Thermal and electrical conductivities of high purity tantalum

The electrical resistivity and thermal conductivity of three high purity tantalum samples have been measured as functions of temperature over a temperature range of 5K to 65K. Sample purities ranged up to a resistivity ratio of 1714. The highest purity sample had a residual resistivity of .76 x 10/sup -10/OMEGA-m. The intrinsic resistivity varied as T/sup 3/./sup 9/ from 10K to 31K. The thermal conductivity of the purest sample had a maximum of 840 W/mK at 9.8K. The intrinsic thermal resistivity varied as T/sup 2/./sup 4/ from 10K to 35K. At low temperatures electrons were scattered primarily by impurities and by phonons with both interband and intraband transitions observed. The electrical and thermal resistivity is departed from Matthiessen's rule at low temperatures.