应变或阴离子交换能否使不稳定结构稳定？锂硫卤化物反钙钛矿（Li$_{3}$$BA$）及其阴离子交换变体（Li$_{3}$$AB$）的能量学、晶格动力学与应变可调带隙
Can Strain or Anion Interchange Make an Unstable Structure Stable? Energetics, Lattice Dynamics and Strain-Tunable Band Gaps of Lithium Chalcohalide Antiperovskites (Li$_{3}$$BA$) and their Anion Interchange Variants (Li$_{3}$$AB$)
AI总结：
本研究通过计算探究锂硫卤化物反钙钛矿的阴离子交换机制，明确了其结构稳定性规律，发现应变可调控部分化合物的动态稳定性与电子带隙，为相关材料设计提供基础。
AI中文摘要：
锂硫卤化物反钙钛矿是一种有前景的无毒铅卤化物钙钛矿替代品，有望作为锂离子电池的固体电解质。我们通过计算研究一种相对未被探索的阴离子交换机制，通过该机制可从母体立方反钙钛矿Li$_{3}$$BA$（$A$ = O、S、Se、Te、Po；$B$ = F、Cl、Br、I）获得立方Li$_{3}$$AB$衍生物。计算得到的相对能量图谱为阴离子位点选择性及其在结构稳定性中的作用提供了有用指南。能量稳定性结果表明，八面体内部的较小阴离子可稳定结构。晶格动力学计算证实，能量上最稳定的化合物Li$_{3}$F$A$（$A$ = Te、Po）和Li$_{3}$O$B$（$B$ = Cl、Br、I）是无虚声子模式的动态稳定立方相；然而，Li$_{3}$FS和Li$_{3}$FSe虽在能量上稳定，但在平衡态下动态不稳定，在三轴压应变下变为动态稳定。此外，我们报告了所有化合物的电子结构和态密度（DOS），其显示阴离子交换会导致带隙发生显著变化。锂硫卤化物家族的应变工程表明，百分之几的应变可在固体电池应用的电化学稳定窗口内调节电子带隙。本研究揭示了阴离子位点交换机制的基本特征，为锂硫卤化物反钙钛矿的理解和设计提供了基础。
英文摘要：
Lithium chalcohalide antiperovskites are a promising, non-toxic alternative to lead halide perovskites, with potential as solid electrolytes for Li-ion batteries. we computationally investigate a relatively unexplored anion-interchange mechanism by which cubic Li$_{3}$$AB$ derivatives are obtained from the parent cubic antiperovskite Li$_{3}$$BA$ ($A$ = O, S, Se, Te, Po; $B$ = F, Cl, Br, I). The calculated relative energy landscape provides a useful guide for anion-site selectivity and its role in structural stability. The energetic stability results reveal that the smaller anion inside the octahedron stabilizes the structures. The lattice-dynamic calculations confirm that Li$_{3}$F$A$ ($A$ = Te, Po) and Li$_{3}$O$B$ ($B$ = Cl, Br, I), which are the most energetically stable compounds, are dynamically stable cubic phases without imaginary phonon modes. However, Li$_{3}$FS and Li$_{3}$FSe, while energetically stable, are dynamically unstable at equilibrium and become dynamically stable under triaxial compressive strain. In addition, we report the electronic structure and density of states (DOS) of all compounds, which show a substantial change in band gap upon anion interchange. The strain engineering of the lithium chalcohalide family illustrates how a few percent of the strain can tune the electronic band gap within the electrochemical stability window for solid battery applications. This study unveils essential characteristics of the anion site-interchange mechanism and provides a foundation for the understanding and design of lithium chalcohalide antiperovskites.
