Borides are a family of materials with valuable properties for various applications. Their diverse structures and compositions, yet disparity in the constituent chemical elements for the known compounds, give elemental substitutions for prototypes great potential for material discovery. To explore uncharted material compositional space, we develop a workflow that joins high-throughput crystal structure prediction and automated diffraction pattern matching to discover new compounds with significant prediction and synthesis hurdles. Utilizing the workflow, we explore the empty Mg–Fe–B ternary compositional space, previously uncharted largely due to the immiscibility of Mg and Fe, as a paradigm. A total of 275 ternary boride prototypes are classified, using which we predict 23 (158) stable and metastable ternary phases within 50 (200) meV/atom above the convex hull. We identify Gd₂(FeB)₇-type Mg₂Fe₇B₇ and ZrCo₃B₂-type MgFe₃B₂ to match previously unsolved experimental powder X-ray diffraction (PXRD) patterns. The discovered Mg₂Fe₇B₇ and related channeled structures feature mismatched Mg and (FeB) sublattice periods, for which we conduct structural analyses with respect to the PXRD. They are predicted to exhibit exceptionally fast superionic transport of Mg and outstanding electrochemical performance, which serve as post-Li-ion battery candidate electrode materials. This result opens a new avenue for borides’ potential applications as electrode materials and fast ionic conductors. This work also portrays the map and landscape of ternary metal borides with similar chemical environments. With high efficiency, the prototype- and PXRD-assisted crystal structure prediction workflow opens a new avenue for exploring various material compositional spaces across the periodic table.

中文翻译：

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空材料组成空间的加速探索：Mg-Fe-B 三元金属硼化物


硼化物是一系列材料，具有适用于各种应用的宝贵特性。它们不同的结构和组成，但已知化合物的组成化学元素存在差异，这使得原型的元素替代具有巨大的材料发现潜力。为了探索未知的材料组成空间，我们开发了一种工作流程，将高通量晶体结构预测和自动衍射花样匹配相结合，以发现具有重大预测和合成障碍的新化合物。利用该工作流程，我们探索了空的 Mg-Fe-B 三元组成空间，以前主要是由于 Mg 和 Fe 的不混溶性而未被探索的。总共对 275 个三元硼化物原型进行了分类，我们使用它们预测了凸包上方 50 （200） meV/原子内的 23 （158） 个稳态和亚稳态三元相。我们鉴定了 Gd₂（FeB）₇ 型 Mg₂Fe₇B₇ 和 ZrCo₃B₂ 型 MgFe₃B₂，以匹配以前未解决的实验粉末 X 射线衍射 （PXRD） 图谱。发现的 Mg₂Fe₇B₇ 和相关的通道结构具有不匹配的 Mg 和 （FeB） 亚晶格周期，为此我们进行了关于 PXRD 的结构分析。预计它们将表现出极快的 Mg 超离子传输和出色的电化学性能，可作为后锂离子电池候选电极材料。这一结果为硼化物作为电极材料和快离子导体的潜在应用开辟了一条新途径。这项工作还描绘了具有相似化学环境的三元金属硼化物的图谱和景观。 原型和 PXRD 辅助晶体结构预测工作流程效率高，为探索元素周期表中的各种材料组成空间开辟了一条新途径。