Effect of dislocations on the thermal conductivity of lithium fluoride

Abstract

Measurements of the thermal conductivity K of Harshaw LiF crystals were made over the temperature range 2°-100°K. A freshly cleaved crystal exhibited K values in agreement with the measurements of Berman, Foster, and Ziman (1956). Annealing raised the maximum K by a factor of two. Dislocations were added by compression, and the dislocation density was determined by the methods of Gilman and Johnston. The K values below 30°K for the deformed specimens were approximately proportional to T2, in agreement with Klemens' theory, but the reduction in K by introduction of dislocations was much larger than Klemens' predictions. The phonon mean free path when limited by dislocation scattering was found to be approximately (4×106)DT, where D is the number of dislocation linescm2 and T is the absolute temperature. © 1959 The American Institute of Physics.