Showing papers on "Seebeck coefficient published in 1979"
TL;DR: In this paper, the electrical resistivity, thermal conductivity and thermopower of bismuth, antimony and arsenic are reviewed, with particular emphasis on measurements performed at low and ultralow temperatures.
Abstract: The group V semimetals are first introduced by comparing their particular band structure with the more familiar typical metals or semiconductors. Recent results on the electrical resistivity, thermal conductivity and thermopower of bismuth, antimony and arsenic are reviewed, with particular emphasis on measurements performed at low and ultralow temperatures. The data are analysed in terms of the peculiar features of the electron and phonon scattering, and reference is made to the band structure and rhombohedral symmetry. Recent improvements in the interpretation of the results are discussed.
174 citations
TL;DR: In this paper, the conditions for obtaining homogeneous glasses were examined, and measurements of resistivity and thermoelectric power were carried out on Ge20Bi10Se70 glass, one of the typical n-type semiconducting glasses in the system Ge‐BiSe.
Abstract: Chalcogenide bulk glasses exhibiting n‐type conduction were first prepared by quenching the melts of mixtures of Ge, Se, and Bi2Se3 or Bi. The conditions for obtaining homogeneous glasses were examined, and measurements of resistivity and thermoelectric power were carried out on Ge20Bi10Se70 glass, one of the typical n‐type semiconducting glasses in the system Ge‐Bi‐Se. The results indicated that the electrical properties of homogeneous glasses were slightly affected by the difference in starting materials, and the resistivity and thermoelectric power were about 3×107 Ω cm and −1.4 mV/K at room temperature, respectively.
107 citations
TL;DR: In this article, the power of polyacetylene polymethylacetylene has been investigated as a function of dopant concentration and temperature, and the results show that the power remains positive over the full range of concentration 0 < y < 0.03, while the semiconductor-metal transition occurs at nc ≅ 3 mole %.
102 citations
TL;DR: In this paper, the Seebeck coefficient, superconducting transition temperature, and upper critical field have been measured in Cs/sub x/WO/sub 3/ for 0.19 < or =x< or =0.30.
Abstract: The resistivity, Seebeck coefficient, superconducting transition temperature, and upper critical field have been measured in Cs/sub x/WO/sub 3/ for 0.19< or =x< or =0.30. In contrast to Rb/sub x/WO/sub 3/, no temperature-dependent anomalies were observed in either the normal resistivity or the Seebeck coefficient. The superconducting transition temperature, T/sub c/, increases monotonically with decreasing x from 2 K at x = 0.30 up to 6.7 K at x=0.20, with an inflection near 0.24. The resistivity as a function of x increases monotonically with decreasing x and also has an inflection near x=0.24.
78 citations
TL;DR: In this paper, the authors presented accurate experimental results for the electrical conductivity σ, the equation of state and its derivatives such as isothermal compressibility, thermal expansion coefficient and thermal pressure coefficient, as a function of pressure and temperature to 2500 bar and 1580°C, respectively.
Abstract: The paper presents accurate experimental results for the electrical conductivity σ, the equation of state and its derivatives such as isothermal compressibility, thermal expansion coefficient and thermal pressure coefficient, as a function of pressure and temperature to 2500 bar and 1580°C, respectively. Special consideration is given to the range of densities d smaller than 9 g cm−3. The results give considerable evidence, that a temperature-dependent mobility gap (E c − E f) occurs for d < 9 g cm−3. The variation of (E c − E f) with d and T, which is determined from a logarithmic plot of σ versus 1/T and the thermoelectric power S, suggests that (E c − E f) vanishes at d about 8.8 g cm−3. The value of σ0 is about 140–200 ohm−1 cm−1 and in excellent agreement with the prediction of Mott (1971). An attempt is made to analyse the equation-of-state data in terms of a rigid-sphere model. The results indicate the first evidence for a change from metallic cohesion to another interatomic force law in t...
59 citations
TL;DR: In this article, the d electronic state in realistic structurally relaxed models of amorphous and liquid transition metals is investigated by using the recursion method and the local density of states is discussed extensively with relation to the local atomic environment.
