Showing papers on "Seebeck coefficient published in 1975"
TL;DR: In this paper, a critical analysis of the observed size effects in all cases depart markedly from the predictions of the Fuchs-Sondheimer theory (and also that of the Mayadas-Shatzkes theory which takes into account the grain boundary surface scattering).
Abstract: The thickness dependence at 300 and 80 K of the electrical resistivity and its temperature coefficient, Hall coefficient, mobility, and thermoelectric power of as‐deposited and annealed thin (< 1000 A) evaporated polycrystalline copper films and films deposited at elevated temperatures have been studied. All transport parameters in carefully prepared and well‐characterized films exhibit monotonically increasing size effects with decreasing film thickness. Both annealing and deposition at elevated temperatures cause considerable reduction of the ’’apparent’’ size effects in all the transport parameters of the room‐temperature deposited films. A critical analysis of the observed size effects shows that the data in all cases depart markedly from the predictions of the Fuchs‐Sondheimer theory (and also that of the Mayadas‐Shatzkes theory which takes into account the grain boundary surface scattering). The departure from theory is different for each transport parameter. The annealing studies show that the enhanced size effects are due to the presence of a large concentration of structural defects in the films. The observed behavior may be understood by assuming the large concentration of point and/or line defects to decrease with film thickness and with annealing as well as deposition of films at elevated temperatures. The thermopower data suggest strongly that the large concentration of defects causes distortion of the Fermi surface and thereby a strong energy dependence of the mfp or relaxation time at the Fermi surface.
89 citations
TL;DR: A theory of the thermoelectric power associated with electronic phonon-assisted tunneling motion between inequivalent sites has been developed in this paper, and general results have been applied to some prototype situations characteristic of hopping in disordered solids.
Abstract: A theory of the thermoelectric power associated with electronic phonon-assisted tunneling (hopping) motion between inequivalent sites has been developed. The general results have been applied to some prototype situations characteristic of hopping in disordered solids. (auth)
76 citations
TL;DR: The electrical properties of La1-xSrxVO3 change from those of semiconductor to those of a metal as x is increased, with a metal-nonmetal transition occurring at x approximately = 0.2 as discussed by the authors.
Abstract: The electrical properties of La1-xSrxVO3 change from those of a semiconductor to those of a metal as x is increased, with a metal-nonmetal transition occurring at x approximately=0.2. This has been studied using AC and DC conductivity and thermopower measurements over a temperature range from 4 to 400K. Evidence for localization is found in AC conductivity and a temperature dependent activation energy at temperatures below 100K. A temperature dependence sigma = sigma 0exp(-B/T1n/), where n approximately 4, is interpreted in terms of a model in which the Fermi level occurs within a tail of states at the edge of the valence band. No evidence is found for polaron formation, but the frequency dependence of AC conductivity suggests that multiple site hopping and possible cluster formation is of importance.
56 citations
01 Jan 1975
56 citations
TL;DR: A method is described whereby absolute values for the Seebeck coefficient, the thermal conductance and the thermal capacity of thermoelectric devices may be obtained without the need to measure temperature differences or heat flows.
Abstract: A method is described whereby absolute values for the Seebeck coefficient, the thermal conductance and the thermal capacity of thermoelectric devices may be obtained without the need to measure temperature differences or heat flows. The only requirement in addition to the device to be calibrated and its usual recording apparatus is a source of d.c. current and some metal blocks of known thermal capacity. A mathematical theory of the method is presented and tested experimentally. The method has been used to calibrate semiconductor thermoelements and muscle thermopiles and it is applicable in principle to many other devices such as calorimeters.
40 citations
TL;DR: In this article, the thickness dependence of the TEP of polycrystalline and epitaxially grown copper films of thickness 100-5000 A has been measured and shown to be independent of the resistivity and its temperature coefficient.
Abstract: Thermoelectric power (TEP) of as‐deposited and annealed polycrystalline and epitaxially grown copper films of thickness 100–5000 A has been measured The TEP increases with the film thickness to reach a saturation value at about 3000 A The thickness dependence decreases markedly with increasing annealing temperature and also with increasing temperature of deposition The saturation value of the TEP of as‐deposited films is about 15 times the bulk value of copper and decreases rapidly with annealing to approach the single‐crystal bulk value In sharp contrast to the behavior of the TEP, the resistivity and its temperature coefficient and the carrier concentration of the same copper films exhibit little size effects and insignificant changes due to annealing for thicknesses larger than 1000 A The observed thickness dependence of the TEP of unannealed and annealed films shows no agreement with the Fuchs‐Sondheimer (F‐S) theory Further, there is no correlation between the thickness dependence of the TEP a
31 citations
TL;DR: In this article, the conditions under which a system of interacting electrons exhibits zero thermoelectric power were examined and it was shown that a half-filled-band system described by the one-dimensional Hubbard model has zero power.
