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Showing papers on "Seebeck coefficient published in 1971"


Journal ArticleDOI
TL;DR: In this article, the electrical conductivity of single-crystal V2O5 doped with copper (α phase) has been measured along the c axis from 77°K to 298°K.

53 citations


Journal ArticleDOI
TL;DR: In this paper, the thermoelectric power and temperature coefficient of resistance of gold films have been measured and related to the energy dependence of both the mean free path of conduction electrons and the area of the Fermi surface.
Abstract: The thermoelectric power and temperature coefficient of resistance of gold films has been measured and related to the energy dependence of both the mean free path of conduction electrons and the area of the Fermi surface. Values obtained for the quantities (dlnλ/dlnW)W=WF and (dlnA/dlnW)W=WF are − 0.60±0.04 and − 0.85±0.04, respectively. These quantities can be determined without knowing the surface‐scattering coefficient or sample thickness if the films have the same structure as the bulk material.

50 citations


Journal ArticleDOI
TL;DR: The electrical resistivity and thermoelectric power of the organic semiconductor tetrathiotetracene (TTT) and its chloride, bromide, iodide, and thiocyanate salts are reported as a function of temperature.
Abstract: The electrical resistivity and thermoelectric power of the organic semiconductor tetrathiotetracene (TTT) and its chloride, bromide, iodide, and thiocyanate salts are reported as a function of temperature. The ion–radical salts, of nearly 1:1 stoichiometry, were discovered to be highly conducting organic semiconductors and have resistivity values at room temperature ranging from 2.3 × 103 Ω·cm for TTT–chloride to 0.71 Ω·cm for TTT–iodide. The sign of the Seebeck coefficient of TTT–chloride corresponds to an n‐type semiconductor, while for TTT and the other salts it indicates p‐type behavior. Infrared absorption spectra of the solids, uv–visible spectra of solutions, preliminary x‐ray powder patterns and density measurements are correlated with electrical properties. The influence of constitution of the ion–radical salts on the electrical resistivity and possible mechanisms of conduction are discussed.

45 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present measurements of thermoelectric power for nickel and cobalt dilute alloys with d transition elements in two temperature ranges: from 1.3 to 4.2 K and from 77 to 300 K. The results of the measurements at room temperature in a two-band conduction model and deduce the thermopowers associated with the matrix (Smσ) and with the impurities (Soσ) in each sub-band σ.
Abstract: We present new measurements of thermoelectric power for nickel and cobalt dilute alloys with d transition elements in two temperature ranges: from 1.3 to 4.2 K and from 77 to 300 K. We analyse the measurements at room temperature in a two-band conduction model and deduce the thermopowers associated with the matrix (Smσ) and with the impurities (Soσ) in each sub-band σ. The results obtained for the impurity thermoelectric power confirm the model of electronic structure suggested for this alloy from magnetization and resistivity measurements; this model is characterized by the occurrence of a virtual bound state supward arrowdupward arrow at the Fermi level when the charge difference between the matrix and the impurity is large enough. From the values of impurity thermoelectric power in the supward arrow sub-band, we deduce the position and the width of the virtual bound state.

40 citations


Journal ArticleDOI
TL;DR: In this paper, the authors show that the Ni 3d states are essentially localized or form a narrow band and the predominant mechanism of conduction is by holes in a wide band.
Abstract: Hexagonal nickel sulphide shows a metal to semiconductor first order phase transition at a temperature TN which depends on sulphur content. Thermoelectric power, conductivity, Hall and magnetic susceptibility measurements have been made on five single crystals of compositions ranging from NiS-NiS1.02 in the temperature range 82-300 K. The results suggest that below TN the Ni 3d states are essentially localized or form a narrow band. The predominant mechanism of conduction is by holes in a wide band. The discontinuity in conductivity at TN is most likely due primarily to a change in mobility. Impurity band conduction occurs at low temperatures. The susceptibility curves have a markedly different shape from that normally expected for an antiferromagnet. This results from the first order character of the phase transition at TN.

