Department of Chemistry and Food Chemistry , TU Dresden , Dresden , Germany.
Max Planck Institute for Chemical Physics of Solids , Dresden , Germany.
Inorg Chem. 2018 May 7;57(9):5507-5513. doi: 10.1021/acs.inorgchem.8b00464. Epub 2018 Apr 9.
The metal-rich compound BiRhI was discovered in a thorough investigation of the Bi-Rh-I phase system. The monoclinic crystal structure was solved via single-crystal X-ray diffraction. It consists of infinite strands of face-sharing distorted square antiprisms [RhBi], which are separated by iodide ions. BiRhI is the high-temperature phase related to the weak three-dimensional topological insulator BiRhI (BiRhI) and forms peritectically at 441 °C, where BiRhI decomposes. The structure of BiRhI is compared with BiRuI and BiRhI, all three sharing a similar intermetallic strand-like structure, although their overall count of valence electrons differs. A chemical bonding analysis of BiRhI via the electron localizability indicator reveals a complex bonding pattern with covalent bonds between rhodium and bismuth, as well as between bismuth atoms and suggests a possible explanation for the formation of this structure type. Band structure calculations indicate a narrow band gap of 157 meV, which was verified by resistivity measurements on a pressed powder pellet and on single crystals. In a broader context, this strandlike structure type accounts for unusual physical phenomena, such as the transition into a charge-density-wave phase.
富金属化合物 BiRhI 是在对 Bi-Rh-I 相体系进行全面研究时发现的。通过单晶 X 射线衍射法解决了其单斜晶体结构。它由无限长的面共享扭曲的正方形反棱柱 [RhBi] 组成，这些反棱柱之间由碘离子隔开。BiRhI 是与弱三维拓扑绝缘体 BiRhI (BiRhI) 相关的高温相，并在 441°C 形成包晶，此时 BiRhI 会分解。BiRhI 的结构与 BiRuI 和 BiRhI 进行了比较，它们都具有相似的金属间链状结构，尽管它们的总价电子数不同。通过电子局域化指标对 BiRhI 进行的化学键分析揭示了一种复杂的化学键模式，其中铑和铋之间以及铋原子之间存在共价键，并为这种结构类型的形成提供了可能的解释。能带结构计算表明带隙为 157meV，这一结果通过对压制粉末和单晶进行电阻率测量得到了验证。从更广泛的角度来看，这种链状结构类型解释了一些异常的物理现象，例如进入电荷密度波相的转变。
