Showing papers on "Seebeck coefficient published in 1974"
TL;DR: In this paper, the absolute Seebeck coefficient of YbAl2 and LuAl2 was measured at temperatures between 4 and 300 K. The results were in conformity with the proposed virtual bound state character of the Yb ground state.
68 citations
TL;DR: In this article, the thermoelectric power of a narrow-band Hubbard chain with an arbitrary number of electrons per site was investigated and the results were carried out to the lowest order in the transfer integral.
Abstract: We study the thermoelectric power of a narrow-band Hubbard chain with an arbitrary number of electrons per site. The calculations are carried out to the lowest order in the transfer integral. We find a characteristic electron density ($\ensuremath{\rho}=\frac{2}{3}$) below which the thermoelectric power is negative at all temperatures. In contrast, for $\ensuremath{\rho}g\frac{2}{3}$, the thermoelectric power is small and negative only above a characteristic temperature, below which there is a change of sign and slope. We comment on the applicability of these results to the charge-transfer salts of tetracyanoquinodimethan (TCNQ).
62 citations
TL;DR: In this article, the electron-diffusion Seebeck coefficient of dilute alloys is investigated in a simple model in which free electrons are scattered by phonons or by substitutional impurities bound in the lattice.
Abstract: The electron-diffusion Seebeck coefficient of metals and dilute alloys is investigated in a simple model in which free electrons are scattered by phonons or by substitutional impurities bound in the lattice. Second-order corrections to the $T$ matrix for electron scattering involving intermediate virtual phonon states are found to be of small magnitude but to have a very strong energy dependence. They thus make a large contribution to the thermoelectric coefficients while leaving the conductivities essentially unaltered. The pronounced temperature dependence of these second-order contributions allows an interpretation of experimental results that relies less on the phonomenon of phonon drag then has previously been the case.
55 citations
TL;DR: The Hall coefficient, magnetoresistance, and thermoelectric power of several specimens of NbSe2 have been measured as a function of temperature for various crystal orientations.
Abstract: The Hall coefficient, magnetoresistance, and thermoelectric power of several specimens of NbSe2 have been measured as a function of temperature for various crystal orientations. A range of behaviou...
53 citations
TL;DR: Oxygen molecules were found to enter into lead phthalocyanine single crystals by thermal diffusion when they were annealed in an oxygen gas of atmospheric pressure above 230°C for more than ten hours.
Abstract: Oxygen molecules were found to enter into lead phthalocyanine single crystals by thermal diffusion when they were annealed in an oxygen gas of atmospheric pressure above 230°C for more than ten hours. Diffusion constant is 7.2 ×10 -9 cm 2 sec -1 at 242°C with activation energy of 1.4 eV. Dark conductivity σ increased by three orders of magnitude at room temperature with the heat treatment. Correspondingly, activation energy of conductivity E defined by σ∝exp (- E / k T ) decreased from 0.85 to 0.54 eV. The measurement of thermoelectric power indicates that positively charge carriers are generated in the presence of oxygen. The experimental results are explained on the model that an oxygen molecule acts as a center of carrier generation by accepting an electron from a neighboring lead phthalocyanine molecule and releasing the hole-like carrier.
49 citations
TL;DR: In this article, the metal-insulator phase transition at about 150 °F was confirmed by the electrical resistivity and the thermoelectric power measurement, based on the V6O13 single crystals grown by chemical transport method.
49 citations
47 citations
TL;DR: In this paper, the Hall effect and resistivity as well as thermoelectric power in the temperature range 300-450 K were measured in terms of a sigmoid function.
Abstract: We have made measurements of the Hall effect and resistivity as well as of thermoelectric power in the temperature range 300–450 K. The results of these measurements are interpreted in terms of a s...
41 citations
TL;DR: In this article, the electrical resistivity, the sign of the Seebeck coefficient, and the optical transmission have been measured for a number of thin Si4+−doped YIG films.
Abstract: Thin films of Si4+‐doped YIG have been grown on Gd3Ga5O12 substrates by liquid phase epitaxy. The electrical resistivity, the sign of the Seebeck coefficient, and the optical transmission have been measured for a number of films prepared from the same melt at different growth temperatures in the range 780–960°C. The measurements show a high optical absorption for films prepared at low growth temperatures, while at intermediate temperatures there is a change from p‐type to n‐type conduction. A resistivity maximum and minimum in the optical absorption are also found. The results are discussed in terms of the charge‐compensation mechanism that occurs as Pb2+ ions are incorporated from the flux into the films at the lower growth temperatures. It is found that intrinsic donors, probably oxygen vacancies, are present in concentrations up to 0.03 per formula unit. The increase in the optical absorption coefficient, Δα, relative to pure YIG, is proportional to the concentration of nonionized holes, [p], i.e., Δα=...
