Showing papers on "Seebeck coefficient published in 1989"
TL;DR: It is discovered that the Ce4+doping and subsequent annealing in reducing atmosphere give rise to 24-K superconductivity in the Nd2CuO4-type structure with sheets of Cu-O squares, in contrast to the previously reported high-Tccuprates.
Abstract: We have discovered that the Ce4+doping and subsequent annealing in reducing atmosphere give rise to 24-K superconductivity in the Nd2CuO4-type structure with sheets of Cu-O squares. In contrast to the previously reported high-Tccuprates, the charge carriers in the new superconductors are doped electrons, not holes; this was confirmed by the measurements of Hall and Seebeck coefficients as well as by chemical analysis of the effective copper valence. An anomalous dependence ofTcon the concentration of doped electrons is shown for these electron-doped superconducting cuprates.
682 citations
Book•
01 May 1989
TL;DR: In this article, a transport theory for amorphous semiconductors is presented for a homogeneous model. But the transport properties of hydrogenated amorphized semiconductor are not discussed.
Abstract: Elementary treatment of transport in amorphous semiconductors.- Review of transport experiments.- A transport theory for a homogenous model.- Detailed presentation of the theory.- The long-ranged random potential.- Temperature dependent reference energies.- The transport properties of hydrogenated amorphous semiconductors.- Concluding remarks.
216 citations
TL;DR: In this article, the conductivity and Seebeck coefficient of perovskite-type oxides La 1−x Sr x CoO 3− δ (x=0-0.7) were measured in 10 −5 -1 atm O 2 gas at temperatures 25 o -1000 o C.
Abstract: The conductivity and Seebeck coefficient of the perovskite-type oxides La 1−x Sr x CoO 3− δ (x=0-0.7) were measured in 10 −5 -1 atm O 2 gas at temperatures 25 o -1000 o C. The results are discussed in relation to the lattice-parameter and oxygen nonstoichiometry
207 citations
TL;DR: In this paper, an analysis of the electronic conduction and thermoelectric power of the Li x CoO 2 cobalt bronze (0 x ⩽1) resulting from the electrochemical disintercalation in the Li/Li + /Li x CO 2 cell was presented.
184 citations
TL;DR: On discute de l'interpretation de la puissance thermoelectrique dans un milieu heterogene, and a l'aide d'une compilation d'un ensemble of donnees, on analyse la thermo-puissance de polymeres conducteurs comme fonction of the conductivite et of the temperature.
Abstract: We discuss the interpretation of thermoelectric power in heterogeneous media, and using a compilation of many sets of data, we analyze the thermopower of conducting polymers as a function of conductivity and of temperature. For samples of very high conductivity, the thermopower (but not the conductivity) shows typical metallic temperature dependence, which is consistent with a heterogeneous model of metallic fibrils separated by thin electrical barriers. Metallic thermopower is expected rather generally to show significant nonlinearities as a function of temperature, and we demonstrate that the observed thermopower in some highly conducting polymers is very similar to the diffusion thermopower of metals in which a knee is produced at low temperatures by the electron-phonon interaction. The thermopower of moderately doped conducting polymers, like their conductivity, is generally consistent with a significant contribution from variable-range hopping.
176 citations
TL;DR: In this article, a single crystal of n -type Bi 2 Te 2..85 Se 0.15 with the composition of a useful thermoelectric cooling material was grown by the Bridgman technique.
159 citations
TL;DR: In this article, drastic anomalies have been found below ∼ 60K in a narrow Ba concentration region around x=0.12, where the superconducting transition temperature is reported by Moodenbaugh et al. to have a significant dip as a function of x.
128 citations
Journal Article•
81 citations
TL;DR: In this article, a correlation between semiconductor properties and electrochemical properties was developed for different degrees of reduction resulting from homogeneous phase stepwise reduction of by the hydrazine method.
