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Showing papers on "Seebeck coefficient published in 1983"


Journal ArticleDOI
TL;DR: In this paper, the defect structure of La1-xSrxFeO3 was determined by considering the imperfections SrLa, Vo, FeFe, and Fe′Fe in the lower range.
Abstract: The electrical conductivity and Seebeck coefficients of La1-xSrxFeO3 (x=0.1, 0.25) were measured as a function of oxygen partial pressure, PO2, at T=900° to 1300°C. The electrical conduction was p type in the higher PO2 range, and n type in the lower PO2 range. The Seebeck coefficient indicated that the conduction was due to electron hopping between Fe×Fe and FeFe, in the higher PO2 range and electron hopping between Fe′Fe and Fe×Fe in the lower range. The carrier concentrations were calculated from the values of electrical conductivity and Seebeck coefficient. From the PO2 dependences of the carrier concentrations, the defect structure of La1-xSrxFeO3 was determined. It was found that the electrical properties can be described by considering the imperfections SrLa, Vo, FeFe, and Fe′Fe.

226 citations


Journal ArticleDOI
TL;DR: In this article, the magnetic and electron transport properties of mixed valence copper oxides have been investigated in the temperature range 120-650 K. The positive sign of the Seebeck coefficient and the evolution of the conductivity and magnetic properties have been interpreted.

83 citations


Journal ArticleDOI
01 Jun 1983
TL;DR: In this article, an octahedral site small polaron mechanism was found to be dominant over the entire temperature range (Ea = 0.1136 eV) at elevated temperatures.
Abstract: Electrical conductivity in magnetite has been studied experimentally as a function of temperature and oxygen activity between 560 and 1400°C. The results indicate that above TC (=575°C) an octahedral site small polaron mechanism is dominant over the entire temperature range (Ea = 0.1136 eV). By comparing data on electrical conductivity and thermoelectric power, a second (small polaron) mechanism (Ea = 0.714 eV) is detected at elevated temperatures. Additionally, equilibrium constants for the cation vacancy formation are derived from fitting the conductivity isotherms as a function of oxygen activity. These agree well with values determined thermogravimetrically.

74 citations


Journal ArticleDOI
TL;DR: In this article, a model for the temperature variations of the thermoelectric power (TEP) of acceptor graphite intercalation compounds (GIC's) is presented.
Abstract: A model for the temperature variations of the thermoelectric power (TEP) of acceptor graphite intercalation compounds (GIC's) is presented. At low temperatures, the TEP in GIC's increases monotonically with $T$, then levels off above \ensuremath{\sim}200 K in striking contrast to that of pristine graphite. The diffusion contribution to the TEP is proportional to $T$ and its magnitude is small as compared with that of the observed data. This observed behavior is attributed to the phonon drag effect. In the temperature region where the TEP is weakly temperature dependent, phonon relaxation is mainly controlled by the Rayleigh scattering due to point defects. The resultant TEP, which is composed of the phonon drag and diffusion terms, leads to a nearly $T$-independent value. Since the cross-sectional diameter of the Fermi surface in GIC's is larger than that of pristine graphite, the relaxation rate of the Rayleigh scattering, which is given by $\frac{1}{{t}_{I}(q)}=f{q}^{3}$, becomes very large at high temperatures ($Tg100$ K). At low temperatures, where the boundary scattering plays a dominant role, the TEP is proportional to ${T}^{3}$. Detailed calculations are carried out by solving the phonon-carrier-coupled Boltzmann equation.

68 citations


Journal ArticleDOI
TL;DR: Amorphous As2Se1Te2 (a-As2Se 1Te2) films, into which Cu or Cd ions were doped by thermal diffusion below the glass transition temperature exhibited the increase of conductivity by several orders of magnitude.
Abstract: Amorphous As2Se1Te2 (a-As2Se1Te2) films, into which Cu or Cd ions were doped by thermal diffusion below the glass transition temperature exhibited the increase of conductivity by several orders of magnitude. In addition, these samples exhibited enhanced photoconductivity and the activation type conduction. From the measurements of the thermoelectric power, it was found that Cu doped samples were p-type and Cd doped samples were n-type. The impurities was also studied by SIMS.

