Effect of Plastic Deformation on the Thermal Conductivity of Bismuth Crystals

Abstract

The thermal conductivity of deformed crystals of bismuth and its dilute alloys has been measured as a function of temperature from 1.5 to 20 K. Most crystals were deformed by compression so as to cause slip on the glide systems (111)[10\bar1] and (001)[1\bar10]. The other crystals were deformed by rapid compression or bending in order to cause mechanical twinning. The thermal conductivity of dilute alloy crystals is lower than that of pure crystals around the temperature at which the maximum thermal conductivity occurs. The plastic deformation results in large decrease of the thermal conductivity on the low temperature side of the maximum. Dislocations of the order of 10⁷ cm⁻² decrease the thermal conductivity to about 20% of that of an undeformed crystal, while the twin boundaries of the order of 10 cm⁻¹ decrease the conductivity to about 30%.