Thermal transport properties of polycrystalline Bi4SeCl2O4 with various texturizations and densities

Bi4SeCl2O4, has recently drawn significant interest for the reported extremely low thermal conductivity (kappa), making it a promising material for thermoelectric applications. The anisotropy nature of this material allows for the manipulation of transport properties for optimization in a certain direction. However, there is still a lack of systematic research on the role of texturization in the thermal transport properties of Bi4SeCl2O4. In this work, single-phase polycrystalline Bi4SeCl2O4 was synthesized by solid-phase reaction and hot-pressing. The effect of both texturization and density on the thermal conductivity of Bi4SeCl2O4 was experimentally investigated in detail. The results show that once the density is higher than 80 %, this work demonstrates a kappa of >0.4 W/m-K even when the orientation factor reaches similar to 0.5. The kappa was verified by different measurement techniques. In addition, the heat insulation performance of Bi4SeCl2O4 was found to be intermediate between that of PTFE and silica.