59 citations


Journal ArticleDOI
TL;DR: In the crystal of β-(BEDT-TTF)2PF6, BEDT TTF (bis(ethylenedithiolo)tetrathiafulvalene) molecules are arranged side-by-side.
Abstract: In the crystal of β-(BEDT-TTF)2PF6, BEDT-TTF (bis(ethylenedithiolo)tetrathiafulvalene) molecules are arranged side-by-side. The anisotropy of the electrical resistivity shows that β-(BEDT-TTF)2PF6 is the first organic conductor where the conductivity is the largest along the direction parallel to the molecular plane. The metal-insulator transition is observed at 297 K. The thermoelectric power corresponds to that due to the hole conduction in highly correlated system.

54 citations


Journal ArticleDOI
TL;DR: In this article, the influence of point-defect gradients on thermoelectric coefficient measurements in oxides is quantified, and alternative techniques of thermopower measurements which maintain the average sample temperature while imposing thermal gradients are suggested.
Abstract: The influence of point-defect gradients on thermoelectric coefficient measurements in oxides is quantified. This permits corrections to be made for data collected by conventional means and suggests alternative techniques of thermopower measurements which maintain the average sample temperature while imposing thermal gradients. Experimental results on CoO, Fe/sub 3/O/sub 4/, and FeO in equilibrium with various atmospheres are considered.

50 citations


Journal ArticleDOI
TL;DR: The resistivity, thermopower and thermal conductivity were measured on single crystals of CeCu2Si2 and CeNi2Ge2 between 60mK and 300 K as mentioned in this paper.

41 citations


Journal ArticleDOI
TL;DR: In this article, principal electrical conductivities and seebeck coefficients, as well as Hall effect, in p-type single crystals of natural molybdenite (MoS2) have been investigated within the temperature range 100°K to 850°K.

40 citations


Journal ArticleDOI
TL;DR: In this article, the linear chain trichalcogenide TiS3 has been investigated and the dc conductivity shows a non-exponential temperature dependence below the conductivity maximum, and σ is also strongly frequency dependent.

36 citations


Journal ArticleDOI
TL;DR: In this article, it was found that the thermoelectric power of the films is independent of temperature in the range studied (300-425°°K) and the inverse thickness dependence predicted by size effect theories.
Abstract: Tin thin films of thicknesses in the range 500–7000 A have been prepared by vacuum deposition at room temperature at a pressure of 5×10−5 Torr on glass substrates. Thermal electromotive forces (emfs) of these films have been measured after aging as a function of temperature difference. It is found that the thermoelectric power of the films is independent of temperature in the range studied (300–425 °K). It is also found that the thermoelectric power of the films obeys the inverse thickness dependence predicted by size effect theories. The electronic mean free path is evaluated to be 530 A.

Journal ArticleDOI
TL;DR: In this article, the thermoelectric power and electrical resistivity of rare earth intermetallics RAl 2 (R: La, Ce, Pr, Nd, Sm, Gd, Tb, Dy and Ho) were measured from liquid He temperature to room temperature.

Journal ArticleDOI
TL;DR: In this paper, the electron density and mobility of polycrystalline Cd 1−x Zn x S films were measured and applied to calculate the dark conductivity and thermoelectric power.

Journal ArticleDOI
TL;DR: In this paper, the Hall effect and magnetoresistance of four tin-doped bismuth samples in the temperature range 4.2-300K and in magnetic fields up to 6 T have been made.
Abstract: Measurements of the Hall effect and magnetoresistance of four tin-doped bismuth samples in the temperature range 4.2-300K and in magnetic fields up to 6 T have been made. The resistivity data are converted to conductivities. These are reported and used to evaluate the temperature dependence of the excess carrier density and of the thermopower. The evaluation is performed with the Fermi energy as the only adjustable parameter within the pseudo-parabolic model which the authors have previously introduced. The excess carrier density is found to decrease with temperature, and this feature is used to analyse the data in terms of an acceptor energy level. A relation valid for all samples is found between this level and the Fermi level. For the thermopower agreement is found between the calculated values and the experimental ones reported in the literature.

