Showing papers on "Thermoelectric effect published in 2005"

Thermoelectrics Handbook : Macro to Nano

Abstract: GENERAL PRINCIPLES AND THEORETICAL CONSIDERATIONS General Principles and Basic Considerations D.M. Rowe Modern Thermodynamic Theory of Thermoelectricity L.I. Anatychuk and O.J. Luste Thermoelectric Phenomena under Large Temperature Gradients L.I. Anatychuk and L.P. Bulat Minority Carriers and Thermoelectric Effects in Bipolar Devices Kevin Pipe Effects of Charge Carriers' Interactions on Seebeck Coefficients David Emin Thermal Conductivity of Semiconductors with Complex Crystal Structure V.K. Zaitsev and M.I. Fedorov A Chemical Approach to the First-Principles Modeling of Novel Thermoelectric Materials Luca Bertini, Fausto Cargnoni, and Carlo Gatti Recent Trends for the Design and Optimization of Thermoelectric Materials: A Theoretical Perspective John S. Tse and Dennis D. Klug Thermoelectric Power Generation: Efficiency and Compatibility G. Jeffrey Snyder A New Upper Limit to the Thermoelectric Figure-of-Merit H.J. Goldsmid Thermoelectric Module Design Theories Gao Min Modeling and Characterization of Power Generation Modules Based on Bulk Materials Timothy P. Hogan and Tom Shih Energy Conversion Using Diode-Like Structures Yan Kucherov and Peter Hagelstein Size Effects on Thermal Transport Chandra Mohan Bhandari Thermoelectric Aspects of Strongly Correlated Electron Systems S. Paschen Theory and Modeling in Nanostructured Thermoelectrics Alexander A. Balandin Thermoelectric Power of Carbon Nanotubes G.D. Mahan Phonon-Drag Thermopower of Low-Dimensional Semiconductor Structures Yu.V. Ivanov MATERIAL PREPARATION AND MEASUREMENTS Solid State Synthesis of Thermoelectric Materials B.A. Cook and J.L. Harringa Review of Methods of Thermoelectric Materials Mass Production Yury M. Belov, Sergei M. Maniakin, and Igor V. Morgunov Structural Studies of Thermoelectric Materials Bo Brummerstedt Iversen Measurements of Resistivity and Thermopower: Principles and Practical Realization A.T. Burkov Electrical and Thermal Transport Measurement Techniques for Evaluation of the Figure-of-Merit of Bulk Thermoelectric Materials Terry M. Tritt Measurement of the Thermal Conductivity of Thin Films F. Voelklein, A. Meier, and M. Blumers Solvothermal Synthesis of Nanostructured Thermoelectric Materials X.B. Zhao, T.J. Zhu, and X.H. Ji Approaches to Thermoelectric Standardization E. Muller, C. Stiewe, D.M. Rowe, and S.G.K. Williams THERMOELECTRIC MATERIALS Thermoelectric Properties of Bismuth Antimony Telluride Solid Solutions H. Scherrer and S. Scherrer Bi-Sb Alloys: Thermopower in Magnetic Field V.M. Grabov and O.N. Uryupin Thermoelectrics on the Base of Solid Solutions of Mg2BIV Compounds (BIV = Si, Ge, Sn) V.K. Zaitsev, M.I. Fedorov, I.S. Eremin, and E.A. Gurieva Thermoelectric Properties of the Group V Semimetals J-P. Issi Thermoelectrics of Transition Metal Silicides M. Fedorov and V. Zaitsev Formation and Crystal Chemistry of Clathrates P. Rogl Structure, Thermal Conductivity and Thermoelectric Properties of Clathrate Compounds George S. Nolas Skutterudite-Based Thermoelectrics Ctirad Uher Oxide Thermoelectrics Kunihito Koumoto, Ichiro Terasaki, Tsuyoshi Kajitani, Michitaka Ohtaki, and Ryoji Funahashi Thermoelectric Properties of Electrically Conducting Organic Materials A.I. Casian Shifting the Maximum Figure-of-Merit of (Bi, Sb)2(Te, Se)3 Thermoelectrics to Lower Temperatures V.A. Kutasov, L.N. Lukyanova, and M.V. Vedernikov Functionally Graded Materials for Thermoelectric Applications V.L. Kuznetsov Recent Developments in Low Dimensional Thermoelectric Materials M.S. Dresselhaus and J.P. Heremans Thermoelectric Properties of Nanocrystalline Transition Metal Silicides J. Schumann and A.T. Burkov Nanostructured Skutterudites Mamoun Muhammed and Muhammet Toprak Thermal Conductivity of Nanostructured Thermoelectric Materials C. Dames and G. Chen THERMOELEMENTS, MODULES AND DEVICES Modeling and Optimization of Segmented Thermoelectric Generators for Terrestrial and Space Applications Mohamed S. El-Genk and Hamed H. Saber Thermocouple with a Passive HTSC Leg V.L. Kuznetsov and M.V. Vedernikov Anisotropic Thermoelements A.A. Snarskii and L.P. Bulat Miniaturized Thermoelectric Converters Harald Boettner, Joachim Nurnus, and Axel Schubert Thermoelectric Microelectromechanical Systems (MEMS) F. Voelklein and A. Meier Nanoscale Thermoelectrics Joachim Nurnus, Harald Boettner, and Armin Lambrecht Superlattice Thin-Film Thermoelectric Material and Device Technologies Rama Venkatasubramanian, Edward Siivola, and Brooks O'Quinn THERMOELECTRIC SYSTEMS AND APPLICATIONS Thermoelectric Power Generation System Recovering Industrial Waste Heat Takenobu Kajikawa The Concept of Thermoelectric Power Generation Topping-Up Co-Generation System Takenobu Kajikawa A Thermoelectric Application to Vehicles Kakuei Matsubara and Mitsuru Matsuura Thermoelectric Microgenerators with Isotope Heat Sources L.I. Anatychuk and A.A. Pustovalov Performance and Mass Estimates of CTM-ARPSs with Four GPHS Bricks Mohamed S. El-Genk and Hamed H. Saber Parametric and Optimization Analyses of Cascaded Thermoelectric-Advanced Radioisotope Power Systems with Four GPHS Bricks Mohamed S. El-Genk and Hamed H. Saber Space Missions and Applications Robert D. Abelson Quantum Well Thermoelectric Devices and Applications S. Ghamaty, J.C. Bass, and N.B. Elsner Thermoelectric Cooling of Electro-Optic Components V.A. Semenyuk Thermoelectric Refrigeration for Mass-Market Applications Montag C. Davis, Benjamin P. Banney, Peter T. Clarke, Brett R. Manners, and Robert M. Weymouth APPENDIX I: HISTORY OF THE INTERNATIONAL THERMOELECTRIC SOCIETY C.B. Vining, D.M. Rowe, J. Stockholm, and K.R. Rao APPENDIX II: SELECTED THERMOELECTRIC SOURCES

