Thermoelectric Properties of Bi2Te3-Sb2Te3 Compounds Prepared by Ma-Pulse Discharge Sintering Process

1999 ◽  
Vol 581 ◽  
Author(s):  
R.E. Park ◽  
Y.H. Park ◽  
T. Abe
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Mechanical Alloying ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Pulse Discharge ◽  
Sintering Process ◽  
Mechanically Alloyed ◽  
Fine Grain ◽  
Process Effects

ABSTRACTThe Bi2Te3-Sb2Te3 compounds with the composition of useful thermoelectric cooling materials were prepared by mechanical alloying-pulse discharge sintering process. Effects of the process on the Seebeck coefficient, electrical resistivity and thermal conductivity were investigated. Temperature dependence of the Hall coefficient was also observed in the temperature range 80 - 325 K.The figure of merit, Z, was found to be about 4.0 × 10−1K−1 at room temperature in the 25%Bi2Te3-75%Sb2Te3 composition sintered at 618K using grain refined mechanically alloyed powders which had the size of under 32 μm. The value of Z was remarkably improved with a decrease of the thermal conductivity shown in the fine grain compacts fabricated by mechanical alloying-pulse discharge sintering process.

Bi2Te3 and Bi2Te3/Nano-SiC Prepared by Mechanical Alloying and Spark Plasma Sintering

2007 ◽  
Vol 280-283 ◽  
pp. 397-400 ◽  
Author(s):  
Jing Liu ◽  
Jing Feng Li
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Mechanical Alloying ◽  
Seebeck Coefficient ◽  
Spark Plasma Sintering ◽  
Thermoelectric Materials ◽  
Room Temperature ◽  
Mechanically Alloyed ◽  
Plasma Sintering ◽  
Spark Plasma

Bi2Te3-based alloys are currently best-known, technological thermoelectric materials near room temperature. In this paper, Bi2Te3 and nano-SiC dispersed Bi2Te3 were prepared by mechanical alloying followed by spark plasma sintering (SPS). Raw powders of Bi, Te and SiC were mixed and mechanically alloyed in an argon atmosphere using a planetary ball mill. The SPS temperature was 623K, and the holding time was 5 minutes. The samples were characterized by X-ray Diffraction (XRD) and Scanning electron Microscope (SEM). The thermoelectric properties: i.e. Seebeck coefficient, electrical resistivity and thermal conductivity were measured at temperatures from room temperature to 573K, followed by the evaluation of figure of merit. The results revealed that the SiC dispersion in the Bi2Te3 matrix increased Seebeck coefficient. Although the electrical resistivity was increased somewhat, the thermal conductivity was reduced by the SiC dispersion, indicating that promising thermoelectric materials with enhanced mechanical properties may be obtained in the nano-SiC dispersed Bi2Te3 composites with optimal compositions.

Thermoelectric Properties of Semiconducting Intermetallic Compounds: FeGa3and RuGa3

2003 ◽  
Vol 793 ◽  
Author(s):  
Y. Amagai ◽  
A. Yamamoto ◽  
C. H. Lee ◽  
H. Takazawa ◽  
T. Noguchi ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Transport Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
High Seebeck Coefficient

ABSTRACTWe report transport properties of polycrystalline TMGa3(TM = Fe and Ru) compounds in the temperature range 313K<T<973K. These compounds exhibit semiconductorlike behavior with relatively high Seebeck coefficient, electrical resistivity, and Hall carrier concentrations at room temperature in the range of 1017- 1018cm−3. Seebeck coefficient measurements reveal that FeGa3isn-type material, while the Seebeck coefficient of RuGa3changes signs rapidly from large positive values to large negative values around 450K. The thermal conductivity of these compounds is estimated to be 3.5Wm−1K−1at room temperature and decreased to 2.5Wm−1K−1for FeGa3and 2.0Wm−1K−1for RuGa3at high temperature. The resulting thermoelectric figure of merit,ZT, at 945K for RuGa3reaches 0.18.

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.

