Showing papers on "Seebeck coefficient published in 1991"
TL;DR: In this paper, the mean free path of those phonons which are responsible for the phonon drag effect was calculated for single-crystalline silicon at temperatures between 2 and 300 K.
Abstract: Electrical conductivity, thermal conductivity, and thermoelectric power of single-crystalline silicon are investigated at temperatures between 2 and 300 K. From the measured data we calculate the mean free path of electrons and phonons and separate diffusion part and phonon-drag part of the thermoelectric power. Using a new method, we evaluate the mean free path of those phonons which are responsible for the phonon drag effect.
293 citations
TL;DR: In this article, the authors studied the thermoelectric properties of a composite medium and derived exact upper and lower bounds for the matrix Qe of the bulk effective transport coefficients under various conditions.
Abstract: We study the thermoelectric properties of a composite medium. Various approximations are developed for calculating the matrix Qe of the bulk effective transport coefficients of the medium, including exact upper and lower bounds for Qe under various conditions. Results are especially detailed for two‐component composites, where a field decoupling transformation is used to reduce the thermoelectric problem to two uncoupled quasi‐conductivity problems. Exact bounds are then obtained for the absolute thermopower αe and the thermoelectric figure of merit Ze in two‐component composites. We prove that Ze of the composite can never exceed the largest value of Z in any component. Some of these results are extended to certain classes of multicomponent composites.
280 citations
TL;DR: The transport coefficients in the self-consistent Hartree approximation are evaluated which interpolates smoothly between the high-tem temperature regime, dominated by Gaussian fluctuations, and the low-temperature flux-flow regime, with no intervening divergence.
Abstract: The time-dependent Ginzburg-Landau theory is used to study both transverse and longitudinal transport properties of a layered superconductor in a magnetic field near the mean-field transition temperature {ital T}{sub {ital c}2}({ital H}). We evaluate the transport coefficients in the self-consistent Hartree approximation which interpolates smoothly between the high-temperature regime, dominated by Gaussian fluctuations, and the low-temperature flux-flow regime, with no intervening divergence. This behavior is in agreement with the experimental results for the Ettingshausen coefficient, Nernst coefficient, longitudinal conductivity, and Hall conductivity in high-temperature superconductors.
256 citations
TL;DR: In this article, the thermoelectric properties of 28 sintered Si(0.8)Ge (0.2) alloys, heavily doped with either B or P and prepared from powders with median particle sizes ranging from about 1 to over 100 microns, have been determined from 300 to 1300 K.
Abstract: The thermoelectric properties of 28 sintered Si(0.8)Ge(0.2) alloys, heavily doped with either B or P and prepared from powders with median particle sizes ranging from about 1 to over 100 microns, have been determined from 300 to 1300 K. The thermal conductivity decreases with decreasing particle size; however, the figure of merit is not significantly increased due to a compensating reduction in the electrical conductivity. The thermoelectric figure of merit is in good agreement with results of Dismukes et al. (1964) on similarly doped alloys prepared by zone-leveling techniques. The electrical and thermal conductivity are found to be sensitive to preparation procedure while the Seebeck coefficient and figure of merit are much less sensitive. The high-temperature electrical properties are consistent with charge carrier scattering by acoustic or optical phonons.
228 citations
TL;DR: In this paper, electrical conductivity, Hall mobility, thermoelectric power and optical properties were studied for indium-doped zinc oxide films produced by the magnetron sputtering technique.
145 citations
TL;DR: In this article, the thermoelectric properties and Hall effects of a number of undoped Bi 2 Te 3 -Sb 2 Te3 pseudo-binary and Sb 2 Se 3 pseudo-ternary single crystal alloys grown by the Bridgman method were measured over the temperature range from 77 to 580 K. All of the alloys showed p -type extrinsic conduction and the analysis of the Seebeck coefficient and electrical conductivity indicated partial degeneracy at lower temperatures.
135 citations
TL;DR: In this article, electrical conductivity and Seebeck measurements are presented on a similar series in which 10 mol % Sr was substituted for La in order to increase the small polaron concentration through the compensation of Sr ions according to the Verway mechanism.
