Showing papers on "Thermoelectric effect published in 2004"
TL;DR: In the temperature range 600 to 900 kelvin, the AgPbmSbTe2+m material is expected to outperform all reported bulk thermoelectrics, thereby earmarking it as a material system for potential use in efficient thermoeLECTric power generation from heat sources.
Abstract: The conversion of heat to electricity by thermoelectric devices may play a key role in the future for energy production and utilization. However, in order to meet that role, more efficient thermoelectric materials are needed that are suitable for high-temperature applications. We show that the material system AgPb m SbTe 2+ m may be suitable for this purpose. With m = 10 and 18 and doped appropriately, n -type semiconductors can be produced that exhibit a high thermoelectric figure of merit material ZT max of ∼2.2 at 800 kelvin. In the temperature range 600 to 900 kelvin, the AgPb m SbTe 2+ m material is expected to outperform all reported bulk thermoelectrics, thereby earmarking it as a material system for potential use in efficient thermoelectric power generation from heat sources.
2,716 citations
TL;DR: In this article, Majumdar argues that the interdisciplinary combination of thermoelectric research with microelectronics and nanotechnology will have a positive impact on both fields, and proposes a new technique for measuring thermodynamic properties over nanometer scales.
Abstract: Thermoelectrics are devices that convert heat to electricity directly, or vice versa. To be technologically useful, thermoelectric materials with high efficiency must be found, along with better tools to understand them. In his Perspective,
Majumdar
discusses the reports by
Hsu
et al .
and
Lyeo
et al .
that tackle these issues. Hsu
et al . have found a new bulk material that exhibits a so-called figure of merit with a value around 2, which is an encouraging step on the road to materials that could compete with conventional thermodynamic devices such as power generators and refrigerators. Lyeo
et al . report on a new technique for measuring thermoelectric properties over nanometer scales. The interdisciplinary combination of thermoelectric research with microelectronics and nanotechnology, Majumdar argues, will have a positive impact on both fields.
916 citations
TL;DR: This work shows through a comprehensive structural analysis using single-crystal X-ray and powder-synchrotron-radiation diffraction methods, that both the electronic and thermal properties of Zn4Sb3 can be understood in terms of unique structural features that have been previously overlooked.
Abstract: By converting waste heat into electricity, thermoelectric generators could be an important part of the solution to today's energy challenges. The compound Zn_4Sb_3 is one of the most efficient thermoelectric materials known. Its high efficiency results from an extraordinarily low thermal conductivity in conjunction with the electronic structure of a heavily doped semiconductor. Previous structural studies have been unable to explain this unusual combination of properties. Here, we show through a comprehensive structural analysis using single-crystal X-ray and powder-synchrotron-radiation diffraction methods, that both the electronic and thermal properties of Zn_4Sb_3 can be understood in terms of unique structural features that have been previously overlooked. The identification of Sb^(3-) ions and Sb_2^(4-) dimers reveals that Zn_4Sb_3 is a valence semiconductor with the ideal stoichiometry Zn_(13)Sb_(10). In addition, the structure contains significant disorder, with zinc atoms distributed over multiple positions. The discovery of glass-like interstitial sites uncovers a highly effective mechanism for reducing thermal conductivity. Thus Zn_4Sb_3 is in many ways an ideal 'phonon glass, electron crystal' thermoelectric material.
760 citations
TL;DR: In this article, the first thermoelectric devices based on the V-VI-compounds Bi/sub 2/Te/sub 3/ and (Bi,Sb) were described.
Abstract: This work describes the first thermoelectric devices based on the V-VI-compounds Bi/sub 2/Te/sub 3/ and (Bi,Sb)/sub 2/Te/sub 3/ which can be manufactured by means of regular thin film technology in combination with microsystem technology. Fabrication concept, material deposition for some 10-μm-thick layers and the properties of the deposited thermoelectric materials will be reported. First device properties for Peltier-coolers and thermogenerators will be shown as well as investigations on long term and cycling stability. Data on metal/semiconductor contact resistance were extracted form device data. Device characteristics like response time for a Peltier-cooler and power output for a thermogenerator will be compared to commercial devices.
387 citations
TL;DR: In this article, the lattice thermal conductivity of ZrNiSn-based half-Heusler thermoelectric compounds for temperatures where phonon scattering is dominated by Umklapp and point defect scattering is calculated.
