Thermoelectromotive Force Research Articles

Thermo-emfs of binary transition-metal solid solutions containing isoelectronic components

An approximate method was derived for calculating the thermoelectromotive force of transition metal binary alloy solid solutions containing isoelectronic components. The method calculates the dependence of the thermoelectromotive force on composition. The electronic structure and lattice parameters were also incorporated into the calculation. The method was tested against experimental data for titanium-zirconium and titanium-hafnium alloy systems.

Quantum hall effect observations in commercial MOSFETs and effects of thermoelectric power

We have performed quantum Hall effect measurements on commercial low-mobilityn-channel MOSFETs. The channel resistancevs. electron concentration has the expected oscillating behaviour and gives the quantized values for the Hall resistance, at least in the region of higher mobility. One class of the tested samples gave a surprising behaviour, both in QHE and in field effect mobility measurements: this is thought to be due to uncontrolled differences in the diffusion zones at the interface between the channel and the contacts. In particular, we attribute the deformation of the QHE curves to the onset of a thermoelectromotive force which is present in the electron gas even if the sample is isothermal. A clear evidence for thermoelectric effects is given by measurements made on a high-quality Hall geometry MOSFET.

熱重量法による石炭液化油の蒸留試験法

A simple distillation method using conduction type thermogravimetric meter (TG) on coal-derived liquids was investigated.It was found that under the following measuring conditions, this distillation method was good agreement with the standard distillation method (ASTM D-2892) which is used crude oil.1) Thermoelectromotive force difference in thermocouples between the heat buffer cover and sample container (bias voltage): 300μV2) Quantity of samples: 300-400mg It was also possible to measure the water content in coal-derived liquids with this method. The one-cycle measuring time required for the TG distillation method using a conduction type thermobalance was less than 90 minutes and this method was far quicker and easier than other methods. Furthermore, in terms of accuracy, it was considered that the method can com-pare well with the ASTM method.

Thermoelectric Power of Sb2Te3 Films

AbstractThe thermoelectromotive force of vacuum deposited Sb2Te3 films on glass substrates has been measured by the integral method in the temperature range 30–250 °C. The film thickness varied between 1200–9600 Å. Thick antimony pads evaporated onto the sample at both ends served as contacts. The thermoelectric power (α) is found to be positive and increases with temperature for thinner samples and at higher temperatures a steady value is achieved. Further increase in the temperature decreases the thermoelectric power. When the film thickness is increased, α decreases. This is explained as due to the reduction in intercrystalline barrier at elevated temperatures and at higher film thicknesses.

Characteristics of Vacuo-Thermojunctions at Ultra-Low Frequency

Characteristics of vacuo-thermo-junctions (VTJ's) at ultra-low frequency are discussed. A method of expansion with series of nonharmonic sine functions has been combined with a method of perturbation to solve the partial differential equation for heat conduction in the heater of a vacuo-thermojunction. Theoretical results have been checked by experiments in which both a photorecorder and a method of Lissajous figures have been used to analyze the amplitude variations and the time lags of thermo-electromotive force (TEMF) and voltage drop through the heater versus its current.

Thermoelectric studies on semiconductingAg2Te thin films: Temperature and dimensional effects

${\mathrm{Ag}}_{2}$Te thin films with thicknesses in the range 600---1400 \AA{} have been prepared by vacuum deposition at a pressure of 5 \ifmmode\times\else\texttimes\fi{} ${10}^{\ensuremath{-}5}$ Torr on clean glass substrates held at room temperature. The thermoelectromotive force of these films has been measured in the temperature range 300---415 K, that is, below the phase-transition temperature. It is found that the thermoelectric power of ${\mathrm{Ag}}_{2}$Te thin films in the above temperature range exhibits degenerate semiconductor behavior, this is, a linear increase in the thermoelectric power with rising temperature. It is also found that the thermoelectric power obeys the inverse thickness dependence predicted by classical size-effect theories.

Optical and Electrical Properties of CuInS2 Thin Films by Spray Pyrolysis

The optical, electrical and structural properties of CuInS2 thin films prepared by spray pyrolysis have been studied. The polycrystalline films produced by spraying a solution of Cu (CH3COO)2H2O, InCl3 and (NH2)2CS with the atomic ratio Cu:In:S=1:1:2.8∼1:1:3.2 and annealing at 500°C for 2 hours were nearly stoichiometric, and the depth profiles of the atomic composition were flat except near the surface. The optical band gap at room temperature was 1.43 eV, and the polarity of the thermoelectromotive force showed p-type conduction at a sulfur concentration ratio to Cu[S]≥2.8. The activation energy of conductivity was 0.3 eV.

Proton conduction in lecithins. III. Nature of charge carriers

The nature of charge carriers was studied in hydrated lecithin using different techniques. The current-voltage characteristics confirmed the ionic nature of conduction. Attempts to determine the charge mobility were unsuccessful. From measurements of the thermovoltage at different hydration levels the charge carrier was found to be positive. The value of the thermo electromotive force (thermo e.m.f.) depends on the phase state of the lipid but is independent of its water content. The mechanism of charge generation is discussed. The activation energy of conduction does not reflect the phase change directly. Its dependence on water content is attributed to charge mobility which involves the motion of the head groups. Electrolysis experiments were carried out and the amount of hydrogen evolved was determined by gas chromatography. A proton mechanism of conduction is suggested.

