Showing papers on "Seebeck coefficient published in 1982"
161 citations
TL;DR: In this paper, the authors measured the thermoelectric power and electrical resistance of two low-dimensional conductors, HfTe5 and ZrTe5, over the temperature range of 7K to 380K.
98 citations
TL;DR: In this paper, measurements on the pressed pellets of six light rare-earth orthochromites, RCrO3, where R = La, Pr, Nd, Sm, Eu and Gd, have been carried out in the temperature range 300 to 1000 K.
Abstract: Electrical conductivity, σ, Seebeck coefficient, S, and dielectric constant, e, measurements on the pressed pellets of six light rare-earth orthochromites, RCrO3, where R = La, Pr, Nd, Sm, Eu and Gd, have been carried out in the temperature range 300 to 1000 K. These are essentially electronic conductors, exhibiting p-type extrinsic semiconducting nature in the studied temperature range. The extrinsic charge carriers (holes) originate from Cr4+ centres which are present due to native defects in these solids. Their room-temperature electrical conductivities lie in the range 10−7 to 10−5 Ω−1 cm−1, which become of the order of 10−2 Ω−1 cm−1 near 1000 K. The conductivity is a maximum in LaCrO3 and drops across the RCrO3 series, with SmCrO3 being an exception. The mechanism involved in the electrical transport is the hopping of holes from Cr4+ centres to neighbouring Cr3+ ions. The activation energy of transport is nearly 0.3 eV. Typical hopping mobility of the holes is of the order of 102 cm−2 V−1 sec−1 at 325 K and of the order of 10 cm2 V−1 sec−1 at 1000 K. The mobility activation energy of the holes in a typcial RCrO3 decreases with temperature due to the smoothing of the potential barriers between Cr4+ and Cr3+ sites. Several discontinuities are observed in the σT against T−1 and S against T−1 plots of RCrO3. The anomalies which these discontinuities reflect here have also been indicated.
64 citations
TL;DR: In this article, the electrical resistance up to 250 kbar and down to 1.7 K, and the thermoelectric power at room temperature have been measured in iodine using a diamond-anvil cell.
Abstract: The electrical resistance up to 250 kbar and down to 1.7 K, and the thermoelectric power up to 250 kbar at room temperature have been measured in iodine using a diamond-anvil cell. The resistance decreases rapidly and continuously with increasing pressure. The resistance anomaly has been found at 225 kbar and room temperature. The resistive characteristic temperature θ in the Gruneisen-Bloch equation is 225 K for metallic iodine at 235 kbar, The thermoelectric power decreases from a large positive value to a small positive one with increasing pressure and is +4±3 µV/deg at 240 kbar. These electrical properties have been discussed in relation to the structural change induced by pressure.
51 citations
TL;DR: In this article, the electrical resistivity, Hall coefficient and thermoelectric power have been measured over a wide temperature range for six amorphous Mg-Zn alloys with compositions between 22.5 and 35 at.% Zn.
Abstract: The electrical resistivity, Hall coefficient and thermoelectric power have been measured over a wide temperature range for six amorphous Mg-Zn alloys with compositions between 22.5 and 35 at.% Zn. The electrical resistivity shows a very shallow minimum at about 10K and then increases as T2 up to about 30K. A small and broad maximum is observed at a temperature Tmax ranging from 30 to 50K. Subsequently, the resistivity decreases as -(T-Tmax)32/. This newly found temperature dependence continues up to a temperature T2, above which more or less linear temperature dependence is seen with negative TCR. All the features described above are composition dependent. The Hall coefficient is negative and temperature independent. The data are employed to determine the critical parameters 2kF/Kp. The value of TCR is found to be always negative, while the ratio 2kF/Kp is situated around 1.1. The thermoelectric power is negative and shows a non-linear behaviour with temperature below about 200K.