High-temperature carrier transport and thermoelectric properties of heavily La- or Nb-doped SrTiO3 single crystals

Abstract: Electron and thermal transport properties, i.e., electrical conductivity, carrier concentration, Hall mobility, Seebeck coefficient, thermal conductivity, of heavily La- or Nb-doped SrTiO3 (STO) bulk single crystals were measured at high temperatures, (300–1050K) to clarify the influence of doping upon the thermoelectric performance of STO. The temperature dependence of Hall mobility and Seebeck coefficient changed at ∼750K in all samples because the dominant mechanism for carrier scattering changed with increasing temperature from coupled scattering by polar optical phonons and acoustic phonons to mere acoustic phonon scattering. The density-of-states effective mass of Nb-doped STO, which was estimated from the carrier concentration and Seebeck coefficient, was larger than that of La-doped STO. Thermal conductivity of the samples, which was similar to that of undoped STO single crystal, decreased proportionally to T−1, indicating that the phonon conduction takes place predominantly and the electronic con...

Bismuth telluride nanotubes and the effects on the thermoelectric properties of nanotube-containing nanocomposites

Abstract: Nanotubes of quasilayered bismuth telluride compound were prepared by hydrothermal synthesis. Nanotubes have diameters smaller than 100nm and spiral tube-walls. The low-dimensional morphology and hollow structure enable bismuth telluride nanotubes to be a potential thermoelectric material with a high figure of merit due to the efficient phonon blocking effect. The experimental results show that the addition of nanotubes leads to a remarkable decrease in the thermal conductivity with the electrical conductivity much less affected and thus to an increase in the figure of merit of the Bi2Te3-based material.