Abstract: We present a model calculation of the lattice thermal conductivity of ZrNiSn-based half-Heusler thermoelectric compounds for temperatures where phonon scattering is dominated by Umklapp and point defect scattering. The difference in mass between impurity and host atoms dominates point defect scattering for alloying Hf on the Zr sublattice, whereas differences in size and interatomic coupling forces between impurity and host atoms dominate point defect scattering for alloying Pd on the Ni sublattice. Because Pt is heavier and larger than Pd, we predict that Pt will further reduce lattice thermal conductivity when alloyed on the Ni sublattice of these half-Heusler compounds.
364 citations
TL;DR: In this article, the cooling capacity, junction temperature, coefficient of performance, and required heat sink thermal resistance at the TEC hot side were computed for thermoelectric cooler applications in the electronic cooling.
287 citations
TL;DR: The high concentration of grain boundaries provided by nanostructuring is expected to lower the thermal conductivity of thermoelectric materials, which favors an increase in their temperature as mentioned in this paper.
Abstract: The high concentration of grain boundaries provided by nanostructuring is expected to lower the thermal conductivity of thermoelectric materials, which favors an increase in their thermoelectric fi ...
264 citations
TL;DR: Using thermoelectric compatibility, efficient TEG generators are rationally designed in this article, with examples of compatible and incompatible systems and materials proposed for targeted development, and a discussion of compatibility and compatibility issues.
Abstract: Using thermoelectric compatibility, efficient thermoelectric generators are rationally designed. With examples, compatible and incompatible systems are explained and materials proposed for targeted development.
250 citations
TL;DR: In this paper, the relative contributions of electronic and lattice effects to figure of merit enhancement are studied, for nanowires made of InSb, InAs, GaAs, and InP, as a function of nanowire thickness.
Abstract: The relative contributions of electronic and lattice effects to figure of merit enhancement are studied, for nanowires made of InSb, InAs, GaAs, and InP, as a function of nanowire thickness. The main thermoelectric magnitudes are computed in the bulk and nanowire cases by the exact solution of the Boltzmann transport equation. The lattice thermal conductivity is obtained by a full dispersions transmission function approach, using interatomic potentials for the system. An upper limit to the maximum power factor is obtained for narrow thickness. InSb nanowires stand out as the best choice for thermoelectric applications among the four compounds considered, while GaAs and InP are not expected to be suitable for practical applications.
242 citations
TL;DR: In this paper, the authors show that the material system AgPb m SbTe 2+ m may be suitable for high-temperature applications with m = 10 and 18 and doped appropriately, n -type semiconductors can be produced that exhibit a high thermoelectric figure of merit material ZT max of ∼2.2 at 800 kelvin.
Abstract: The conversion of heat to electricity by thermoelectric devices may play a key role in the future for energy production and utilization. However, in order to meet that role, more efficient thermoelectric materials are needed that are suitable for high-temperature applications. We show that the material system AgPb m SbTe 2+ m may be suitable for this purpose. With m = 10 and 18 and doped appropriately, n -type semiconductors can be produced that exhibit a high thermoelectric figure of merit material ZT max of ∼2.2 at 800 kelvin. In the temperature range 600 to 900 kelvin, the AgPb m SbTe 2+ m material is expected to outperform all reported bulk thermoelectrics, thereby earmarking it as a material system for potential use in efficient thermoelectric power generation from heat sources.
236 citations
TL;DR: In this paper, the authors analyzed the flows of heat and electricity in a column-type micro-thermoelectric cooler by modeling the various interfacial resistances, including barrier tunneling and phonon boundary resistances.
Patent•
15 Mar 2004TL;DR: In this article, a tissue ablation probe, system, and method are provided, which comprises an elongated member, an ablative element mounted on the distal end of the elongated members, and at least one thermoelectric device mounted to the member in thermal communication with the ablative elements.
Abstract: A tissue ablation probe, system, and method are provided. The ablation probe comprises an elongated member, an ablative element mounted on the distal end of the elongated member, and at least one thermoelectric device mounted to the member in thermal communication with the ablative element. The system may include the ablation probe, thermal control circuitry for controlling the thermal effect of the thermoelectric device, and an ablation source for suppying ablation energy to the ablative element. A plurality of circumferentially distributed thermoelectric devices can be provided, so that radial tissue sectors can be selectively affected by independently controlling the thermal effect of the thermoelectric devices. In one embodiment, the thermoelectric device(s) can be used to cool a heat ablative element. In another embodiment, the thermoelectric device(s) can be used to heat an ablative element, thereby forming a heat ablative element. In still another embodiment, the thermoelectric device(s) can be used to cryogenically cool an ablative element, thereby forming a cryogenic ablative element.
TL;DR: In this paper, the design, fabrication and testing of a novel thermoelectric device comprised of arrays of silicon nanowires embedded in a polymer matrix was discussed, where parylene, a low thermal conductivity and extremely conformal polymer, was embedded within the arrays.