Reductions in the Lattice Thermal Conductivity of Ball-milled and Shock compacted TiNiSn1−XSbX Half-Heusler alloys

2001 ◽  
Vol 691 ◽  
Author(s):  
S. Bhattacharya ◽  
Y. Xia ◽  
V. Ponnambalam ◽  
S.J. Poon ◽  
N. Thadani ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Heusler Alloys ◽  
Lattice Contribution ◽  
Grain Sizes ◽  
Shock Compaction ◽  
High Figure

ABSTRACTHalf-Heusler alloys are currently being investigated for their potential as thermoelectric materials [1], [2]. They exhibit high negative thermopower (40-250μV/K) and favorable electrical resistivity (0.1-8mW•cm) at room temperature. Attractive power factors (α2σT) of about (0.2-1.0W/m•K) at room temperature and about 4W/m•K at 600K [3] have been reported in these materials. But in order to achieve a high figure-of-merit in the half-Heusler alloys, the relatively high thermal conductivity in these materials (∼ 10 W/m•K) must be reduced. The thermal conductivity in these materials is composed of mainly a lattice contribution, compared to a very small electronic component. The challenge is to reduce the relatively high lattice thermal conductivity in these materials. Reported in this paper is a significant reduction of lattice thermal conductivity (∼1.5 - 3.5W/m•K) in some Ti-based half-Heusler alloys. Samples have been prepared by ball milling and followed by shock-compaction that has resulted into reduced grain sizes in these materials. The effects of the microstructure on the thermal transport properties of the Half-Heusler alloys have been investigated and are presented and discussed herein.

Effect of Ca and/or Mn substitution on thermoelectric properties of SrTiO3

2021 ◽  
Author(s):  
D. Mohan Radheep
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Mixed Valence ◽  
Solid State Reaction Method ◽  
Reaction Method ◽  
Cubic Lattice ◽  
Mn Substitution

Thermoelectric properties have been investigated for Sr0.5Ca0.5Ti1-xMnxO3 (x = 0.25, 0.5, 0.75) and Sr0.75Ca0.25Ti0.75Mn0.25O3 perovskite polycrystalline samples synthesized by solid-state reaction method. Following physical properties such as thermal conductivity, electrical resistivity, Seebeck coefficient, power factor and figure of merit (ZT) were measured. The substitution of Ca2+ in Sr2+ site or/and mixed valence Mn in Ti site creates appreciable enhancement in the thermoelectric properties with an increase of ZT from 0.5 to 0.69 at room temperature. The origin for the enrichment of ZT of the investigated samples around room temperature is due to substitution induced distortion in the cubic lattice.

Thermoelectric Properties of La-doped BaSi2 and (Ba,Sr)Si2 Solid Solutions

2007 ◽  
Vol 1044 ◽  
Author(s):  
Kohsuke Hashimoto ◽  
Ken Kurosaki ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Solid Solution ◽  
Electrical Resistivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Dimensionless Figure Of Merit ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
La Doped

AbstractWe studied the thermoelectric properties of BaSi2 and SrSi2. The polycrystalline samples were prepared by spark plasma sintering (SPS). The electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ) were measured above room temperature. The maximum values of the dimensionless figure of merit (ZT) were 0.01 at 954 K for BaSi2 and 0.09 at 417 K for SrSi2. We tried to enhance the ZT values of BaSi2 and SrSi2 by prepareing and characterizing La-doped BaSi2 and (Ba,Sr)Si2 solid solution.

Thermoelectric properties of the Al-TM-Si (TM = Mn, Re) 1/1-cubic approximant

2003 ◽  
Vol 805 ◽  
Author(s):  
Tsunehiro Takeuchi ◽  
Toshio Otagiri ◽  
Hiroki Sakagami ◽  
Uichiro Mizutani
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Thermoelectric Power ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Low Thermal Conductivity ◽  
Dimensionless Figure Of Merit

ABSTRACTThe electrical resistivity, thermoelectric power, and thermal conductivity were investigated for the Al71.6-xMn 17.4Six and Al71.6-xRe 17.4Six (7 ≤ x ≤ 12) 1/1-cubic approximants. A large thermoelectric power ranging from -40 to 90 μV/K and a low thermal conductivity less than 3 W/K·cm were observed at room temperatures. The electrical resistivity at room temperature for these approximants was kept below 4,000 μΩcm, that is much smaller than that in the corresponding quasicrystals. As a result of the large thermoelectric power, the low thermal conductivity, and the low electrical resistivity, large dimensionless figure of merit ZT = 0.10 (n-type) and 0.07 (p-type) were achieved for the Al71.6Re17.4Si11 and Al71.6Mn17.4Si11 at room temperature, respectively.