Abstract: The d electronic state in the realistic structurally relaxed models of amorphous and liquid transition metals is investigated by using the recursion method. The local density of states is discussed extensively with relation to the local atomic environment. It is found that the density of states for the amorphous case has a double-peaked structure, whereas that for the liquid case is single-peaked. The electronic transport is discussed in a model after Mott (1972) involving s-d transitions and with different mean free paths for s and d electrons. The numerical results of the resistivity and thermoelectric power show quite excellent agreement with experimental ones.
47 citations
TL;DR: In this paper, the formation of spinel Li[Mn2]O4 from Li2CO3 and Mn3O4 by solid state reaction was examined as a function of temperature.
46 citations
TL;DR: In this article, the authors investigated the properties of Na, K, and Cs-implanted specimens and found that they were thermally stable up to about 400°C, whereas Li-doped specimens showed rapidly increasing changes even after short annealing at 250°C.
Abstract: The implantation of Na, K and Cs ions into films of a-Si prepared by the glow-discharge technique has been investigated. It is found that the range of control of conductivity that can be achieved with these ions in hot implantations is the same as that from substitutional doping by P atoms. The efficiency of Na-, K-and Cs-interstitial doping lies between that of P doping from the gas phase and from implantation. The electrical properties of Na-, K- and Cs-implanted specimens are thermally stable up to about 400°C, whereas those of Li-doped specimens showed rapidly increasing changes even after short annealing at 250°C. Preliminary thermoelectric power measurements confirm that the doped specimens are n-type and also that the changes in conductivity with implantation arise from a shift of the Fermi energy towards ∊c rather than from hopping paths associated with introduced defects.
46 citations
IBM1
TL;DR: In this article, the temperature dependence of the thermoelectric power and electrical conductivity of polyacetylene heavily doped with arsenic pentafluoride was measured and the results were interpreted as the first conclusive evidence for the existence of a metallic state at all temperatures in this material.
45 citations
TL;DR: In this paper, the drift mobility of BaTiO3 single crystals was determined in the 20 degrees C to 80 degrees C temperature range, using the Spear method, and the results were interpreted in terms of nonadiabatic small-polaron hopping theory in the semi-classical and quantum mechanical cases.
Abstract: The drift mobility mu d of melt-grown BaTiO3 single crystals has been determined in the 20 degrees C to 80 degrees C temperature range, using the Spear method. At room temperature, mu d=(3+or-1)*10-7 m2 V-1 s-1 with a resistivity of 4*108 Omega m. The mobility thermally activated with an activation energy of 0.15+or-0.04 eV. The results are interpreted in terms of non-adiabatic small-polaron hopping theory in the semi-classical and quantum mechanical cases. The related polaron and band parameters are deduced; taking into account the LO phonon energy h(cross) omega 0, the half-bandwidth J lies between 0.03 and 0.06 eV. Hall mobility, Seebeck coefficient and absorption coefficient are obtained as functions of parameters h(cross) omega 0, Ea and J and compared with existing experimental data.
43 citations
TL;DR: In this article, the electrical conductivities and thermoelectric power of phthalocyanine with halogen (iodine or bromine) have been studied and shown to increase up to 10 to 11 orders of magnitude, and activation energies of the complexes with higher conductivities are smaller than those with lower conductivities.
Abstract: Electrical conductivities and thermoelectric power of the complexes of phthalocyanine with halogen (iodine or bromine) have been studied. The electrical conductivity of phthalocyanines exposed to halogen vapor increases drastically up to 10 to 11 orders of magnitude, and its activation energies of the complexes with higher conductivities are smaller than those with lower conductivities. Positive thermoelectric power is observed in these complexes, which indicates a hole conduction in these materials. The absorption spectra of thin films of these complexes are also strongly influenced by halogen.
TL;DR: The resistivity and thermopower of the system Fe3O4_ x F x (0 ≤ x ≤ 015) have been measured in the temperature range 20 to 300 K as discussed by the authors.
