Thermal transport characteristics of diamond under stress

Abstract

Diamond exhibits extremely high hardness and thermal conductivity, which makes it widely used in industrial fields such as diamond cutting tools and piezoelectric materials. At the same time, during the diamond applications, the internal characteristics and thermal transport properties of diamond will change under high stress, which has an important impact on its service life and device accuracy. However, the internal properties and thermal transport response of diamond under high stress have not been systematically studied. This paper employed first-principles software to investigate the reaction of the diamond lattice structure, electronic properties, lattice vibration properties, thermodynamic properties, lattice thermal conductivity, phonon group velocity, and phonon free path when subjected to uniaxial compressive stress, shear stress, and hydrostatic pressure. The results show that at a stress of 120 GPa, the response of diamond exhibited distinct anisotropic properties in three kinds of stress states. Changes occur in the position of the carbon atoms, CC bond length, and CC bond angle within the diamond structure when subject to the three kinds of stress fields. The main reason for the above phenomenon is that the stress caused the redistribution of charges around the C atoms in the diamond. Furthermore, the symmetry of the diamond crystal was broken, and the diamond lattice vibration properties undergone alteration, leading to a state of dynamic instability. The thermodynamic properties and phonon group characteristics of diamond changed, and the lattice thermal conductivity of diamond is 2380, 99, and 806 W·m-1K-1, respectively. This theoretical study offers valuable insights into the impact of stress fields on the heat transfer properties of diamonds, providing practical guidance for their use in high-stress environments.