Li Jue, Yan Ting, Gong Xiangnan, Zou Hanjun, Zhang Bin, Wu Hong, Wang Guoyu, Zhou Xiaoyuan
Analytical and Testing Center, Chongqing University, Chongqing 401331, P. R. China.
College of Physics, Chongqing University, Chongqing 401331, P. R. China.
J Phys Chem Lett. 2023 Aug 24;14(33):7346-7353. doi: 10.1021/acs.jpclett.3c01600. Epub 2023 Aug 10.
Tin sulfide has outstanding thermoelectric properties in the -axis direction of crystallography as a IV-VI group layered compound, which arouses great attention. In this study, temperature-dependent Raman spectroscopy (TDRS) is used to quantify the phonon anharmonicity in SnS crystals from 77 to 475 K, where the three-phonon process dominates in this temperature region. Moreover, integration of the four-phonon process and lattice thermal expansion will better describe the temperature-dependent Raman experimental phenomenon. The good agreement between the calculated and experimental lattice thermal conductivity confirms the three-phonon scattering process is the dominant scattering mechanism at this temperature range. Further, combining the atomic thermal displacement and charge density through density functional theory calculation, the inherently low thermal conductivity of SnS is because of strong lattice anharmonicity, which is brought by the presence of asymmetric chemical bonding resulting from the Sn 5s lone pair electrons. These results provide key insights for studying thermal properties of other low-dimensional materials.
作为一种IV-VI族层状化合物，硫化锡在晶体学的轴方向上具有出色的热电性能，这引起了人们的极大关注。在本研究中，使用温度相关拉曼光谱（TDRS）来量化77至475K温度范围内SnS晶体中的声子非简谐性，在此温度区域内三声子过程占主导。此外，四声子过程和晶格热膨胀的综合作用将更好地描述与温度相关的拉曼实验现象。计算得到的晶格热导率与实验结果之间的良好一致性证实了三声子散射过程是该温度范围内的主要散射机制。进一步地，通过密度泛函理论计算将原子热位移和电荷密度相结合，SnS固有低导热率的原因是由于存在由Sn 5s孤对电子导致的不对称化学键所带来的强晶格非简谐性。这些结果为研究其他低维材料的热性能提供了关键见解。