36 citations


Journal ArticleDOI
TL;DR: In this paper, the Hall mobility and thermoelectric power of n-and p-type CdxPb1?x Te alloys with x = 0?03, 0?06 and 0?11 have been measured at temperatures within the range 77 to 450 K for carrier concentrations within a range 1016 to 1020 cm?3.
Abstract: The Hall mobility and thermoelectric power of n- and p-type CdxPb1?x Te alloys with x = 0?03, 0?06 and 0?11 have been measured at temperatures within the range 77 to 450 K for carrier concentrations within the range 1016 to 1020 cm?3. The results have been interpreted using a two valence band model. The energy separation between valence bands was found to decrease with alloying and this had the important consequence that direct information could be obtained concerning heavy-mass hole conduction.

33 citations


Journal ArticleDOI
TL;DR: In this paper, the Hall mobility, thermoelectric power, magnetoresistance and optical absorption coefficient of MgxPb1−x Te alloys with 0less-than-or-eq, slantx less-thanor-equivalent, and slant006 have been measured at temperatures within the range 77 to 450 K.
Abstract: The Hall mobility, thermoelectric power, magnetoresistance and optical absorption coefficient of MgxPb1−x Te alloys with 0less-than-or-eq, slantxless-than-or-eq, slant006 have been measured at temperatures within the range 77 to 450 K. It has been found that alloying PbTe with MgTe increases the direct energy gap and the resulting transport properties are similar to those of CdxPb1−x Te alloys.

32 citations


Journal ArticleDOI
TL;DR: In this paper, the authors measured the thermoelectric power of a number of Au-Fe alloys, with Fe concentrations between similar 10 and 1900 ppm, and found that the thermopower of all but the most dilute alloys shows an initial increase in magnetic field, which is caused by Fe-Fe interactions.
Abstract: We have measured the thermoelectric power of a number of Au-Fe alloys, with Fe concentrations between similar 10 and 1900 ppm. Measurements were made between 0.4 and 30 K in fields up to 70 kOe. The alloys exhibited the familar `giant' thermopower in zero field, the peak value observed being - 15 μ V K-1 at about 10 K. Both the order of magnitude and the temperature dependence of the zero-field thermopower agree fairly well with Kondo's theory of spin-flip scattering. The thermopower of all but the most dilute alloys shows an initial increase in a magnetic field, which we believe is caused by Fe-Fe interactions. The thermopower then decreases due to `freezing-out' of spin-flip scattering and a simple pair-interaction model accounts for most of this observed behaviour. For the most concentrated alloy the decrease is not observed, even for the maximum field applied. For still higher fields (and lower concentrations) the thermopower decreases approximately as 1/H, as is suggested by a recent perturbation calculation.

31 citations



Journal ArticleDOI
TL;DR: The Seebeck coefficient can be related to the specific heat of the charge carriers of the ferromagnetic ferromagnet nickel as mentioned in this paper, and it has been shown that the Seebeck effect agrees closely with that determined from conventional specific heat measurements.
Abstract: The Seebeck coefficient can be related to the specific heat of the charge carriers. Experiments on the itinerant ferromagnet nickel show that the specific heat determined from the Seebeck effect agrees closely with that determined from conventional specific-heat measurements.

28 citations


Journal ArticleDOI
TL;DR: In this article, the authors measured thermoelectric power, isothermal transverse-Nernst coefficient and Hall mobility from 100 to 400 K on polycrystalline Cd3-xZnxAs2 alloys, with x=0, 06, 12, 18 and 3, together with transmission and reflectivity spectra from 1-15 μm.
Abstract: Measurements of thermoelectric power, isothermal transverse-Nernst coefficient and Hall mobility from 100 to 400 K on `as-grown' and doped poly-crystalline Cd3-xZnxAs2 alloys, with x=0, 06, 12, 18 and 3, together with transmission and reflectivity spectra from 1-15 μm for the bulk alloys and thin evaporated films are reported. It is believed that the principal valence band of Cd3-xZnxAs2 is a heavy-mass band possibly displaced in k-space with respect to the conduction band, the latter being highly nonparabolic and located at the centre of the reduced zone. The energy separation between the principal valence and conduction bands is zero in Cd3As2, but quickly becomes positive and large with the addition of Zn. The smallest direct energy gap has also been found to increase steadily with alloying, resulting in a more parabolic conduction band. The carrier scattering in the Cd-rich alloys was found to be by a mixture of acoustical and optical phonons, the magnitude of the relative contributions depending on the carrier density. The scattering of the heavy-mass holes in the Zn-rich alloys is believed to be by acoustical phonons.

