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Showing papers on "Thermoelectric effect published in 1968"


Journal ArticleDOI
F.D. Rosi1
TL;DR: In this article, a review of experimental data and the theoretical interpretation of these data on thermal transport and phonon scattering mechanisms in alloy semiconductors at high temperatures is given, with a focus on the study of the thermoelectric properties in GeSi alloys, as well as their application in stable power generating devices operating at temperatures up to 1025°C.
Abstract: Thermoelectric phenomena result from the diffusion of electrons and phonons along a temperature gradient in electrically conducting solids. These diffusion currents are determined by the concentration of these particles, and their interaction with each other as well as with impurities and defects. By using simple physical arguments, expressions are derived for the basic thermoelectric transport parameters. These are the electrical and thermal conductivities and the Seebeck coefficient. For application of thermoelectricity to power generation, it is desirable to maximize the electronic diffusion and to minimize the phonon diffusion. The physical and materials requirements to achieve these desired transport properties will also be discussed, and particular attention will be given to a review of experimental data and the theoretical interpretation of these data on thermal transport and phonon scattering mechanisms in alloy semiconductors at high temperatures. Emphasis will be placed on the study of the thermoelectric properties in GeSi alloys, as well as their application in stable power generating devices operating at temperatures up to 1025°C. For completeness, the paper will also include the status of compound tellurides and their alloys for use up to 500°C, and recent research on the thermoelectric properties of selected III–V compound alloys to be used in a segmented thermocouple arrangement with GeSi alloys for improved power generating efficiency.

216 citations


Journal ArticleDOI
TL;DR: In this article, measurements of electrical conductivity and Seebeck coefficient have been made on p-type cuprous oxide single crystals in the temperature range from 300° to 500°K.

57 citations


Journal ArticleDOI
TL;DR: In this paper, measurements of high-temperature Hall coefficient, electrical conductivity, and thermoelectric power in polycrystalline n-type samples of InAsxSb1−x alloys of extrinsic carrier concentration ~1017/cm3 were made.
Abstract: Measurements have been made of the high-temperature Hall coefficient, electrical conductivity, and thermoelectric power in polycrystalline n-type samples of InAsxSb1−x alloys of extrinsic carrier concentration ~1017/cm3. From the Hall-coefficient data, values of the extrapolated absolute-zero band gap E00 have been determined over the whole alloy range, the thermoelectric power results being used to provide a correction factor to allow for effects of degeneracy. In all cases this correction was found to be very small. The resultant values of E00 for the alloys are somewhat lower than those obtained previously from optical absorption data and show a minimum of 0.17 eV at x ~0.4. From the electrical conductivity data, values of electron mobility μc have been obtained as a function of temperature T and composition x. At all temperatures in the range 0–500 °C, μc is found to vary linearly with x, indicating that the effects of alloy scattering are negligible. For each value of x, μc is found to satisfy the re...

43 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of fabrication by powder processes on the density and thermoelectric properties of an n-type pseudo-binary Bi2Te2.55Se0.45 alloy have been examined.
Abstract: The effects of fabrication by powder processes on the density and thermoelectric properties of an n-type pseudo-binary Bi2Te2.55Se0.45 alloy have been examined. The large effects on the thermoelectric properties are ascribed primarily to the generation and removal of point defects, together with the doping effects of atmospheric contamination in finer powders (−50 mesh).

36 citations


Patent
28 Oct 1968
TL;DR: A thermoelectric apparatus is formed of a plate of heat insulating material having holes therethrough in which are positioned a plurality of P-type and N-type thermoeðric elements.
Abstract: A thermoelectric apparatus is formed of a plate of heatinsulating material having holes therethrough in which are positioned a plurality of P-type and N-type thermoelectric elements. The members of the two types are alternately connected by heat-transfer members on both sides of the plate and in contact with the elements. Bolts extending through the thermoelectric elements connect two of the heat-transfer members and press them against the elements.

35 citations



Journal ArticleDOI
TL;DR: In this paper, the absolute thermoelectric powers of the alkali metals, including the changes at the melting points, are discussed and a short discussion is given on the extent to which experiment and theory are now in agreement.
Abstract: Data are presented on the absolute thermoelectric powers of the alkali metals, including the changes at the melting points, and a short discussion is given on the extent to which experiment and theory are now in agreement. The author is also grateful to A. S. Marwaha for many helpful discussions and to J. W. Harrison of the Metallurgy Division, Harwell, for providing the computer programme.

