Enhancement of Thermopower due to Deficiency of Sb in FeSb2

2013 ◽  
Vol 665 ◽  
pp. 179-181 ◽  
Author(s):  
Anup V. Sanchela ◽  
Varun Kushwaha ◽  
Ajay. D. Thakur ◽  
C.V. Tomy
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Low Temperatures ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Parent Compound ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Thermoelectric Power Factor ◽  
Anomalous Peak

FeSb2 was recently found to be a narrow-gap semiconductor with strong electronelectron correlation and a large thermopower at low temperatures. We report measurements of the electrical resistivity, Seebeck coefficient and thermal conductivity between 5 K to 300 K on polycrystalline samples of FeSb2 and FeSb1.9. We found that the deficiency of Sb in the parent compound leads to a giant anomalous peak in thermopower (S) at low temperatures, reaching ~ 426 μV/K at 20 K, resulting in a high thermoelectric power factor at low temperatures, achieving 10 μW/K2m at 27 K.. Consequently, a significantly enhanced thermoelectric figure of merit ZT ~ 0.0015 is achieved near room temperature. At low temperatures there is no improvement in ZT values due to the high thermal conductivity (phonon dominant region). Keywords: Seebeck coefficient, thermal conductivity, resistivity, thermoelectric figure of merit. PACS: 72.20.Pa, 71.27.+a, 71.28.+d

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.

High Thermoelectric Performance of p-Type Bi0.5Sb1.5Te3+xTe Crystals Prepared via Gradient Freezing

2012 ◽  
Vol 621 ◽  
pp. 167-171
Author(s):  
Tao Hua Liang ◽  
Shi Qing Yang ◽  
Zhi Chen ◽  
Qing Xue Yang
Keyword(s):  
Thermal Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Performance ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
P Type

p-type Bi0.5Sb1.5Te3+xTe thermoelectric crystals with various percentages of Te (x = 0.00 wt.%–3.00 wt.%) excess were prepared by the gradient freeze method. By doping with different Te contents, anti-site defects, Te vacancies and hole carrier concentrations were controlled. The Seebeck coefficient, resistivity, thermal conductivity, carrier concentration, and mobility were measured. The relationships between the Te content and thermoelectric properties were investigated in detail. The results suggested that the thermoelectric figure of merit ZT of the Bi0.5Sb1.5Te3+0.09wt.% crystals was 1.36 near room temperature, the optimum carrier concentration was 1.25 × 1019 cm-3, and the mobility was 1480 cm2 V-1 S-1, respectively.

Thermoelectric Properties of CoSb3-based Skutterudite Compounds

2010 ◽  
Vol 1267 ◽  
Author(s):  
Adul Harnwunggmoung ◽  
Ken Kurosaki ◽  
Hiroaki Muta ◽  
Shinsuke Yamanaka
Keyword(s):  
Thermal Conductivity ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Filling Ratio ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Alloy Scattering ◽  
Skutterudite Compound

AbstractCoSb3 is known as a skutterudite compound that could exhibit high thermoelectric figure of merit. However, the thermal conductivity of CoSb3 is relatively high. In order to enhance the thermoelectric performance of this compound, we tried to reduce the thermal conductivity of CoSb3 by substitution of Rh for Co and by Tl-filling into the voids. The polycrystalline samples of (Co,Rh)Sb3 and Tl-filled CoSb3 were prepared and the thermoelectric properties such as the Seebeck coefficient, electrical resistivity, and thermal conductivity were measured in the temperature range from room temperature to 750 K. The Rh substitution for Co reduced the lattice thermal conductivity, due to the alloy scattering effect. The minimum value of the lattice thermal conductivity was 4 Wm-1K-1 at 750 K obtained for (Co0.7Rh0.3)Sb3. Also the lattice thermal conductivity rapidly decreased with increasing the Tl-filling ratio. T10.25Co4Sb12 exhibited the best ZT values; the maximum ZT was 0.9 obtained at 600 K.

scholarly journals N-Type Bismuth Telluride Nanocomposite Materials Optimization for Thermoelectric Generators in Wearable Applications

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1529 ◽  
Author(s):  
Amin Nozariasbmarz ◽  
Jerzy S. Krasinski ◽  
Daryoosh Vashaee
Keyword(s):  
Thermal Conductivity ◽  
Power Generation ◽  
Seebeck Coefficient ◽  
Figure Of Merit ◽  
Microwave Cavity ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Efficient Operation ◽  
High Seebeck Coefficient ◽  
Body Heat

