Reduced dependence of thermal conductivity on temperature and pressure of multi-atom component crystalline solid solutions

Abstract

We investigate the effect of mass disorder, temperature, and pressure on the spectral thermal conductivity of multicomponent crystalline solid solutions via molecular dynamics simulations. The thermal conductivities of Lennard-Jones based solid solutions with one to five different atomic components in the crystalline lattice are simulated at a range of uniaxial strain levels and temperatures. Our results show that for multicomponent alloys, increasing only the mass impurity scattering by adding atoms with different masses in the solid solution does not lead to significant changes in the spectral contributions to thermal conductivity. However, increasing the impurity concentration or changing the local force-field of the impurity atoms in the solid solution has a relatively significant impact on the spectral contributions to thermal conductivity. The effect of chemical order in these alloys is shown to drastically alter the temperature dependence due to the different scattering mechanisms dictating thermal conductivities in the ordered and disordered states. Furthermore, in comparison to a homogeneous solid, crystalline solid solutions (especially the disordered states) show a reduced pressure dependence on thermal conductivity, which becomes more prominent as the number of components is increased. This is attributed to the fact that while anharmonic effects in homogeneous solids lead to the large temperature and pressure dependencies in their thermal conductivities, impurity scattering in solid solutions leads to a largely reduced dependence on pressure and temperature.