26 citations


Journal ArticleDOI
TL;DR: The electrical resistivity, Hall coefficient, thermoelectric power, and magnetic susceptibility of polycrystalline samples of thorium tetraboride and thorium hexaboride have been measured over a range of temperatures as discussed by the authors.
Abstract: The electrical resistivity, Hall coefficient, thermoelectric power, and magnetic susceptibility of polycrystalline samples of thorium tetraboride and thorium hexaboride have been measured over a range of temperatures. Both compounds exhibit metallic properties. The carrier concentration, about 2 electrons per thorium atom, is that predicted by the bonding model of Lipscomb and Britten.

21 citations


Journal ArticleDOI
TL;DR: In this paper, the thermoelectric figures of merit of ternary chalcogenides A2IBIVX3, AIBVX2 and A3IBVX4 (AI=Cu; BIV=Ge, Sn; BV=Sb; X=S, Se, Te) were evaluated at room temperature.
Abstract: Electrical conductivity, Seebeck coefficient, thermal conductivity and microhardness of ternary chalcogenides A2IBIVX3, AIBVX2 and A3IBVX4 (AI=Cu; BIV=Ge, Sn; BV=Sb; X=S, Se, Te) were measured and their thermoelectric figures of merit are evaluated at room temperature. All of the compounds have positive Seebeck coefficients. The lattice thermal conductivity increases linearly with the increase of the microhardness for AIBVX2 and A3IBVX4s eries. The Keyes' relationship between lattice thermal conductivity and melting point are applicable for AIBVX2 and A3IBVX4 series. On the other hand, the lattice thermal conductivity of A2IBIVX3 series does not satisfy the usual relationships mentioned above. Values of zmax, the value of the thermoelectric figure of merit at the optimized carrier concentration estimated by the formulas based on the simplified assumptions are in the order of 10-5 deg-1., 10-4 deg-1. and 10-3 deg-1. for sulphides, selenides and tellurides, respectively. The value of zmax of Cu3SbTe4 is estimated to be 2.8×10-3 deg-1.

20 citations


Journal ArticleDOI
TL;DR: In this article, the influence of segregated tellurium phase, determined metallographically, on the thermoelectric figure of merit (Z), electrical conductivity (σ), Seebeck coefficient (α), and thermal conductivity was investigated.
Abstract: A study has been made in n‐type Bi2Te3+x, n‐type Bi2Se0.45Te3+x, and p‐type Bi0.5Sb1.5Te3+x of the influence of segregated tellurium phase, determined metallographically, on the thermoelectric figure of merit (Z), electrical conductivity (σ), Seebeck coefficient (α), and thermal conductivity (κ). It was found that Z and σ at a given α value were reduced by excessive amounts of the Te phase. Calculation using an idealized two‐phase model has shown that in this case circulating currents are unimportant. The effects appear to be due to a redistribution of electrical and thermal current by the Te phase located mostly between cleavage planes where any misalignment can have a strong influence. Zone melting of p‐type Bi0.5Sb1.5Te3.13 at low speeds of about 0.1 cm/h produced an increase in the average value of Z and a decrease in the amount of Te phase.

16 citations


Journal ArticleDOI
TL;DR: In this article, an exploratory investigation of thermoelectric power in three different specific situations was conducted to investigate the effect of extrinsic photoexcitation involving imperfection states in the crystal.
Abstract: Thermoelectric power measurements have seldom been used to investigate the photoelectronic properties of semiconductor crystals. This paper presents the results of an exploratory investigation of thermoelectric power in three different specific situations: (1) the effect on thermoelectric power of extrinsic photoexcitation involving imperfection states in the crystal, (2) the effect on thermoelectric power of optical quenching of photoconductivity, and (3) thermally stimulated thermoelectric power, associated with the emptying of electron and hole traps in the crystal. The increased sensitivity of the thermoelectric effect to two‐carrier phenomena as compared to the Hall effect, makes it a valuable effect for investigating the contribution of electrons and holes to photoelectronic behavior. The results obtained with single‐crystal CdS suggest that: (1) The thermoelectric effect is quite useful in imperfection‐level spectroscopy, (2) Sensitizing imperfections for photoconductivity have a complex dipole‐like structure, and (3) Holes play a larger role in photo‐electronic effects than commonly attributed. Further investigations of the techniques using thermoelectric power are certainly indicated.


Journal ArticleDOI
TL;DR: Isochronal anneal studies have been made on n-and p-type germanium bombarded with Germanium and several substitutional impurities, using the four-point and thermoelectric probes as means of indica as discussed by the authors.
Abstract: Isochronal anneal studies have been made on n- and p-type germanium bombarded with germanium and several substitutional impurities, using the four-point and thermoelectric probes as means of indica...