Thermoelectric materials could play a crucial role in the future of wearable electronic devices. They can continuously generate electricity from body heat. For efficient operation in wearable systems, in addition to a high thermoelectric figure of merit, zT, the thermoelectric material must have low thermal conductivity and a high Seebeck coefficient. In this study, we successfully synthesized high-performance nanocomposites of n-type Bi2Te2.7Se0.3, optimized especially for body heat harvesting and power generation applications. Different techniques such as dopant optimization, glass inclusion, microwave radiation in a single mode microwave cavity, and sintering conditions were used to optimize the temperature-dependent thermoelectric properties of Bi2Te2.7Se0.3. The effects of these techniques were studied and compared with each other. A room temperature thermal conductivity as low as 0.65 W/mK and high Seebeck coefficient of −297 μV/K were obtained for a wearable application, while maintaining a high thermoelectric figure of merit, zT, of 0.87 and an average zT of 0.82 over the entire temperature range of 25 °C to 225 °C, which makes the material appropriate for a variety of power generation applications.

THERMOELECTRIC PROPERTIES OF n-TYPE Bi2Te3–Bi2Se3 ALLOYS

1967 ◽  
Vol 45 (11) ◽  
pp. 3611-3626 ◽  
Author(s):  
C. H. Champness ◽  
W. B. Muir ◽  
P. T. Chiang
Keyword(s):  
Thermal Conductivity ◽  
Carrier Concentration ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Composition Range ◽  
Energy Gap ◽  
Dopant Concentration ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Close Relationship

Room temperature measurements of the Seebeck coefficient (α), electrical conductivity (σ), thermal conductivity (κ), and thermoelectric figure of merit (Z) were made on samples of n-type Bi2Te3–Bi2Se3 pseudobinary alloys over the whole composition range. To obtain maximum Z, doping was carried out at each composition by the addition of CuBr (donor) from 0 to 66 mole% Bi2Se3 and by lead and excess Se (acceptors) thereafter. Experimentally determined values of the materials parameter β were found to saturate (β∞) at high conductivity in a given alloy and close relationship was found between β∞ and Zmax The optimized values of σ, κ, and CuBr-dopant concentration were found to show a maximum at 33 mole% Bi2Se3, while the optimized value of α showed a minimum at this composition. These results, together with the fact that no maximum was observed in σ at constant α (i.e., constant carrier concentration), suggest that a maximum in the carrier concentration occurs in optimized material at this composition. Further support for this was provided by the observed variation of σ with α at a given composition which was found to be more consistent with a minimum in the apparent energy gap near 33% Bi2Se3 rather than the maximum reported by other workers.

scholarly journals Thermoelectric Lead Telluride with ZnO Nanoparticles

2015 ◽  
Vol 16 (1) ◽  
pp. 62-67
Author(s):  
O. M. Matkivsky
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Figure Of Merit ◽  
Lead Telluride ◽  
Thermoelectric Figure Of Merit ◽  
X Ray Diffraction ◽  
Thermoelectric Figure ◽  
X Ray ◽  
Zno Powder

An X-ray diffraction structural study and measurement of Seebeck coefficient (S), the electrical conductivity (σ) and thermal conductivity (χ) for Lead Telluride with nanoinclusions of ZnO. The calculated value of the specific thermoelectric power (S2σ) and thermoelectric figure of merit (ZT). It was established that the addition of ZnO powder Nanodispersed diameter grains (40-60) nm PbTe reduces the thermal conductivity of the material, and at 0.5 wt.% ZnO to an increase of lead telluride thermoelectric figure of merit to ZT≈1,3.

scholarly journals Measuring Device and Material ZT in a Thin-Film Si-Based Thermoelectric Microgenerator

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 653 ◽  
Author(s):  
Pablo Ferrando-Villalba ◽  
Antonio Pablo Pérez-Marín ◽  
Llibertat Abad ◽  
Gustavo Gonçalves Dalkiranis ◽  
Aitor F. Lopeandia ◽  
...  
Keyword(s):  
Thin Film ◽  
Thermal Conductivity ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Generators ◽  
Thermoelectric Figure ◽  
Measuring Device ◽  
Different Temperatures ◽  
Si Thin Film

Thermoelectricity (TE) is proving to be a promising way to harvest energy for small applications and to produce a new range of thermal sensors. Recently, several thermoelectric generators (TEGs) based on nanomaterials have been developed, outperforming the efficiencies of many previous bulk generators. Here, we presented the thermoelectric characterization at different temperatures (from 50 to 350 K) of the Si thin-film based on Phosphorous (n) and Boron (p) doped thermocouples that conform to a planar micro TEG. The thermocouples were defined through selective doping by ion implantation, using boron and phosphorous, on a 100 nm thin Si film. The thermal conductivity, the Seebeck coefficient, and the electrical resistivity of each Si thermocouple was experimentally determined using the in-built heater/sensor probes and the resulting values were refined with the aid of finite element modeling (FEM). The results showed a thermoelectric figure of merit for the Si thin films of z T = 0.0093, at room temperature, which was about 12% higher than the bulk Si. In addition, we tested the thermoelectric performance of the TEG by measuring its own figure of merit, yielding a result of ZT = 0.0046 at room temperature.