Abstract: This paper discusses the design, fabrication and testing of a novel thermoelectric device comprised of arrays of silicon nanowires embedded in a polymer matrix. By exploiting the low-thermal conductivity of the composite and presumably high-power factor of the nanowires, a thermoelectric figure of merit, higher than the corresponding bulk value, should result. Arrays were first synthesized using a vapor-liquid-solid (VLS) process leading to one-dimensional (1-D) growth of single-crystalline nanowires. To provide structural support while maintaining thermal isolation between nanowires, parylene, a low thermal conductivity and extremely conformal polymer, was embedded within the arrays. Mechanical polishing and oxygen plasma etching techniques were used to expose the nanowire tips and a metal contact was deposited on the top surface. Scanning electron micrographs (SEMs) illustrate the results of the fabrication processes. Using a modification of the 3/spl omega/ technique, the effective thermal conductivity of the nanowire matrix was measured and 1 V characteristics were also demonstrated. An assessment of the suitability of this nanocomposite for high thermoelectric performance devices is given.
TL;DR: Thermoelectric power measurements have been performed for an ordered oxygen-deficient perovskite, HoBaCo2O5.5, in which the alternative layers of CoO6 octahedra and of [CoO(5)](2) bipyramids are occupied by Co3+ species.
Abstract: Thermoelectric power measurements have been performed for an ordered oxygen-deficient perovskite, HoBaCo2O5.5, in which the alternative layers of CoO6 octahedra and of [CoO(5)](2) bipyramids are occupied by Co3+ species. The T-dependent Seebeck coefficient S shows a clear change of the conduction regime at the metal-insulator (MI) transition (T(MI) approximately 285 K). The sign change of S from S 0 can be explained assuming that a spin state transition occurs at T(MI). In the metallic state, Co2+ e(g) electrons are moving in a broad band on the background of high or intermediate spin Co3+ species. In contrast, the insulating behavior may result from the Co3+ spin state transition to a low-spin Co3+ occurring in the octahedra. In this phase the transport would occur by hopping of the low-spin Co(4+)t(2g) holes, whereas the high-spin Co2+ electrons become immobilized due to a spin blockade.
TL;DR: Optimization studies on the thermoelectric properties with a variety of doping agents show that the electrical properties of CsBi(4)Te(6) can be tuned to yield an optimized thermoeLECTric material which is promising for low-temperature applications.
Abstract: The highly anisotropic material CsBi4Te6 was prepared by the reaction of Cs/Bi2Te3 around 600 °C. The compound crystallizes in the monoclinic space group C2/m with a = 51.9205(8) A, b = 4.4025(1) A, c = 14.5118(3) A, β = 101.480(1)°, V = 3250.75(11) A3, and Z = 8. The final R values are R1 = 0.0585 and wR2 = 0.1127 for all data. The compound has a 2-D structure composed of NaCl-type [Bi4Te6] anionic layers and Cs+ ions residing between the layers. The [Bi4Te6] layers are interconnected by Bi−Bi bonds at a distance of 3.2383(10) A. This material is a narrow gap semiconductor. Optimization studies on the thermoelectric properties with a variety of doping agents show that the electrical properties of CsBi4Te6 can be tuned to yield an optimized thermoelectric material which is promising for low-temperature applications. SbI3 doping resulted in p-type behavior and a maximum power factor of 51.5 μW/cm·K2 at 184 K and the corresponding ZT of 0.82 at 225 K. The highest power factor of 59.8 μW/cm·K2 at 151 K was o...
TL;DR: In this article, the local thermoelectric power of semiconductor nanostructures with the use of ultra-high-vacuum scanning microscopy was probed.
Abstract: We have probed the local thermoelectric power of semiconductor nanostructures with the use of ultrahigh-vacuum scanning thermoelectric microscopy. When applied to a p-n junction, this method reveals that the thermoelectric power changes its sign abruptly within 2 nanometers across the junction. Because thermoelectric power correlates with electronic structure, we can profile with nanometer spatial resolution the thermoelectric power, band structures, and carrier concentrations of semiconductor junctions that constitute the building blocks of thermoelectric, electronic, and optoelectronic devices.
TL;DR: The experimental electron density of the high-performance thermoelectric material Zn4Sb3 has been determined by maximum entropy (MEM) analysis of short-wavelength synchrotron powder diffraction data, found to be more accurate than conventional single-crystal data due to the reduction of common systematic errors.
