Showing papers on "Thermoelectric effect published in 1980"

Electrical and optical properties of n-type semiconducting chalcogenide glasses in the system Ge-Bi-Se

Abstract: The glass‐forming region was determined for the system Ge‐Bi‐Se; 13 at.% Bi was found to be incorporated at its maximum content into glasses, the Ge content of which was 20 at.%. Electrical resistivity, thermoelectric power, and optical absorption coefficient were measured mainly on a series of Ge20BixSe80−x glasses (x=0 –13). The resistivity decreased by about four orders of magnitude between x=9 and 10, and remained almost constant for x?10. The thermoelectric measurement showed the change of conduction type from p to n, accompanied by the above‐mentioned abrupt decrease of resistivity. In n‐type glasses, hopping conduction in the tail of localized states was proposed in parallel with conduction in extended states. The optical band gap was very slightly changed with the incorporation of more than 2.5 at.% Bi, in contrast to the remarkable decrease in the activation energy for conduction between x=9 and 10. The discussion based on the concentration of covalent bonds formed in the glasses led to the conclusion that the formation of a fairly large number of Bi‐Se bonds and the disappearance of Se‐Se bonds near x=10 were closely related to the composition dependence of the electrical and optical properties of the glasses in the present system.

Silicon–germanium alloys as high-temperature thermoelectric materials

Abstract: This article reviews the preparation and properties of silicon–germanium alloys, mentions some recent developments in their technology, and assesses their potential for further improvement as high ...

Experimental study of thermoelectricity in superconducting indium

Abstract: This paper reports on a comprehensive study of thermoelectricity in pure superconducting indium near the transition temperature. The samples consisted of hollow bimetallic toroids of lead and indium. Upon application of a temperature gradient, a magnetic flux was produced within the hollow cavity of the toroids which could be coupled, via a superconducting flux transformer, into a superconducting quantum interference device magnetometer. The thermoelectric origins of the magnetic flux and the experimental method are discussed in detail. The magnetic flux was measured in seven specimens, and in each was found to diverge as the transition temperature was approached with a ${(1\ensuremath{-}\frac{T}{{T}_{c}})}^{\ensuremath{-}\frac{3}{2}}$ power-law dependence. The magnitude of the flux varied by about a factor of 40 among the different samples and appeared to scale with the normal-state thermoelectric properties of the indium. Tests intended to eliminate possible spurious causes for the magnetic flux are also discussed.

Field effect and thermoelectric power on boron doped amorphous silicon

Abstract: Field effect and thermoelectric power measurements have been made as a function of temperature on a series of B doped amorphous silicon samples prepared by glow discharge decomposition of silane. The investigation complements an earlier one on As doped amorphous silicon prepared by the same method. Incorporation of boron leads to an increase in the density of localized states lying 0.42 eV above the valance edge. The density of surface states is less than or equal to 1.5×1011 cm−2 eV.−1 Electrical transport is interpreted in a two channel model, involving transport both in extended valence states and in a band of localized states associated with the B acceptors. The effect of hydrogen evolution due to thermal annealing on the localized state densities and transport processes is also investigated.

New thermoelectric effect in tunnel junctions

Abstract: A new type of thermoelectric current effect is derived for tunneling through oxide barriers between metals at different temperatures, for both superconducting and normal tunnel junctions. This effect was observed in both current and voltage measurements on Al-PbBi tunnel junctions in which one electrode was heated by laser irradiation. The existence of this thermoelectric effect may resolve long-standing discrepancies between experimental results and theoretical predictions for a series of point-contact experiments.

Diffusion thermoelectric power of bismuth in non-quantising magnetic fields. Pseudo-parabolic model

Abstract: The pseudo-parabolic model (Heremans and Hansen, 1979) for the analysis of the thermoelectric power of bismuth in zero and weak magnetic fields is analysed further by calculation of the effect of intermediate and strong, non-quantising magnetic fields. The calculations are performed for elements of the thermoelectric power and of the electronic thermal conductivity. Comparison with experimental data in the range from 20K to room temperature shows that a variety of complicated field dependences in the intermediate field range, previously unexplained, follow from the present analysis. In strong fields a number of disagreements appear. The field values at which the disagreements set in are found to coincide quite well with the Landau quantisation limits.

Thermoelectric properties and phase transition in Sb2Te3 under hydrostatic pressure up to 9 GPa

Abstract: The thermoelectric tensor component S11 and the relative electrical resistance along the binary axis of Sb2Te3 single crystals are measured at room temperature under hydrostatic pressure up to 9 GPa both, during the up stroke and during the down stroke of pressure cycle. Reversible first order phase transition and anomalous behavior of thermo- e.m.f. near to this transition in antimony telluride are found. [Russian Text Ignored].