Abstract: A minimum exists in the electrical conductivity of the perovskite-type ceramic ${\mathrm{LaCr}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Mn}}_{\mathit{x}}$${\mathrm{O}}_{3}$ as a function of Mn content near x=0.05. This minimum has been explained in terms of a crossover from multiple trapping to percolation among energetically lower Mn sites. In this paper electrical conductivity and Seebeck measurements are presented on a similar series in which 10 mol % Sr was substituted for La in order to increase the small polaron concentration through the compensation of Sr ions according to the Verway mechanism. The data suggests that there is an apparent suppression of the Verway compensation mechanism in all Mn-doped samples. The hopping crossover observed in the Sr-free series is retained with Sr doping, although the position and depth of the electrical-conductivity minimum are altered. Difficulties in the present understanding and interpretation of the electrical conductivity and Seebeck measurements as a function of Mn and Sr content in these materials are discussed. An electronic structure is suggested, which seems to resolve many of these problems.
104 citations
Book•
17 Sep 1991
TL;DR: In this paper, the authors discuss the effect of transition metal alloys on the Fermi-Sommerfeld theory of electricity and its application to modern theory of electromagnetism.
Abstract: INTRODUCTION. THERMOELECTRICITY. RELATED THERMAL EFFECTS. DRUDE-LORENTZ THEORY OF METALS. BEGINNINGS OF SOLID STATE THEORY. Black-Body Radiation. Electron Emission. Bases for Modern Theory. SUGGESTED READING. STATISTICAL TREATMENT OF ELECTRONS. NEWTONIAN CONCEPTS. SCHRODINGER'S EQUATION. LIMITATIONS ON SCHRODINGER'S EQUATION. ELECTRONS IN POTENTIAL WELLS. One-Dimensional Wells. Three-Dimensional Wells. THE PRINCIPLE OF EXCLUSION. QUANTUM NUMBERS. ELECTRON CONFIGURATIONS OF ATOMS. SUGGESTED READING . SOLID-STATE THEORIES. SOMMERFELD THEORY. THE FERMI-DIRAC THEORY. The Fermi Energy. The Fermi-Dirac Function. COMPARISON OF CLASSICAL AND MODERN STATISTICS. THE FERMI-SOMMERFELD THEORY. Metals. Heat Capacity. Electrical Conductivity-Normal Metals. BAND THEORY. Relation to Fermi-Sommerfeld Theory. BRILLOUIN ZONE THEORY. Applications of the Brillouin Theory. ELECTRICAL CONDUCTIVITY OF SEMICONDUCTORS. Intrinsic Conduction. Electron Properties. Extrinsic Conduction. SUGGESTED READING. THERMOELECTRIC PHENOMENA. RELATIVE SEEBECK COEFFICIENT. PELTIER EFFECT. THOMSON EFFECT. THERMODYNAMIC INTERRELATIONS. Fundamental Theorem. The Role of Entropy. Relation of the Peltier Effect to the Thomson Effect. Relation of the RSC to the Thomson Effect. ABSOLUTE EMF AND THE THOMSON EFFECT. Thermoelectric Laws. UTILITY OF ASC. THERMOELECTRIC CIRCUIT ANALYSES. REFERENCES. SUGGESTED READING. MODERN THEORIES OF THERMOELECTRICITY. ROLE OF HEAT CAPACITY. Normal Metallic Elements. Transition Elements. Semiconductors. ROLE OF ELECTRICAL CONDUCTIVITY. Normal Metallic Elements. Transition Metals. Semimetals. ROLE OF INTERNAL POTENTIALS. Normal Metallic Elements. Transition Elements. Alternate Evaluation of the Conduction Function. Semiconductors. RELATIONS TO OTHER PHYSICAL PROPERTIES. RELATIVE THERMOELECTRIC PROPERTIES. SUGGESTED