Thermovoltages under a non‐linear Seebeck coefficient

The thermovoltages in the case of a nonlinear absolute Seebeck‐coefficient S ( T ) of a material A are discussed up to the quadratic term in the expansion of S ( T ) for inhomogeneous (AB) as well as for homogeneous (AA) material rings. The quadratic term results in additional thermovoltages and in particular in a Benedicks effect, Δ u AA ∼ (Δ T ) 3 , but only if there is a thermal asymmetry in the bisectional ring AA, too. The coefficients of the expansion of S ( T ) are calculated for the case that the quadratic term originates from the thermal expansion of a metallic material, using the Boltzmann–Fermi theory.