Thermal transport properties of polycrystalline Bi4SeCl2O4 with various texturizations and densities

Bi₄SeCl₂O₄, has recently drawn significant interest for the reported extremely low thermal conductivity (κ), 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 κ of >0.4 W/m-K even when the orientation factor reaches ∼0.5. The κ 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.