Measuring the thermoelectric effect of a simple metal

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SUMMARY

The discussion focuses on measuring the thermoelectric effect of a simple metal using the formulation of the thermoelectric effect represented by the equations involving tensors \(\mathbf{L}_{ij}\). It highlights the challenges of obtaining absolute values of the coefficients for a single metal due to temperature gradients caused by voltmeter connections. Participants suggest using the Seebeck effect in conjunction with a known reference, such as a thermocouple setup or maintaining a constant temperature point, to accurately measure the unknown Seebeck coefficient.

PREREQUISITES
  • Understanding of thermoelectric effects, specifically the Seebeck, Peltier, and Thomson effects.
  • Familiarity with tensor notation and its application in material characterization.
  • Basic knowledge of experimental physics and temperature measurement techniques.
  • Experience with thermocouples and their use in measuring temperature differences.
NEXT STEPS
  • Research the principles of the Seebeck effect and its applications in thermoelectric measurements.
  • Explore the construction and operation of thermocouples for accurate temperature gradient measurements.
  • Investigate methods for maintaining constant temperature points in experimental setups.
  • Study the implications of using Peltier and Thomson effects in thermoelectric experiments.
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Physicists, materials scientists, and engineers interested in thermoelectric materials and their characterization methods.

SmD
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By using the following formulation of the thermoelectric effect:

[tex]\mathbf{j} = \mathbf{\L}_{11}\mathbf{\xi} + \mathbf{\L}_{12}(-\mathbf{\nabla}T)[/tex]
[tex]\mathbf{j} = \mathbf{\L}_{21}\mathbf{\xi} + \mathbf{\L}_{22}(-\mathbf{\nabla}T)[/tex]

where [tex]\mathbf{\L}_{ij}[/tex] are tensors that charaterizes a given material.

What would be the easiest conceivable experiment to measure [tex]\mathbf{\L}_{ij}[/tex] of a certain material. One cannot exploit the Seebeck effect to get the ABSOLUTE VALUES of the coefficients of ONE METAL, since when you connect the leads of a voltmeter on the metal, it creates a temperature gradient inside of the meter itself (which would lead to false data). On the other hand, the use of the Peltier and Thomson effect leads to certain problems. I'm pretty sure that I must use one these effects to measure these coefficients, but I'm not sure how to do it .
:cry:
 
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What if you use two metals, as in a thermocouple, with one of them a known reference? I think you can then figure out the unknown Seebeck coefficient from this.

If you really want to stick to one metal, I think you can use a reference temperature (passing one of the leads through ice or maintaining a point along the line at constant temperature.)

Either way, I think you can simply use the Seebeck effect.
 

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