Low-Temperature Thermal Conductivity of High-Purity and Doped Tantalum Single Crystals after Plastic Deformation

Abstract

The thermal conductivity of plastically deformed, high-purity and doped tantalum single crystals was measured in the temperature range between 50 mK and about 2 K. The deformation was performed in such a way that comparable dislocation arrangements and dislocation densities are produced for both, high-purity and doped specimens. Surprisingly, the thermal resistivity Wd due to plastic deformation depends strongly on the purity of the crystals and the deformation temperature. In the high-purity specimens a thermal resistivity is observed which is much larger than in the case of doped specimens. This additional thermal resistivity is larger after deformation at intermediate temperature than after deformation at low temperatures and has to be attributed to a dynamic interaction between phonons and non-screw dislocations. In the present paper the scattering mechanism is related to oscillations of geometrical kinks in non-screw dislocations.