Journal ArticleDOI
TL;DR: In this paper, the frequency of the de Haas-van Alphen type is measured over a wide range of angles between the magnetic field and the c axis of the Brillouin zone.
Abstract: Quantum oscillations as a function of magnetic field in the Hall effect and thermoelectric power are studied in two samples of pressure-annealed pyrolytic graphite. Only the oscillations originating from minority-Fermi-surface carriers are discussed. Frequencies of the de Haas-van Alphen type are measured over a wide range of angles between the magnetic field and the c axis of the Brillouin zone. Results are given graphically and analyzed.


Journal ArticleDOI
TL;DR: In this article, the authors show that at high temperature, Li's constant volume resistivity becomes larger than the zero (atmospheric) pressure value, which is contrary to what is observed in the other alkalis.
Abstract: In Li, at high temperature, the constant volume resistivity becomes larger than the zero (atmospheric) pressure value. This is contrary to what is observed in the other alkalis. It has been suggested that it is a result of an increase in the distortions of the lithium Fermi surface with application of hydrostatic pressure. We show that the effect can be understood much more simply and naturally on the basis of a spherical Fermi surface and a simple electron-ion pseudopotential form factor. The form factor is used to evaluate the absolute value and the volume dependence of the thermoelectric power. the thermal conductivity and the electron-phonon mass renormalization.

Journal ArticleDOI
TL;DR: In this article, conductivity modulation was observed in thin films of chalcogenide glass by applying an electric field through the (mica or plastic) substrate, in agreement with the Seebeck coefficient.
Abstract: Conductivity modulation was observed in thin films of chalcogenide glass by applying an electric field through the (mica or plastic) substrate. At room temperature, the surface potential could be varied through ± 3kT, the surface being always p type, in agreement with the Seebeck coefficient. Comparison of the field‐effect curves with equilibrium space‐charge theory suggests a bulk density of localized states in the range from 1019 to 2 × 1020 cm−3 eV−1 within ± 0.1 eV of the Fermi level.

Journal ArticleDOI
TL;DR: In this article, conductivity and Hall effect measurements were performed on a series of chalcogenide glasses As 2 Se 3− x As 2 Te 3 with x = 0.5, 1, 1.5 and 3 in the temperature range from −10 to 100°C.
Abstract: Conductivity and Hall effect measurements are reported on a series of the chalcogenide glasses As 2 Se 3− x As 2 Te 3 with x = 0.5, 1, 1.5, 2, 2.5 and 3 in the temperature range from −10 to 100°C. The Hall effect measurements were extended to samples with low conductivity down to 5 × 10 −8 Ω −1 cm −1 . The measuments were performed with a dc apparatus. Both conductivity and Hall coefficient vary exponentially with temperature, but the conductivity lines are somewhat steeper than the Hall coefficient lines. Apparent values of the energy gap were derived from conductivity and Hall effect measurements, the latter being about 10 per cent smaller. The energy gap decreases with increasing tellurium content. the values derived from Hall effect measurements are 1.17 and 0.87 eV for x = 0.5 and 3 respectively. The sign of the Hall coefficient, in all the alloys investigated, showed n-type conductivity which is in apparent contradiction with the sign of the thermoelectric power which indicates p-type conductivity. The Hall mobility increases slightly with the tellerium content. The calculated values for x = 0.5 and 3 are 0.03 and 0.05 cm 2 V −1 sec −1 respectively. The Hall mobility shows a slight exponential increase with temperature. The calculated values of the activation energy of the mobility are about 0.05 eV.

Journal ArticleDOI
TL;DR: In this article, the temperature dependence of the Seebeck coefficient θ of pure and partially Ni, Co and Mn substituted magnetic between 63 and 300°K was investigated, and the most striking feature was the rather sharp change in sign of θ at the Verwey transition in pure magnetite.