Magnetic field structure of a laser jet plasma at low radiation flux densities

Measurements were made of the structure and growth dynamics of the toroidal component of a magnetic field generated by a laser jet produced by a radiation flux of ~ 200 MW/cm2 density at a pressure of ~ 5 × 10−2 Torr. The experimental results were compared with calculations for an axisymmetric jet and this made it possible to identify a thermoelectromotive force acting in the plasma of the laser jet as the main source of the magnetic field.

Anomalous temperature dependence of thermoelectric power of PbTe thin films

PbTe thin films of thicknesses ranging from 400 to 4000 Å 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.

Thermoelectromotive force of a Pt-(ZrB2 + 5% Mo)-Mo cell at 1300–1960°K in a vacuum and in argon

Thermoelectromotive force of a Pt-(ZrB2 + 5% Mo)-Mo cell at 1300–1960°K in a vacuum and in argon

Preparation and Electrical Properties of Eu(II)xNb(IV)O2+x

Abstract Nonstoichiometric compounds, EuxNbO2+x, were prepared. A cubic tungsten bronze type structure was found in the single phase region of EuxNbO2+x (0.5≤x≤1.0). Magnetic susceptibility measurements showed that the oxidation state of europium in the bronzes was bivalent. The EuxNbO2+x was a metallic conductor in the temperature range 4.2–300 K. Thermoelectromotive force measurements (100–350 K) indicated that the charge carriers were electrons and that the effective mass of the electrons increased with decreasing x in EuxNbO2+x.

Kinetics of the variation in the thermoelectromotive force in the process of the first transformation during the tempering of carbon steel

1. Variation of the thermoelectromotive force during the tempering of carbon steels occurs in three stages, corresponding to the three stages of tempering. The first stage is the segregation of carbon atoms from the solid solution into dislocations, the second is the formation of atmospheres of carbon atoms around the dislocations, and the third is the outset of segregation of low-temperature e-carbide. 2. After hardening and between tempering stages, TEMF varies continuously without delays.

Measurement of transient variations of thermoelectromotive force

Measurement of transient variations of thermoelectromotive force

Thermoelectromotive force of VR 5/20 thermocouples of various constructions

Thermoelectromotive force of VR 5/20 thermocouples of various constructions

Measuring the thermoelectromotive force under nuclear radiation

Measuring the thermoelectromotive force under nuclear radiation

Kinetic properties of the alloy NiMn in the B2 phase

The electron energy spectrum of the B2 phase of NiMn was calculated by the nonself-consistent MI KKP method. Calculations were carried out for the electronic density of states, the cross sections of the Fermi surface, and the temperature dependences of the resistivity ρ and the thermoelectromotive force S. Experimental measurements were made of ρ and S in the region of existence of the B2 phase. Satisfactory agreement was obtained between the calculated dependences of ρ and S and the experimental data.

Thermopower method for detecting the ferrite‐austenite transition: applications to surface reaction and diffusion

Difference of the thermoelectromotive force (temf.) for ferrite and austenite. Measurement of the change of thermopower during the transition ferrite–austenite, as a method for determination of rate parameters and diffusion constants. Application on the carburization and decarburization of Fe and Fe‐Ti alloys and on the carbon diffusion in ferrite and austenite.

Nonvolatile memory effects of chalcogenide amorphous semiconductor doped with AG

AbstractWith Ag‐photodoped amorphous As2S3 specimens that have nonvolatile memory effect, the electric conduction, temperature and frequency characteristics and thermoelectromotive force are investigated. The fabrication yield of this specimen is almost 100%. This device has a switching function, and the off‐state has a semiconductor type electric conduction with energy gap of 2 eV. The on‐state has metallic conduction and its temperature coefficient is almost the same as that of Ag, 4.0 × 10−3/°C. With a lateral‐type specimen (Au‐Ag electrodes), Ag dendrites are observed under a microscope. The dendrites bridge the two electrodes, resulting in memory action. The bridging of an Ag dendrite played the same role as a crystalline‐amorphous phase change in ordinary semiconductor memory operation.

Strain gauge characteristics of Ni-base amorphous alloys

The strain gauge characteristics of Ni-Si-B amorphous alloys prepared from the melt By rapid quenching were measured. The temperature coefficient of electrical resistance is very small. The strain gauge factor of them is about 2.0 and is independent of the strain rate. The electrical resistivity of those amorphous alloy is relatively high and the thermoelectromotive force is small. Because these amorphous alloys are paramagnetic, the magnetoresistance shows no anisotropy. The addition of Cr, V, Ti or Fe improves their strain gauge characteristics. From these results, it is concluded that Ni-Si-B amorphous alloys and its alloys containing Cr, V, Ti or Fe have excellent strain gauge characteristics.