Effect of Ti substitution on the thermoelectric properties of (Zr,Hf)NiSn half-Heusler compounds

Abstract: The effect of Ti substitution on the thermoelectric properties of (Zr,Hf)NiSn half-Heusler compounds was studied. It was found that the substitution of Ti for (Zr,Hf) reduced the thermal conductivity significantly to a low value of 3.0W∕mK at room temperature. In addition, a remarkable enhancement of the Seebeck coefficient due to Ti substitution was observed. Furthermore, doping of the Sn sites in (Ti,Zr,Hf)NiSn with Sb led to a reduction in the electrical resistivity and to a corresponding enhancement of the power factor. In Sb-doped (Ti,Zr,Hf)NiSn compounds, the dimensionless figure of merit, ZT, increased with the increase in temperature and reached a high maximum value of 1.5 at 700K.

Zintl Phases as Thermoelectric Materials: Tuned Transport Properties of the Compounds CaxYb1–xZn2Sb2†

Abstract: Zintl phases are ideal candidates for efficient thermoelectric materials, because they are typically small-bandgap semiconductors with complex structures. Furthermore, such phases allow fine adjustment of dopant concentration without disrupting electronic mobility, which is essential for optimizing thermoelectric material efficiency. The tunability of Zintl phases is demonstrated with the series Ca_xYb_(1-x)Zn_2Sb_2 (0 <= x <= 1). Measurements of the electrical conductivity, Hall mobility, Seebeck coefficient, and thermal conductivity (in the 300-800 K temperature range) show the compounds to behave as heavily doped semiconductors, with transport properties that can be systematically regulated by varying x. Within this series, x = 0 is the most metallic (lowest electrical resistivity, lowest Seebeck coefficient, and highest carrier concentration), and x = 1 is the most semiconducting (highest electrical resistivity, highest Seebeck coefficient, and lowest carrier concentration), while the mobility is largely independent of x. In addition, the structural disorder generated by the incorporation of multiple cations lowers the overall thermal conductivity significantly at intermediate compositions, increasing the thermoelectric figure of merit, zT Thus, both zT and the thermoelectric compatibility factor (like zT, a composite function of the transport properties) can be finely tuned to allow optimization of efficiency in a thermoelectric device.

Reversible thermoelectric nanomaterials

Abstract: A nanostructured thermoelectric material is described. There is a spatial variation in temperature between a first end (108) and a second end (109, 110) of the material. The material has a substantially delta-like density of states (DOS) and a spatial variation in an energy gap between a central energy of the DOS and a quasi-Fermi energy of the material is proportional to the spatial variation in temperature such that the Seebeck coefficient of the material is substantially spatially invariant. The spatial variation in the energy gap may be determined by inhomogeneous doping (7) or by a spatial variation in the energy of the miniband (102, 104) of the material.

Nanostructured thermoelectric materials

Abstract: High values of thermoelectric figures of merit ZT, ranging from ZT=1.6 at 300 K to ZT=3 at 550 K, are reported for Bi-doped n-type PbSeTe/PbTe quantum-dot superlattice (QDSL) samples grown by molecular beam epitaxy (MBE). These ZT values were determined by directly measuring Seebeck coefficients and electrical conductivities and using the low lattice thermal conductivity value (∼3.3 mW/cm-K) determined experimentally from measurements of a one-legged thermoelectric cooler. Initial experiments have also shown that high values of ZT (∼1.1 at 300 K) are achievable for complementary Na-doped p-type PbSeTe/PbTe QDSL samples, in which the conduction and valence bands mirror those in the Bi-doped Pb chalcogenides.

Thermopower enhancement in PbTe with Pb precipitates

Abstract: The thermoelectric power of polycrystalline PbTe samples containing nanometer-sized precipitates of Pb metal is enhanced over that of bulk PbTe. Samples of PbTe containing excess Pb and Ag were prepared using conventional metallurgical heat treatments. These samples are shown, by x-ray diffraction, by microscopy, and by the presence of a superconductive transition, to contain Pb precipitates with sizes on the order of 30–40nm. The thermopower enhancement is related to an increase in the energy dependence of the relaxation time, as evidenced by a complete set of measurements of thermoelectric and thermomagnetic transport coefficients.

