Substitution Versus Full-Heusler Segregation in TiCoSb

Half-Heuslers (HHs) are promising thermoelectric materials with great compositional flexibility. Here, we extend work on the p-type doping of TiCoSb using abundant elements. Ti0.7V0.3Co0.85Fe0.15Sb0.7Sn0.3 samples with nominal 17.85 p-type electron count were investigated. Samples prepared using powder metallurgy have negative Seebeck values, S ≤ −120 µV K−1, while arc-melted compositions are compensated semiconductors with S = −45 to +30 µV K−1. The difference in thermoelectric response is caused by variations in the degree of segregation of V(Co0.6Fe0.4)2Sn full-Heusler and Sn phases, which selectively absorb V, Fe, and Sn. The segregated microstructure leads to reduced lattice thermal conductivities, κlat = 4.5−7 W m−1 K−1 near room temperature. The largest power factor, S2/ρ = 0.4 mW m−1 K−2 and ZT = 0.06, is observed for the n-type samples at 800 K. This works extends knowledge regarding suitable p-type dopants for TiCoSb.

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Effect of Microwave Processing and Glass Inclusions on Thermoelectric Properties of P-Type Bismuth Antimony Telluride Alloys for Wearable Applications

Energies ◽

10.3390/en13174524 ◽

2020 ◽

Vol 13 (17) ◽

pp. 4524

Author(s):

Amin Nozariasbmarz ◽

Daryoosh Vashaee

Keyword(s):

Seebeck Coefficient ◽

Thermoelectric Materials ◽

Room Temperature ◽

Electronic Devices ◽

Microwave Processing ◽

Glass Inclusion ◽

Wearable Electronic ◽

P Type ◽

Wearable Electronic Devices ◽

Body Heat

Depending on the application of bismuth telluride thermoelectric materials in cooling, waste heat recovery, or wearable electronics, their material properties, and geometrical dimensions should be designed to optimize their performance. Recently, thermoelectric materials have gained a lot of interest in wearable electronic devices for body heat harvesting and cooling purposes. For efficient wearable electronic devices, thermoelectric materials with optimum properties, i.e., low thermal conductivity, high Seebeck coefficient, and high thermoelectric figure-of-merit (zT) at room temperature, are demanded. In this paper, we investigate the effect of glass inclusion, microwave processing, and annealing on the synthesis of high-performance p-type (BixSb1−x)2Te3 nanocomposites, optimized specially for body heat harvesting and body cooling applications. Our results show that glass inclusion could enhance the room temperature Seebeck coefficient by more than 10% while maintaining zT the same. Moreover, the combination of microwave radiation and post-annealing enables a 25% enhancement of zT at room temperature. A thermoelectric generator wristband, made of the developed materials, generates 300 μW power and 323 mV voltage when connected to the human body. Consequently, MW processing provides a new and effective way of synthesizing p-type (BixSb1−x)2Te3 alloys with optimum transport properties.

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Doping Studies of n-Type CsBi4Te6 Thermoelectric Materials

MRS Proceedings ◽

10.1557/proc-626-z7.5 ◽

2000 ◽

Vol 626 ◽

Author(s):

Melissa A. Lane ◽

John R. Ireland ◽

Paul W. Brazis ◽

Theodora Kyratsi ◽

Duck-Young Chung ◽

...

Keyword(s):

Power Factor ◽

Thermoelectric Materials ◽

Figure Of Merit ◽

Doping Concentration ◽

High Figure ◽

P Type ◽

Optimum Doping Concentration

ABSTRACTWe have previously reported the successful p-type doping of CsBi4Te6 which had a high figure of merit at temperatures below 300 K. In this study, several dopants were explored to make n-type CsBi4Te6. A program of measurements was performed to identify the optimum doping concentration for several series of dopants. The highest power factors occurred around 125 K for the 0.5% Sn doped CsBi4Te6 sample which had a power factor of 21.9 μW/cm•K2 and 1.0% Te doped CsBi4Te6 which had a power factor of 21.7 μW/cm•K2.

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New Conjugated Polymers Derived from Carbazole as Thermoelectric Materials

MRS Proceedings ◽

10.1557/proc-871-i9.41 ◽

2005 ◽

Vol 871 ◽

Cited By ~ 2

Author(s):

Isabelle Lévesque ◽

Xing Gao ◽

Christopher I. Ratcliffe ◽

Dennis D. Klug ◽

John S. Tse ◽

...

Keyword(s):

Band Structure ◽

Seebeck Coefficient ◽

Conjugated Polymers ◽

Power Factor ◽

Thermoelectric Materials ◽

Doping Level ◽

Room Temperature ◽

Polymer Structure ◽

Band Structure Calculations ◽

Structure Calculations

AbstractNovel poly(3,6-hexyl-2,7-N-octylcarbazole) derivatives and poly(diindolocarbazole)s were synthesized. Optical, electrochemical, electrical and thermoelectric properties were investigated. Band structure calculations were used to predict which polymers were promising as thermoelectric materials. The best combination of Seebeck coefficient and conductivity (power factor) was 9,4 x10-8 Wm-1K-2 with a copolymer of carbazole and thiophene. This corresponds to a ZT at room temperature of 0.0003. Optimization of the polymer structure and doping level should lead to an increased ZT.

