Anomalous Behavior of Phonon Diffusiveness Coefficient of Cubic Compounds with Anomalous Elastic Properties

Abstract

The phonon diffusiveness coefficient D related to scattering of phonons by point mass defects embedded in cubic crystalline media can be written as product of diffusiveness coefficient for a corresponding reference isotropic medium D is , and the dimensionless coefficient $$\widetilde D$$ which depends on two dimensionless elastic parameters s 2 , s 3. This coefficient is studied in the triangle–shaped region of plane (s 2 ,s 3 ) in which cubic elastic crystalline media are mechanically stable. As a function of s 2 and s 3 the coefficient $$\widetilde D$$ is nonmonotoneous and behaves singularly on the line s 2 = s 3. The underlying physical mechanism is considered.