Thermoelectric Properties of Ag-Tl-Te Ternary System

Kurosaki, Ken; Kosuga, Atsuko; Goto, Keita; Muta, Hiroaki; Yamanaka, Shinşuke

doi:10.1557/proc-0886-f09-07

Cited by 6 publications

(13 citation statements)

References 12 publications

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“…steadily increases with increasing temperature for the Sb series but not for the Bi series. Finally, the power factor of the cold-pressed and sintered Tl 9 SbTe 6 reported earlier 25 is significantly lower, with approximately 6.0 μW cm −1 K −2 at 500 K and culminating in 6.5 μW cm −1 K −2 at 591 K. The thermal conductivity, however, is larger across the board in the case of the Sb samples, for example, κ = 0.72 W m −1 K −1 for Tl 9 SbTe 6 versus 0.50 W m −1 K −1 for Tl 9 BiTe 6 (both at 325 K). This is a consequence of a larger electronic contribution (κ el = 0.24 vs 0.09 W m −1 K −1 ) stemming from the larger electrical conductivity as well as the larger lattice thermal conductivity (κ Ph = 0.48 vs 0.41 W m −1 K −1 ).…”

Section: Chemistry Of Materialsmentioning

confidence: 53%

“…Table 4 summarizes the key data of the best Bi and Sb samples introduced here along with the literature data on Kurosaki's hot-pressed 23 and Wolfing's zone-refined Tl 9 BiTe 6 24 as well as cold-pressed, sintered Tl 9 SbTe 6 . 25 A substantial improvement of the thermoelectric figure of merit, ZT, was achieved both in the Bi and Sb systems over the previous data on hot-pressed Tl 9 BiTe 6 and cold-pressed Tl 9 SbTe 6 , respectively. For example, at 500 K, we report ZT values of 1.1 for Tl 9 Bi 0.98 Te 6 (and 0.98 for Tl 9 BiTe 6 ) and 0.90 for Tl 8.98 Sb 1.02 Te 6 (and 0.84 for Tl 9 SbTe 6 ) compared to 0.78 for Tl 9 BiTe 6 23 and 0.34 for Tl 9 SbTe 6 .…”

Section: ■ Conclusionmentioning

confidence: 61%

“…24 Its lighter homologue, Tl 9 SbTe 6 , was investigated as well prior to this work and was reported to achieve ZT = 0.41 at 591 K after cold-pressing and sintering. 25 With this contribution, we demonstrate that Tl 9 SbTe 6 can yield ZT values around unity as well and that the thermoelectric properties of both Tl 9 SbTe 6…”

Section: ■ Introductionmentioning

confidence: 62%

“…For example, at 500 K, we report ZT values of 1.1 for Tl 9 Bi 0.98 Te 6 (and 0.98 for Tl 9 BiTe 6 ) and 0.90 for Tl 8.98 Sb 1.02 Te 6 (and 0.84 for Tl 9 SbTe 6 ) compared to 0.78 for Tl 9 BiTe 6 23 and 0.34 for Tl 9 SbTe 6 . 25 Wolfing's zone-refined Tl 9 BiTe 6 remains the best sample, having the lowest electrical conductivity and the highest Seebeck coefficient, with an extrapolated ZT = 1.2 at 500 K.…”

Section: ■ Conclusionmentioning

confidence: 90%

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Enhanced Thermoelectric Properties of Variants of Tl₉SbTe₆ and Tl₉BiTe₆

et al. 2013

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Tl9BiTe6, a substitution variant of Tl5Te3, is one of the leading midtemperature thermoelectrics and is postulated to exceed ZT = 1 above 450 K when prepared by zone-melting and reach ZT = 0.86 at 560 K after hot-pressing. We have prepared the isostructural series Tl9Sb1–x Te6, Tl9–x Sb1+x Te6, Tl9Bi1–x Te6, and Tl9–x Bi1+x Te6, with x ranging from 0 to 0.05, from the elements in the stoichiometric ratios and determined their thermoelectric properties after hot-pressing. In theory, these tellurides are narrow-gap semiconductors when x = 0, with all elements in common oxidation states, according to (Tl+)9(Sb/Bi)3+(Te2–)6. The as-prepared samples of this 9-1-6 stoichiometry, however, exhibit relatively high electrical conductivity, which decreases with increasing temperature, indicative of the presence of extrinsic charge carriers. The Seebeck coefficient is generally above +100 μV K–1. Decreasing the Sb and Bi content increases the hole carrier concentration and thus increases the electrical conductivity while decreasing the Seebeck coefficient. The best feature of these thermoelectrics is their low thermal conductivity, which is consistently well below 0.7 W m–1 K–1. In combination with reasonable electrical conductivity and a high Seebeck coefficient, high ZT values in excess of 1 can also be achieved via simple hot-pressing after experimental optimization of the carrier concentration via introducing deficiencies on the Bi site. Moreover, the variants with Sb instead of Bi exhibit similar thermoelectric performance, a result of the combination of a better electrical performance and higher thermal conductivity.