42 citations
TL;DR: In this paper, the a.c., d.c. and d.d. electrical conductivity and thermoelectric power of a single crystal of MnWO4 were reported in the temperature range 300-1200 K. The data have been analyzed using the polaronic concept of electrical conduction.
39 citations
TL;DR: In this paper, a consistent and quantitatively correct interpretation of the temperature and doping dependence of S can be given on the basis of crystalline transport theory, where it is shown that the effective density of states at ϵs is proportional to Tv, where v varies systematically with doping level.
Abstract: The paper deals with transport measurements and their interpretation in microcrystalline silicon specimens deposited directly in a silane glow discharge, strongly diluted with hydrogen. Also included are the results of field-effect experiments. The thermoelectric power S and the Hall effect have been measured on a series of undoped and n-type specimens between 470 and 170 K. Using the carrier densities derived from the Hall effect, it is shown that a consistent and quantitatively correct interpretation of the temperature and doping dependence of S can be given on the basis of crystalline transport theory. From the analysis it is found that the effective density of states at ϵs is proportional to Tv , where v varies systematically with doping level. With an average value for the heat of transport of A c = 2·5, the Fermi level position is deduced from the thermoelectric power data as a function of temperature and doping level. ϵc - ϵf vanishes at a donor density of about 5 × 1019 cm−1. The results ...
39 citations
TL;DR: In this article, a phenomenological interpretation is proposed, using an analysis of the relative effects of diffusion and phonon drag components, leading to the values for the specific thermoelectric powers of various impurities.
33 citations
TL;DR: In this paper, the electrical conduction at T > T c (T c denotes the magnetic transition temperature) is of an activation type, while at T T c is proportional to 1/T in all samples and that at T t c is about three times larger than that estimated from the thermoelectric power.
Abstract: Electric resistivities and thermoelectric powers of the system (La 0.8 Ca 0.2 )MnO 3- y were measured in several samples with y less than 0.07, in which the amounts of the oxygen deficiencies y were carefully controlled. The electrical conduction at T > T c ( T c denotes the magnetic transition temperature) is of an activation type, while at T T c is proportional to 1/ T in all samples and that at T T c is about three times larger than that estimated from the thermoelectric power. These experimental results are discussed on the basis of the conventional semiconductor model.
31 citations
TL;DR: In this article, the measurements of electrical conductivity and thermoelectric power in the temperature range 450 to 1250 K of rare-earth iron garnets (REIG) with a general chemical formula RE3Fe5O12 (where RE=Y, Gd, Dy, Ho, Er and Yb) are reported.
Abstract: The measurements of electrical conductivity (σ) in the temperature range 450 to 1250 K and thermoelectric power (S) in the temperature range 600 to 1200 K of sintered pressed pellets of rare-earth iron garnets (REIG) with a general chemical formula RE3Fe5O12 (where RE=Y, Gd, Dy, Ho, Er and Yb) are reported. Values corresponding to the crystalline state have been evaluated employing pore fraction correction. It is observed that plots of log σT againstT−1 are linear with breaks in the slopes of temperatureT1 (lying between 560 and 578 K) andT2 (~ 1000 K). However, plots ofS againstT−1 are linear over the entire temperature range. The results have been discussed using the usual electrical transport theories and it has been concluded that electrical conduction in these solids up to a temperature of 1250 K is extrinsic in which holes localized on Fe3+ sites (Fe4+ centres created by native defects) conduct via a thermally activated hopping mechanism. Mobility activation energy, mobility and the number of such centres in each garnet are also evaluated.
26 citations
TL;DR: In this article, the electrical conductivity of mixed Co-Zn ferrites was studied as a function of composition and temperature, and the existence of the single-phase spinel structure was established by X-ray analysis of the specimens.
Abstract: The electrical conductivity of mixed CoZn ferrites was studied as a function of composition and temperature. The existence of the single-phase spinel structure was established by X-ray analysis of the specimens. The Seebeck coefficient for these ferrites was determined in order to discuss the conductivity which is explained in terms of the hopping mechanism. Plots of the logarithm of conductivity versus the reciprocal temperature are almost linear and show a transition near the Curie temperature. The activation energy in the paramagnetic region is higher than that in the ferrimagnetic region.
