Thermal Conductivity Reduction Paths in Thermoelectric Materials

2009 ◽  
Vol 1166 ◽  
Author(s):  
Claude Godart ◽  
Antonio Goncalves ◽  
Elsa Lopes ◽  
Benjamin Villeroy
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Essential Element ◽  
Complex Structures ◽  
Nano Structure ◽  
Structured Systems ◽  
Large Size ◽  
Plasma Sintering ◽  
Spark Plasma

AbstractThe figure of merit ZT = sS2T/k (S the Seebeck coefficient, s and k the electrical and thermal conductivity respectively) is an essential element of the efficiency of a thermoelectric material for applications which convert heat to electricity or, conversely, electric current to cooling. From the expression of the power factor sS2 it was deduced that a highly degenerated semiconductor is necessary. In order to reduce the lattice part of the thermal conductivity, various mechanisms were tested in new thermoelectric materials and those had been the topics of several reviews. These include cage-like materials, effects of vacancies, solid solutions, complex structures (cluster, tunnel, …,), micro- and nano-structured systems, and more recently semiconducting glasses. We plan to review such aspects in the modern thermoelectric materials and include results of the very last years. Moreover, as micro- and nano-composites seem to be promising to increase ZT in large size samples, we will also briefly discuss the interest of spark plasma sintering technique to preserve the micro- or nano- structure in highly densified samples.

Fabrication of Bi-Te Based Thermoelectric Semiconductors by Using Hybrid Powders

2005 ◽  
Vol 297-300 ◽  
pp. 875-880
Author(s):  
Cheol Ho Lim ◽  
Ki Tae Kim ◽  
Yong Hwan Kim ◽  
Dong Choul Cho ◽  
Young Sup Lee ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Single Crystals ◽  
Thermoelectric Properties ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Bending Strength ◽  
Mixing Ratio ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

P-type Bi0.5Sb1.5Te3 compounds doped with 3wt% Te were fabricated by spark plasma sintering and their mechanical and thermoelectric properties were investigated. The sintered compounds with the bending strength of more than 50MPa and the figure-of-merit 2.9×10-3/K were obtained by controlling the mixing ratio of large powders (PL) and small powders (PS). Compared with the conventionally prepared single crystal thermoelectric materials, the bending strength was increased up to more than three times and the figure-of-merit Z was similar those of single crystals. It is expected that the mechanical properties could be improved by using hybrid powders without degradation of thermoelectric properties.

Enhanced Thermoelectric Properties of Mg2Si0.3Sn0.7 Compounds by Bi Doping

2014 ◽  
Vol 616 ◽  
pp. 174-177
Author(s):  
Mei Jun Yang ◽  
Qiang Shen ◽  
Lian Meng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Doping Concentration ◽  
Single Phase ◽  
Doping Content ◽  
Maximum Value ◽  
Plasma Sintering ◽  
Bi Doping ◽  
Spark Plasma

The single phase of Bi-doped Mg2Si0.3Sn0.7compounds have been successfully fabricated by solid state reaction and spark plasma sintering (SPS). The effect of Bi doping concentration on the thermoelectric properties of Mg2Si0.3Sn0.7is investigated. The doping of Bi atom results in the increase of carrier concentrations and ensures the increase of electrical conductivity. Although the thermal conductivity and Seebeck coefficient shows a slight increase, the figure of merit of Mg2Si0.3Sn0.7compounds still increases with the increasing contents of Bi-doping. When Bi-doping content is 1.5at%, the Mg2Si0.3Sn0.7compound obtained the maximum value,ZT, is 1.03 at 640 K.

Thermoelectrical properties of α phase and γ phase NaxCo2O4 ceramics prepared by spark plasma sintering method

2013 ◽  
Vol 1490 ◽  
pp. 57-62 ◽  
Author(s):  
Natsuko Mikami ◽  
Keishi Nishio ◽  
Koya Arai ◽  
Tatsuya Sakamoto ◽  
Masahiro Minowa ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Spark Plasma Sintering ◽  
Figure Of Merit ◽  
Dimensionless Figure Of Merit ◽  
Α Phase ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Sintering Method ◽  
Acid Compound

ABSTRACTThe thermoelectrical properties of α and γ phases of NaxCo2O4 having different amounts of Na were evaluated. The γ NaxCo2O4 samples were synthesized by thermal decomposition in a metal-citric acid compound, and the α NaxCo2O4 samples were synthesized by self-flux processing. Dense bulk ceramics were fabricated using spark plasma sintering (SPS), and the sintered samples were of high density and highly oriented. The thermoelectrical properties showed that γ NaxCo2O4 had higher electrical conductivity and lower thermal conductivity compared with α NaxCo2O4 and that α NaxCo2O4 had a larger Seebeck coefficient. These results show that γ NaxCo2O4 has a larger power factor and dimensionless figure of merit, ZT, than α NaxCo2O4.