Abstract: The experimental electron density of the high-performance thermoelectric material Zn4Sb3 has been determined by maximum entropy (MEM) analysis of short-wavelength synchrotron powder diffraction data. These data are found to be more accurate than conventional single-crystal data due to the reduction of common systematic errors, such as absorption, extinction and anomalous scattering. Analysis of the MEM electron density directly reveals interstitial Zn atoms and a partially occupied main Zn site. Two types of Sb atoms are observed: a free spherical ion (Sb3-) and Sb2(4-) dimers. Analysis of the MEM electron density also reveals possible Sb disorder along the c axis. The disorder, defects and vacancies are all features that contribute to the drastic reduction of the thermal conductivity of the material. Topological analysis of the thermally smeared MEM density has been carried out. Starting with the X-ray structure ab initio computational methods have been used to deconvolute structural information from the space-time data averaging inherent to the XRD experiment. The analysis reveals how interstitial Zn atoms and vacancies affect the electronic structure and transport properties of beta-Zn4Sb3. The structure consists of an ideal A12Sb10 framework in which point defects are distributed. We propose that the material is a 0.184:0.420:0.396 mixture of A12Sb10, A11BCSb10 and A10BCDSb10 cells, in which A, B, C and D are the four Zn sites in the X-ray structure. Given the similar density of states (DOS) of the A12Sb10, A11BCSb10 and A10BCDSb10 cells, one may electronically model the defective stoichiometry of the real system either by n-doping the 12-Zn atom cell or by p-doping the two 13-Zn atom cells. This leads to similar calculated Seebeck coefficients for the A12Sb10, A11BCSb10 and A10BCDSb10 cells (115.0, 123.0 and 110.3 microV K(-1) at T=670 K). The model system is therefore a p-doped semiconductor as found experimentally. The effect is dramatic if these cells are doped differently with respect to the experimental electron count. Thus, 0.33 extra electrons supplied to either kind of cell would increase the Seebeck coefficient to about 260 microV K(-1). Additional electrons would also lower sigma, so the resulting effect on the thermoelectric figure of merit of Zn4Sb3 challenges further experimental work.
TL;DR: In this article, a detailed theory of nonisothermal electron transport perpendicular to multilayer superlattice structures is presented, and the currentvoltage and cooling power density are calculated using Fermi-Dirac statistics, density-of-states for a finite quantum well and the quantum mechanical reflection coefficient.
Abstract: A detailed theory of nonisothermal electron transport perpendicular to multilayer superlattice structures is presented. The current–voltage (I–V) characteristics and the cooling power density are calculated using Fermi–Dirac statistics, density-of-states for a finite quantum well and the quantum mechanical reflection coefficient. The resulting equations are valid in a wide range of temperatures and electric fields. It is shown that conservation of lateral momentum plays an important role in the device characteristics. If the lateral momentum of the hot electrons is conserved in the thermionic emission process, only carriers with sufficiently large kinetic energy perpendicular to the barrier can pass over it and cool the emitter junction. However, if there is no conservation of lateral momentum, the number of electrons participating in a thermionic emission will increase. This has a significant effect on the I–V measurements as well as the cooling characteristics. Theoretical calculations are compared with...
TL;DR: In this article, the temperature dependences of the electrical resistivity, Seebeck coefficient, and thermal conductivity have been measured on these compounds in the 300-800 K temperature range and they identified Ca as being a true n-type filler atom and offer, for this family of skutterudite, several valuable insights into the potential of Ca to provide good thermoelectric performance.
Abstract: Partially filled CoSb3 skutterudite compounds are emerging materials for thermoelectric energy conversion at high temperature. CaxCo4Sb12 with different Ca contents has been prepared by the conventional metallurgical route. The temperature dependences of the electrical resistivity, Seebeck coefficient, and thermal conductivity have been measured on these compounds in the 300–800 K temperature range. These measurements have identified Ca as being a true n-type filler atom and offer, for this family of skutterudite, several valuable insights into the potential of Ca to provide good thermoelectric performance.
Patent•
02 Dec 2004TL;DR: In this article, high performance thin film thermoelectric couples and methods of making the same are disclosed. And they allow fabrication of at least microwatt to watt-level power supply devices operating at voltages greater than one volt even when activated by only small temperature differences.
Abstract: High performance thin film thermoelectric couples and methods of making the same are disclosed. Such couples allow fabrication of at least microwatt to watt-level power supply devices operating at voltages greater than one volt even when activated by only small temperature differences.
01 Mar 2004
TL;DR: This method can profile with nanometer spatial resolution the thermoelectric power, band structures, and carrier concentrations of semiconductor junctions that constitute the building blocks of thermoeLECTric, electronic, and optoelectronic devices.