37 citations
01 Jan 1974
TL;DR: In this paper, the defect structure of 2Fe1-yO has been investigated by electrical conductivity and gravimetric measurements in CO2-CO atmospheres in the temperature range 1000 to 1150°C.
Abstract: The possible disorder types in iron orthosilicate, 2Fe1-yO.SiO2 are discussed on the basis of knowledge of its crystal structure and the defect structure of transition-metal oxides. The defect structure has been investigated by electrical-conductivity and gravimetric measurements in CO2-CO atmospheres in the temperature range 1000 to 1150°C. The results are consistent with a disorder type of doubly ionized iron vacancies and an equivalent number of electron holes. In comparison with Fe1-yO, the point-defect concentrations in the iron orthosilicate are found to be lower by a factor of 102. For the interpretation of conductivity, the same models as for transition-metal oxides have been used. The Po2 dependence and Seebeck coefficient indicate a p conduction. The calculated mobility of electron holes of 6 x 10-3 cm2/v-sec as well as the activation enthalpy for motion of 5.8 kcal/mole suggest a small polaron mechanism.
36 citations
TL;DR: In this paper, the resistivity and thermoelectric power of three binary alloy systems in the liquid state, Ga-Te, Ge-Te and Pb-Te were investigated.
Abstract: Results are reported for the resistivity and thermoelectric power of three binary alloy systems in the liquid state, Ga-Te, Ge-Te, and Pb-Te. In two of these systems there is clear evidence for what may loosely be termed ‘compound formation’, at concentrations corresponding to Ga2Te3 and PbTe, and there is some sign that GeTe2 exists as a compound in the third. An attempt is made to classify the numerous Te-based systems which have now been studied in the liquid state, nearly all of which show evidence for compound formation, according to the nature of the bonding mechanism involved. The way in which the thermoelectric power varies with concentration is qualitatively the same for all the systems within one group, but there are significant differences between one group and the next.
TL;DR: In this paper, the electric and magnetic properties of the La x Eu 1−x B 6 solid solutions have been investigated and a sharp evolution from semiconducting to metallic character is observed between x = 0 and X = 0.01.
TL;DR: In this article, the effect of annealing on the electronic structure of unannealed and annealed gold films was investigated and the following results were obtained: the specularity parameter was increased by the annaling and was dependent on the temperature.
TL;DR: In this article, conductivity, Hall coefficient, thermoelectric power and magnetoresistance were measured on polycrystalline samples of hexagonal Ni 1-x S (0.004≦ x ≦ 0.050).
Abstract: Hexagonal nickel sulfide NiS shows a metal-nonmetal transition with the appearance of antiferromagnetism as temperature is lowered below 265 K ( T t ). Measurements of conductivity, Hall coefficient, thermoelectric power and magnetoresistance were made on polycrystalline samples of hexagonal Ni 1- x S (0.004≦ x ≦0.050). The low temperature phase is found to be a degenerate semiconductor with a high hole density from 3.13×10 20 cm -3 ( x =0.004) to 1.60 ×10 21 cm -3 ( x =0.020), which is essentially due to ionized nickel vacancies. Carriers are mainly scattered by ionized and neutral impurities associated with nickel vacancies. The effective mass is estimated from Seebeck coefficients to have a value between 1.50 m 0 and 2.90 m 0 . Above T t , the compound is a normal metal without a magnetic moment. The low temperature resistivity has revealed the Debye temperature to be 175 K for the metallic phase. There is no apparent evidence of a strong correlation effect although the electronic state densities are l...
TL;DR: In this article, the thermoelectric power in the fluctuation region above the superconducting transition temperature was studied theoretically and it was shown that the power tends to zero as the temperature approaches the transition temperature.
Abstract: The thermoelectric power in the fluctuation region above the superconducting transition temperatureT
c
is studied theoretically. Use is made of the time-dependent Ginzburg-Landau (TDGL) equation due to Ebisawa and Fukuyama, which includes the correction term of the order ofT/μ as well, whereT is the temperature and μ is the chemical potential. It is shown that the thermoelectric power tends to zero as (T−T
c
) ln [T/(T−T
c
)] and as (T−T
c
) as the temperature approaches the transition temperatureT
c
for the two-dimensional and the one-dimensional systems, respectively.
TL;DR: In this paper, the authors reported the occurence of very large positive peaks and smaller negative peaks in the absolute Seebeck coefficient of Ce 1− x La x Al 3 compounds (x = 0.50, 0.90 and 0.99) in the temperature range of 4 to 300 K.