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Electrical Properties and Figures of Merit for New Chalcogenide-Based Thermoelectric Materials

MRS Proceedings ◽

10.1557/proc-478-327 ◽

1997 ◽

Vol 478 ◽

Cited By ~ 4

Author(s):

Jon L. Schindler ◽

Tim P. Hogan ◽

Paul W. Brazis ◽

Carl R. Kannewurf ◽

Duck-Young Chung ◽

...

Keyword(s):

Thermoelectric Materials ◽

Figure Of Merit ◽

Room Temperature ◽

Thermoelectric Figure Of Merit ◽

Thermoelectric Figure ◽

Figures Of Merit ◽

Lattice Symmetry ◽

Thermoelectric Refrigeration ◽

Polychalcogenide Flux ◽

P Type

AbstractNew Bi-based chalcogenide compounds have been prepared using the polychalcogenide flux technique for crystal growth. These materials exhibit characteristics of good thermoelectric materials. Single crystals of the compound CsBi4Te6 have shown conductivity as high as 2440 S/cm with a p-type thermoelectric power of ≈ +110 μV/K at room temperature. A second compound, β-K2Bi8Se13 shows lower conductivity ≈ 240 S/cm, but a larger n-type thermopower ≈ −200 μV/K. Thermal transport measurements have been performed on hot-pressed pellets of these materials and the results show comparable or lower thermal conductivities than Bi2Te3. This improvement may reflect the reduced lattice symmetry of the new chalcogenide thermoelectrics. The thermoelectric figure of merit for CsBi4Te6 reaches ZT ≈ 0.32 at 260 K and for β-K2Bi8Se13 ZT ≈ 0.32 at room temperature, indicating that these compounds are viable candidates for thermoelectric refrigeration applications.

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Lanthanide Based Ternary Intermetallics as Advanced Thermoelectric Materials

MRS Proceedings ◽

10.1557/proc-980-0980-ii05-44 ◽

2006 ◽

Vol 980 ◽

Author(s):

Ken Kurosaki ◽

Takeyuki Sekimoto ◽

Kenta Kawano ◽

Hiroaki Muta ◽

Shinsuke Yamanaka

Keyword(s):

Electrical Resistivity ◽

Seebeck Coefficient ◽

High Temperatures ◽

Thermoelectric Properties ◽

Power Factor ◽

Thermoelectric Materials ◽

Room Temperature ◽

Single Phase ◽

Type Structure ◽

Large Power

AbstractPolycrystalline ingots of the lanthanide based ternary intermetallics: LaNiSb, GdNiSb, ErNiSb and ErPdSb were prepared and characterized. The thermoelectric properties of ErNiSb and ErPdSb were measured at high temperatures. We succeeded in preparing the single phase ingots of ErNiSb and ErPdSb, while the ingots of LaNiSb and GdNiSb contain appreciable quantities of the impurity phases. ErNiSb and ErPdSb crystallize the MgAgAs-type structure (half-Heusler structure). ErNiSb and ErPdSb indicate positive values of the Seebeck coefficient. The values at room temperature are 36 and 240 micro VK-1 for ErNiSb and ErPdSb, respectively. The electrical resistivity of ErNiSb and ErPdSb decreases with temperature, indicating semiconductor-like behavior. ErPdSb exhibits a relatively large power factor 1.5x10-3 Wm-1K-2 at around 700 K, which is approximately two times larger than that of ErNiSb.

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Investigations of Oxidation Dependence on Type of Porous Silicon Near Room Temperature by Isothermal Microcalorimeter

MRS Proceedings ◽

10.1557/proc-485-79 ◽

1997 ◽

Vol 485 ◽

Cited By ~ 2

Author(s):

J. Salonen ◽

V-P. Lehto ◽

E. Laine

Keyword(s):

Activation Energy ◽

Porous Silicon ◽

Room Temperature ◽

Activity Monitoring ◽

Thermal Activity ◽

Autocatalytic Reactions ◽

The Difference ◽

P Type ◽

Isothermal Microcalorimeter

AbstractOxidation of porous silicon has been studied using thermal activity monitoring, i.e. isothermal microcalorimeter. It was found that, at room temperature (25 °C) the micro-calorimetric signal from the oxidation of the p+-type porous silicon (PS) reduces exponentially, while in the case of n-type PS, the signal starts to increase slowly, reaching its highest value after some hours. This kind of behaviour is typical of autocatalytic reactions. To clarify the origin of the difference, we varied the preparation parameters of the porous silicon. We determined the activation energy from the measurements near the room temperature (25–70 °C). The results of this research have been compared with the previous observations and the possible origin of the difference has been discussed.

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