Large thermoelectric performance of heavily Nb-doped SrTiO3 epitaxial film at high temperature

Abstract: Carrier concentration dependence of the thermoelectric figure of merit, ZT of SrTiO3 at high-temperature (1000 K) is clarified using heavily Nb-doped SrTiO3 epitaxial films, which were grown on insulating (100)-oriented LaAlO3 single-crystalline substrates by a pulsed-laser deposition method. Carrier concentration, Hall mobility, Seebeck coefficient, and thermal conductivity of Nb-doped SrTiO3 epitaxial films were experimentally evaluated at 1000 K with an aid of theoretical analysis. ZT of Nb-doped SrTiO3 increases with Nb concentration and it reaches ∼0.37 (20% Nb doped), which is the largest value among n-type oxide semiconductors ever reported.

Thermoelectric properties of Bi-doped Mg2Si semiconductors

Abstract: The thermoelectric properties of Bi-doped Mg2Si (Mg2Si:Bi=1:x) fabricated by spark plasma sintering process have been characterized by Hall effect measurements at 300 K and by measurements of electrical resistivity ( ρ ) , Seebeck coefficient (S), and thermal conductivity ( κ ) between 300 and 900 K. Bi-doped Mg2Si samples are n-type in the measured temperature range. The electron concentration of Bi-doped Mg2Si at 300 K ranges from 1.8×1019 cm−3 for the Bi concentration x = 0.001 to 1.1×1020 cm−3 for x = 0.02 . The solubility limit of Bi in Mg2Si is estimated to be about 1.3 at% and first-principles calculation revealed that Bi atoms are expected to be primarily located at the Si sites in Mg2Si. The electrical resistivity, Seebeck coefficient, and thermal conductivity are strongly affected by the Bi concentration. The sample of x = 0.02 shows a maximum value of the figure of merit, ZT, is 0.86 at 862 K.

Thermopower Enhancement in PbTe with Pb Precipitates

Abstract: The thermoelectric power of polycrystalline PbTe samples containing nanometer-sized precipitates of Pb metal is enhanced over that of bulk PbTe. Samples of PbTe containing excess Pb and Ag were prepared using conventional metallurgical heat treatments. These samples are shown, by x-ray diffraction, by microscopy, and by the presence of a superconductive transition, to contain Pb precipitates with sizes on the order of 30–40nm. The thermopower enhancement is related to an increase in the energy dependence of the relaxation time, as evidenced by a complete set of measurements of thermoelectric and thermomagnetic transport coefficients.

Finite elements for thermoelectric device analysis in ANSYS

Abstract: A new set of ANSYS coupled-field elements enables users to accurately and efficiently analyze thermoelectric devices. This paper reviews the finite element formulation, which, in addition to Joule heating, includes Seebeck, Peltier, and Thomson effects. Examples of steady-state and transient simulations of a thermoelectric generator and a single-stage Peltier cooler are presented for thermoelectric analysis verification. An analysis of a multistage thermoelectric cooler is performed to demonstrate ANSYS parametric analysis capability.

Ag9TlTe5: A high-performance thermoelectric bulk material with extremely low thermal conductivity

Abstract: We studied a high-performance thermoelectric material whose chemical formula is Ag9TlTe5. Ag9TlTe5 is simple and easy to prepare. Its highest dimensionless figure of merit (ZT) value is 1.23, obtained at 700K. The values of individual thermoelectric properties at 700K are 2.63×10−4Ωm for electrical resistivity, 319μVK−1 for Seebeck coefficient, and 0.22Wm−1K−1 for thermal conductivity. Ag9TlTe5 is a unique material combining extremely low thermal conductivity and relatively low electrical resistivity.