READING. VARIATIONS OF THE FERMI ENERGY. TEMPERATURE. EFFECTS OF ALLOYING ELEMENTS IN NORMAL METALS. EFFECTS OF ALLOYING ELEMENTS IN TRANSITION METALS. Dilute Alloys. Concentrated Alloys. STRESS EFFECTS. THERMOELECTRIC INSTABILITY. REFERENCES. SOME EFFECTS OF ALLOYING. ALLOYS OF MONOVALENT METALS. ALLOYS OF MULTIVALENT METALS. ALLOYS OF TRANSITION METALS. Normal-Metals Alloying Elements. Transition-Metal Alloying Elements. REFERENCES. SUGGESTED READING. STANDARD THERMOELEMENTS (DILUTE ALLOYS). PLATINUM AND ITS ALLOYS (TYPES S, R, AND B). The Influence of Alloying with Rhodium. Factors Affecting the Use of Platinum-Base Thermocouples. NICKEL AND ITS ALLOYS (TYPES K, E, AND N). The Short-Range Order Hypothesis. The Effects of Magnetic Transformations. Alumel (Type KN). Nicrosil (Type NP). Chromel (Type KP). Nisil (Type NN). Limitations on the Use of Nickel-Base Thermocouples. IRON ALLOYS (TYPE JP). SOME NONSTANDARD THERMOCOUPLES. 19 Alloy-20 Alloy Thermocouple. Tungsten-Rhenium Thermocouples. Other Platinum Alloy Thermocouples. IRIDIUM-RHODIUM/IRIDIUM THERMOCOUPLES. PLATINEL THERMOCOUPLES. THERMOCOUPLE LEADS (EXTENSION WIRES). REFERENCES. SUGGESTED READING-MAGNETIC EFFECTS. CONSTANTANS. BINARY ALLOY THEORY. TERNARY ALLOY THEORY. EFFECT OF TEMPERATURE. THERMOELECTRIC PROPERTIES OF BINARY ALLOYS. THERMOELECTRIC PROPERTIES OF TERNARY ALLOYS. Scattering of Hybridized s-d Electrons. Temperature Dependence of d-Level Holes. DESIGN OF CONSTANTAN-TYPE ALLOYS (TYPES EN, JN, OR TN). REFERENCES. THERMOELECTRIC APPLICATIONS OF SEMICONDUCTORS. THEORY. PRACTICE. PELTIER MATERIALS. SUGGESTED READING. THERMOELECTRICITY AS A RESEARCH TOOL. PHASE BOUNDARIES. IMPERFECTION DENSITY. BAND STRUCTURE. PURITY EVALUATION. REFERENCES. APPENDICES. THE CONTACT POTENTIAL. THE DEBYE THEORY OF HEAT CAPACITY. METHODS FOR APPROXIMATING MAGNETIC PARAMTERS OF NICKEL-BASE THERMOELECTRIC ALLOYS. Numbers of Effective Nearest Neighbors in an Electronic Spin Cluster. Paramagnetic Transformation Temperatures. Magnetic Transformation Temperatures. INDEX
90 citations
78 citations
TL;DR: In this article, the thermoelectric power and conductivity of polyacetylene doped with iodine were measured and a nonlinearity in the thermopower was observed, similar to the electron-phonon effect in metallic diffusion thermopowers.
Abstract: We report measurements of the thermoelectric power and conductivity of ‘‘new’’ polyacetylene doped with iodine. In highly doped samples in which the conductivity extrapolates to finite values at zero temperature, we observe a nonlinearity in the thermopower very similar to that characteristic of the electron–phonon effect in metallic diffusion thermopower. The size of this nonlinearity is unusually small in the most highly conducting samples, as expected when the intrinsic conductivity is very large. For samples with additional sp3 defects or lower doping levels, in which the conductivity follows variable‐range hopping behavior, we also find evidence for a hopping contribution in the thermopower.
65 citations
TL;DR: In this article, the phase segregation is not triggered by or coupled to the point at which long-range 3D magnetic order develops within the insulating component of the two-phase mixture.
