Ba₁₆Ga₄₀Sn₉₆

Kishimoto

Akai

2019

Jpn. J. Appl. Phys.

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Cs 8 Ba 16 Ga 40 Sn 96 was expected to have good thermoelectric properties; we prepared almost single-phase sintered samples of the clathrate. They exhibited a maximum dimensionless figure-of-merit, 0.87, room-temperature (RT) mobility, ∼50 cm 2 V −1 s −1 , and RT lattice thermal conductivity, 12 mW cm −1 K −1 . However, these values were inferior to those, 1.19, 170 cm 2 V −1 s −1 , and 5 mW cm −1 K −1 , of (K, Ba) 24 (Ga, Sn) 136 , respectively. Band structure calculation suggests that Cs 8 Ba 16 (Ga, Sn) 136 would have high carrier mobility like (K, Ba) 24 (Ga, Sn) 136 . However, the former sintered samples strongly suffered from potential barrier scattering and impurity band conduction; the impurity band conduction may be associated with localized states due to Sn vacancies. Also, the clathrate had relatively large atomic displacement parameters (ADP) of ∼0.1 Å 2 , but the rattling effect to suppress thermal conduction was not so strong because the ADP were in "on center" mode.

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Inorganic thermoelectric materials: A review

et al. 2020

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Summary Thermoelectric generator, which converts heat into electrical energy, has great potential to power portable devices. Nevertheless, the efficiency of a thermoelectric generator suffers due to inefficient thermoelectric material performance. In the last two decades, the performance of inorganic thermoelectric materials has been significantly advanced through rigorous efforts and novel techniques. In this review, major issues and recent advancements that are associated with the efficiency of inorganic thermoelectric materials are encapsulated. In addition, miscellaneous optimization strategies, such as band engineering, energy filtering, modulation doping, and low dimensional materials to improve the performance of inorganic thermoelectric materials are reported. The methodological reviews and analyses showed that all these techniques have significantly enhanced the Seebeck coefficient, electrical conductivity, and reduced the thermal conductivity, consequently, improved ZT value to 2.42, 2.6, and 1.85 for near‐room, medium, and high temperature inorganic thermoelectric material, respectively. Moreover, this review also focuses on the performance of silicon nanowires and their common fabrication techniques, which have the potential for thermoelectric power generation. Finally, the key outcomes along with future directions from this review are discussed at the end of this article.

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Preparation and thermoelectric properties of sintered type-II clathrates (K,Ba)24(Al,Sn)136

Cited by 9 publications

References 17 publications

Synthesis and structural characterization of the type-I clathrates K₈Al_xSn_46–xand Rb₈Al_xSn_46–x(x≃ 6.4–9.7)

Synthesis and structural characterization of the type-I clathrates K₈Al_xSn_46–xand Rb₈Al_xSn_46–x(x≃ 6.4–9.7)

Thermoelectric and transport properties of sintered type-II clathrate Cs₈Ba₁₆Ga₄₀Sn₉₆

Inorganic thermoelectric materials: A review

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Preparation and thermoelectric properties of sintered type-II clathrates (K,Ba)24(Al,Sn)136

Cited by 9 publications

References 17 publications

Synthesis and structural characterization of the type-I clathrates K8AlxSn46–xand Rb8AlxSn46–x(x≃ 6.4–9.7)

Synthesis and structural characterization of the type-I clathrates K8AlxSn46–xand Rb8AlxSn46–x(x≃ 6.4–9.7)

Thermoelectric and transport properties of sintered type-II clathrate Cs8Ba16Ga40Sn96

Inorganic thermoelectric materials: A review

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Synthesis and structural characterization of the type-I clathrates K₈Al_xSn_46–xand Rb₈Al_xSn_46–x(x≃ 6.4–9.7)

Synthesis and structural characterization of the type-I clathrates K₈Al_xSn_46–xand Rb₈Al_xSn_46–x(x≃ 6.4–9.7)

Thermoelectric and transport properties of sintered type-II clathrate Cs₈Ba₁₆Ga₄₀Sn₉₆