Journal ArticleDOI
TL;DR: In this paper, the thermoelectric power of a highly disordered semiconductor having a band of localized energy levels, partially filled, near the middle of the mobility gap is calculated.
Abstract: Starting from a general formula given by Cutler and Mott, the thermoelectric power S is calculated for the case of a highly disordered semiconductor having a band of localized energy levels, partially filled, near the middle of the mobility gap. The different approximations in solving this equation are discussed. Using the expression of the conductivity for variable-range hopping, it is shown that the thermoelectric power exhibits a simple temperature dependence of the form S/T ∝ T−1/n+1, where n is the dimension of the system. The theory is applied to some results obtained on amorphous SiC.

Journal ArticleDOI
TL;DR: In this article, the results of investigations of the Os-Si phase diagram and crystal growth from this system were obtained at significantly lower growth temperatures when PdSi was used as the solvent.

Journal ArticleDOI
TL;DR: In this article, conductivity and thermopower measurements of polyacetylene doped with FeCl4 are reported, showing that the conductivity changes over 10 orders of magnitude and reaches the maximum value of 200 Ω-1 cm-1 at y = 0.07.

Journal ArticleDOI
TL;DR: In this paper, the electrical resistance and thermopower of amorphous Pd 83 Si 17, Pd 79 X 4 Si 17 and Pd 73 X 10 Si 17 (X = Ag, Co, Cr, Cu, Fe, Ni ) were measured as functions of the hydrogen pressure in the range 1 bar-20 kbar.
Abstract: The electrical resistance and thermopower of amorphous Pd 83 Si 17 , Pd 79 X 4 Si 17 and Pd 73 X 10 Si 17 ( X = Ag , Co , Cr , Cu , Fe , Ni ) were measured as functions of the hydrogen pressure in the range 1 bar–20 kbar. The electrical resistance of some of these alloys was measured as a function of the deuterium pressure in the range 1 bar–0.8 kbar. A distinct isotope effect was found. In most cases the absolute thermoelectric power is a linear function of the logarithm of hydrogen fugacity and thus is a linear function of the chemical potential of gaseous hydrogen. The electrical resistance exhibits a non-linear dependence on the chemical potential of hydrogen or deuterium in all cases. No discontinuities were observed in either property in the total pressure range. Hysteresis was observed during absorption and desorption, with increasing values at higher pressures. This suggests local restructuring in the glassy matrix as a result of the presence of hydrogen atoms. No evidence of saturation behaviour was obtained. All the measurements were carried out at 25 °C.


Journal ArticleDOI
TL;DR: In this paper, the Seebeck coefficient, thermal conductivity, electrical conductivity and Hall coefficient of ternary alloys of Bi2Te3-Sb2Te-3-Se3 and Sb2Se3 were measured between 10 and 300 K. The difference between the temperature dependence of the Hall effect in n-and p-type alloys can be explained by the presence of sub-bands of light and heavy holes in the valence band of p type alloys.
Abstract: The Seebeck coefficient, thermal conductivity, electrical conductivity and Hall coefficient of cooler grade, p-and n-type ternary alloys of Bi2Te3-Sb2Te3-Sb2Se3 were measured between 10 and 300 K. Between 300 K and about 150 K the temperature dependence of the transport properties can be explained by assuming nondegeneracy and a lattice scattering mechanism. The difference between the temperature dependence of the Hall effect in n-and p-type alloys can be explained by the presence of sub-bands of light and heavy holes in the valence band of p-type alloys.

Journal ArticleDOI
TL;DR: In this paper, the photoelectronic properties of a magnetoplumbite single crystal of composition Pb1.19Fe11.88O18.91 have been characterized.

