2024/11/16 by Yuting Wu, Wu, Yu, Linxuan Ji +7 · 1 citation
Materials Science · #Advancements in Solid Oxide Fuel Cells #FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci) #Thermal Expansion and Ionic Conductivity
paper · pdf · doi:10.48550/arxiv.2411.10780
openalex publication_date 2024/11/16 · openalex created_date 2024/11/21 · openalex updated_date 2026/07/28
The low-frequency phonon branches of metal halide perovskites typically exhibit the characteristic of hardening with the increase of the cation mass, which leads to anomalous thermal transport phenomenon. However, the underlying physical mechanism is not yet understood. Here, we theoretically compare the thermal transport properties of A2SnI6 (A=K, Rb, and Cs) perovskites. The thermal transport in perovskites is widely explained using the rattling model, where ``guest'' cations inside the metal halide framework act as ``rattlers'', but this fails to explain the following phenomenon: The low-frequency phonon branch of A2SnI6 perovskites is insensitive to the mass of the A+ cation and strongly correlated with the interaction of the A+ cation with the I- anion in the octahedral structures. The failure of the rattling model stems mainly from the weak interactions between the octahedral structures. By developing a new spring model, we successfully explain the thermal transport behavior in A2SnI6 perovskites. Our work gives new insights into the thermal transport mechanism in metal halide perovskites, which has a guiding significance for designing extremely low thermal conductivity materials.