Abstract: Superoxygenated La 2 CuO 4+δ , produced at 1800 atm and 550°C, has been investigated by the following means; resistivity, Seebeck coefficient Hall coefficient, magneto-resistance, electron microscopy, AC and DC susceptibility, and specific heat. The results are contrasted with those from “reduced” (stoichiometric) La 2 CuO 4 . Unlike the latter Mott insulator, the oxygenated material shows mixed valent, delocalized behaviour. That behaviour is rendered more complex because of phase segregation via spinodal decomposition onsetting just below room temperature. The observed microstructure permits detailed interpretation of the resulting modification in properties. The degree to which the observed superconductivity mirrors that of (La/Sr) 2 CuO 4 is discussed. Restricting the phase segregation by fast cooling inhibits the superconductive behaviour, by promoting lower effective carrier counts and mobilities and greater magnetic admixture. It is shown that phase segregation is not triggered by or coupled to the point at which long-range 3D magnetic order develops within the insulating component of the two-phase mixture. The super-conductivity is presented in terms of the negative- U charge fluctuation model developed earlier.
TL;DR: In this article, the authors present measurements of the electrical resistivity, thermal conductivity, and Hall, Nernst, and Seebeck effects in the mixed state of single crystalline Bi2Sr2CaCu2Ox.
Abstract: We present measurements of the electrical resistivity, thermal conductivity, and Hall, Nernst, and Seebeck effects in the mixed state of single crystalline Bi2Sr2CaCu2Ox. It is shown that the sign of the Hall voltage changes twice as temperature decreases below Tc. From the Nernst effect we estimate the transport entropy Sφ to be about 10−10 erg/K cm. Sφ is equal to zero in the normal state, increases and passes through a maximum at the mixed state as expected. The temperature dependences of the thermoelectric power in magnetic fields are analogous to the resistive transition curves. These phenomena are discussed in terms of flux flow. The contribution of the flux flow to the thermal conductivity is estimated to be negligible. Lowering of the thermal conductivity at temperatures below Tc by a magnetic field is attributed to phonon scattering by the vortex lines.
TL;DR: In this paper, the electrical transport behavior and defect structure of Ca-doped YCrO3 were studied using electrical conductivity and Seebeck coefficient measurements as a function of oxygen activity and temperature.
TL;DR: In this paper, the thermoelectric properties of GeTe-based materials for the medium temperature range (600 to 900 K) are measured and the best p-type new material is the composition (GeTe)0.4 × 10−3 K−1 at about 700 K.
Abstract: Basic thermoelectric p-type materials for the medium temperature range (600 to 900 K) are GeTe-based materials. Hot-pressed samples of (GeTe)1−x[(Ag2Te)1-y(Sb2Te3)y]x solid solutions with y = 0.6, y = 0.75 are prepared. Their thermoelectric properties (thermoelectric power S, electric conductivity σ and thermal conductivity K) in the temperature range 300 to 750 K are measured. The thermoelectric figure of merit Z = S2σ/K for some compositions in calculated. The best p-type new material is the composition (GeTe)0.8[(Ag2Te)0.4(Sb2Te3)0.6]0.2 with Zmax = 2.4 × 10−3 K−1 at about 700 K.
[Russian Text Ignored].
TL;DR: In this paper, electrical properties of Fe2O3 were studied by using several electrical methods such as electrical conductivity, thermopower (Seebeck effect) and work function, and it was found that the exponent of the po2 dependence resulting from the work function measurements (1/nφ) is about 1/2.
Abstract: Electrical properties of Fe2O3 were studied by using several electrical methods such as electrical conductivity, thermopower (Seebeck effect) and work function. The studies were performed at elevated temperatures (1053–1153 K) and under controlled oxygen activity (102∓105 Pa). Samples of different thickness varying between 103 nm and 1 mm were taken for the measurements of both electrical conductivity and thermopower. It has been found that the exponent of the po2 dependence resulting from the work function measurements (1/nφ) is about 1/2. Both thermopower and electrical conductivity data are well consistent with work function data for the thin film (1000 nm) of Fe2O3. The charge transport in Fe2O3 has been interpreted in terms of small polaron mechanism. Analysis of measured electrical parameters, regarding the thickness of studied specimens, indicates that the near-surface layer of Fe2O3 exhibits much higher deviation from stoichiometry than the bulk phase and resulting strong interaction between charge carriers. This effect has been interpreted in terms of segregation of intrinsic lattice defects to the surface, and presumably also to grain boundaries, of Fe2O3.