TL;DR: In this paper, the thermoelectric power of expanded fluid Hg and dilute amalgams in the range of temperature and pressure up to 1700°C and 2100 bar was measured.
Abstract: The thermoelectric power S has been measured for expanded fluid Hg and dilute amalgams in the range of temperature and pressure up to 1700°C and 2100 bar. In the supercritical region S for fluid Hg and dilute amalgams containing Bi and Cd change rapidly from large negative to large positive by raising temperature. Such an anomalous behaviour of S can be attributed to the transition from the liquid semiconducting state to the plasma state in which the drift of the charged atoms plays an essential role in the conduction.
TL;DR: In this article, the magnetic susceptibility, magnetization, electrical resistivity, thermoelectric power and specific heat of the amorphous alloy Ce75.5Co24.5 have been investigated.
Abstract: The amorphous alloy Ce75.5Co24.5 prepared by melt spinning has been studied through measurements of the magnetic susceptibility, magnetization, electrical resistivity, thermoelectric power and specific heat. The results are interpreted in terms of a homogeneous intermediate valence state of the Ce ions. This is inferred from a temperature-independent magnetic susceptibility at low temperature and the absence of magnetic ordering, a large linear term in the specific heat, and aT2 dependence of the electrical resistivity at low temperature followed by a steep increase with temperature up to 50 K. At this temperature, the thermoelectric power displays a maximum. The intrinsic properties are partially obscured at low temperatures by a contribution from roughly a few percent of magnetic ‘impurities’, presumably Ce3+ ions. They manifest themselves by an increase of the susceptibility towards low temperatures and by a broad Schottky-like contribution to the specific heat resulting from the excitation of magnetic clusters.
TL;DR: In this paper, the resistivity and thermoelectric power of liquid Ni-Te alloys have been measured as a function of temperature over a wide range of compositions and a unified model for the atomic and electronic structure is proposed.
Abstract: For pt.I see ibid., vol.15, p.4627 (1982). The resistivity and thermoelectric power of liquid Ni-Te alloys have been measured as a function of temperature over a wide range of compositions. It is shown that the resistivity of liquid Te can be halved by the addition of less than 10 at.%Ni. Comparison with other liquid alloys containing Te is made and a unified model for the atomic and electronic structure is proposed.
TL;DR: In this article, the conductivity and thermoelectric power of CoO at elevated temperatures suggest that the charge carriers (holes) in this material are itinerant carriers and that the nonstoichiometric defects are complex.
TL;DR: In this paper, the Hall coefficient, thermoelectric power and electrical resistivity of the liquid quenched amorphous Mg80.4Cu19.6 alloy have been measured over a wide temperature range below room temperature.
TL;DR: In this article, the face and edge sharing of RhO6 octahedra is discussed in terms of face-and edge-sharing of a semimetal polygonal oxide.
TL;DR: In this paper, the resistance of pure and Nb doped VO 2 and the Seebeck coefficient have been measured in the temperature range of 78-360 K. A simple analysis of the results shows that above 140 K and below the transition temperature the effective density of states in the conduction band of VO 2 is of the order of (but larger than) one state per vanadium atom.
TL;DR: In this article, the temperature dependence of conductivity and thermoelectric power has been investigated for glow-discharge a-Ge : H doped with phosphorus and boron.
TL;DR: In this article, the two-mode nature of the polar optic phonons is considered jointly with deformationpotential acoustic, piezoelectric, alloy, ionized-impurity, and electron-electron scattering.
