Observable Variables in Thermoelectric Phenomena

Abstract

New transport equations for the thermoelectric phenomena have been deduced. All of the variables in this formulation are observable quantities. The limitations of the usual formulations, which work with nonobservable quantities, have been overcome. The electric potential can be measured by using auxiliary probes which connect the electronic conductor to a potentiometer. This observable electric potential depends on the nature of the probes but not on the room temperature where the potentiometer is placed. Also, we emphasize that absolute values for the thermoelectric power are in contradiction with the thermodynamic limitation of measuring electric potential differences in these systems. Therefore, the thermoelectric powers calculated either through the Thomson coefficient or in reference to a superconductor cannot be absolute quantities.

On the different formalisms for the transport equations of thermoelectricity: A review

“…Since B / = 86.7 μV/K and is always a few orders of magnitude smaller than the Fermi temperature F = F / B of a metal, it is accepted that (36) and (37) explain the typical orders of magnitude of the Seebeck coe cient of metals and semiconductors [50].…”

“…Recently, a new formulation of the thermoelectricity transport equations based on experimentally observable quantities has been proposed [36][37][38][39][40]. The observable electric potential when the potential di erence in (18) is measured with probes of material R is de ned as [36][37][38] …”

“…The observable electric potential when the potential di erence in (18) is measured with probes of material R is de ned as [36][37][38] …”

“…Equivalently, as explained in [36][37][38], it can be considered as a di erential relation between the change d in the electric potential measured between two probes R connected to the conductor when one of them undergoes a di erential displacement d ⃗ between points whose di erence in temperature and electrochemical potential of the electrons are d and d̃ . When the probes are of the same material as the conductor under study, the observable electric potential is the same as the Ohmic potential, and this formalism reduces to the Ohmic formalism; but only the Thomson e ect can be observed then in isotropic conductors.…”

“…Novel recent approaches to the subject [36][37][38][39][40] are also discussed. The prevalence of the electrochemical formalism is explained.…”