Thermoelectric Properties of Manganese Monosilicide Synthesized by Mechanical Alloying Process

2012 ◽  
Vol 724 ◽  
pp. 111-114
Author(s):  
Moon Kwan Choi ◽  
Woong Jae Lee ◽  
Il Ho Kim ◽  
Young Geun Lee ◽  
Soon Yong Kweon ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Mechanical Alloying ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Single Phase ◽  
High Temperature Application ◽  
Mechanically Alloyed ◽  
Fundamental Investigation ◽  
Manganese Silicide ◽  
Temperature Application

Manganese silicide is one of the potential thermoelectric materials for high temperature application. As a fundamental investigation on these materials group, manganese monosilicides were synthesized by the mechanical alloying of stoichiometric elemental powder compositions, and the as-milled powders were consolidate by vacuum hot pressing. Phase transformation and microstructure evolution during mechanical alloying and hot consolidation were investigated using XRD and SEM. Near single phase of monosilicides were successfully produced in this process. Thermoelectric properties as a function of temperature were evaluated in terms of Seebeek coefficient, electrical resistivity, thermal conductivity and the figure of merit for the hot pressed specimens. Mechanically alloyed manganese monosilicide, MnSi, appeared to have a potential as a thermoelectric material in this study.

Thermoelectric Properties of Tl-X-Te (X=Pb, Sn, Ge) Systems

2005 ◽  
Vol 886 ◽  
Author(s):  
Atsuko Kosuga ◽  
Ken Kurosaki ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Solid State ◽  
Electrical Properties ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Dimensionless Figure Of Merit

ABSTRACTPolycrystalline-sintered samples of Tl2GeTe3, Tl4SnTe3, and Tl4PbTe3 were prepared by a solid-state reaction. Their thermoelectric properties were evaluated at temperatures ranging from room temperature to ca. 700 K by using the measured electrical resistivity (ρ), Seebeck coefficient (S), and thermal conductivity (κ). Despite their poor electrical properties, the dimensionless figure of merit ZT of all the compounds was relatively high, i.e., 0.74 at 673 K for Tl4SnTe3, 0.71 at 673 K for Tl4PbTe3, 0.29 at 473 K for Tl2GeTe3, due to the very low lattice thermal conductivity of the compounds.

scholarly journals Local ferroelectric polarization switching driven by nanoscale distortions in thermoelectric $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Aastha Vasdev ◽  
Moinak Dutta ◽  
Shivam Mishra ◽  
Veerpal Kaur ◽  
Harleen Kaur ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Direct Evidence ◽  
Temperature Dependent ◽  
Force Microscopy ◽  
Ferroelectric Domains ◽  
Pdf Analysis ◽  
Ferroelectric Transition Temperature

AbstractA remarkable decrease in the lattice thermal conductivity and enhancement of thermoelectric figure of merit were recently observed in rock-salt cubic SnTe, when doped with germanium (Ge). Primarily, based on theoretical analysis, the decrease in lattice thermal conductivity was attributed to local ferroelectric fluctuations induced softening of the optical phonons which may strongly scatter the heat carrying acoustic phonons. Although the previous structural analysis indicated that the local ferroelectric transition temperature would be near room temperature in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te , a direct evidence of local ferroelectricity remained elusive. Here we report a direct evidence of local nanoscale ferroelectric domains and their switching in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te using piezoeresponse force microscopy(PFM) and switching spectroscopy over a range of temperatures near the room temperature. From temperature dependent (250–300 K) synchrotron X-ray pair distribution function (PDF) analysis, we show the presence of local off-centering distortion of Ge along the rhombohedral direction in global cubic $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te . The length scale of the $${\text {Ge}}^{2+}$$ Ge 2 + off-centering is 0.25–0.10 Å near the room temperatures (250–300 K). This local emphatic behaviour of cation is the cause for the observed local ferroelectric instability, thereby low lattice thermal conductivity in $${\text {Sn}}_{0.7}{\text {Ge}}_{0.3}{\text {Te}}$$ Sn 0.7 Ge 0.3 Te .

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