Abstract: Electron drift and Hall mobility, and thermoelectric power in In 1-x Ga x As y P 1-y , lattice-matched to InP, are calculated for different temperatures and compositions. The two-mode nature of the polar optic phonons is considered jointly with deformation-potential acoustic, piezoelectric, alloy, ionized-impurity, and electron-electron scattering. Band nonparabolicity, admixture of p functions, arbitrary degeneracy of the electron distribution, and the screening effects of free carriers on the scattering probabilities are incorporated. The Boltzmann equation is solved by an iterative method using the currently established values of the material parameters. The agreement with the available experimental data is found to be satisfactory.
TL;DR: In this paper, the variation of electrical resistance with hydrostatic pressure has been measured at room temperature for a number of amorphous Cu-Zr alloys, and no correlation is found with the thermoelectric power of these materials and, in a detailed analysis, it is argued that such a simple correlation is most unlikely.
TL;DR: In this paper, the thermal conductivity, electrical resistivity, and thermoelectric power of Cs have been measured from 40'k, through the melting point which is near 300'k up to 600'k.
Abstract: The thermal conductivity, electrical resistivity, and thermoelectric power of Cs have been measured from 40 K, through the melting point which is near 300 K, up to 600 K. The thermal resistivity of both solid and liquid Cs contains a contribution from electron–electron scattering, which agrees well with theory. The electrical resistivity shows an appreciable "premelting" effect, which is tentatively attributed to impurities.
TL;DR: In this paper, the problem of charge density wave motion in presence of defects is discussed in connection with the problems of the Hall effect and thermoelectric power measurements, which demonstrate the consequences of the pinning on the electronic properties of several low temperature chargedensity wave insulators.
Abstract: The concentration of defects produced by irradiation can be measured by several independent methods such as longitudinal and transverse conductivity measurements at room temperature, spin susceptibility at low temperature, volume or lattice parameters change. The physical consequences of this kind of disorder are as follows. The superconductivity in (TMTSF)2PF6 is destroyed by a molecular concentration of 10−4. The concentration of 2.10−3 corresponds to the full pinning of charge density waves in monoclinic TaS3, 1T-TaS2, TTF-TCNQ, TMTSF-DMFCNQ… Microdiffraction experiments demonstrate some structural aspects of this pinning and conductivity, Hall effect and thermoelectric power measurements demonstrate the consequences of the pinning on the electronic properties of several low temperature charge density wave insulators. In most of the cases the metallic state is stabilized by a weak disorder. The problem of the charge density wave motion in presence of defects is discussed in connection with the...
TL;DR: In this article, the electrical conductivity of sintered ZnO was increased at high temperatures by CoO doping, and temperature-independent behavior of the carrier density was observed.
Abstract: Electrical conductivity of sintered ZnO was increased at high temperatures by CoO doping. Thermoelectric power measurements confirmed that ZnO doped with CoO was still an n-type semiconductor. Temperature-independent behavior of the carrier density was observed.
TL;DR: In this article, thermoelectric power measurements have been made on well characterized crystals of orthorhombic TaS 3 as a function of temperature down to 80 K.
TL;DR: In this article, the Seebeck coefficient or thermoelectric power (TEP) of HgSe at high pressures confirm the existence of an inverted band ordering, similar to that in HgTe.
Abstract: Measurements of the Seebeck coefficient or thermoelectric power (TEP) of HgSe at high pressures confirm the existence of an inverted band ordering, similar to that in HgTe. The pressure-induced phase transition from the zincblende- to the cinnabar-type structure, which occurs around 10 kbar, is manifested as a large change in TEP. The temperature behaviour of the resistivity has also been studied in both of these structural modifications. These studies indicate that the energy gap in the high-pressure semiconducting phase decreases with increase of pressure; this is similar to what is observed in the elemental semiconductors Se and Te.
TL;DR: In this article, the absolute thermoelectric powers of three glassy ferromagnetic metals Fe40Ni40P14B6, Fe29Ni49P 14B6Si2 and Fe74Co10B16 have been determined between 77 K and 700 K. The results are interpreted in terms of Grest and Nagel theory.