Maldistribution of Chemical Bond Strength Inducing Exceptional Anisotropy of Thermal Conductivity in Non‐Layered Materials

Currently, the efforts to find materials with high κ anisotropy ratios mainly focus on layered materials, however, the limited quantity and lower workability comparing to non‐layered ones boost the exploration of non‐layered materials with high κ anisotropy ratios. Here, taking PbSnS3, a typical non‐layered orthorhombic compound, as an example, we propose that maldistribution of chemical bond strength can lead to large anisotropy of κ in non‐layered materials. Our result reveals that the maldistribution of Pb−S bonds lead to obvious collective vibrations of dioctahedron chain units, resulting in an anisotropy ratio up to 7.1 at 200 K and 5.5 at 300 K, respectively, which is one of the highest ever reported in non‐layered materials and even surpasses many classical layered materials such as Bi2Te3 and SnSe. Our findings can not only broaden the horizon for exploring high anisotropic κ materials but also provide new opportunities for the application of thermal management. We propose that maldistribution of chemical bond strength can lead to large anisotropy of κ in non‐layered materials. Taking PbSnS3, a typical non‐layered orthorhombic compound, as an example, our result reveals that the maldistribution of Pb−S bonds leads to an anisotropy ratio up to 7.1 at 200 K and 5.5 at 300 K, respectively, which are among the highest values ever reported in non‐layered materials and even surpass many classical layered materials.