Tremendous interest in solid-state devices has prompted the development of descriptors that can be utilized to develop better materials. Previous work mostly focused on the static structure, while discovery of the interplay between cation mobility and anion dynamics can also provide a powerful descriptor. Here, we demonstrate that [PS₄] rotation is remarkably facile in fast ion conductors β-Li₃PS₄ and its Si-substituted analog, Li_3.25Si_0.25P_0.75S₄, whereas it is absent in the non-conductive phase, γ-Li₃PS₄. Phonon calculations identify the increased entropy upon substitution of Si for P as the origin of the stabilization of the high-temperature phase (β-Li₃PS₄) at room temperature. Joint-time correlation analysis and power spectra reveal that [PS₄]/[SiS₄] anion rotational dynamics are coupled to and greatly enhance cation diffusion via the paddle-wheel effect by widening the bottleneck for Li⁺-ion transport. These findings shed light on the critical role of anion dynamics and can serve as a general guideline for the design of new conductors.

对固态器件的极大兴趣促使描述符的开发，可以将其用于开发更好的材料。先前的工作主要集中在静态结构上，而发现阳​​离子迁移率和阴离子动力学之间的相互作用也可以提供有力的描述。在这里，我们证明了[PS ₄ ]旋转是显着容易在快离子导体β-栗₃ PS ₄和其Si的取代的类似物，栗_3.25的Si _0.25 P _0.75小号₄，而它是在非导电相不存在， γ-锂₃ PS ₄。声子计算时的Si置换识别增加的熵对于P作为高温相（β-Li的稳定的原点₃ PS ₄）在室温下。联合时间相关分析和功率谱显示，[PS ₄ ] / [SiS ₄ ]阴离子旋转动力学通过桨轮效应耦合并极大地增强了阳离子扩散，从而扩大了Li ⁺离子传输的瓶颈。这些发现揭示了阴离子动力学的关键作用，并可作为设计新导体的一般指南。