Phonon and electron components of the thermal conductivity of tantalum at intermediate temperatures

Thermal conductivity, electrical resistivity, and absolute Seebeck-coefficient values for Ta and four Ta-base alloys are reported. The data, which cover the temperature range 80—400 K, were analyzed to identify the phonon and electron contributions to the thermal conductivity of Ta. Reflecting the strong electron-phonon interaction, the phonon thermal conductivity is rather small and equal to about $\frac{2}{3}$ of the prediction of a theoretical formula. At the highest temperatures investigated, the electronic thermal conductivity and electrical resistivity are consistent with the Sommerfeld-Lorenz number. The electrical resistivity and Seebeck-coefficient results can be satisfactorily fitted to standard theoretical formulas, and these results indicate that deviations from Matthiessen's rule are small and positive.