TL;DR: The magneto-Seebeck coefficient α11 (B3) and α33 (B1) have been measured for pure bismuth crystals between about 20 K and room temperature in magnetic fields of up to 5.5 T.
Abstract: The magneto-Seebeck Coefficients α11 (B3) and α33 (B1) have been measured for pure bismuth crystals between about 20 K and room temperature in magnetic fields of up to 5.5 T. The observed behaviour has been compared with a theory due to Korenblit. It appears that a phonon-drag component of the Seebeck coefficient at very high fields persists up to well above liquid nitrogen temperature. However, some features of the results are not in accordance with theory.
Die Magneto-Seebeck-Koeffizienten α11 (B3) und α33 (B1) wurden fur reine Wismutkristalle zwischen ungefahr 20 K und Zimmertemperatur in magnetischen Feldern bis zu 5.5 T gemessen. Das beobachtete Verhalten wurde mit einer Theorie von Korenblit verglichen. Es scheint, das eine ”Phonon-Drag”-Komponente bei sehr hohen Feldern bis betrachtlich uber der Temperatur von flussigem Stickstoff erhalten bleibt. Allerdings sind einige Einzelheiten der Resultate nicht im Einklang mit der Theorie.
TL;DR: The thermoelectric powers of polycrystalline Cu, Ag, and Au wires have been measured in transverse fields up to 48 kG between 4 and 100 K as mentioned in this paper.
TL;DR: In this article, the authors measured the thermoelectric power of LaAl2 and of (La, Ce)Al2 alloys between 0.3 and 9 K and observed a large negative peak caused by the Kondo effect of the Ce impurities.
Abstract: We have measured the thermoelectric power of LaAl2 and of (La, Ce)Al2 alloys between 0.3 and 9 K. A large, negative peak caused by the Kondo effect of the Ce impurities has been observed at about 1 K. The peak value of about −16 µV/K obtained from the Nordheim-Gorter rule suggestsV=+0.05 eV andJ=−0.11 eV for the interaction energies of the potential and exchange scattering of the conduction electrons by the Ce impurities.
TL;DR: In this paper, a longitudinal heat flow technique for precise measurement of thermal conductivity, electrical resistivity, and Seebeck coefficient over the temperature range from 80 to 400 K is described, based on the use of a calibrated platinum resistance thermometer to provide in situ calibrations of specimen thermocouples.
Abstract: A longitudinal heat‐flow technique for precise measurement of thermal conductivity, electrical resistivity, and Seebeck coefficient over the temperature range from 80 to 400 K is described. The basis of the technique is the use of a calibrated platinum resistance thermometer to provide in situ calibrations of specimen thermocouples. The total determinate errors at 273 K are ± 0.23% for electrical resistivity, ± 0.49% for thermal conductivity, and ± 0.07 μV/K for the Seebeck coefficient when Pt wire is used as the reference. Experimental results on two high‐purity molybdenum specimens with cross‐sectional areas differing by a factor of four are presented to demonstrate the system precision and low level of indeterminate erros.
TL;DR: In this article, electrical conductivity, thermoelectric power, and weight change were measured for polycrystalline Ta2O5 from 900° to 1400°C, and the predominant ionic and electronic defects in this temperature range are oxygen vacancies and electrons.
Abstract: Electrical conductivity, thermoelectric power, and weight change were measured for polycrystalline Ta2O5 from 900° to 1400°C. The predominant ionic and electronic defects in this temperature range are oxygen vacancies and electrons. The oxygen-vacancy and electron mobilities are 8.1 × 103exp (−1.8 eV/kT) and ∼0.05 cm2/V-s, respectively. At O2 partial pressures near 1 atm, the ionic-defect concentration is essentially fixed by the presence of lower-valence cation impurities, and the total electrical conductivity is predominantly ionic, whereas at low Po2's the conductivity is electronic and proportional to PPo2−1/6.
TL;DR: In this paper, the thermoelectric power of a series of palladium-silver alloys covering the entire range of alloy composition was measured and shown to have a sharp negative peak at just less than 50% silver, indicating a sharp sharpness in the upper energy tail of the density of d-electron states.
Abstract: New measurements are reported of the thermoelectric power below 9 K of a series of palladium-silver alloys covering the entire range of alloy composition. The thermoelectric power as a function of alloy composition shows a sharp negative peak at just less than 50% silver; this would appear to indicate a marked sharpness in the upper energy tail of the density of palladium d-electron states.
TL;DR: In this paper, the authors compared the photoconductivity of several binary amorphous semiconductors, including Sb2Te3, As2SeTe2 and Ge3Se2Te4, to compare with more complex multicomponent chalcogenides.
