论文标题
$ \ textit {pnma} $ sn（s $ _ {1-x} $ se $ _ {x} $）的晶格动力学
Lattice dynamics of $\textit{Pnma}$ Sn(S$_{1-x}$Se$_{x}$) solid solutions: energetics, phonon spectra and thermal transport
论文作者
论文摘要
合金被广泛用作通过降低晶格导热率来微调热电材料的性质的一种手段。但是，尚不能够很好地理解成分变化对合金系统晶格动力学的影响，部分原因是难以构建结构性复合实体解决方案的现实第一原理模型。这项工作基于我们先前对Sn $ _ {n} $的研究（S $ _ {1-x} $ SE $ _ {X} $）$ _ {M} $ solid Solutions [gunn $ \ textit {et al。} $，$ \ textit {chem chem chem chem。 Mater.}$ $\textbf{31}$, $\textit{10}$, 3672, $\textbf{2019}$] to explore the lattice dynamics of the $\textit{Pnma}$ Sn(S$_{1-x}$Se$_{x}$) system, which has been widely studied for potential thermoelectric applications.我们发现，振动的内部能量和熵对混合自由能具有很大的定量影响，并且在具有竞争阶段的合金系统中可能尤其重要。热力学平均的声子分散和状态曲线的密度表明，合金保留了与SN Sublattice相关的模式的低频带的结构，但在50/50混合组合物中将高频chalcogen带扩大到近乎连续的光谱中。这导致声子模式组速度的总体降低，并增加了携带热频率低频模式的能量持续散射通道的数量，这与实验测量中观察到的热导率的降低是一致的。最后，我们讨论了我们的第一原则建模方法的一些局限性，并提出了在以后的研究中解决这些方法的方法。
Alloying is widely used as a means to fine-tune the properties of thermoelectric materials by reducing the lattice thermal conductivity. However, the effects of compositional variation on the lattice dynamics of alloy systems are not well understood, due in part to the difficulty of building realistic first-principles models of structurally-complex solid solutions. This work builds on our previous study of Sn$_{n}$(S$_{1-x}$Se$_{x}$)$_{m}$ solid solutions [Gunn $\textit{et al.}$, $\textit{Chem. Mater.}$ $\textbf{31}$, $\textit{10}$, 3672, $\textbf{2019}$] to explore the lattice dynamics of the $\textit{Pnma}$ Sn(S$_{1-x}$Se$_{x}$) system, which has been widely studied for potential thermoelectric applications. We find that the vibrational internal energy and entropy have a large quantitative impact on the mixing free energy and are likely to be particularly important in alloy systems with competing phases. The thermodynamically-averaged phonon dispersions and density of states curves show that alloying preserves the structure of the low-frequency bands of modes associated with the Sn sublattice but broadens the high-frequency chalcogen bands into a near-continuous spectrum at the 50/50 mixed composition. This results in a general reduction in the phonon mode group velocities and an increase in the number of energy-conserving scattering channels for heat-carrying low-frequency modes, which is consistent with the decrease in thermal conductivity observed in experimental measurements. Finally, we discuss some of the limitations of our first-principles modelling approach and propose methods to address these in future studies.