TL;DR: In this paper, the authors measured the conductivity of tridecylmethylammonium-Au(dmit) films for 300-4 K and found that the conductivities after electrochemical oxidation are 30-50 S/cm at room temperature, increasing with decreasing temperature, and beginning to decrease at about 200 K.
Abstract: Electronic transport measurements are reported for Langmuir-Blodgett (LB) films of tridecylmethylammonium-Au(dmit)2 for 300-4 K. The conductivity after electrochemical oxidation is 30-50 S/cm at room temperature, increases with decreasing temperature, and begins decrease at about 200 K. The conductivity at lower temperatures is explained by two-dimensional variable range hopping (2D VRH). The thermoelectric power (S) is positive and well fitted by a linear combination of the temperature dependence of 2D VRH (Sv\proptT1/3) and that of metal (Sm\proptT). These results can be explained by a model in which highly conductive metallic regions are separated by thin weakly conductive regions. The UV/visible absorption spectra and the X-ray diffraction patterns indicate that a large structural change occurs accompanied by electrochemical oxidation.
TL;DR: The electrical conductivity and thermoelectric power of single-phase cubic nickel manganite spinels NixMn3−xO4 with 0.57 was shown in this paper.
TL;DR: In this paper, the authors made thermoelectric power studies of MnMg mixed ferrites over the temperature range 300-700 K by the differential method and found that the Seebeck coefficient S decreases while the carrier concentration n and the charge carrier mobility μ increase with increasing temperature.
Abstract: Thermoelectric power studies are made of MnMg mixed ferrites over the temperature range 300–700 K by the differential method. The Seebeck coefficient S is found to decrease while the carrier concentration n and the charge carrier mobility μ are found to increase with increasing temperature. On the basis of these results an explanation for the conduction mechanism in MnMg mixed ferrites is suggested.
TL;DR: In this paper, a misfit layer structure with unit cell dimensions for the SnSe subsystem was solved by X-ray powder diffraction, and the structure was isostructural with (PbS)1.14NbS2.
TL;DR: In this paper, an attempt is made to investigate the thermoelectric power of the electrons under strong magnetic quantization in n-channel inversion layers of ternary chalcopyrite semiconductors at low temperatures, taking n−channel inversions layers on CdGeAs2 as examples, under both the weak and strong electric field limits, respectively.
Abstract: An attempt is made to investigate the thermoelectric power of the electrons under strong magnetic quantization in n‐channel inversion layers of ternary chalcopyrite semiconductors at low temperatures, taking n‐channel inversion layers on CdGeAs2 as examples, under both the weak and strong electric field limits, respectively. We have formulated the magneto‐thermo power on the basis of newly derived two‐dimensional electron energy spectra for both the limits by considering various types of anisotropies of the band parameters within the frame work of k■p formalism. It has been observed that, the magneto‐thermo power decreases with increasing surface electric field and decreasing quantizing magnetic field in an oscillatory manner for both the limits. The crystal field parameter enhances the numerical magnitudes and the corresponding results for n‐channel inversion layers of parabolic semiconductors have also been obtained as special cases from the generalized expressions under certain limiting conditions.
TL;DR: From the measured values of the Seebeck and Nernst-Ettingshausen effects, it is found that this contribution is as large as the direct flux-flow contribution to the Hall effect, but has the opposite sign for a positive Seebeck coefficient, which leads to a sign change of the Hall resistance.
Abstract: We consider a contributon to the flux-flow Hall effect that arises from the existence of large thermomagnetic effects in the mixed state of the high-{ital T}{sub {ital c}} superconductors. From the measured values of the Seebeck and Nernst-Ettingshausen effects we find that this contribution is as large as the direct flux-flow contribution to the Hall effect, but has the opposite sign for a positive Seebeck coefficient. Therefore it leads to a sign change of the Hall resistance. A calculation of the temperature and field dependence of the Hall resistivity yields good agreement with the data.