High performance n-type PbTe-based materials for thermoelectric applications

Abstract: Lead telluride-based compounds are known for their favorable thermoelectric properties in the 50–600 °C temperature range. The transport properties of homogeneous, cold-compacted and sintered PbI 2 -doped PbTe samples were measured and compared to those of cast samples with similar dopant concentrations. Such a comparison is mandatory in order to determine the potential of graded samples, prepared by powder metallurgy, for thermoelectric applications. The present work focuses on improving the thermoelectric efficiency of PbTe-based materials by functional grading and by taking advantage of the specific features of indium as dopant element. The potential for achieving high thermoelectric efficiency in In-doped n-type PbTe-based thermoelectric compounds is described, and is compared to that of PbI 2 -doped PbTe. Design, synthesis and characterization procedures are reported for fabricating In- and PbI 2 -doped PbTe compounds with desired composition profiles.

Thermoelectric properties of individual electrodeposited bismuth telluride nanowires

Abstract: For an electrodeposited bismuth telluride (BixTe1−x) nanowire from one batch with x found to be about 0.46, the Seebeck coefficient (S) was measured to be 15%–60% larger than the bulk values at temperature 300K. For four other nanowires from a different batch with x≈0.54, S was much smaller than the bulk values. The electrical conductivity of the nanowires showed unusually weak temperature dependence and the values at 300K were close to the bulk values. Below 300K, phonon-boundary scattering dominated phonon-phonon Umklapp scattering in the nanowires, reducing the lattice thermal conductivity.

Nanostructured bulk thermoelectric material

Abstract: A thermoelectric material comprises two or more components, at least one of which is a thermoelectric material. The first component is nanostructured, for example as an electrically conducting nanostructured network, and can include nanowires, nanoparticles, or other nanostructures of the first component. The second component may comprise an electrical insulator, such as an inorganic oxide, other electrical insulator, other low thermal conductivity material, voids, air-filled gaps, and the like. Additional components may be included, for example to improve mechanical properties. Quantum size effects within the nanostructured first component can advantageously modify the thermoelectric properties of the first component. In other examples, the second component may be a thermoelectric material, and additional components may be included.

High-yield synthesis of single-crystalline antimony telluride hexagonal nanoplates using a solvothermal approach.

Abstract: We report a high-yield synthesis of single-crystal hexagonal Sb2Te3 nanoplates using a solvothermal approach. The experimental results show that the concentration of capping agent CTAB played a key role in the formation of nanoplates. This new nanostructure may provide opportunity for the exploration of novel thermoelectric properties and have potential applications in thermoelectric nanodevices.

Preparation of Ca3Co4O9 and Improvement of its Thermoelectric Properties by Spark Plasma Sintering

Abstract: The precursor powders of Ca3Co4O9 were synthesized by a sol–gel method. The results of X-ray diffraction and thermogravimetric and differential thermal analyses patterns indicate that pure Ca3Co4O9 powders could be obtained by calcining the precursor at 800°C for 2 h. High dense Ca3Co4O9 ceramic samples (∼99% of theoretical density) were prepared by the spark plasma sintering (SPS) method. Compared with the conventional sintering (CS), the SPS samples exhibit much higher electrical conductivity and power factor which are respectively about 118 S/cm and 3.51 × 10−4 W·(m·K2)−1. The SPS method is greatly effective for improving the thermoelectric properties of Ca3Co4O9 oxide ceramics.

Enhanced thermoelectric performance in PbTe-based superlattice structures from reduction of lattice thermal conductivity

Abstract: We have fabricated two-dimensional n-type PbTe∕PbTe0.75Se0.25 structures using an evaporation process. In optimized films exhibiting a high-quality superlattice structure, a significant reduction in lattice thermal conductivity has been experimentally measured. The reduction would indicate enhanced thermoelectric device performance compared to standard PbTeSe alloys given that the electrical components, specifically, the Seebeck coefficient and electrical resistivity, were not observed to deteriorate from bulk values. The analysis of these films shows continuous layers with a true two-dimensional superlattice structure, as opposed to the PbTe∕PbSe system that exhibits zero-dimensional structures from self-assembly. The room-temperature measurement of cross-plane figure-of-merit in a n-type PbTe∕PbTe0.75Se0.25 device structure by the transient method has been combined with temperature-dependent measurements of in-plane resistivity and Seebeck coefficient to yield evidence of enhanced thermoelectric perform...

