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

Currently, the efforts to find materials with high kappa 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 kappa 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 kappa 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 kappa materials but also provide new opportunities for the application of thermal management.

Automated summary

Currently, the focus has been on layered materials in the search for materials with high kappa anisotropy ratios. However, the limited quantity and lower workability of these materials compared to non-layered ones have led to exploration of non-layered materials instead. In this study, using PbSnS3 as an example, it was found that the maldistribution of chemical bond strength in non-layered materials can result in large anisotropy of kappa. The findings reveal an anisotropy ratio in PbSnS3 that is among the highest ever reported in non-layered materials, surpassing classical layered materials like Bi2Te3 and SnSe. These findings not only expand the exploration of high anisotropic kappa materials but also offer new possibilities for thermal management applications.