Abstract: We have probed the local thermoelectric power of semiconductor nanostructures with the use of ultrahigh-vacuum scanning thermoelectric microscopy. When applied to a p-n junction, this method reveals that the thermoelectric power changes its sign abruptly within 2 nanometers across the junction. Because thermoelectric power correlates with electronic structure, we can profile with nanometer spatial resolution the thermoelectric power, band structures, and carrier concentrations of semiconductor junctions that constitute the building blocks of thermoelectric, electronic, and optoelectronic devices.
Patent•
17 Aug 2004
TL;DR: In this paper, a number of compact, high efficiency and high power density thermoelectric systems utilizing the advantages of thermal isolation are described, which exhibit high system efficiency and power density.
Abstract: A number of compact, high-efficiency and high-power density thermoelectric systems utilizing the advantages of thermal isolation are described. Such configurations exhibit high system efficiency and power density. Some configurations exhibit a substantial reduction in the amount of thermoelectric material required.
TL;DR: In this paper, the Eu substitution has been investigated on polycrystalline Ca 3− x Eu x Co 4 O 9+ δ (x = 0, 0.15,0.3 and 0.45) samples using a sol-gel process followed by SPS sintering.
Patent•
03 May 2004
TL;DR: In this paper, a thermoelectric generating device with an introducing passage introduced a part of the exhaust gas from an engine into an intake of the engine is described. And a controller controls an opening degree of the introducing valve according to a load of the generator.
Abstract: A thermoelectric generating device has a thermoelectric element which utilizes an exhaust gas from an engine as a high temperature heat source and an engine coolant as a low temperature heat source in order to generate electricity. An introducing passage introduces a part of the exhaust gas passed through the thermoelectric element into an intake of the engine. An introducing valve opens and closes the introducing passage. A controller controls an opening degree of the introducing valve according to a load of the engine.
TL;DR: In this article, BaTiO3−SrTiOO3 solid solutions were prepared and the thermoelectric properties were measured from room temperature to 873 K. The thermal conductivity increased with increasing Sr concentration.
TL;DR: In this paper, X-ray diffraction was used to study polycrystalline samples of CaMn 1− x M x O 3 (M=Nb and Ta, 0≤ x ≤ 0.30).
TL;DR: In this paper, structural, chemical, and transport properties of a series of CoSb3 skutterudite samples modified by fullerene additions of 0, 0.52, 3.28, 4.77, and 6.54 mass were measured.
Abstract: We have measured the structural, chemical, and transport properties of a series of CoSb3 skutterudite samples modified by fullerene additions of 0, 0.52, 3.28, 3.90, 4.77, and 6.54 mass%. Fullerene is a 60-atom carbon molecule that forms microsize clusters between the grain boundaries of CoSb3. We observed that the dominant scattering mechanism in the electrical transport changes from impurity scattering to grain-boundary scattering near a C60 content of ∼5–6 mass%, and that thermal conductivity decreases with increasing C60 content. A significant increase in the thermoelectric figure of merit is achieved for 6.54 mass% C60 compared to the pure CoSb3.
TL;DR: In this article, the authors explored many cobalt-based oxide systems and encountered the compound Ca3Co4O9, which is a misfit-layered compound consisting of two interpenetrating monoclinic subsystems.
TL;DR: In this article, tunneling spectroscopy of Bi2Se3 and Bi2Te3 layered narrow gap semiconductors reveals finite in-gap density of states and suppressed conduction in the energy range of high valence-band states.
Abstract: Scanning tunneling spectroscopy of Bi2Se3 and Bi2Te3 layered narrow gap semiconductors reveals finite in-gap density of states and suppressed conduction in the energy range of high valence-band states. Electronic structure calculations suggest that the surface effects are responsible for these properties. Conversely, the interlayer coupling has a strong effect on the bulk near-gap electronic structure. These properties may prove to be important for the thermoelectric performance of these and other related chalcogenides.
TL;DR: In this paper, the dimensionless thermoelectric figure-of-merit of Bi2Te3 based alloys was investigated under a large temperature difference using a recently reported "open/short circuit" measurement technique.
Abstract: The dimensionless thermoelectric figure-of-merit, ZT, of Bi2Te3 based alloys was investigated under a large temperature difference using a recently reported 'open/short circuit' measurement technique. It is shown that the measured ZT decreases with an increase in temperature difference. Theoretical analysis indicates that this dependence can be explained by taking into account the Thomson effect. An equation is obtained for a modified thermoelectric figure-of-merit which is valid for measurement over large temperature differences.