Abstract: In the past, investigation of the semiconductor properties concentrated mainly on the conductivity of unreduced manganese dioxide. Now semiconductor properties have been investigated on samples of different degrees of reduction resulting from homogeneous phase stepwise reduction of by the hydrazine method. In the range of ; from 2 to 1.6, all samples exhibited n‐type semiconductor properties. Other properties investigated were dc conductivity, Seebeck coefficient, and electron mobility. A correlation between semiconductor properties and electrochemical properties was developed.
60 citations
TL;DR: In this article, the experimental results of Hall effect, thermoelectric power and magnetic susceptibility of the Cu-free high-Tc oxides, (Ba,K)BiO3 are presented.
Abstract: Experimental results of Hall effect, thermoelectric power and magnetic susceptibility of the Cu-free high-Tc oxides, (Ba,K)BiO3 are presented. It is shown that the electronic nature of (Ba,K)BiO3 is quite different from those of high-Tc oxides with CuO2 planes. One of the remarkable differences between the Bi and Cu systems is that the charge carriers of the former are electrons with small effective mass, while the charge carriers of the latter are holes with large effective mass. We also measured the effect of oxygen isotope substitution on its Tc, where we first synthesized BaO2, KO2 and Bi2O3 by using 16O and 18O in parallel , and then the superconducting oxide (Ba,K)BiO3 was synthesized from these oxides, which guaranteed the complete substitution of 16O by 18O. A large oxygen isotope effect (α≅0.35) suggests that the usual phonon mediated pairing mechanism is working in the present system.
60 citations
TL;DR: In this paper, the same single crystal of Yba2Cu3O6.8 was analyzed using a two-carrier model adapted to the particular nature of the crystal and in which the in-plane transport is exclusively insured by holes.
TL;DR: The role of the magnetic field splitting and the Kondo effect on thermoelectric power and thermal conductivity of single crystals was investigated in this article. But the role of crystal electric field splitting was not considered.
Abstract: Measurements of thermoelectric power (TEP) and thermal conductivity of single crystals CeRu{sub 2}Si{sub 2} and Ce{sub 1-x}La{sub x}Ru{sub 2}Si{sub 2} are reported with special emphasis on the effect of the magnetic field. The roles of the crystal electric field splitting and the Kondo effect on TEP curves are debated. The TEP results at low temperature are analyzed with a two-band model, and the parameters are compared with those extracted from the thermodynamic measurements. In CeRu{sub 2}Si{sub 2} the occurrence of a coherent regime at very low temperature is discussed. The influence of the magnetic field on the TEP and the thermal conductivity is investigated and related with the occurrence of the metamagnetic-like transition already reported in magnetization measurements.
TL;DR: In this paper, temperature dependent electrical conductivity and thermoelectric power are measured for newly processed polyacetylene film doped with transition metal halides and the four-probe and Montgomery methods for the dc conductivity measurement are presented.
TL;DR: In this paper, the properties of high-Tc oxide superconductors are discussed in relation to the x-dependence of the electronic state of the system and the inverse of RH has been found to be linear in temperature T, which gives us an evidence that the relation RH−1∝T is not characteristic of high Tc oxides.
TL;DR: In this paper, the second-order transition from a paramagnetic semiconductor to an antiferromagnetic metal takes place at T N =47 K without any significant lattice deformation.
Abstract: Measurements of magnetic susceptibility, electrical resistivity, thermoelectric power and thermal expansion have been performed on the half-metallic magnet UNiSn. A second-order transition from a paramagnetic semiconductor to an antiferromagnetic metal takes place at T N =47 K without any significant lattice deformation. Unlike in the usual antiferromagnets, the curve of magnetic susceptibility sharply turns up at T N . Magnetic fields up to 13.5 T have no significant influence either on T N or the semiconducting energy gap. On the contrary, hydrostatic pressure increases T N at a rate of d T N /d p =0.50 K/kbar, but suppresses the gap energy at a rate of d E g /d p =-0.6 meV/ kbar. Thermoelectric power has an extremely sharp peak at 42 K, which is 5 K lower than T N .