Journal ArticleDOI
TL;DR: In this paper, thin films of thicknesses ranging from 400 to 4000 A have been prepared by vacuum evaporation at a pressure of 5×10−5 Torr on clean glass substrates held at room temperature.
Abstract: PbTe thin films of thicknesses ranging from 400 to 4000 A have been prepared by vacuum evaporation at a pressure of 5×10−5 Torr on clean glass substrates held at room temperature. The thermoelectromotive force of these films has been measured in the temperature range 300–600 K. It is found that thermoelectric power, SF varies anomalously with temperature, being constant at lower temperatures, and rapidly decreasing at higher temperatures. SF is found to be positive indicating that the samples are p type. The anomalous behavior is explained by assuming that at higher temperatures additional donor levels are generated due to creation and ionization of defects in the system.

Journal ArticleDOI
TL;DR: In this article, the electrical conduction in tetragonal β-Bi2O3 doped with Sb 2O3 was investigated by measuring electrical conductivity, ionic transference number, and Seebeck coefficient.
Abstract: Electrical conduction in tetragonal β-Bi2O3 doped with Sb2O3 was investigated by measuring electrical conductivity, ionic transference number, and Seebeck coefficient. The β-Bi2O3 doped with 1 to 10 mol% Sb2O3 was stable up to 600°C and showed an oxygen ionic and electronic mixed conduction, where the electron conduction was predominant at low oxygen pressures. The oxygen-ion conductivity showed a maximum at 4 mol% Sb2O3, whereas the activation energy for the ionic conduction remained unchanged for 4 to 10 mol% Sb2O3-doped specimens. These results were interpreted in terms of the oxygen vacancy concentration and the distortion of the tetragonal structure. The electron conductivity and its oxygen pressure dependence decreased with increasing Sb2O3 content. The fact that Sb5+ is partially reduced by excess electrons in heavily doped β specimens at low oxygen pressures is explained.

Journal ArticleDOI
TL;DR: In this paper, the thermoelectric power of TaS 3 filaments was measured as a function of temperature between 90-400K and its positive sign in the whole temperature range and its linear dependence on reciprocal temperature between 120-200K were discussed.

Journal ArticleDOI
TL;DR: In this article, resistivity, Hall coefficient and thermoelectric power measurements of ZrSe 3 single crystals along the chain axis were carried out in the temperature range from 200 to 400 K. Experimental results are explained by the model of compensated semiconductors with two-dimensional characteristics.

Journal ArticleDOI
TL;DR: In this paper, the electrical resistivity, temperature coefficient of resistivity and Hall constant and thermoelectric power of antimony films were measured in situ and it was shown that holes were the majority carriers in these films.

Journal ArticleDOI
TL;DR: In this article, the ionic conductivity and the thermoelectric power in superionic conductors are expressed as functions of the concentration of ions and the interaction energy in the framework of the lattice gas model.
Abstract: The ionic conductivity and the thermoelectric power in superionic conductors are expressed as functions of the concentration of ions and the interaction energy in the framework of the lattice gas model. Under appropriate conditions, the results obtained are in good agreement with those of experiments.

Journal ArticleDOI
TL;DR: In this paper, the rastered ion beam was used to mix thin bismuth films with slightly thicker tellurium (Te) films, and two junctions each of mixed and unmixed Bi + Te were formed at the ends of the region exposed to the Kr beam, and upon heating one junction, quite large e.m.s.

Journal ArticleDOI
TL;DR: In this paper, the thermoelectric power of LaB 6, PrB 6 and NdB 6 was measured in the temperature range 2-20K. But the accuracy of the measurements was not analyzed.

Journal ArticleDOI
TL;DR: In this paper, the effect of Tl2Te3 on the transport properties of antimony and bismuth tellurides was studied and it was found that the addition of tl 2Te3 caused a lessening of the increase of hole concentration as low temperatures were approached, resulting in a slower decrease of the Seebeck coefficient.
Abstract: The effect on transport properties of the addition of 0.5-5% Tl2Te3 to p-type solid solutions of antimony and bismuth tellurides was studied. It was found that the addition of Tl2Te3 caused a lessening of the increase of hole concentration as low temperatures were approached, resulting in a slower decrease of the Seebeck coefficient with a decrease in temperature.