Quantification of switchable thermal conductivity of ferroelectric materials through second-principles calculation

Materials with tunable thermal properties at room temperature have attracted great attention owing to their applications as solid-state thermal switches for thermal management. As a typical ferroelectric material, barium titanate (BaTiO₃) is regarded as promising candidate for thermal switch because its ferroelectric polarization can be switched by external electric field. However, BaTiO₃ presents a low-symmetry tetragonal phase at room temperature, calculating its thermal conductivity through first-principles calculations is rather time-consuming. By solving Boltzmann transport equation with the interatomic force constants from second-principles model, we develop a time-efficient strategy to calculate the thermal conductivity of tetragonal BaTiO₃. The calculated thermal properties of BaTiO₃ based on the strategy are consistent with those from first-principles calculations while the calculation time is greatly reduced. It is found that both in-plane and out-of-plane thermal conductivity can be adjusted by external electric field. A thermal switch with a switch ratio of 5.1 at room temperature is predicted based on the polarization switching under external electric field. This work not only provides an efficient approach to study thermal properties but also suggests a room-temperature thermal switch controlled by an electric field.