Are higher order structures present in coordination-polyhedron structures of alloys, just like proteins?

在三维过渡金属的金属间化合物中发现的配位多面体结构的特征是存在络合配位（CN）多面体，如CN12多面体。因为这些多面体可以被视为结构单元，我们这项研究的动机是基于一个简单的问题，即在配位多面体结构中是否存在高阶结构，就像在蛋白质的情况下一样。为了得到这个问题的答案，在本研究中，我们试图在Fe-Mo合金体系的g和R结构中识别高阶结构，其中CN12、14、15和16多面体参与其中。具体来说，这两个结构中的高阶结构是根据bcc结构与它们之间的固体反应中出现的亚稳态的原子排列来确定的。透射电镜的实验数据清楚地表明，两种情况下都存在亚稳态：μ情况下存在无序原子柱态和原子柱块的短程有序态，R情况下存在无序原子柱态和由纳米级原子柱区域组成的域结构态。基于这些亚稳态的出现，我们试图确定μ和R结构中的高阶结构。因此，该结构中存在与CN12多面体相关的四个高阶结构，而R结构中存在两个结构，其中一个是CN16多面体作为主要结构。因此，这些高阶结构在μ和R结构中的存在表明，涉及3d过渡金属的金属间化合物中的配位多面体结构应该具有晶体结构的层次结构，这与金属体系中共价键的形成和发展直接相关。

Coordination-polyhedron structures found in intermetallic compounds involving 3d-transition metals are characterized by the presence of complex coordination(CN) polyhedra such as a CN12 polyhedron. Because these polyhedra can be regarded as structural units, our motivation of this study is based on a simple question whether higher order structures are present in coordination-polyhedron structures or not, just as in the case of proteins. To get an answer of this question, in this study, we have tried to identify higher order structures in the g. and R structures of the Fe-Mo alloy system, where CN12, 14, 15, and 16 polyhedra are involved Concretely higher order structures in these two structures were determined on the basis of atomic arrangements of metastable states appearing in solid-state reactions from the bcc structures to them. The present experimental data obtained by transmission electron microscopy clearly revealed that there existed metastable states for both cases : the disordered atomic-column state and the short-range ordered state of atomic-column blocks in the μ case, and another disordered atomic-column state and the domain-structure state consisting of nanometer-sized atomic-column regions in the R case. Based on the appearance of these metastable states, we tried to determine higher order structures in the μ and R structures. As a result, four higher order structures related to a CN12 polyhedron are present in the structure, while there are two structures in the R structure, one of which is a CN16 polyhedron as a primary one. Thus the presence of these higher order structures in the μ and R structures is indicative of the fact that coordination-polyhedron structures in intermetallic compounds involving 3d-transition metals should have the hierarchy of crystal structures, which is directly associated with the formation and development of covalent bonds in a metallic system.