Berlin 2005 – wissenschaftliches Programm

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M: Metallphysik

M 28: Elektronische Eigenschaften

M 28.6: Vortrag

Montag, 7. März 2005, 11:45–12:00, TU H2038

Redetermination and calculation of the thermopower of lead — •Horst Brodowsky and Matthias Albus — Institut f. Physikalische Chemie, Uni Kiel

Precise Thomson heat measurements by Roberts resulted in a shift of the previously accepted lead standard of Christian et al. by 0.30 µV/K. Superconductor measurements between 16 and 112 K suggest a shift of 0.41 ± 0.02 µV/K instead.

It has been shown for a number of transition metal alloys as well as for the alkali metals, that it is not necessary to calculate the ratio of the intractable transport coefficients of the Onsager equations. The diffusional thermopower happens to be equal to the more readily accessible entropy of the electrons divided by the electronic charge (Z. Metallkunde 90 (1999) 111; 91 (2000) 375; 93 (2002) 1164; 95 (2004) 698). This surprising result is obtained, because in metals the electron/atom ratio is constant along the length of the wire (besides the pressure) and the electrochemical potential of the electrons is a unique function of the temperature. This fact allows the more direct evaluation of Onsager’s equation compared to the conventional method.