TL;DR: In this article, the size dependence of thermoelectric power and electrical resistivity have been analyzed by the effective mean free path model of size effect, and it is found that both the thermoeellectric powers and the electrical resistivities are linear functions of the reciprocal of thickness of the films.
Abstract: Crystalline Sb2Te3 thin films of different thicknesses have been prepared by subsequent annealing (at 500 K) of vacuum deposited, as‐grown, amorphous thin films of Sb2Te3 prepared on glass substrates at room temperature. Thermoelectric power and electrical resistivity of these annealed (crystalline) films have been determined as a function of temperature. The size dependence of thermoelectric power and electrical resistivity have been analyzed by the effective mean free path model of size effect. It is found that both the thermoelectric power and the electrical resistivity are linear functions of the reciprocal of thickness of the films. The data from the analyses of thermoelectric power and electrical resistivity have been combined to evaluate important material parameters such as carrier concentration, their mean free path, Fermi energy, and effective mass. The values of some of these are compared with the previous available values from literature.
TL;DR: In this paper, the temperature dependence of the thermoelectric power of the semiconducting bismuth-vanadate glasses was presented in a range of compositions, and the high-temperature power was satisfactorily explained by Heikes' relation.
Abstract: The temperature dependence of the thermoelectric power of the semiconducting bismuth‐vanadate glasses was presented in a range of compositions. The high‐temperature thermoelectric power was satisfactorily explained by Heikes’ relation [R. R. Heikes and R. W. Ure, Eds., Thermoelectricity (Interscience, New York, 1961), p. 81]. The thermoelectric power data also showed evidence of small polaron formation in the glass and revealed that the disorder energy happened to increase with the increase of V2O5 content in the glass. An estimate of the disorder energy was made from the low‐temperature thermoelectric power data.
TL;DR: In this paper, the preparation and properties of phosphorus-doped SnO2 films, deposited on a heated borosilicate glass using the chemical vapour deposition, are reported.
TL;DR: In this paper, small polarons generated by the reaction 2U 4+ → U 3+ + U 5+ were used to model the electrical conductivity, Seebeck coefficient and electronic thermal conductivity of UO 2 ± x, and the reaction parameters which were found to best fit the data were a band gap of 2 eV, a vibrational entropy of 2k and an electron-to-hole mobility ratio of unity.
TL;DR: In this article, an experimental study has been performed on the temperature dependence of thermopower and electrical conductivity in polypyrrole which has been doped to different levels.
IBM1
TL;DR: In this article, the compositional properties and subsequent thermoelectric power of reduced, Ce-doped Nd 2 CuO 4−y and for the undoped parent compound as well were investigated.
TL;DR: In this paper, the results of simultaneous measurements of resistivity and of thermoelectric power of YBa 2 Cu 3 O x over a range of temperatures and oxygen pressures (100 K T p (O 2 )≤1 atm), both under conditions of equilibrium and of non-equilibrium with the ambient.
Abstract: We report the results of simultaneous measurements of resistivity and of thermoelectric power of YBa 2 Cu 3 O x over a range of temperatures and oxygen pressures (100 K T p (O 2 )≤1 atm), both under conditions of equilibrium and of non-equilibrium with the ambient. The results have been interpreted using a simple model of conduction in a narrow band, where the carrier concentration in the band and the dominant scattering mechanism are determined by the concentration of oxygen vacancies. There is good agreement between the experimental results and the predictions of the model.
TL;DR: In this article, the results of studies on electrical (electrical conductivity and thermoelectric power) and electrochemical (Li/Li + /Li x VO 2 ) properties of monocrystal and polycrystal vanadium dioxide were presented.
Patent•
23 Mar 1989
TL;DR: In this paper, a powder of metal or metal alloy was used as the raw material and then sintered to produce ultra fine powders containing Fe and Si as main components and having a mean particle diameter of 50 to 5,000 Å.