Effect of Oxygen Content on Thermoelectric Properties of Sintered Bi-Te Based Compounds

2004 ◽  
Vol 449-452 ◽  
pp. 905-908 ◽  
Author(s):  
Dong Choul Cho ◽  
Cheol Ho Lim ◽  
D.M. Lee ◽  
Seung Y. Shin ◽  
Chung Hyo Lee
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Oxygen Content ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Air Atmosphere ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Effect Of Oxygen

The n-type thermoelectric materials of Bi2Te2.7Se0.3 doped with SbI3 were prepared by spark plasma sintering technique. The powders were ball-milled in an argon and air atmosphere. Then, powders were reduced in H2 atmosphere. Effects of oxygen content on the thermoelectric properties of Bi2Te2.7Se0.3 compounds have been investigated. Seebeck coefficient, electrical resistivity and thermal conductivity of the sintered compound were measured at room temperature. It was found that the effect of atmosphere during the powder production was remarkable and thermoelectric properties of sintered compound were remarkably improved by H2 reduction of starting powder. The obtained maximum figure of merit was 2.4 x 10-3/K.

Synthesis and Thermoelectric Properties of WO3/Cu2SnSe3 Composites

2018 ◽  
Vol 913 ◽  
pp. 811-817 ◽  
Author(s):  
Di Wu ◽  
Ji Ai Ning ◽  
De Gang Zhao ◽  
Xue Zhen Wang ◽  
Na Liu
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Electrical Properties ◽  
Grain Boundary ◽  
Figure Of Merit ◽  
Milling Process ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma

In this study, nanometer WO3 powder was uniformly dispersed into the Cu2SnSe3 powder by ball milling process, and the WO3/Cu2SnSe3 thermoelectric composite was prepared by spark plasma sintering (SPS). The results showed that the nano-WO3 particles were mainly distributed in the grain boundary of Cu2SnSe3 matrix, and the grain growth of Cu2SnSe3 was inhibited. The addition of nano-WO3 could enhance the electrical conductivity of Cu2SnSe3, and while the Seebeck coefficient increased slightly for the 0.4% WO3/Cu2SnSe3 composite. The thermal conductivity was not decreased until the content of WO3 exceeded 1.6%. The highest thermoelectric figure of merit ZT of 0.177 was achieved at 700 K for 0.4% WO3/Cu2SnSe3 composite. The enhancement of ZT value of WO3/Cu2SnSe3 thermoelectric material was mainly attributed to the improvement of the electrical properties.

Preparation and Thermoelectric Properties of Bi-Doped Mg2Si Nanocomposites

2009 ◽  
Vol 66 ◽  
pp. 17-20 ◽  
Author(s):  
Mei Jun Yang ◽  
Wei Jun Luo ◽  
Qiang Shen ◽  
Hong Yi Jiang ◽  
Lian Meng Zhang
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Dimensionless Figure Of Merit ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Heavy Doping ◽  
Nanocomposite Structures

Nanocomposites and heavy doping both are regarded as effective way to improve materials’ thermoelectric properties. 0.7at% Bi-doped Mg2Si nanocomposites were prepared by spark plasma sintering. Results of thermoelectric properties tests show that the doping of Bi atom effectively improves the electrical conductivity of Mg2Si，and the nanocomposite structures are helpful to reduce thermal conductivity and increase Seebeck coefficient, hence improving the thermoelectric performance. A maximum dimensionless figure of merit of 0.8 is obtained for the Bi-doped Mg2Si nanocomposite with 50 wt % nanopowder inclusions at 823K, about 63% higher than that of Bi-doped Mg2Si sample without nanopowder inclusions and 119% higher than that of microsized Mg2Si sample without Bi-doped, respectively.

