Low-temperature thermal conductivity of plastically deformed niobium single crystals

Abstract

The thermal conduction of four niobium single crystals deformed at 77 K, 195 K 295 K and 470 K has been measured in the temperature region between 0·3 K and 20 K. From these measurements the thermal resistivity W _pd due to plastic deformation was calculated in the temperature region below 5 K. After weak and medium deformation at 77 K and 195 K a thermal resistivity proportional to about T ⁻³ was found. Strong deformation at 195 K and also medium and strong deformation at 295 K and 470 K gave rise to a thermal resistivity proportional to T ⁻². The dislocation arrangement has been studied by X-ray topography and transmission electron microscopy. Comparison between the experimental results and different models of the static and dynamic interactions between phonons and dislocations shows that the results are consistent with the model of the scattering of phonons by the static distortion field of dislocations. No influence of dynamic processes has been observed.