Abstract: Thermoelectric elements with excellent thermoelectric characteristics such as Seebeck coefficient thermoelectromotive force and thermal conductivity can be produced by molding a powder of metal or metal alloy as the raw material and then sintering; by using as such raw material, ultra fine powders containing Fe and Si as main components and having a mean particle diameter of 50 to 5,000 Å.
TL;DR: A family of highly conducting transition metal complex polymers, poly(metal tetrathiooxalates) of Ni(II), Cu(II, and Cu(I), have been synthesized and characterized as discussed by the authors.
TL;DR: In this paper, the authors measured resistivity, Seebeck coefficient, and magnetic susceptibility for sintered pellets to see if a random distribution of Ti and V makes the oxide insulating.
Abstract: Resistivity, Seebeck coefficient, and the magnetic susceptibility were measured for the sintered pellets to see if a random distribution of Ti and V makes the oxide insulating The oxide seems to be an insulator in the composition range 08 1 It was a sum of the Pauli paramagnetic one of Ti 3+ electrons and the Curie-Weiss one of V 3+ electrons for x <1 A mechanism of the metal-insulator transition was discussed
TL;DR: In this article, the authors investigated the thermoelectric power of the electrons in 3D quantum well structures of small-gap materials under cross field configuration by formulating a new electron energy spectrum within the framework of the k·p formalism.
TL;DR: In this article, the temperature dependence of electrical conductivity and thermoelectric power for La2NiO4 single crystals between 77 and 300 K was analyzed, showing that the electrical properties are highly anisotropic.
Abstract: The temperature dependence of electrical conductivity and thermoelectric power for La2NiO4 single crystals between 77 and 300 K is analysed. The electrical properties are highly anisotropic. The conductivity and the carrier mobility are thermally activated, but the activation energies depend on the orientation (parallel or perpendicular to the basal (a,b) plane). The positive Seebeck coefficient found along the two orientations indicates that holes are the dominant charge carriers. Careful analysis of present data based on a phenomenological model indicates that electrons are also present in the “LaO” layers between the conducting layers.
TL;DR: In this paper, it was shown that the ordinary electron-phonon interaction can produce a high Tc as a result of the polaron narrowing of the electron band, which is not considered by the traditional theory of strong-coupling superconductors, based on the Migdal-Eliashberg equations.
Abstract: It is shown that the ordinary electron-phonon interaction can produce a high Tc as a result of the polaron narrowing of the electron band, which is not considered by the traditional theory of strong-coupling superconductors, based on the Migdal-Eliashberg equations. The main properties of high-Tc superconductors are explained by New (polaron) theory of strong-coupling superconductors /3–5/ namely the value of Tc, of the magnetic field penetration depth λ L and its temperature dependence, of the normal electron heat capacity γ M′ of the thermoelectric power S, the upward curvatury of the upper critical field H c2 , the small value of the coherence length, the temperature dependence and the value of the heat capacity jump ΔC, the anomalous pressure dependence of Tc, the tunneling spectrum, the temperature dependence of sound velocity and some other properties.
TL;DR: In this paper, the Seebeck coefficient has been studied for type K and type N thermocouples and it is shown that it is possible to produce type K thermocouple with a performance comparable with that previously reported for type N.
Abstract: Hysteresis in the Seebeck coefficient has been studied for type K and type N thermocouples. The temperature range was 0 to 1200 degrees C, heating periods were up to 530 h and the alloys were supplied from a number of different sources (five for type K and two for type N). In both types, changes of about 1% in Seebeck coefficient were found but the hysteresis extended over a larger temperature range for the type N thermocouple. Thermoelectric hysteresis is a major cause of instability in Ni-based thermocouples, especially in the more stable, Nicrosil-sheathed mineral-insulated configuration. It is shown that it is possible to produce type K thermocouples with a performance comparable with that previously reported for type N.