Significantly enhanced thermoelectric figure of merit of p-type Mg3Sb2-based Zintl phase compounds via nanostructuring and employing high energy mechanical milling coupled with spark plasma sintering

2015 ◽  
Vol 3 (20) ◽  
pp. 10777-10786 ◽  
Author(s):  
A. Bhardwaj ◽  
N. S. Chauhan ◽  
D. K. Misra
Keyword(s):  
Thermoelectric Materials ◽  
Mechanical Milling ◽  
Figure Of Merit ◽  
High Energy ◽  
Thermoelectric Figure Of Merit ◽  
Zintl Phase ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
P Type

Several nanostructuring methods have been demonstrated to produce a variety of nanostructured materials, and these methods are well recognized as effective paradigms for improving the performance of thermoelectric materials.

Raising the Thermoelectric Performance of Fe3CoSb12 Skutterudites via Nd Filling and In-Situ Nanostructuring

2016 ◽  
Vol 16 (4) ◽  
pp. 3841-3847 ◽  
Author(s):  
Lijie Guo ◽  
Zhengwei Cai ◽  
Xiaolong Xu ◽  
Kunling Peng ◽  
Guiwen Wang ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Performance ◽  
Large Reduction ◽  
Dimensionless Figure Of Merit ◽  
Plasma Sintering ◽  
Spark Plasma

p-type skutterudites NdxFe3CoSb12 with x equaling 0.8, 0.85, 0.9, 0.95, 1.0 have been synthesized by solid state reaction followed by spark plasma sintering. The influence of Nd filling on electrical and thermal transport properties has been investigated in the Nd-filled skutterudite compounds in the temperature range from room temperature to 800 K. It was found that the Seebeck coefficient is drastically enhanced via filling Nd in p-Type skutterudites as well as the corresponding power factor although electrical conductivity is reduced. In addition, a large reduction in thermal conductivity is achieved by Nd fillers through rattling effect along with the In-Situ nanostructured precipitate through scattering phonons with much wider frequency. These concomitant effects result in an enhanced thermoelectric performance with the dimensionless figure of merit ZT. These observations demonstrate an exciting scientific opportunity to raise the figure-of-merit of p-type skutterudites.

scholarly journals Is LiI a Potential Dopant Candidate to Enhance the Thermoelectric Performance in Sb-Free GeTe Systems? A Prelusive Study

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 643 ◽  
Author(s):  
Bhuvanesh Srinivasan ◽  
David Berthebaud ◽  
Takao Mori
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Figure Of Merit ◽  
Lattice Thermal Conductivity ◽  
Short Communication ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Plasma Sintering ◽  
Spark Plasma

As a workable substitute for toxic PbTe-based thermoelectrics, GeTe-based materials are emanating as reliable alternatives. To assess the suitability of LiI as a dopant in thermoelectric GeTe, a prelusive study of thermoelectric properties of GeTe1−xLiIx (x = 0–0.02) alloys processed by Spark Plasma Sintering (SPS) are presented in this short communication. A maximum thermoelectric figure of merit, zT ~ 1.2, was attained at 773 K for 2 mol% LiI-doped GeTe composition, thanks to the combined benefits of a noted reduction in the thermal conductivity and a marginally improved power factor. The scattering of heat carrying phonons due to the presumable formation of Li-induced “pseudo-vacancies” and nano-precipitates contributed to the conspicuous suppression of lattice thermal conductivity, and consequently boosted the zT of the Sb-free (GeTe)0.98(LiI)0.02 sample when compared to that of pristine GeTe and Sb-rich (GeTe)x(LiSbTe2)2 compounds that were reported earlier.

High-Pressure Synthesis of Skutterudite-Type Thermoelectric Materials

2016 ◽  
Vol 879 ◽  
pp. 1737-1742 ◽  
Author(s):  
Chihiro Sekine ◽  
Hirotaka Kato ◽  
Yukihiro Kawamura ◽  
Chul Ho Lee
Keyword(s):  
High Pressure ◽  
Thermoelectric Materials ◽  
Figure Of Merit ◽  
Manufacturing System ◽  
Synthesis Method ◽  
Filled Skutterudite ◽  
High Pressure Synthesis ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Pressure Synthesis

We have developed a manufacturing system by combination of high-pressure synthesis method using a multi-anvil press, and spark plasma sintering (SPS) method. By means of the system, we have succeeded in synthesizing new filled skutterudite-type thermoelectric materials MmxCo4Sb12 (Mm=mischmetal). The thermoelectric properties of partially filled skutterudite compounds MmxCo4Sb12 synthesized under high pressure have been investigated. The Seebeck coefficient of MmxCo4Sb12 shows negative value, which means n-type conductivity. The highest dimensionless figure of merit ZT value is 0.25 for Mm0.6Co4Sb12 at 700 K.

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