Modeling and analysis of thermoelectric modules

Abstract: The objective of this work was to develop a SPICE compatible equivalent circuit of a thermoelectric module (TEM). A methodology is developed for extracting the parameters of the proposed model from manufacturers' data of thermoelectric coolers (TEC) and thermoelectric generators (TEG). The model could be helpful for analyzing the drive requirements of TECs and loading effects of TECs. The present model is compatible with PSPICE or other electric circuit simulators. An important feature of the model is its ability to generate small signal transfer functions that can be used to design feedback networks for temperature control applications.

Fabrication and thermoelectric performance of textured n-type Bi2(Te,Se)3 by spark plasma sintering

Abstract: The n-type Bi 2 (Te,Se) 3 thermoelectric materials with preferred grain orientation have been fabricated through the spark plasma sintering (SPS) technique. The c -axis of the grains in the sintered samples were preferentially oriented parallel to the pressing direction, the orientation factor of the (0 0 l ) planes changed from 0.4 to 0.85 with the sintering conditions. The anisotropy was investigated by measuring the electrical conductivities in the two directions perpendicular and parallel to the pressing direction. The optimal figure of merit ZT ( ZT = α 2 σT / κ ) of the sintered materials in the direction perpendicular to the pressing direction was comparative to that of the zone-melted materials in the same crystallographic direction, while the bending strength reached about 80 MPa, which is 7–8 times of that of the zone-melted materials.

Low-Dimensional Thermoelectricity

Abstract: Thermoelectric materials are used as solid-state heat pumps and as power generators The low e‐ciency of devices based on conventional bulk thermoelectric materials conflnes their applications to niches in which their advantages in compactness and controllability outweigh that drawback Recent developments in nanotechnologies have led to the development of thermoelectric nano-materials with double the e‐ciency of the best bulk materials, opening several new classes of applications for thermoelectric energy conversion technology We review here flrst the physical mechanisms that result in the superior thermoelectric performance of low-dimensional solids, compared to bulk thermoelectric materials: they are a reduction of the lattice thermal conductivity, and an increase in the Seebeck coe‐cient S for a given carrier density The second part of this review summarizes experimental results obtained on macroscopic arrays of bismuth, antimony, and zinc nanowires with diameters ranging from 200 to 7 nm We show how size-quantization efiects greatly increase S for a given carrier concentration, as long as the diameter of the nanowires remains above 9 nm, below which localization efiects start dominating In a third part, we give data on PbTe nanocomposites, particularly bulk samples containing 30 nm diameter Pb inclusions These inclusions afiect the electron scattering in such a way as to again increase the Seebeck coe‐cient

Structural, optical and electrical properties of chemically sprayed CdO thin films

Abstract: The cadmium oxide (CdO) thin films have been deposited onto amorphous and fluorine doped tin oxide (FTO) glass substrates using spray pyrolysis technique. The aqueous solution containing precursor of Cd has been used to obtain good quality deposits at optimized preparative parameters. The films have been characterized by techniques such as X-ray diffraction (XRD), optical absorption, electrical resistivity and thermoelectric power (TEP) measurements. The XRD study reveals that the films are polycrystalline with cubic structure. Optical absorption studies reveal that the value of absorption coefficient is in the order of 10 4 cm −1 , indicating direct band to band transition with band gap energy 2.26 eV, close to its value of intrinsic band gap energy. The electrical characterization shows that the electrical resistivity ( ρ ) is of the order 10 −3 Ω cm and it decreases with increase in temperature indicate the samples are semiconducting in nature. The value of activation energy is found to be 0.077 eV. TEP measurement shows the thermoelectric voltage for CdO films is positive towards the hot end, indicating n-type behavior of sample. The value of TEP increases with increase in temperature. The Hall effect measurement study reveals that the carrier concentration ( n ), Hall coefficients ( R H ) and carrier mobility ( μ H ) are of the order of 10 23 cm −3 , 10 −8 cm 3 /C and 10 −4 cm −2 /V s, respectively.

Thermoelectric power factor in semiconductors with buried epitaxial semimetallic nanoparticles

Abstract: We have grown composite epitaxial materials that consist of semimetallic ErAs nanoparticles embedded in a semiconducting In0.53Ga0.47As matrix both as superlattices and randomly distributed throughout the matrix. The presence of these particles increases the free electron concentration in the material while providing scattering centers for phonons. We measure electron concentration, mobility, and Seebeck coefficient of these materials and discuss their potential for use in thermoelectric power generators.