Journal ArticleDOI
TL;DR: In this article, a current balance model for the Seeback effect is introduced and used to derive the full theoretical formula for phonon drag thermoelectric power derived by Bailyn in 1967.
Abstract: A `current balance' model for the Seeback effect is introduced and used to derive in a elementary way the full theoretical formula for phonon drag thermoelectric power derived by Bailyn in 1967.

Journal ArticleDOI
TL;DR: In this article, the thermal emf and magnetoresistance of liquid selenium were measured with graphite electrodes in a pressure vessel up to 1300K and a sign change of the thermoelectric power was observed at about 990K.
Abstract: The thermal emf and the magnetoresistance of liquid selenium were measured with graphite electrodes in a pressure vessel up to 1300K. A sign change of the thermoelectric power was observed at about 990K. Above this temperature selenium is an n-type semiconductor. A relatively high magnetoresistance was measured above 990K. Experiments for measuring the Hall effect with graphite electrodes up to 870K failed. Considering the results of the experiments a model for the conduction mechanism could be suggested.

Journal ArticleDOI
TL;DR: The absolute thermoelectric powerS of chromium and chromium-silicon alloys containing 0.46, 0.90, 1.37,1.85, 2.74, 3.19 and 3.67 at. % was determined as a function of temperatureT between 50° and 350 °K as discussed by the authors.
Abstract: The absolute thermoelectric powerS of chromium and chromium-silicon alloys containing 0.46, 0.90, 1.37, 1.85, 2.74, 3.19 and 3.67, at. % silicon has been determined as a function of temperatureT between 50° and 350 °K. TheS vs. T curves exhibit large anomalies in this temperature range due to the transition from a paramagnetic to an antiferromagnetic state. These transitions in samples containing 1.37, 1.85 and 2.74 are essentially discontinuous and similar to that observed in the chromium-3.3 at. % iron sample at 248 °K, where it undergoes a transformation from a transverse spin-density wave state to a commensurate antiferromagnetic structure. It is suggested that a commensurate antiferromagnetic structure also exists in the chromiumsilicon system for silicon concentrations larger than 1 at. %.

Journal ArticleDOI
TL;DR: The in-plane thermoelectric power of single-crystal graphite in the presence of a magnetic field applied parallel to the c direction was measured at temperatures (T) from 4.2°K up to 300°K.
Abstract: The in-plane thermoelectric power () of single-crystal graphite in the presence of a magnetic field applied parallel to the c direction was measured at temperatures (T) from 4.2°K up to 300°K. With an increase of the field intensity (H), the sharp negative dip of the  versus T diagram previously found to be (0) = −11.5μv/°K at 35°K exhibited a slight shift of position to near 30°K and a remarkable growth of depth to (H) ⋍ −80μv/°K for H = 1.7 kG and (H) ⋍ − 2000 μv/°K for H = 8.0 kG. In accordance with Sugihara's theory on the phonon drag effect in semimetals, these anomalies have been ascribed to the strong interaction between carriers and phonons in graphite.

Journal ArticleDOI
TL;DR: In this paper, the authors measured electrical conductivity, activation energy for conduction, thermoelectric power and Hall mobility in compactions of a series of simple and complex TCNQ salts.
Abstract: Electrical conductivity, activation energy for conduction, thermoelectric power and Hall mobility have been measured in compactions of a series of simple and complex TCNQ salts. The results indicate nearly intrinsic semi-conduction in extremely narrow bands, with an average drift mobility of about 10–2 cm2/Vs.

Journal ArticleDOI
TL;DR: In this article, measurements of Hall mobility, thermoelectric power and transverse Nernst-Ettingshausen coefficients have been made on n-and p-type SnxPb1-xTe, CdxPb 1-exTe, MgXPb 2-exSe, CdPb 3-xSe and Mgxpb 1 -exSe alloys with 0less-than-or-eq, slant-less, similar01.
Abstract: Measurements of Hall mobility, thermoelectric power and transverse Nernst-Ettingshausen coefficients have been made on n- and p-type SnxPb1-xTe, CdxPb1-xTe, MgxPb1-xTe, CdxPb1-xSe and MgxPb1-xSe alloys with 0less-than-or-eq, slantxless, similar01. The measurements covered the temperature range 100 to 400 K and the alloys had carrier concentrations within the range 5 × 1017 to 1 × 1019 cm−3. To explain the results several scattering mechanisms were considered and the non-parabolicity of the energy bands was taken into account. It was found that the charge carrier scattering in all the materials under the conditions of experimentation was predominantly by acoustical phonons.