Effects of Oxygen-Reduction on Thermoelectric Properties of Sr0.61Ba0.39Nb2O6 Ceramics

2014 ◽  
Vol 787 ◽  
pp. 210-214 ◽  
Author(s):  
Yi Li ◽  
Jian Liu ◽  
Chun Lei Wang ◽  
Wen Bin Su ◽  
Yuan Hu Zhu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Oxygen Reduction ◽  
Thermoelectric Power ◽  
Thermoelectric Properties ◽  
Power Factor ◽  
Figure Of Merit ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Thermoelectric Power Factor

The thermoelectric properties of Sr0.61Ba0.39Nb2O6 ceramics, reduced in various conditions, were investigated in the temperature range from 323K to 1073K. Both the electrical resistivity and the absolute Seebeck coefficient decreased with the deepening degree of oxygen-reduction. However, the decrease of the electrical resistivity had a major influence on the thermoelectric power factor. Therefore, the more heavily reduced sample can gain the higher value of thermoelectric power factor. It has been observed that the thermal conductivity increased with the deepening degree of oxygen-reduction, which indicates that the scattering of the oxygen vacancies produced by reduction does not play a dominant role in the thermal conduction. In spite of the increase of the thermal conductivity, the oxygen-reduction still promoted the thermoelectric figure of merit via the increase of the thermoelectric power factor. And the most heavily reduced Sr0.61Ba0.39Nb2O6 ceramic has the highest thermoelectric figure of merit (~0.18 at 1073 K) among all the samples.

scholarly journals Влияние температуры спекания на термоэлектрические свойства соединения Bi-=SUB=-1.9-=/SUB=-Gd-=SUB=-0.1-=/SUB=-Te-=SUB=-3-=/SUB=-

2019 ◽  
Vol 53 (5) ◽  
pp. 620
Author(s):  
М.Н. Япрынцев ◽  
А.Е. Васильев ◽  
О.Н. Иванов
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Elemental Composition ◽  
Figure Of Merit ◽  
Sintering Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Total Thermal Conductivity ◽  
Thermoelectric Figure ◽  
Antisite Defects

AbstractThe regularities of the influence of the sintering temperature (750, 780, 810, and 840 K) on the elemental composition, crystal-lattice parameters, electrical resistivity, Seebeck coefficient, total thermal conductivity, and thermoelectric figure of merit of the Bi_1.9Gd_0.1Te_3 compound are investigated. It is established that the elemental composition of the samples during high-temperature sintering varies due to intense tellurium evaporation, which can lead to the formation of various point defects (vacancies and antisite defects) affecting the majority carrier (electron) concentration and mobility. The sintering temperature greatly affects the electrical resistivity of the samples, while the influence on the Seebeck coefficient and total thermal conductivity is much weaker. The largest thermoelectric figure of merit ( ZT ≈ 0.55) is observed for the sample sintered at 750 K.

Thermoelectric Figure of Merit, ZT, of Single Crystal Pentatellurides (MTe5-XSex: M = Hf, Zr and x = 0, 0.25)

2000 ◽  
Vol 626 ◽  
Author(s):  
R. T. Littleton ◽  
Terry M. Tritt ◽  
B. Zawilski ◽  
J. W. Kolis ◽  
D. R. Ketchum ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Power Factor ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Thermoelectric Figure Of Merit ◽  
Thermoelectric Figure ◽  
Large Power ◽  
Parent Materials ◽  
Se Substitution ◽  
Factor Α

ABSTRACTThe thermoelectric figure of merit, ZT = α2σT/λ, has been measured for pentatelluride single crystals of HfTe5, ZrTe5, as well as Se substituted pentatellurides. The parent materials, HfTe5 and ZrTe5, exhibit relatively large p- and n- type thermopower, |a| > 125 μV/K, and low resistivity, ρ ≤ 1 mΩ•cm. These values lead to a large power factor (α2σT) which is substantially increased with proper Se substitution on the Te sites. The thermal conductivity of these needle-like crystals has also been measured as a function of temperature from 10 K ≤ T ≤ 300 K. The room temperature figure of merit for these materials varies from ZT “0.1 for the parent materials to ZT ≈ 0.25 for Se substituted samples. These results as well as experimental procedures will be presented and discussed.

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