In this paper, the phonon properties and thermal conductivity of a new clathrate SrB₃C₃ are investigated by utilizing first principles calculations combined with phonon Boltzman transport equation. Through analyzing the intrinsic symmetry, four Raman active phonon modes (2T_2g and 2E_g) are revealed in the phonon spectrum, and their corresponding vibrational features are presented as well. The lattice thermal conductivity of SrB₃C₃ at room temperature is calculated to be merely 8.69 W/mK, which is evidently smaller than that of traditional Si-based clathrates. Meanwhile, owing to the comparable group velocity with acoustic phonon modes, the optical phonons of SrB₃C₃ abnormally contribute 40% to the total thermal conductivity. Such low thermal conductivity in SrB₃C₃ is mainly attributed to the strong phonon anharmonic including both scattering strength and channel. The findings clarify the intrinsic phonon property of SrB₃C₃, and could help us to pave the way for its future applications in ferroelectric devices.

Graphical abstract

中文翻译：

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具有主客体包合物结构的新型铁电碳硼骨架中的声子传输特性

本文利用第一性原理计算结合声子玻尔兹曼输运方程研究了新型包合物SrB ₃ C _{3的声子性质和热导率。}通过分析固有对称性，在声子光谱中揭示了四种拉曼有源声子模式（2T _2g和2E _g），并给出了它们相应的振动特征。SrB ₃ C ₃在室温下的晶格热导率经计算仅为8.69 W/mK，明显小于传统的硅基包合物。同时，由于与声学声子模式相当的群速度，SrB _{3的光学声子}C ₃异常地贡献了总热导率的40%。SrB ₃ C ₃的低热导率主要归因于包括散射强度和通道在内的强声子非谐波。这些发现阐明了 SrB ₃ C ₃的固有声子特性，并可以帮助我们为其未来在铁电器件中的应用铺平道路。

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