Calculation of the Thermoelectric Power of Vanadium, Niobium, and Tantalum

In previous studies, the diffusional thermopower of more than 20 metals was calculated on the assumption that local thermal equilibrium between electrons and metal ion cores is established at high temperatures. In that case, the diffusional thermopower is approximately equal to the gradient of the electrochemical potential of the electrons (calculated from the density of states, DOS), divided by the electronic charge. The method, illustrated here for the transition metals V, Nb, and Ta, is expected to be applicable to all metals of the Periodic Table, as well as to alloys of adjacent metals. At temperatures well below the Debye temperature, the diffusional thermopower is overwhelmed by the phonon drag effect. The assumption of local equilibrium does not apply because the condition of equality between electron and ion core temperatures is not fulfilled.