Journal ArticleDOI
TL;DR: Very large changes of the Seebeck coefficient on the application of a high magnetic field have been observed for extrinsic (Te-doped)Bi 95 Sb 5, and it was found that these changes are compatible with a non-parabolic band structure as mentioned in this paper.

Patent
09 Oct 1968
TL;DR: In this article, the authors present an approach for measuring the effect of different levels of temperature control on the performance of a large-scale simulation of a hot plate and a cold plate.
Abstract: THIS INVENTION COMPRISES AN APPARATUS EMPLOYING THERMOELECTRIC HEAT PUMPS TO EFFECT THE REQUIRED LEVEL OF TEMPERATURE CONTROL NECESSARY TO PROVIDE AN ADEQUATE MEASUREMENT OF THE THERMAL CONDUCTIVITY OF INSULATING FOAMS. THE METHOD OF ESTABLISHING A FIXED THERMAL DIFFERENCE ACROSS THE SAMPLE IS ACCOMPLISHED BY PLACING THE SAMPLE BETWEEN TWO SURFACES WHOSE TEMPERATURES ARE ACCURATELY CONTROLLED. THE COLD PLATE TEMPERATURE IS ACCURATELY SET AND CONTROLLED BY A THERMOELECTRIC HEAT PUMP DRIVEN BY A HIGH GAIN PROPORTIONAL CONTROLLER. THE HOT PLATE IS ALSO OPERATED AT AN ACCURATELY CONTROLLED TEMPERATURE, HEAT BEING SUPPLIED FROM A CLOSE-COUPLED PROPORTIONALLY CONTROLLED LOW MASS HEATER. THE HEAT FLOW THROUGH THE SAMPLE IS MEASURED WITH A HEAT FLOW TRANSDUCER WHICH PRODUCES AN EMF THAT IS PROPORTIONAL TO THE HEAT FLOW PER UNIT TIME AND AREA THROUGH THE FOAM. THE EMF THUS DERIVED IS VOLTAGE DIVIDED BY A SLIDE WIRE WHICH IS MECHANICALLY COUPLED ANALOG CORRECTIONS ARE MADE TO PROVIDE A SIGNAL FOR DIRECT DIGITAL READ-OUT OF "K."

Patent
06 Nov 1968
TL;DR: In this paper, a high pressure resistant compact housing structure is provided which is particularly useful in connection with thermoelectric radioisotope generator constructions and is particularly constructed for use at high external pressures as at great depths in the ocean and is resistant to galvanic corrosion and high pressure.
Abstract: A high pressure resistant compact housing structure is provided which is particularly useful in connection with thermoelectric radioisotope generator constructions. The housing is particularly constructed for use at high external pressures as at great depths in the ocean and is resistant to galvanic corrosion and high pressure. An outer housing shell transfers high pressures to interior structure which absorbs substantially the entire pressure load. Preferably a radioisotope heat source is enclosed in the housing. Heat at both ends of the source is utilized to obtain maximized efficiency of the source in thermoelectric conversion. A novel mounting structure for the heat source and associated thermoelectric conversion means comprises utility mounting plates and associated radiation shielding preferably incorporating a novel double seal arrangement in accordance with this invention. The construction permits low power-weight ratios in high pressure resistant radioisotope thermoelectric generators.


Journal ArticleDOI
TL;DR: In this paper, a theoretical model is proposed which enables the electrical and thermal conductivities of a thermoelectric ingot to be predicted, and measurements of the conductivities in principal directions have been made on good single crystals of alloys in the range 0.20 mol.% Bi2Se3 in Bi2Te3.

Journal ArticleDOI
TL;DR: The thermoelectric powers of alloys of alkalis in alkalis at very low temperatures are calculated in this paper, and the Faber-Ziman theory is found to be semiquantitatively applicable in the corresponding liquids.
Abstract: The thermoelectric powers of alloys of alkalis in alkalis at very low temperatures are calculated, and satisfactory agreement with experiment is obtained. In particular, the correct sign is found for the first time. The Faber-Ziman theory is found to be semiquantitatively applicable in the corresponding liquids.


