Yue Chen
Department of Mechanical Engineering, The University of Hong Kong, Pokfulam Road,
Hong Kong SAR, China 

EXTENDED ABSTRACT: Crystalline and amorphous materials exhibit distinctly different thermal transport behaviors. Understanding the lattice thermal conduction in solids is critical for various technologically important applications, e.g., materials with ultra-high thermal conductivities are needed for microelectronics for efficient heat dissipation, while low thermal conductivity is favored in thermoelectrics. In this presentation, the lattice thermal conduction in crystalline argyrodites will be discussed. Based on our study combining the unified theory for thermal transport, nonequilibrium molecular dynamics simulations, and laser flash experiments, we unveil a glass-like thermal transport behavior in argyrodite compounds with complex crystal structures. The results are of great significance for the search for new materials with strongly suppressed thermal transport at high temperatures. The alloying effects on the thermal conduction of argyrodites will also be discussed. Different from the classical impurity scattering of phonons that reduces the lattice thermal conductivity of an alloyed system, we find that alloying can increase the wave-like phonon tunneling and lead to an overall enhancement of the lattice thermal conduction in argyrodites. This distinct alloying effect is further investigated via the calculation of the phonon properties.
Keywords: thermal transport; lattice dynamics; complex crystals