Thermopower

The thermopower, thermoelectric power, or Seebeck coefficient of a material describes how it functions thermoelectrically.

The Seebeck coefficients, represented as S, are non-linear, and depend on the conductors' absolute temperature, material, and molecular structure.

If the temperature difference between the two nodes of a thermocouple is small,

and a voltage ΔV is seen at the terminals, then the thermopower of the entire thermocouple is defined as:

This can also be written in relation to the electric field E and the temperature gradient ∇T, by the equation

Superconductors have zero thermopower, and can be used to make thermocouples. This allows a direct measurement of the thermopower of the other material, since it is the thermopower of the entire thermocouple as well.

In semiconductors the sign of the thermopower is used to decide whether the charge carriers are electrons or holes.