Journal ArticleDOI
TL;DR: In this paper, an exact theory of staging of heat engines or coolers is given for the case where individual stage efficiencies or coefficients of performance are functions only of the fractional temperature difference ΔT/T between the hot and cold sides of the stage.
Abstract: An exact theory of staging of heat engines or coolers is given for the case where the individual stage efficiencies or coefficients of performance are functions only of the fractional temperature difference ΔT/T between the hot and cold sides of the stage. In this case, it is exactly true that, for an extremum in efficiency or coefficient of performance, the fractional temperature differences of each stage are equal. For the constant ZT case of thermoelectric and thermomagnetic engines and coolers this extremum is a maximum. Z is the isothermal thermoelectric or the adiabatic thermomagnetic figure of merit and T is the absolute temperature. The cases α=constant, ρ ∝ T and κ=constant for the thermoelectric engine or cooler, and α ∝ T−1, ρ ∝ T−1 and κ=constant for the thermomagnetic engine or cooler are considered. Here α, ρ, and κ are, respectively, the appropriate thermopowers, resistivities, and thermal conductivities. Exact expressions are given for the efficiency and coefficient of performance for a si...

Journal ArticleDOI
TL;DR: The most effective process in raising the sample resistivity was the oxidation process and the efficiencies of these heat treatment processes were compared as discussed by the authors, and the effects of heat treatments on the thermoelectric, microwave line width, and dielectric properties of the samples were also reported.
Abstract: Polycrystalline lithium ferrite samples were subjected to a variety of heat treatments. The most effective process in raising the sample resistivity was the oxidation process. The efficiencies of these heat treatment processes were compared. Effects of heat treatments on the thermoelectric, microwave line width, and dielectric properties of the samples were also reported.

Patent
29 Oct 1968
TL;DR: In this paper, an integrated thermoelectric generator/antenna is described, which consists of a sandwich of hot and cold thermolectric elements, such as bismuth and tellurium.
Abstract: This disclosure describes an integrated thermoelectric generator/antenna. An antenna is formed of a sandwich of hot and cold thermoelectric elements, such as bismuth and tellurium. Power storage means are connected to the antenna to receive and store the power generated by the thermoelectric action between the elements. In addition, transmitting and receiving means are connected to the antenna so that the antenna transmits and receives signals. Further, a separate source of heat is connected to the ''''hot'''' thermoelectric element to provide an auxiliary source of heat for that element when the antenna is not receiving energy from a hot body. The invention described herein was made by an employee of the United States Government and may be manufactured and used by or for the Government for governmental purposes without the payment of any royalties thereon or therefor.

Journal ArticleDOI
C. Crevecoeur1, H.J. de Wit1
TL;DR: In this paper, the thermoelectric force and electrical resistivity of MnO were measured at 1100°C in the region of mixed electron-and hole-conduction.

Journal ArticleDOI
TL;DR: In this article, the suitability of molten salts for thermoelectric generation depends on their potential and the ratio of their electrical to thermal conductivities, and the theories and experimental data on these properties have been examined and measured as 0·46 and 0·53 mv degk−1.
Abstract: The suitability of molten salts for thermoelectric generation depends on their thermoelectric potential and the ratio of their electrical to thermal conductivities. The theories and experimental data on these properties have been examined and the thermoelectric potentials of cuprous bromide and cuprous iodide measured as 0·46 and 0·53 mv degk−1. The figure of merit has been estimated for a few of the more promising salts. Molten-salt thermocells have certain advantages over semiconductor thermoelements as there are no contact junction, doping or thermal expansion problems, and they are inexpensive. But the mass transfer between the electrodes forms a major development problem.


Journal ArticleDOI
TL;DR: In this paper, the authors presented a study for the optimization of the coefficient of performance of a thermoelectric heat pump through the use of cascaded stages, where the electrical and thermal conductivities of the n-and p-type elements were assumed to be the same and are constant.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the thermo-electric power of hot carriers due to a high electric field E. The experimental results were found to be in a satisfactory agreement with theory and concluded that the energy relaxation for high-energy electrons in n-Ge is determined mainly by acoustical modes.
Abstract: The thermo-electric power of hot carriers UT due to a high electric field E is investigated. Two cases are considered: 1) weak electric field (E ≦ 103 V/cm) and 2) high electric field (E ≧ 103 V/cm). The theory is developed for both cases in the approximation of the isotropic mass and quasi-elastic scattering. Dc pulse measurements on n-type germanium in a weak electric field yield a quadratic dependence of UT on the electric field strength. The experimental results are found to be in a satisfactory agreement with theory. In high electric fields the microwave technique is used. It is concluded that the energy relaxation for high-energy electrons in n-Ge is determined mainly by acoustical modes. [Russian Text Ignored]