Lu Erdong, Gressel Danica G, Fredrickson Daniel C
Department of Chemistry, University of Wisconsin-Madison, 1101 University Avenue, Madison, Wisconsin 53706, United States.
Inorg Chem. 2022 May 30;61(21):8298-8308. doi: 10.1021/acs.inorgchem.2c00752. Epub 2022 May 18.
Atomic packings based on icosahedra and tricapped trigonal prisms are prone to frustration─indeed, these polyhedra represent common configurations in metallic glasses. In this Article, we illustrate how these packing issues can serve as a driving force for the formation of modular intermetallic structures. Using Density Functional Theory-Chemical Pressure (DFT-CP) analysis, we relate the HfMoB-type structure of MoZrP to interatomic pressures experienced by the atoms in two parent structures: ZrP, whose structure is built from tricapped trigonal prisms, and ZrMo, a Laves phase containing icosahedra. CP analysis of ZrP reveals that it has particularly frustrated packing because of the entangling of its tricapped trigonal prisms. In the ternary phase, the frustration is significantly relieved as the units become isolated from each other. Further analysis points to the stabilizing effect of a face-sharing network of octahedra in MoZrP that largely separates the structure into Zr-Mo and Zr-P domains and serves as a buffering region for the relaxation of interatomic distances. These conclusions are generalized to the broader members of this structure type with the examination of the CP schemes for the isostructural MoZrB, AlCo, and MgPd phases. Finally, we screen the structural literature using the ToposPro software to identify three additional structure types that have similar intergrowth patterns: the DyCoCd, LaNiMg, and GdCoIn types. An analysis of the interatomic distances within the octahedral networks of these structures suggests that these networks commonly facilitate the reconciliation of packing incompatibilities in intermetallic chemistry.
基于二十面体和三帽三棱柱的原子堆积容易出现受挫情况——实际上，这些多面体是金属玻璃中的常见构型。在本文中，我们阐述了这些堆积问题如何能够成为形成模块化金属间化合物结构的驱动力。通过密度泛函理论-化学压力（DFT-CP）分析，我们将MoZrP的HfMoB型结构与两种母体结构中原子所经历的原子间压力联系起来：ZrP，其结构由三帽三棱柱构建而成；以及ZrMo，一种含有二十面体的Laves相。对ZrP的CP分析表明，由于其三帽三棱柱的缠结，它具有特别受挫的堆积。在三元相中，随着单元彼此分离，受挫情况显著缓解。进一步分析指出，MoZrP中八面体的面共享网络具有稳定作用，该网络在很大程度上将结构分隔为Zr-Mo和Zr-P域，并作为原子间距离弛豫的缓冲区域。通过研究同构的MoZrB、AlCo和MgPd相的CP方案，这些结论被推广到该结构类型的更广泛成员。最后，我们使用ToposPro软件筛选结构文献，以识别另外三种具有相似共生模式的结构类型：DyCoCd型、LaNiMg型和GdCoIn型。对这些结构的八面体网络内原子间距离的分析表明，这些网络通常有助于协调金属间化学中堆积不相容性。
