A medium-range structure motif linking amorphous and crystalline states
A medium-range structure motif linking amorphous and crystalline states
复制标题
连接非晶态和晶态的中程结构基序
DOI：
10.1038/s41563-021-01011-5
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发表时间：
2021-05-20
期刊：
影响因子：
41.2
通讯作者：
Wang, Xun-Li
中科院分区：
文献类型：
--
作者：
Lan, Si;Zhu, Li;Wang, Xun-Li
非晶材料没有长程有序，但在短程（2-5埃）、中程（5-20埃）甚至更长的长度尺度（1-5）都有有序结构。虽然规则（6，7）和半规则多面体（8-10）经常被发现作为非晶材料中的短程有序，但中程有序的性质仍然难以捉摸（11-14）。因此，很难确定在无定形材料和其结晶对应物之间是否存在中等范围或更长长度尺度的任何结构连接。此外，无定形材料通常结晶成具有不同组成的相（15），具有非常不同的基础结构构建块，进一步使问题复杂化。在这里，我们捕获的Pd-Ni-P非晶合金中的中间结晶立方相，并揭示了中程秩序的结构，一个六元三帽三角棱柱簇（6 M-TTP）的长度尺度为12.5埃。我们发现，6 M-TTP可以周期性地堆积到几十纳米，形成立方相。我们的实验观察提供了证据的Pd-Ni-P合金中的非晶相和晶相之间的结构联系在中程长度尺度，并建议，这是区分晶相和非晶相的6 M-TTP集群的连接。这些发现将揭示非晶材料的结构，在扩展的长度尺度超出了短程秩序。
Amorphous materials have no long-range order, but there are ordered structures at short range (2-5 angstrom), medium range (5-20 angstrom) and even longer length scales(1-5). While regular(6,7) and semiregular polyhedra(8-10) are often found as short-range ordering in amorphous materials, the nature of medium-range order has remained elusive(11-14). Consequently, it is difficult to determine whether there exists any structural link at medium range or longer length scales between the amorphous material and its crystalline counterparts. Moreover, an amorphous material often crystallizes into a phase of different composition(15), with very different underlying structural building blocks, further compounding the issue. Here, we capture an intermediate crystalline cubic phase in a Pd-Ni-P amorphous alloy and reveal the structure of the medium-range order, a six-membered tricapped trigonal prism cluster (6M-TTP) with a length scale of 12.5 angstrom. We find that the 6M-TTP can pack periodically to several tens of nanometres to form the cube phase. Our experimental observations provide evidence of a structural link between the amorphous and crystalline phases in a Pd-Ni-P alloy at the medium-range length scale and suggest that it is the connectivity of the 6M-TTP clusters that distinguishes the crystalline and amorphous phases. These findings will shed light on the structure of amorphous materials at extended length scales beyond that of short-range order.