Journal ArticleDOI
TL;DR: In this article, the authors compared the transport properties of bismuth telluride and its alloys for single crystal, polycrystalline, and hot pressed powder samples under equivalent conditions of temperature and carrier concentration.
Abstract: Measurements of the transport properties of bismuth telluride and its alloys are reported in the literature for single crystal, polycrystalline and hot pressed powder samples. Since these materials are highly anisotropic, the transport properties of these three types of sample are not in general the same under equivalent conditions of temperature and carrier concentration. The author compares theoretically the electrical and thermal conductivities, the Seebeck coefficient and the Hall coefficient of three types of sample so that meaningful comparisons may be made between the various results reported in the literature. The theory presented is applicable, in general, to anisotropic semiconductors having uniaxial symmetry.

Journal ArticleDOI
TL;DR: In this article, the thermal conductivities of the three states of Ni3Fe exhibit peaks between 142 and 175 K, and the unusual relative shift of the temperatures of the maximum conductivities is related directly to the large deviation of the electrical resistivity differences from Matthiessen's rule.
Abstract: Thermal conductivity λ, electrical resistivity ρ, and Seebeck coefficient S measurements have been made from 80 to 400 K on a Ni3Fe alloy (74.77‐at. % Ni and 25.33‐at. % Fe) in both disordered and highly ordered states. The effect of lattice disorder is to lower λ and S and increase ρ. Although λ and ρ for the three states studied differ by about 50%, the Lorenz ratios λρ/T are the same to within the combined uncertainty of the measurements. This ratio is near the Sommerfeld value Lo from 200 to 400 K, and the positive deviation from Lo below 200 K indicates a significant lattice component to λ in all states of disorder. The thermal conductivities of the three states of Ni3Fe exhibit peaks between 142 and 175 K. The unusual relative shift of the temperatures of the maximum conductivities is related directly to the large deviation of the electrical resistivity differences from Matthiessen's rule.

Journal ArticleDOI
TL;DR: In this article, the synthesis of CuSe and the examination of prepared samples by means of density measurements, Debye-Scherrer analysis and measurement of its electrical properties are described.
Abstract: This paper describes the synthesis of CuSe and the examination of prepared samples by means of density measurements, Debye-Scherrer analysis and measurement of its electrical properties. Considering the temperature-dependence of electrical conductivity and the values of thermoelectric power and the Hall constant, one may conclude that synthetic klockmannite behaves as a metal.

Journal ArticleDOI
TL;DR: In this paper, the results of the measurement of three low-field thermomagnetic coefficients /b a/sub 231, /b b/sub 3311/ and /b B/sub 322/ are reported.

Journal ArticleDOI
TL;DR: In this article, the Hall coefficient and electrical conductivity of Li-NH3, K−NH3 and Ca-NH 3 solutions were measured as a function of concentration and temperature.
Abstract: The Hall coefficient and electrical conductivity of Li–NH3, K–NH3, and Ca–NH3 solutions were measured as a function of concentration and temperature. The temperature range extended from 203–243°K and the concentration extended from metal saturation down to ≈ 4 MPM. The Hall coefficient was temperature independent for all solutions studied, but upon dilution, increased to values above the free‐electron value at different electron concentrations for the monovalent and divalent solutions. The conductivity values ranged from 100–5000 Ω−1·cm−1, and dσ / dT was positive. Using an ionized impurity scattering model and an adjustable effective mass for the metal–ammonia solutions, a qualitative fit for the conductivity, Hall coefficient, and thermopower can be made in the region 4–8 MPM. The loss of degeneracy upon dilution seems to be responsible for anomalies in this region, and hence the metal–nonmetal transition can be narrowed down to the 1–4 MPM region.

Journal ArticleDOI
TL;DR: In this article, the authors measured the absolute thermoelectric power of chromium and chromium-iron alloys containing 1.8, 3.3, 4.9, 9.5, and 11.2 at.