Abstract: Measurements of photoconductivity versus intensity and temperature, photoconductivity decay, thermoelectric power versus temperature, and field effect have been extended to several binary amorphous semiconductors: Sb2Te3, As2Te3, As2Se3, and Ge2Te7, to be compared with earlier measurements on As2SeTe2 and Ge3Se2Te4 and more complex multicomponent chalcogenides. Analogous behavior is found in all these materials: about 1019 cm−3 eV−1 localized recombination levels within about 0.1 eV of the gap edges; about 1019 cm−3 eV−1 localized levels near the equilibrium Fermi level; thermally activated mobility with activation energy of the order of 0.1–0.2 eV. Crystallization produces an increase in photoconductivity at 100°K by over a factor of 106.
TL;DR: In this article, low temperature thermoelectric power is calculated in the LSF approximation of the Anderson model, and theoretical results are compared with the experimental data for aluminium based transition metal alloys.
Abstract: Low temperature thermoelectric power is calculated in the LSF approximation of the Anderson model. Theoretical results are compared with the experimental data for aluminium based transition metal alloys.
TL;DR: In this article, a resonance of the type postulated early by Korringa and Gerritsen (1953) is found in the energy dependence of conduction electron scattering from interaction spin pairs.
Abstract: A resonance of the type postulated early by Korringa and Gerritsen (1953) is found in the energy dependence of conduction electron scattering from interaction spin pairs. Added to the well known effect of spin freezing, this resonance drastically reduces Kondo's giant TEP of the free spin limit. A sign change can be caused by antiferromagnetic interactions in systems with low Kondo temperature. For the average interaction effect in a random alloy a scaling in C/T is derived. Spin changes and low temperature maxima in the experimental TEP of AuMn and CuMn are interpreted.
TL;DR: In this paper, the authors compared the thermoelectric power measurements on several supersaturated AlMn alloys containing up to 2 at.% Mn in solid solution, to an accuracy of + or 5% by making corrections for phonon scattering and phonon drag.
Abstract: Thermoelectric power (S) measurements have been made on several supersaturated AlMn alloys containing up to 2 at.% Mn in solid solution. The Mn contribution has been obtained from 2 to 440K to an accuracy of +or-5% by making corrections for phonon scattering and phonon drag. The results are compared with data for the more strongly magnetic alloys, CuFe, AuV and AuCo, by plotting S/SN against T/ Theta R, where Theta R is the characteristic temperature from the -T2 term in the low temperature electrical resistivity (except for AuCo), and SN is a normalization factor. The data for all the alloys lie on the same curve in the temperature range considered, (T/ Theta R
TL;DR: In this article, the thermal and electrical conductivities and thermoelectric power of Pb from 260 to 550 K were compared with literature values and it was shown that there are no anomalous purity effects in the thermal conductivity at high temperatures and that some of the recently recommended values for this parameter may be some 2% too high.
Abstract: New data are given for the thermal and electrical conductivities and thermoelectric power of Pb from 260 to 550 K. Comparison of these data with literature values suggests that, contrary to some reports, there are no anomalous purity effects in the thermal conductivity at high temperatures and that some of the recently recommended values for this parameter may be some 2% too high.
TL;DR: In this article, the virtual bound d-density of states arising from small concentrations of d resonant impurities in transition metal and noble metal based disordered alloys is calculated, using a slightly modified version of the theory of Riedinger.
Abstract: The virtual bound d-density of states arising from small concentrations of d resonant impurities in transition metal and noble metal based disordered alloys is calculated, using a slightly modified version of the theory of Riedinger. With this information, the changes in specific heat, residual resistivity, thermoelectric power and optical absorption on alloying, may be obtained. The d component of the local density of states is given. From this follows the degree of localization of the impurity charge and the impurity contribution to the soft X-ray L amd M emission spectra. Results are presented for CuNi, CuCo and CuFe alloys and compared with known experimental values.
TL;DR: In this article, the effect of fast neutrons on the electrical conductivity and thermoelectric power and also the neutron-induced defects in β-Ga2O3 lattices were investigated.
Abstract: A study is made of the effect of fast neutrons on the electrical conductivity and thermoelectric power and also the neutron-induced defects in β-Ga2O3 It is found that the conductivity decreases while the thermoelectric power increases after an irradiation of about 1017 nvt This is explained by assuming that the defects introduced into the Ga2O3 lattices act as trapping centres for electrons The defect anneal by thermally activated processes at temperatures up to about 1000 °K with an activation energy of about 2 eV The defects are the most likely vacancies of the galium atoms