Scattering of lattice waves by point defects

Abstract

Abstract Thermal and electrical conductivity measurements have been made between 2 and 90°K on samples of copper containing 0.5, 1 and 2 at. % platinum, of copper containing 2 and 4 at. % silicon, and of silver containing 2 at. % platinum and aluminium respectively. The lattice components of their thermal conductivities are deduced. Theoretical estimates are derived for the reduction in the lattice thermal conductivity at high temperatures due to solute atoms, and the observed reduction due to these solute atoms at 90°K is compared with this theory, assuming that phonons are scattered mainly due to the mass difference between solute and solvent atoms. Reasonable agreement is obtained between theory and observations, even in the case of copper–silicon alloys, where distortion effects are not negligible. Previous observations by Kemp et al. (1957) on two copper–gold also fit this theory.