Abstract: The resistivity and thermopower of the system Fe3O4_ x F x (0 ≤ x ≤ 015) have been measured in the temperature range 20 to 300 K A sharp Veruey transition occurs in the concentration range 0 ≤ x ≤ 015 and a thermal hysteresis is observed in both the resistivity and thermopower at the transition At the lowest temperatures a T −1/4 law in the conductivity and the behaviour of the thermopower are attributed to the onset of impurity conduction Measurements on samples in the concentration range 005 ≤ x ≤ 015, which do not show a sharp Verwey transition, are interpreted in terms of hopping between ‘Anderson-localized’ states
Abstract: It has been suggested in the past that the thermoelectric power of expanded fluid mercury near the critical density rapidly decreases to zero. A new experiment has been performed to check whether this is really so or whether the observations can be attributed to the effect of high temperature on the other materials in the measuring system. It is concluded that the thermoelectric power of Hg really does cease to vary monotonically with temperature near the critical point and that it changes sign twice. This behaviour is tentatively connected with the critical point itself and the situation is discussed. The critical point is found to be at pc=0.1675+or-0.0025 GPa and Tc=1495+or-8 degrees C.
TL;DR: A series of measurements of the Hall coefficient, infrared reflectivity, thermoelectric power and electrical resistivity of Ti1+xS2 single crystals with various degrees of stoichiometry is described, where, for the first time, each measurement was made on the same crystal (or crystals from the same batch).
Abstract: A series of measurements of the Hall coefficient, infrared reflectivity, thermoelectric power and electrical resistivity of Ti1+xS2 single crystals with various degrees of stoichiometry is described, where, for the first time, each measurement was made on the same crystal (or crystals from the same batch). None of these measurements taken alone can distinguish between the semimetallic or semiconducting models of TiS2. However, by making all four measurements on each sample, it has been possible to establish correlations between the results for different samples. It was found that the product of the Hall coefficient and the square of the plasma frequency is the same for all samples, a result that is consistent with a semiconductor model, but is inconsistent with a semimetal. Nevertheless the most stoichiometric samples remain metallic with electron concentrations of 2*1020 cm-3. It was also found that the resistivity data cannot be explained by carrier-carrier or optical phonon scattering. Therefore, both the source of the residual conduction electrons and the scattering mechanism in TiS2 remain unknown.
TL;DR: In this paper, thermal energy gap (0.99 eV) is approximately the same as the optical one (1.03 eV), the effective mass of electrons in the conduction band is not very different from the mass of the free electron (m* = 0.76m), and the dielectric constant of the medium is K ≈ 34.
Abstract: Thermoelectric power and de electrical conductivity measurements are made on MoTe2 single crystals in a wide temperature range (77 to 770 K). The results are analyzed on the basis of impurity conduction. It is shown that three processes contribute to the total conductivity: hopping conduction between impurity sites, scattering by optical modes, and, in the intrinsic domain, scattering by impurities. The thermal energy gap (0.99 eV) is approximately the same as the optical one (1.03 eV). The effective mass of electrons in the conduction band is not very different from the mass of the free electron (m* = 0.76m), and the dielectric constant of the medium is K ≈ 34. The agreement between theoretical and experimental results is quite good. A comparison with previous results performed on compact polycrystalline samples is given.
TL;DR: In this paper, it was shown that the electronic properties of amorphous germanium (a-Ge) prepared by the glow-discharge decomposition of germane can be controlled systematically by substitutional phosphorus doping from the gas phase.
Abstract: It is shown that the electronic properties of amorphous germanium (a-Ge) prepared by the glow-discharge decomposition of germane can be controlled systematically by substitutional phosphorus doping from the gas phase. Specimens with different doping levels have been investigated by conductivity, thermoelectric power and Hall effect measurements in a temperature range between 160 and 450 K. The dependence of conductivity on doping level is qualitatively similar to that in a-Si, but the range of control is limited in a-Ge by the smaller mobility gap. Also the larger overall density of gap states in this material reduces the doping sensitivity. The above transport measurements and their temperature dependence can be interpreted in a quantitatively consistent manner by a two-path model in which conduction takes place in the extended states and in another path through the localized states. As in a-Si, the photoconductivity of glow-discharge Ge can be appreciably sensitized by phosphorus doping. The μτ...
