seebeck coefficient Measurement

[becidea]

Hi,

can you please add this "" the slope of dV versus dT "". I mean that there is voltage vs time and delta T vs time in the vi I sent. Could you please add this in to my vi. and one more thing is that Pt or Pt/Rh. You mean I should cut those wires and insert them into system or use them as thermocouple and measure somehow. I have Pt and Pt/Rh wire as 0.5 mm thickness. Are they appropriate to do so.

[becidea]

is this should be like this?

[nitad54448]

for measurement yes, you can use Pt wire, say 10 mm length

for the slope : make XY graph, then calculate slope

try and show what you'got

[becidea]

if you are using Nb wire for voltage source, how you insulate this wire from the thermocouples? Also Nb wire should be used in vacuum, because it is teribly oxidative

[nitad54448]

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@becidea wrote:

if you are using Nb wire for voltage source, how you insulate this wire from the thermocouples? Also Nb wire should be used in vacuum, because it is teribly oxidative

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no, not Nb for voltage source but for measuring dV (I am measuring dV directly through the thermocouple leg via a matrix card). and no, Nb can be used in air

[becidea]

hi, I am also using thermocouple leg (+ one). K-type thermocuople I am using but the problem is how to subtract voltage coming from thermocuople leg. Also I have Nb wire and for high temperature application , It is oxidiced. My vacuum is not so high, that's why Nb wire's surface becomes white and britle.

So, how to subtract voltage coming from thermocouple leg? please help me on this because I am getting crazy and I have no one to ask.. I appriciat you for this help.Best.

[nitad54448]

hi

Imagine you are measuring the thermopower of a Chromel wire with a Chromel/Alumel thermocouple. If you are measuring the voltage through the Chromel wire, you will se that there is no voltage difference even though there is a temperature difference. It is like your sample (Chromel) has S=0. We know that's not correct : you need to correct the value you measure with the absolute value of the leg Chromel.

Here are some S+, S- and S for the K thermocouple S=S+-S-

[nitad54448]

[becidea]

Thank you so much for this information. Sorry to distrub you but I have a comment and question. I am putting my sample bewtween 2 K-type thermocouples. There is one K type on one end and the other K typr on the other end os the sample. Then I connect my Keithley 182 nanovoltmeter cables to the positive leg of K ytpe thermocouples as you can se in the picture.

Here I am measuring voltage coming from my sample and also from thermocouples. Please tell me how to substract this voltage coming from thermocouple. Should I connect two thermocouples together without my sample and create gradient then measure voltage, thus subtract this voltage from voltage coming from sample and thermocouple.

Or I should use another voltmeter and connect somehow: hot to connect if I need to use additional voltmeter.

thank you again nitad. you are the best. I appriciate your help and informations.

Best.

[nitad54448]

Hi

You need to measure three voltages : one for T1, one for T2 and one for dV. How do you measure right now ?

please make a sketch

N