Thermocouples, dissimilar metals?

[microG]

Thermocouples, dissimilar metals??

Hello everyone, this is my first post so go easy on me.

Looking into making a thermopile and trying to decide what two metals to use, everywhere I look for thermocouple theory it says two dissimilar metals.

My question is in what respect do they have to be dissimilar? resistivity, thermal coefficients, conductivity?

Cheers, Graham.

 

[jsgruszynski]

http://en.wikipedia.org/wiki/Thermocouple

There are well-known choices that tend to give the best results which are designated by a "type" such as Type T or K (probably the most common) or other types listed in the ilke above. It has to do with metal work functions which are an intrinsic parameter of a metal.