Low-frequency ac measurement of the Seebeck coefficient

Chen, F.; Cooley, J. C.; Hults, W. L.; Smith, Judy

doi:10.1063/1.1406930

Cited by 27 publications

(21 citation statements)

References 10 publications

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“…This implies that the interlayer distance between the (Fe 2 As 2 )-layers and the relevant As-As distances decrease with Sr content. ̺(T) was measured by employing a standard 4-probe method using a Linear Research LR-700 ac bridge operated at 19 Hz and the magnetic field effect on ̺ was measured using a Quantum Design PPMS system for temperatures down to 1.8 K and magnetic fields up to 7 T. The temperature dependence of the dc-magnetic susceptibility χ(T) was measured using Quantum Design SQUID magnetometer at fields up to 5 T. The Seebeck coefficient was measured using a very low frequency ac two-heater method [12].…”

mentioning

confidence: 99%

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2with
Sasmal
¹
,
Lv
²
,
Lorenz
³

et al. 2008
Phys. Rev. Lett.

712

274

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New high-Tc Fe-based superconducting compounds, AFe2As2 with A = K, Cs, K/Sr and Cs/Sr, were synthesized. The Tc of KFe2As2 and CsFe2As2 is 3.8 and 2.6 K, respectively, which rises with partial substitution of Sr for K and Cs and peaks at 37 K for 50-60% Sr substitution, and the compounds enter a spin-density-wave state (SDW) with increasing electron number (Sr-content). The compounds represent p-type analogs of the n-doped rare-earth oxypnictide superconductors. Their electronic and structural behavior demonstrate the crucial role of the (Fe2As2)-layers in the superconductivity of the Fe-based layered systems, and the special feature of having elemental Alayers provides new avenues to superconductivity at higher Tc.

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mentioning

confidence: 99%

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2with
Sasmal
¹
,
Lv
²
,
Lorenz
³

et al. 2008
Phys. Rev. Lett.

712

274

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“…Measurements with variable temperature difference allow to eliminate or significantly reduce errors associated with inhomogeneity of branches of thermocouples, with slow instrumental drift or constant voltages caused by inhomogeneity of electrical circuits due to thermoelectric effects. This method has an advantage comparing to measurements with static temperature difference at low temperatures, when amplitude of ΔT is very small, because condition, which must be satisfied is ΔT << T. Therefore, there have been numerous variants of its implementation, designed for measuring thermopower at low temperatures [31][32][33][34][35][36]. At high temperatures, gradient modulation does not bring significant increase in accuracy, and implementation of this method is more difficult.…”

Section: Devices For Measuring Thermopower and Electrical Conductivitymentioning

confidence: 99%

Methods and Apparatus for Measuring Thermopower and Electrical Conductivity of Thermoelectric Materials at High Temperatures

Бурков¹,

Федотов²,

Новиков³

2016

Thermoelectrics for Power Generation - A Look at Trends in the Technology

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The principles and methods of thermopower and electrical conductivity measurements at high temperatures (100-1000 K) are reviewed. These two properties define the socalled power factor of thermoelectric materials. Moreover, in combination with thermal conductivity, they determine efficiency of thermoelectric conversion. In spite of the principal simplicity of measurement methods of these properties, their practical realization is rather complicated, especially at high temperatures. This leads to large uncertainties in determination of the properties, complicates comparison of the results, obtained by different groups, and hinders realistic estimate of potential thermoelectric efficiency of new materials. The lack of commonly accepted reference material for thermopower measurements exaggerates the problem. Therefore, it is very important to have a clear understanding of capabilities and limitations of the measuring methods and set-ups. The chapter deals with definitions of thermoelectric parameters and principles of their experimental determination. Metrological characteristics of state-of-the-art experimental set-ups for high temperature measurements are analyzed.

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“…Integrated heatersensor techniques 4,5 utilize metal or polysilicon heaters and platinum resistance thermometers (PRTs) integrated into the test structure. Two-thermocouple (two-tc) techniques utilize temperature gradients created externally (off-sample) usually by Joule heating based components [6][7][8][9][10] or alternately by light a) E-mail: ashok.ramu@gmail.com. pulses.…”

Section: Introductionmentioning

confidence: 99%

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material

Ramu

Mages

Zhang

et al. 2012

Review of Scientific Instruments

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The Seebeck coefficient of a typical thermoelectric material, silicon-doped InGaAs lattice-matched to InP, is measured over a temperature range from 300 K to 550 K. By depositing and patterning a thermometric reference bar of silicon-doped InP adjacent to a bar of the material under test, temperature differences are measured directly. This is in contrast to conventional two-thermocouple techniques that subtract two large temperatures to yield a small temperature difference, a procedure prone to errors. The proposed technique retains the simple instrumentation of two-thermocouple techniques while eliminating the critical dependence of the latter on good thermal contact. The repeatability of the proposed technique is demonstrated to be ±2.6% over three temperature sweeps, while the repeatability of two-thermocouple measurements is about ±5%. The improved repeatability is significant for reliable reporting of the ZT figure of merit, which is proportional to the square of the Seebeck coefficient. The accuracy of the proposed technique depends on the accuracy with which the high-temperature Seebeck coefficient of the reference material may be computed or measured. In this work, the Seebeck coefficient of the reference material, n+ InP, is computed by rigorous solution of the Boltzmann transport equation. The accuracy and repeatability of the proposed technique can be systematically improved by scaling, and the method is easily extensible to other material systems currently being investigated for high thermoelectric energy conversion efficiency.

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Low-frequency ac measurement of the Seebeck coefficient

Cited by 27 publications

References 10 publications

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2with
Sasmal
¹
,
Lv
²
,
Lorenz
³

et al. 2008
Phys. Rev. Lett.

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2with
Sasmal
¹
,
Lv
²
,
Lorenz
³

et al. 2008
Phys. Rev. Lett.

Methods and Apparatus for Measuring Thermopower and Electrical Conductivity of Thermoelectric Materials at High Temperatures

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material

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Low-frequency ac measurement of the Seebeck coefficient

Cited by 27 publications

References 10 publications

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2withSasmal1, Lv2, Lorenz3 et al. 2008Phys. Rev. Lett.

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2withSasmal1, Lv2, Lorenz3 et al. 2008Phys. Rev. Lett.

Methods and Apparatus for Measuring Thermopower and Electrical Conductivity of Thermoelectric Materials at High Temperatures

Measurement of the high-temperature Seebeck coefficient of thin films by means of an epitaxially regrown thermometric reference material

Contact Info

Product

Resources

About

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2with
Sasmal
¹
,
Lv
²
,
Lorenz
³

et al. 2008
Phys. Rev. Lett.

Superconducting Fe-Based Compounds(A1−xSrx)Fe2As2with
Sasmal
¹
,
Lv
²
,
Lorenz
³

et al. 2008
Phys. Rev. Lett.