Thermoelectric device and process for making the same

Abstract: There is disclosed a portable refrigerator which is formed by casting an insulating wall of foamed-in-place insulating foam in a manner which provides inner and outer shell portions on the insulating wall and a depression therein which exposes a surface of the internal thermal sink and, except for a pigtail and positive and negative contact points which points project through the outer shell portion in position to be connected with the positive and negative poles, respectively, of the thermoelectric element, completely imbeds the electrical connections. A thermoelectric element is disposed in the depression in heat-exchange with the surface of the internal thermal sink exposed by the depression and the positive and negative poles of the thermoelectric element are connected with the respective positive and negative contact points. An annular gasket of resilient and compressible sealing material is disposed on the outer shell in position such that it completely surrounds the depression and the thermoelectric element therein and covers the contact points. An external thermal sink is disposed in sealing contact with the sealing gasket and the two thermal sinks are drawn toward each other until the gasket is compressed and the thermal sinks are in heat-exchange with the thermoelectric element. The thermoelectric cooling device has a rim extending around but spaced from the external thermal sink of such height that the edge of the rim and the outermost surfaces of the external thermal sink are substantially in a common plane.

Temperature measuring method and apparatus

Abstract: A thermoelectric temperature sensing apparatus in which the thermoelectric reference junction is not maintained at a constant temperature but instead heat is supplied to it or extracted from it at a predetermined, preferably constant, rate by a heater or cooler. The open circuit output voltage of the apparatus is referenced to this predetermined rate of heat supply or extraction to determine the temperature of the other thermoelectric junction. Where the heater or cooler is input responsive, the output voltage of the thermoelectric circuit is referenced to the heater or cooler input.

Effects of contact resistance and dopant concentration in metal—Semiconductor thermoelectric coolers

Abstract: The maximum heat that can be pumped by a metal-semiconductor thermoelectric cooling stage depends strongly on the dopant concentration in the semiconductor and on contact resistance at the metal-semiconductor interface which is cooled. A comparison is made between theoretical models describing these effects and experimental data for GaAs, both taken from original measurements and compiled from the literature. A convenient, new technique for determining the Peltier coefficient and the contact resistance of a metal-semiconductor contact is described. The results indicate that, in the case of GaAs, Au:Ge:Ni alloy contacts are effective in minimizing the contact resistance.

Effects of inhomogeneity on thermoelectric and photothermoelectric analyses

Abstract: The author analysed the effects of inhomogeneity in the measurements of thermoelectric and photothermoelectric power. Physical lumped circuit models have been used to simulate longitudinal and layered inhomogeneities commonly found in insulating semiconductors. The results indicated a marked difference between the measured thermoelectric power and that calculated from conductivity data for inhomogeneous samples. The measured values were always too small. A quantitative comparison between theory and experiment gave a very good correlation for longitudinal inhomogeneity found in a CdS single crystal. The effects of layered inhomogeneity were demonstrated in the case of surface absorption in a CdS-CdSe sample. The results thus seem to explain some of the anomalous effects frequently observed in the measurements of thermoelectric power in light-sensitive single crystals.

Thermoelectric properties of thin electroplated foils. Application to the measurement of heat fluxes

Abstract: The thermoelectric properties of electrical conductors in the form of sheets and covered with an electrolytic deposit of a different nature are due to induced currents passing across the surface separating the superposed conductors These currents are proportional to the instantaneous value of the calorific flux located in the electrolytic deposit This particular thermoelectric effect has been used to develop a new solution to the problem of measuring superficial calorific fluxes and temperatures

Galvanomagnetic properties of Fe3S4

Abstract: Galvanomagnetic properties of Fe3S4 are studied through electrical resistivity and Hall effect measurements between 4.2 and about 300 K using synthetic thin films prepared by vacuum deposition method. The resistivity is on the order of 10−4–10−3 Ω cm between 4.2 K and room temperature, and has a positive temperature dependence with increasing temperature which can be explained by a metallic conduction. Hall effect reveals that the metallic conduction is mainly due to hole carriers, 0.2±0.1 per formula unit of Fe3S4, independent of temperature. The extraordinary Hall coefficient is positive and is in linear relation to the resistivity above about 130 K. Thermoelectric effect also supports the p‐type conduction. Magnetization is 36.0±1.0 emu/gram at 77 K extrapolated to H=∞, which is much smaller than that expected from cations in the spinel structure.

Study and characterisation of a new heat fluxmeter

Abstract: A new type of thermopile has been developed by integrating multiple thermoelectric junctions (made by electrolytic deposition) on a thin conductor sheet. This heat fluxmeter gives an electric signal directly proportional to a heat flux. It can be manufactured by a conventional printed circuitry method.

Thermoelectric power of bcc transition‐metal alloys of the second period

Abstract: The absolute thermoelectric power of Nb‐rich Zr, Mo‐Nb, and Mo‐rich Re alloy crystals was measured between 4.2 and 300 K. The composition of these alloys covered the entire composition range in which a continuous solid solution of bcc structure prevails. The diffusion component of the thermopower as a function of composition is generally proportional to the change of the density of states at the Fermi level with respect to composition. The curves exhibit two extrema: a minimum at 5.35 and a maximum at 6.1 valence electrons per atom. The phonon‐drag component of the thermopower is positive for all the alloys and is attenuated by the addition of alloying elements to Nb. The phonon‐drag component of Mo is particularly sensitive to alloy content.