Abstract: We examine the conditions under which a system of interacting electrons exhibits zero thermoelectric power. We show, in particular, that a half-filled-band system described by the one-dimensional Hubbard model has zero thermoelectric power. These results are discussed in relation to the organic charge-transfer salts based on the acceptor molecule TCNQ (tetracyanoquinodimethan).
30 citations
TL;DR: In this article, the authors measured the thermoelectric power along the a-axis as well as the highly conducting b-axis in TTF-TCNQ crystals.
29 citations
TL;DR: In this paper, room-temperature electrical resistivity, Hall mobility, and Seebeck coefficient measurements on relatively low-density, hot-pressed, boron-doped Ge20Si80 alloys are reported as functions of 1/RHe in the range 2*1019-3.4*1020 cm-3.
Abstract: Room-temperature electrical resistivity, Hall mobility and Seebeck coefficient measurements on relatively-low-density, hot-pressed, boron-doped Ge20Si80 alloys are reported as functions of 1/RHe in the range 2*1019-3.4*1020 cm-3. The temperature variations of resistivity and Seebeck coefficient are reported over the temperature range 300-1200K and of 1/RHe and the Hall mobility over the range 300-950K. Within experimental error the absolute values and 1/RHe dependence of the Seebeck coefficients are indistinguishable from single-crystal values. Substantial reductions in carrier mobility accompany the hot-pressing method of preparation, although the reduction is not solely due to porosity effects. A simple mixed scattering model is employed in analysing the electrical data and the conclusion reached that assigning a Hall factor of unity leads to an overestimation in carrier concentration by between 30 and 40%.
22 citations
TL;DR: In this article, the crystal structure, conductivity and thermoelectric power of N,N9 -diethyl-4,49-bipyridylium (TCNQ) 4 are reported.
Abstract: The crystal structure, conductivity and thermoelectric power are reported of N,N9 -diethyl-4,49-bipyridylium (TCNQ) 4 . The complex crystallizes in the monoclinic system with the space group P2 1 /c and lattice constants a = 13.077, b = 25.316, c = 7.838 A, β = 92.66° and having Z = 2. The anisotropic electrical data are discussed in terms of the crystal structure. A band model approach to conduction is suggested with phonon scattering of charge carriers within a two dimensional TCNQ lattice. Temperature dependences of mobility of T -1.6 and T -1.1 for electron and hole respectively were obtained.
21 citations
TL;DR: In this article, the thermoelectric power of a binary alloy with off-diagonal disorder as well as diagonal one is calculated by means of the extended coherent potential approximation due to Shiba and others.
Abstract: The thermoelectric power of a binary alloy with off-diagonal disorder as well as diagonal one is calculated by means of the extended coherent potential approximation due to Shiba and others. It is shown that the off-diagonal disorder has a very striking effect on the thermoelectric power as well as on the conductivity. In the calculation the “underturbed” band is treated accurately for a simple cubic tight-binding model. Our improved treatment of the van Hove singularities of the “unperturbed” band reveals that the effect of the singularities on the transport coefficient is more pronounced than that calculated by Levin et al.
TL;DR: In this paper, the authors show that the amount of charge transfer for a large class of TCNQ systems can be deduced from a measurement of the high temperature saturation value of the thermoelectric power.
01 Nov 1975
TL;DR: In this paper, detailed measurements have been made on 20 amorphous binary semiconductors for electrical conductivity, photoconductivity, field effect, and thermoelectric power and their temperature dependence.
Abstract: Detailed measurements have been made on 20 amorphous binary semiconductors for electrical conductivity, photoconductivity, field effect, and thermoelectric power and their temperature dependence Information is obtained on the density and location of localized states, the mechanism of the transport processes, and the way in which these processes vary with the optical absorption gap and other properties of these materials (auth)
TL;DR: The resistivity rho of palladium has been investigated on both sides of the melting point, and the thermoelectric power S has been measured in the liquid phase.
