Reversible reciprocal relation of thermoelectricity

Area of Science:

• Thermodynamics
• Condensed Matter Physics
• Materials Science

Background:

• The first Kelvin relation connects Peltier and Seebeck coefficients, crucial for thermoelectricity.
• It's considered a verification of the Onsager reciprocal relation (ORR) in irreversible thermodynamics.
• Existing proofs of the Kelvin relation raise questions about irreversibility and linearity requirements.

Purpose of the Study:

• To address fundamental questions regarding the first Kelvin relation's validity and derivation.
• To clarify the role of irreversibility and linearity in thermoelectric transport.
• To establish a robust theoretical framework for thermoelectric reciprocal relations.

Main Methods:

• Redefining Seebeck and Peltier coefficients based on reversible processes.
• Deriving a "reversible reciprocal relation" from Maxwell relations.
• Adopting the local equilibrium assumption (LEA).

Main Results:

• The first Kelvin relation is validated by reversible thermodynamics and LEA, independent of linear transport.
• Proper generalized force-flux pairs for ORR derivation correspond to conjugate variables yielding Maxwell relations.
• The theoretical framework supports extensions to other coupled transport phenomena.

Conclusions:

• The first Kelvin relation's validity stems from fundamental reversible thermodynamic principles and LEA.
• The study provides a clear method for selecting appropriate force-flux pairs for ORR derivation.
• This work offers a unified theoretical perspective on thermoelectric phenomena.