Development of a preprototype thermoelectric integrated membrane evaporation subsystem for water recovery

Abstract: A three-man urine water recovery preprototype subsystem using a new concept to provide efficient potable water recovery from waste fluids on extended duration space flights has been designed, fabricated, and tested. Low power, compactness, and gravity insensitive operation are featured in this vacuum distillation subsystem that combines a hollow fiber polysulfone membrane evaporator with a thermoelectric heat pump. Application and integration of these key elements have solved problems inherent in previous reclamation subsystem designs. The hollow fiber elements provide positive liquid/gas phase control with no moving parts other than a waste liquid recirculation pump and a product water withdrawal pump. Tubular membranes provide structural integrity, improving on previous flat sheet membrane designs. A thermoelectric heat pump provides latent energy recovery.

Thermoelectric Ocean Thermal Energy Conversion

Abstract: A novel thermoelectric OTEC concept is proposed and compared with the ammonia closed-cycle designs. The thermoelectric OTEC is a much simpler system which uses no working fluid and therefore requires no pressure vessel, working fluid pumps, or turbogenerator. These components are replaced by power modules which are heat exchangers integrated with thermoelectric generators. The thermoelectric OTEC offers several potential advantages including: simpler and more easily mass-produced components; higher reliability system performance through the use of a high level of redundancy and long-lived, solid-state thermoelectric generators; greater safety for crew and environment by elimination of the pressurized working fluid; and the possibility of lower system costs. These comparisons are discussed and plans for future work are presented.

Thermoelectric generator mfr. - requires homogeneous semiconductor strips alternated and cut to form generator blocks

Abstract: Thermoelectric generators of the Seebeck and Peltier type comprise several strips of P and N semiconductor material. These strips form a composite assembly to which electrical connections are readily made to form the generator assembly. Strips of P and N type semiconductor material are assembled in three axes (OX, OY, OZ) to form a larger block. An insulating leaf is inserted between the P and N strips and fixed by gluing. After cleaning these are cut into sections (C1) and reassembled so that the semiconductor strips alternate P and N. An insulating leaf (T1-3) is inserted between each section and each alternate leaf is displaced vertically so that conductors (K) can be inserted. The block is further cut into sections to form thermoelectric generators with electrical connections made by a metallic foil.

Thermoelectric photocathode cooler allowing rapid interchange of end-on photomultipliers

Abstract: CNR Laboratorio per lo Studio delle Proprieta Fisiche di Biomolecole e Cellule, 56100 Pisa, Italy. Received 8 November 1979. 0003-6935/80/060832-03$00.50/0. © 1980 Optical Society of America. Efficient cooling of photomultiplier tubes is generally mandatory in experiments involving the detection of low light levels. Trialkali photocathodes and most of those based on III-V compounds are to be cooled down to temperatures between —30 and —40°C to minimize practically the thermionic emission. Although several commercial cooling units are currently available for this purpose, their dimensions, flexibility, and performance in some important respects are often not satisfactory in research applications. For instance, many laboratory applications demand that the performance of the detector be matched to varying spectral properties of the radiation to be measured and require that suitable photocathodes be used in the same instrumental setup, interchanging or testing the tubes between experiments. On the other hand, the design of current cooling units is most commonly based on putting the entire detector in a cold atmosphere, but this makes it difficult or even impossible to interchange the devices, and wiring limitations exist especially for fast pulse applications. This depends on the fact that the

Temperature dependence of electrical and thermoelectrical properties of Mo1–x WxSe2 solid solutions

Abstract: Electrical resistivity and Seebeck coefficients are measured on Mo1-xWxSe2 single crystals (0 ≦ x ≦ 1), in the temperature range 300 to 475 K, grown by direct vapour transport method. The results obtained are compared with those of earlier workers. Elektrische Leitfahigkeit und Seebeck-Koeffizienten werden an Mo1–xWxSe2 - Einkristallen (0 ≦ x ≦ 1), die durch eine direkte Transportgasmethode gezuchtet werden, im Temperaturbereich 300 bis 475 K gemessen. Die erhaltenen Ergebnisse werden mit fruheren Arbeiten verglichen.

Thermoelectric device for heat transfer between two fluids

Abstract: This device constitutes, for example, a water-air heat pump comprising a battery (P1) formed of a succession of stages electrically powered in series and each comprising two thermoelectric elements (20 and 22) of opposite types separated by heat conductors (54, 16) incorporated in heat exchangers for the two fluids, the water exchanger structure (16) creating at each stage a longitudinal elasticity, while the stack of air exchangers (54, 40, 42, 28) constitutes a maintenance column ensuring the mechanical stability of the device and avoiding any mechanical stress in the thermoelectric elements. Application to domestic heating.