Abstract: The resistivity rho of palladium has been investigated on both sides of the melting point, and the thermoelectric power S has been measured in the liquid phase. The values for rho and S in the liquid are respectively 83+or-2 mu Omega cm and -41+or-3 mu V deg-1, which are in general accord with the theoretical predictions of Brown (1973). An interesting feature is the comparatively large value of Delta rho / rho solid across the melting point. Two possible contributions to this effect are identified.
TL;DR: In this paper, the authors measured thermoelectric power and Hall coefficient values on compact polycrystalline samples from the MoTe 2− x and MoSe 2−x systems and discussed in terms of a quasi amorphous semi-conductor model.
TL;DR: In this article, the variation of electrical conductivity and thermoelectric power with composition and temperature in the As-Te and As40-xTe60-yInx+y molten systems were investigated.
Abstract: Experimental investigation has been made of the variation of electrical conductivity and thermoelectric power with composition and temperature in the As-Te and As40-xTe60-yInx+y molten systems. For the As-Te system, the electrical conductivity, sigma , is a continuous and decreasing function of the arsenic content over the range 5-55 atomic per cent arsenic; while the thermoelectric power is a continuous and increasing function of the arsenic content over the range of 15-55 atomic per cent arsenic. The temperature coefficient of conductivity, d sigma /dT, is positive for all investigated alloys. Just above the melting points of these alloys, in a temperature range which increases with increasing As content, the conductivity activation energy is constant and independent of composition. Thereafter, the activation energy decreases with temperature. The behaviour of the thermoelectric power, S, is consistent with the behaviour of the electrical conductivity discussed above. Additions of small quantities of indium to replace either arsenic or tellurium in As2Te3 lead to a decrease in conductivity.
TL;DR: In this article, the structural defects in thin copper films were used to obtain the contribution to thermoelectric power by the structural defect in the films, which is comparable in magnitude to the bulk value.
Abstract: Thermoelectric power and electrical resistivity of thin (<1000 A) copper films annealed at different temperatures have been studied. The data have been utilized to obtain the contribution to thermoelectric power by the structural defects in the films. This contribution is comparable in magnitude to the bulk value. It increases with film thickness giving rise to a strong thickness dependence of thermoelectric power at thicknesses considerably larger than the mean free path of the conduction electrons.
TL;DR: In this article, stable homogeneous amorphous alloy films of Ge with different concentrations of Al, Cu and Fe have been prepared by the simultaneous vapor deposition technique and the cyclic annealing and crystallization temperature of these films have been analyzed.
TL;DR: In this article, a new mechanism for anomalous thermoelectric power (ATP) in the paramagnetic state of certain rare earth metals and their compounds, in which the ions possess a nonmagnetic ground state in a given crystal field.
Abstract: We propose a new mechanism for an anomalous thermoelectric power (ATP) in the paramagnetic state of certain rare earth metals and their compounds, in which the ions possess a nonmagnetic ground state in a given crystal field. The ATP is found to be due to higher order inelastic scattering (second Born approximation) of the conduction electrons by the crystal field split rare earth ions. It has a peak at a temperatureΔ/3 ~Δ/2, whereΔ is the splitting energy between the ground state and the first excited state. Our main result is that the appearance of an ATP requires interactions between the conduction electrons and the ions of other than the simple isotropic exchange type. This implies that the ATP may serve as a valuable tool to detect more complicated types of thek-f interaction than the isotropic exchange.
TL;DR: In this paper, a polycrystalline sample of 4,4′-bipyridyl (tetracyanoquinodimethane)2 was analyzed in terms of band theory.
Abstract: Conduction and thermoelectric power measurements are reported for polycrystalline sample of 4,4′-bipyridyl–(tetracyanoquinodimethane)2. The data are interpreted in terms of band theory with ionic impurity scattering of carriers, resulting in a positive temperature dependence of both mobility and pre-exponential factor for conductivity.
TL;DR: In this paper, a method for measuring and interpreting the Seebeck coefficient in high resistivity (≧ 105 Ωcm) materials is discussed; the technique is applied to pure V2O3 between 50 and 300 K.
Abstract: A method for measuring and interpreting the Seebeck coefficient in high resistivity (≧ 105 Ωcm) materials is discussed; the technique is applied to pure V2O3 between 50 and 300 K. The results indicate that the low temperature phase of V2O3 is a band-type semiconductor.