TL;DR: In this paper, quasi-one-dimensional sulfides TlCu7S4 and KCu 7S4 with (NH4) Cu7S 4 type structure were prepared by direct synthesis from the elements.
TL;DR: Measurements of the Seebeck coefficient performed with epitaxial {ital c}-axis-oriented YBa{sub 2}Cu{sub 3}O{sub 7} films show excellent agreement with the theory.
Abstract: The temperature dependence of the Seebeck coefficient in the mixed state of a superconductor is closely related to the resistivity due to flux motion. This is a result of the counterflow of normal current and supercurrent in the presence of a temperature gradient, as discussed by Ginzburg. Measurements of the Seebeck coefficient performed with epitaxial {ital c}-axis-oriented YBa{sub 2}Cu{sub 3}O{sub 7} films show excellent agreement with the theory.
TL;DR: In this article, the Seebeck coefficient of the yttria-stabilized zirconia has been used to estimate the entropy change of the hydrogen reaction on platinum electrodes.
Abstract: This paper reports on the dependence on hydrogen partial pressure of the entropy change of the hydrogen electrode reaction on platinum electrodes on yttria-stabilized zirconia that was estimated from measurements of the Seebeck coefficient of the yttria-stabilized zirconia. The entropy change of the oxygen reaction also was estimated by Seebeck coefficient measurements. The total entropy change of the reaction in a solid oxide fuel cell was calculated from the thermodynamic data. An empirical equation for the dependence of the entropy change of the hydrogen electrode reaction on hydrogen partial pressure was obtained from the observed entropy change of the oxygen electrode and the total entropy change. The observed dependence of the entropy change of the hydrogen reaction on hydrogen partial pressure was in good agreement with the empirical equation.
TL;DR: In this paper, the authors measured the electrical transport properties of misfit layer SnS (PbS) and sandwiches TiS2 (1T-TiS2) and showed that the rho-ab versus temperature curves are nonlinear from 4 to 300 K.
TL;DR: In this paper, the results of the investigations on electrical conductivity and thermoelectric power of YBa 2 Cu 3 O 7− y as a function of temperature (680 −1170K) and oxygen pressure (10 5 −30 Pa) at thermodynamic equilibrium were presented.
Abstract: This paper presents the results of the investigations on electrical conductivity and thermoelectric power of YBa 2 Cu 3 O 7− y as a function of temperature (680–1170K) and oxygen pressure (10 5 –30 Pa) at thermodynamic equilibrium. The analysis of electrical properties as a function of the deviation from stoichiometry allowed one to determine the type of dominating electronic defects and transport properties in different temperatures and nonstoichiometry. A qualitative model for the electronic structure of YBa 2 Cu 3 O 7 − y at high temperatures is proposed.
15 Mar 1991-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, a survey on electron-structure interrelations in disordered metals is presented. But the authors focus on the electron-structural relation itself, the Hall coefficient, and the thermopower.
Abstract: We give a survey on our current understanding of electron-structure interrelations in disordered metals. The ability to decrease the electronic ground-state energy induces a peak in the static structure function close to 2kF over large composition ranges and a corresponding pseudo gap in the electronic density of states at the Fermi energy. The depth of the gap is directly related to the intensity of the peak at 2kF and shows influences on many physical properties. We report on the electron-structure relation itself, the Hall coefficient and the thermopower. Both the Hall coefficient and the thermopower show typical deviations of the free electron behaviour whenever a pseudo gap at EF exists.
TL;DR: The electrical resistivity, thermoelectric power, Hall effect, magnetoresistivity, magnetic susceptibility and magnetization of intermetallic ternary compounds RERuSn3 (RE=La, Ce, Pr, Nd and Sm), CeRuSnx (2.85
Abstract: The electrical resistivity, thermoelectric power, Hall effect, magnetoresistivity, magnetic susceptibility and magnetization of intermetallic ternary compounds RERuSn3 (RE=La, Ce, Pr, Nd and Sm), CeRuSnx (2.85