Thermal conductivity in intermetallic clathrates: A first-principles perspective

摘要: Inorganic clathrates such as Ba8GaxGe46-x and Ba8AlxSi46-x commonly exhibit very low thermal conductivities. A quantitative computational description of this important property has proven difficult, in part due to the large unit cell, role disorder, fact that both electronic carriers phonons contribute transport. Here, we conduct a systematic analysis temperature composition dependence low-frequency modes associated with guest species ("rattler modes"), well transport stoichiometric Ba8Ga16Ge30. To end, account for phonon-phonon interactions by means temperature-dependent effective interatomic force constants, which find be crucial order achieve an accurate lattice conductivity. While conductivity is often largely focused on rattler modes, here it shown at room temperatures ω 10meV 50% heat Finally, contribution computed, shows Wiedemann-Franz law only approximately fulfilled. As result, employ correct prefactor when separating contributions experimental data.