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Section: Chemistry Of Materialsmentioning

confidence: 53%

Section: ■ Conclusionmentioning

confidence: 61%

Section: ■ Introductionmentioning

confidence: 62%

Section: ■ Conclusionmentioning

confidence: 90%

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Enhanced Thermoelectric Properties of Variants of Tl₉SbTe₆ and Tl₉BiTe₆

et al. 2013

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“…We prepared and characterized various ternary thallium tellurides exist in Tl 2 Te-Ag 2 Te [5], Tl 2 Te-Cu 2 Te [6], Tl 2 Te-Sb 2 Te 3 [7,8], Tl 2 Te-Bi 2 Te 3 [8,9], Tl 2 Te-In 2 Te 3, and Tl 2 Te-GeTe [10] pseudo-binary systems. The first group is thallium telluride and metal telluride (Tl 2 Te-MTe x ) pseudo-binary system.…”

Section: Results and Discussion Thermoelectric Characterization Of Tementioning

confidence: 99%

Thallium-Free Thermoelectric Materials with Extremely Low Thermal Conductivity

et al. 2007

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With the goal of developing high-performance bulk thermoelectric materials, we have characterized ternary silver thallium tellurides. The ternary silver thallium tellurides exhibit extremely low thermal conductivity (<0.5 Wm -1 K -1 ) and consequently their thermoelectric performance is excellent. Although the extremely low thermal conductivity materials, as typified by the ternary silver thallium tellurides, would be a new class of next-generation thermoelectric materials, thallium compounds are unsuitable for practical application because of their toxicity. Against such a background, we are currently exploring thallium-free thermoelectric materials with extremely low thermal conductivity. In this paper, we will briefly summarize the thermoelectric properties of ternary thallium tellurides obtained in our group. Further experiments aimed at improving the ZT of these materials will be presented. Finally, we will propose two candidates: Ag 8 GeTe 6 and Ga 2 Te 3 as thallium-free low thermal conductivity materials.

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From semi-metal to superconductor: The New Mo12 Cluster Sulfides Rb1+xMo12S14 (x = 0.08, and 1.65)

Gougeon

Gall

2021

Journal of Alloys and Compounds

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The novel Mo 12 cluster sulfides Rb 2.65 Mo 12 S 14 have been synthesized by direct solidstate reaction at a temperature of about 1500°C in a welded Mo tubing. The crystal structure of Rb 2.65 Mo 12 S 14 (space group P-31c: a = 9.2828(6) Å, c = 16.446(5) Å) was solved from Xray single-crystal data. It is isomorphous with the K 1+x Mo 12 S 14 compounds in which x ranges from 0 to 1.6. Consequently, the Mo-S network presents interconnected Mo 12 S 14 cluster units delimiting large tunnels that are randomly occupied by a part of the Rb + ions, the other ones being localized in large voids between two consecutive Mo 12 S 14 units along the [001] direction. By topochemical redox reactions at around 90°C, we could remove a part of the Rb + ions from the channels and thus, form the oxidized phase Rb 1.08 Mo 12 S 14 . Electrical resistivity measurements performed on single crystals of Rb 2.65 Mo 12 S 14 and Rb 1.08 Mo 12 S 14shows that the oxidized form is a semimetal while the reduced form is a metal and becomes superconducting below 4.07 K. The evolution of Mo-Mo bond lengths within the trioctahedral Mo 12 cluster with respect to the cationic charge x is discussed and, compared with that found in the potassium series.

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Thermoelectric Properties of Ag-Tl-Te Ternary System

Cited by 6 publications

References 12 publications

Enhanced Thermoelectric Properties of Variants of Tl₉SbTe₆ and Tl₉BiTe₆

Enhanced Thermoelectric Properties of Variants of Tl₉SbTe₆ and Tl₉BiTe₆

Thallium-Free Thermoelectric Materials with Extremely Low Thermal Conductivity

From semi-metal to superconductor: The New Mo12 Cluster Sulfides Rb1+xMo12S14 (x = 0.08, and 1.65)

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Thermoelectric Properties of Ag-Tl-Te Ternary System

Cited by 6 publications

References 12 publications

Enhanced Thermoelectric Properties of Variants of Tl9SbTe6 and Tl9BiTe6

Enhanced Thermoelectric Properties of Variants of Tl9SbTe6 and Tl9BiTe6

Thallium-Free Thermoelectric Materials with Extremely Low Thermal Conductivity

From semi-metal to superconductor: The New Mo12 Cluster Sulfides Rb1+xMo12S14 (x = 0.08, and 1.65)

Contact Info

Product

Resources

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Enhanced Thermoelectric Properties of Variants of Tl₉SbTe₆ and Tl₉BiTe₆

Enhanced Thermoelectric Properties of Variants of Tl₉SbTe₆ and Tl₉BiTe₆

From semi-metal to superconductor: The New Mo12 Cluster Sulfides Rb1+xMo12S14 (x = 0.08, and 1.65)