Eine Methode fur die Messung und Interpretation des Seebeckkoeffizienten in hochohmigen (≧ 105 Ωcm) Materialien wird diskutiert; diese Technik wird auf reines V2O3 zwischen 50 und 300 K angewendet. Die Ergebnisse zeigen, das die Tieftemperaturphase von V2O3 ein Banderhalbleiter ist.
TL;DR: Magnetic susceptibilities, electrical resistivities and thermoelectric powers of liquid In-Bi alloys are measured in this article, and the curve of the electron susceptibility versus composition shows a little anomaly.
Abstract: Magnetic susceptibilities, electrical resistivities and thermoelectric powers of liquid In-Bi alloys are measured. The curve of the electron susceptibility versus composition shows a little anomaly...
TL;DR: In this paper, the authors showed that the conduction should be understood in terms of the hopping transport of charge carriers in the localized states formed in the forbidden band by random networks of conjugate double bond systems of carbon to carbon and carbon to nitrogen.
Abstract: Thin films of polyacrylonitrile obtained by vacuum deposition were made semiconductive by the heat-treatment in N2. Electrical condtuctivity and Hall mobility have been measured for the films heat-treated at various temperatures. Conductivity increases and the activation energy for conduction decreases with increasing heat-treatment temperature. Hall mobility is small (10-1~10-4cm2/V.s) and has nearly the same activation energy as that of conductivity. Hall measurements indicate the evaporated films to be n-type while the thermoelectric power exhibits p-type. These results suggest that the conduction should be understood in terms of the hopping transport of charge carriers in the localized states which are formed in the forbidden band by random networks of conjugate double bond systems of carbon to carbon and carbon to nitrogen.
TL;DR: In this paper, the thermal and electrical resistivity and thermoelectric power of two samples of Ca (with residual resistance ratios of 10 and 70) between 30 and 300 K were analyzed.
Abstract: Data are presented for the thermal and electrical resistivity and thermoelectric power of two samples of Ca (having residual resistance ratios of 10 and 70) between 30 and 300 K. Large deviations from both Matthiessen's rule and the Wiedemann–Franz relationship are observed. The former are tentatively attributed to the presence of two distinct groups of carriers in Ca, and analyzed using the two band model. The latter deviations are interpreted as the effects of band structure. The thermoelectric power of Ca is large. In many respects the transport properties of Ca appear to be similar to those of the transition metals.
TL;DR: In this article, the high-temperature X-ray structure of (CrxV1−x)2O3 phases (withx < 0.10) has been studied.
TL;DR: In this article, the electrical conductivity and thermoelectric power of ten ternary compounds ABC2 (A: Cu, Ag; B: Tl, Sb, Bi; C: Se, Te) have been measured both in the solid and liquid states.
Abstract: The electrical conductivity and thermoelectric power of ten ternary compounds ABC2 (A: Cu, Ag; B: Tl, Sb, Bi; C: Se, Te) have been measured both in the solid and liquid states. The observed conductivity values of these compounds just above their respective melting points range from 2.5 to 2300 ω−1·cm−1 and increase with increasing temperature. The obtained electrical properties are discussed in terms of the current models for amorphous semiconductors.
TL;DR: In this paper, the authors measured thermal power using reversible silver electrodes and electrical conductivity on the compressed pellets of (Me 4 N) 2 Ag 13 I 15, and (Et 4 N] 2 Ag 14 I 15.
TL;DR: In this paper, electrical conductivity and thermal EMF of liquid Se1-x-tex (x
Abstract: The electrical conductivity and thermal EMF of liquid Se1-x-Tex(x
TL;DR: In this article, the Hall effect and thermoelectric power have been measured over the temperature range 77-300K for two kinds of bismuth films (99.9999% purity), one prepared at 150° C and the other at room temperature on a glass substrate.
Abstract: The Hall effect and thermoelectric power have been measured over the temperature range 77–300K for two kinds of bismuth films (99.9999% purity), one prepared at 150° C and the other at room temperature on a glass substrate. The former films exhibit an enhancement of positive nature of the conductivity as the film thickness is decreased, indicating the presence of a number of local acceptor states. From the present results it becomes apparent that the transport properties of evaporated films are structure-sensitive.