Bringing order to large-scale disordered complex metal alloys: Gd2Au15−xSbx and BaAuxGa12−x†,CrystEngComm

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Bringing order to large-scale disordered complex metal alloys: Gd2Au15−xSbx and BaAuxGa12−x†
CrystEngComm ( IF 2.6 ) Pub Date : 2017-11-28 00:00:00 , DOI: 10.1039/c7ce01865g
Chris Celania _{1,

2,

3,

4,

5} , Volodymyr Smetana _{1,

2,

3,

4,

5} , Anja-Verena Mudring _{1,

2,

3,

4,

5}

Affiliation

Herein, two new tetragonal complex metallic alloys (CMAs) have been discovered and characterized: Gd₂Au_15−xSb_x [x = 3.0–3.6; I4/mmm; tI34; a = 7.31–7.33 Å, c = 14.05–14.11 Å; V = 750.2–758 Å³] and BaAu_xGa_12−x [x = 3.6–4.4; I4/mcm; tI104; a = 8.77–8.78 Å, c = 26.06–26.13 Å; V = 2006.5–2010 Å³]. Both structures incorporate significant anionic site mixing and intricate positional disorder. Gd₂Au_15−xSb_x represents a new structure type with in-plane disordered, but strongly geometrically restricted rhombi motifs. These rhombi connect through additional mixed Au/Sb positions along the c axis; this forms octahedral fragments. BaAu_xGa_12−x finds its place within the extended NaZn₁₃ structural family, displaying cation-centered snub cubes with empty, distorted icosahedra (allowing for the 1 : 12 ratio) and tetrahedral stars. The split positions order due to geometric constraints to form nets of crown cyclooctane-like sheets in two different conformations. Adjacent planes adopt opposite conformations, forming layers of snub cubes with order between layers, but disorder across the greater structure. The substantial degree of mixing in both structures, together with mutual orientation of the ordered and disordered positions, suggests significant importance of heteroatomic bonding, typically found in polar intermetallic compounds.

中文翻译：

整理大型无序复杂金属合金：Gd ₂ Au _{15− x} Sb _x和BaAu _x Ga _{12− x} †

在这里，已经发现并表征了两种新型的四方络合物金属合金：Gd ₂ Au _{15− x} Sb _x [ x = 3.0–3.6; 我4 /毫米; tI 34；a = 7.31–7.33Å，c = 14.05–14.11Å；V = 750.2-758埃³ ]和BaAu _X嘎_{-12- X} [ X = 3.6-4.4; 我4 /平方厘米; tI 104；a = 8.77–8.78Å，c = 26.06–26.13Å；V = 2006.5–2010Å³ ]。两种结构均包含明显的阴离子位点混合和错综复杂的位置紊乱。Gd₂ Au_{15− x} Sb_x代表一种新的结构类型，具有面内无序但几何形状受严格限制的菱形图案。这些菱形沿c轴通过其他混合的Au / Sb位置连接；形成八面体碎片。BaAu_x Ga_{12− x}在扩展的NaZn_13中找到其位置结构族，显示带有以扭曲的空二十面体（允许1:12的比例）和四面体星形的以阳离子为中心的缓冲立方体。分离位置由于几何约束而排序，以形成两种不同构型的冠状环辛烷样片状网。相邻平面采用相反的构象，形成层间有序的缓冲立方体层，但在更大的结构上无序。两种结构中的大量混合以及有序和无序位置的相互取向表明杂原子键合的重要性，通常在极性金属间化合物中发现。

更新日期：2017-11-28

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