TL;DR: The electrical conductivity and thermoelectric power of two forms (tetragonal and orthorhombic) of the new organic conductor (tetraphenyldithiapyranilidene) [φ4DTP)(I-3] have been measured as discussed by the authors.
TL;DR: In this article, the authors investigated the metal-nonmetal transition in amorphous Si-Au system by means of electrical conductivity and thermoelectric power, and found that the Au atoms act as acceptors and form a narrow band in pseudo-gap of Si.
Abstract: Metal-nonmetal transition in amorphous Si–Au system has been investigated by means of electrical conductivity and thermoelectric power. It is found that the Au atoms act as acceptors and form a narrow band in pseudo-gap of amorphous Si. The metal-nonmetal transition occurs at x =14% and is assigned to the Anderson transition. In the nonmetallic region, the transport is dominated by the variable range hopping conduction in the lower temperature range and by the ambipolar conduction in the host band in the higher temperature range.
TL;DR: In this paper, field effect and thermoelectric power measurements have been made as a function of temperature on a series of As-doped amorphous silicon samples prepared by glow discharge decomposition of silane.
Abstract: Field effect and thermoelectric power measurements have been made as a function of temperature on a series of As-doped amorphous silicon samples prepared by glow discharge decomposition of silane. At lower temperatures field effect screening is by localized states at the Fermi level, whereas at higher temperatures it is by mobile carriers in extended states. The density of localized states at the Fermi level increases as the As density increases, at least partially due to the creation of localized states by As donors. The density of surface states is less than or equal to 5 × 1011 cm−2 eV−1. Electrical transport is interpreted in a two-channel model, involving transport both in extended states and in a band of localized states lying above the Fermi level, the center of which shifts toward the extended states as the doping concentration increases.
TL;DR: Seebeck coefficients of dry haemoglobin and NaDNA have been shown to be p-type, adsorption of water causing a change to n-type behavior as mentioned in this paper.
Abstract: Seebeck coefficients show “dry” compressed discs of haemoglobin and NaDNA to be p-type, adsorption of water causing a change to n-type behaviour. The magnitude of the effect suggests that simultaneous thermodiffusion of adsorbed water may occur so as to magnify the changes in Seebeck coefficient with hydration for haemoglobin.Step function d.c. transients applied to compressed discs of dry haemoglobin reveal two relaxations, designated α for the higher frequencies and Ω for the lower frequencies. The α peak is attributed to a Maxwell–Wagner interfacial polarisation, involving trapping of holes at defects in the compressed discs and the Ω peak to a polarisation at the electrode–semiconductor interface. An alternative explanation relating the α peak to dipolar orientation is also considered.The possibility is discussed that the charge carriers are electrons and holes arising from a charge transfer within the protein, as earlier postulated for NaDNA.
TL;DR: In this article, the electrical resistivity, thermal conductivity and thermopower of sixteen well characterised tin-doped bismuth samples were reported in the temperature range 2-300K.
Abstract: The electrical resistivity, thermal conductivity and thermopower of sixteen well characterised tin-doped bismuth samples are reported in the temperature range 2-300K. The results are compared with the existing data on single crystals which they complement. It is shown that good agreement is reached in the overlapping ranges when the tin concentrations are correctly assessed.
TL;DR: In this article, the authors describe the sublimation of amorphous tungstic oxide films and the conditions for the preparation of films exhibiting electrochromic behaviour, which suggests carrier motion by hopping in states near the Fermi energy.
TL;DR: In this article, the authors reported the results of electrical conductivity and thermoelectric power of light rare-earth tungstates in the temperature range 600-1200K.
