Computer-controlled simultaneous measurements of the thermopower and conductivity of thin films
01 Feb 1988-Journal of Physics E: Scientific Instruments (IOP Publishing)-Vol. 21, Iss: 2, pp 159-163
TL;DR: In this paper, a microcomputer-controlled apparatus for simultaneous measurement of the conductivity and the Seebeck coefficient of thin solid films is described, and the investigated temperature range lies from room temperature to 1100 degrees C. It is shown that the noise in the measured quantities is small enough to allow a further discrimination between the various models of electron transport.
Abstract: A microcomputer-controlled apparatus for the simultaneous measurement of the conductivity and the Seebeck coefficient of thin solid films is described. The investigated temperature range lies from room temperature to 1100 degrees C. The apparatus was tested on thin films of oxides produced in argon gas by RF sputtering. It is shown that the noise in the measured quantities is small enough to allow a further discrimination between the various models of electron transport. The overall noise in the thermopower is 1.5%, whereas it is 3*10-3 for the conductivity. It is found that noise is essentially an electronic noise and so could be improved.
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TL;DR: In this paper, the Seebeck coefficient of 40TeO2-V2O5-xMoO3 bulk glasses was measured in the temperature range 260-450 K.
Abstract: The Seebeck coefficient, Q, of ternary 40TeO2–(60−x)V2O5–xMoO3 bulk glasses was measured in the temperature range 260–450 K. The thermoelectric power at 400 K was measured and was in the range from −677 to −501 µV K−1 for TeO2–V2O5–MoO3 glasses. For the present glass systems, Heikes' formula was satisfied and a small polaron hopping conduction mechanism was confirmed, which was in agreement with the results of dc electrical conductivity measurement of these glasses. The 40TeO2–50V2O5–10MoO3 glass system had the highest power factor, Q2σ, and probably the highest figure of merit among the others.
36 citations
TL;DR: In this paper, the superconducting properties of Ca-substituted YBa2Cu3Oz have been investigated and the results show that Y0.7Ca0.3Ba2C3C4Oz samples remain superconducted in the 6.02≤z≤6.845 range as predicted by theoretical study.
Abstract: Superconducting properties of Ca-substituted YBa2Cu3Oz have been investigated. Electrical and magnetic measurements as a function of oxygen stoichiometry have been carried out. The results show that Y0.7Ca0.3Ba2Cu3Oz samples remain superconducting in the 6.02≤z≤6.845 range as first predicted by theoretical study. We also correlate this superconducting behaviour with the thermopower measurements performed.
31 citations
TL;DR: In this paper, a system for measuring thermoelectric power, electrical resistivity and differential conductance under the controlled partial pressure of oxygen including vacuum or reducing atmosphere for samples that are sensitive to oxygen.
Abstract: Several devices able to measure the Seebeck coefficient have been devised over the years but most of these were designed to perform under vacuum or under inert atmosphere We describe here a system designed for measuring thermoelectric power, electrical resistivity and differential conductance up to 1200 K, under the controlled partial pressure of oxygen including vacuum or reducing atmosphere for samples that are sensitive to oxygen, which allows the in situ investigation of the electrical properties of oxide materials and their phase diagram The instrument we present here can also be used to ‘tune’ the properties of a compound through thermal treatment This system is reliable and has been in use in our laboratory for more than three years
21 citations
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...presence of oxygen [14, 18, 37–41]....
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...challenging task, have been proposed [12–38]....
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TL;DR: In this paper, a system for simultaneous measurement of thermoelectric power and resistivity of one and/or two samples over a temperature range of 300-1000 K in a vacuum chamber is designed and implemented.
Abstract: A system for the simultaneous measurement of thermoelectric power and resistivity of one and/or two samples over a temperature range of 300–1000 K in a vacuum chamber is designed and implemented. A sample probe is developed to provide its easy mounting and usage. In addition, two samples can be measured at the same time. Measurement accuracy has been enhanced by beadless thermocouples and micro-heaters that are specifically designed in order to minimize the 'cold-finger effect' and to eliminate some possible source of contact, design and measurement errors. A broad range of physical types and shapes of samples, such as bulk, bar or disc, can be measured by a software controlled system. A differential steady-state method has been applied for Seebeck coefficient measurement. Resistivity measurement is conducted with the axial technique of the four-point probe method. Platinum wire and a niobium rod are chosen as the standard samples. The total data error for the Seebeck coefficient and resistivity measurements is estimated to be less than 2.6% and 1%, respectively.
16 citations
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TL;DR: In this paper, the thermoelectric properties of 40TeO2-(60−−x)V2O5-xSb2O3, amorphous materials (with 0−⩽ ǫ −10 in mole%) were studied by measuring the Seebeck coefficient, S, from 280 to 440 K.
Abstract: Today, solar energy is one of the most useful renewable energy. But, efficiency of photovoltaic (PV) systems is not enough high. On the other hand, the PV panel output power depends on some factors such as the irradiation (resulting in increasing of panel temperature) and temperature. Researchers are trying to improve the efficiency of solar cells; thus, application of thermal stable thermoelectric materials as thermoelectric coolers (TECs) can improve the PV efficiency. In this work, sample preparation and the study of thermoelectric properties of tri-component 40TeO2-(60 − x)V2O5-xSb2O3, amorphous materials (with 0 ⩽ x ⩽ 10 in mole%) were done, which can be used in PV systems. The thermoelectric behavior of the mentioned samples, termed as 40TVSx in continue, were studied by measuring the Seebeck coefficient, S, from 280 to 440 K. For these glassy systems, the variation trend of figure of merit (F) was obtained at typical temperatures 310 K, 370 K and 435 K, to elucidate the suitable candidate for thermoelectric applications; to do this, the Seebeck coefficients, S, (thermoelectric power) at mentioned temperatures was measured, which were ranged from (−591) to (−698) μV K−1 and show increasing trend with increasing of antimony oxide for all samples. In these samples, the applicability of Heikes’ equation (S dependency to ln(CV/1 − CV), which CV = [V4+]/Vtot is the ratio of the content of reduced vanadium ions) and also Mackenzie’s equation (S dependency to ln([V5+]/[V4+])) were examined and so justified. The obtained thermoelectric data ascertained the mechanism of electrical conduction as small polaron hopping (SPH), which confirms the previously published dc-electrical output of the same glassy systems. Finally, to introduce the more suitable samples for TEC applications, figure of merit (F) was determined, which show the highest value for 40TVS0 sample as a more suitable option in thermoelectric applications and so in heat releasing part of PV systems.
14 citations
References
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01 Nov 1958
361 citations
TL;DR: In this paper, the Seebeck coefficient (S) and electrical conductivity (σ) of thin-film thermoelectric materials were measured continuously over the temperature range of 20 to 1000 degrees C.
Abstract: This paper describes the design and performance of a novel automated apparatus for measuring the Seebeck coefficient (S) and the electrical conductivity (σ) of thin‐film thermoelectric materials continuously over the temperature range of 20 to 1000 °C. An inert substrate coated with a thin film thermoelectric material is increased and decreased in temperature at a predetermined rate set by program control while maintaining a constant temperature gradient across the sample. A fully automated computer data acquisition system is used to control instrumentation, measurements, and data storage. This approach is particularly useful for studying the transition from amorphous to crystalline structure in the semiconducting materials. Thin‐film thermoelectric materials were prepared by magnetron sputtering and rf glow discharge. Parameters S and σ were measured as a function of temperature, histology, type, and amount of doping. Materials studied had the compositions Bi2Te3, GeTe, Ge80Te20, PbTe, and S.
8 citations