TL;DR: In this article, mixed oxides of the type Ln 2 (V 3+ 4 3 W 6+ 2 3 )O 7, Ln=GdLu, Y have been synthesized in vacuum via solid state reactions of the constituent oxides at 1150-1300°C.
TL;DR: In this paper, the authors measured the thermoelectric power of glasses in the As2Se3As2Te3 system and found that there is an anomalous increase in temperature at the As 2Te3 end of the composition.
Abstract: The result of the measurement of the thermoelectric power of glasses in the As2Se3As2Te3 system are reported. The results indicate that towards the As2Te3 end of the composition, there is an anomalous increase in thermoelectric power, the origin of which is not clear. Polaron hopping seems to contribute to conductivity in tellurium rich glasses. Structural restrictions on polaron hopping, such as the availability of AsTeAsTe chains seems to be important in discussing transport behaviour.
TL;DR: In this article, the electronic densities of d states in ferromagnetic amorphous cobalt and liquid cobalt have been calculated by using a hard sphere model in conjunction with tight-binding limit.
Abstract: Electronic densities of d states in ferromagnetic amorphous cobalt and liquid cobalt have been calculated by using a hard sphere model in conjunction with tight-binding limit. The calculated densities of states have been used to calculate the heat of fusion of cobalt and are shown to account for the fall of resistivity in going from amorphous to crystalline case. For liquid cobalt the authors' calculated density of states is comparable to density of states obtained in a semiphenomenological way and leads to a reasonable value for d contribution to thermoelectric power in cobalt.
TL;DR: In this paper, the thermoelectric power and electrical conductivity of Dy3Fe5O12 (Dysprosium Iron Garnet DyIG) were investigated and it was concluded that the charge carriers in this solid are extrinsic and conduct via the thermally activated hopping mechanism.
Abstract: The thermoelectric power \varTheta (600–1200 K) and electrical conductivity σ (500–1200K) of Dy3Fe5O12 (Dysprosium Iron Garnet DyIG) are reported. Breaks in the slope of log σ vs T-1 were observed round 562 and 1000 K. Apart from these breaks, the log σ vs T-1 curves are linear, and their slopes correspond to activation energies of 0.72 eV (T 1000 K). \varTheta remains practically constant above 1000 K, but below this temperature \varTheta vs T-1 is linear and can be expressed by the relation \varTheta=-(\frac{0.242{\times}10^{3}}{T}+0.06)\frac{\text{mV}}{\text{K}} It is concluded that the charge carriers in this solid are extrinsic and conduct via the thermally-activated hopping mechanism.
TL;DR: In this paper, the authors calculate the thermoelectric power of a metal by considering particularly the particle-hole transformation symmetry and show that if there is complete symmetry with respect to this transformation, the thermopower is absent.
Abstract: We calculate the thermoelectric power of a metal by considering particularly the particle-hole transformation symmetry. If there is complete symmetry with respect to this transformation, the thermopower is absent. However, the elec- tron-phonon and the electron-impurity interactions are intrinsically such that they change sign under this transformation. Thus a finite thermopower arises due to an interference between different orders in a perturbation expansion in these interactions.
TL;DR: The thermoelectric power of polycrystalline Bi-Sn alloys (0.02-0.16 at.%Sn) was measured in the temperature range from 50 mK up to about 25K as mentioned in this paper.
Abstract: The thermoelectric power of polycrystalline Bi-Sn alloys (0.02-0.16 at.%Sn) was measured in the temperature range from 50 mK up to about 25K. The disappearance of the thermoelectric voltage at the lowest temperatures correlates well with previously observed superconducting transitions in the resistance. Above 1K the thermopower is dominated by phonon drag and a large maximum is observed near 4K. With increasing Sn concentration the maximum diminishes and shifts to higher temperatures. The thermopower of a 0.02 at.%Sn alloy is particularly large and reaches 85 mu VK-1 at its maximum. Above the maximum the phonon drag contribution follows an exponential temperature dependence characteristic of a two-stage mechanism. In higher concentration alloys the exponential temperature dependence is suppressed by impurity scattering.