Martin James D, Goettler Stephen J, Fossé Nathalie, Iton Lennox
Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695-8204, USA.
Nature. 2002 Sep 26;419(6905):381-4. doi: 10.1038/nature01022.
Amorphous materials are commonly understood to consist of random organizations of molecular-type structural units. However, it has long been known that structural organizations intermediate between discrete chemical bonds and periodic crystalline lattices are present even in liquids. Numerous models--including random networks and crystalline-type structures with networks composed of clusters and voids--have been proposed to account for this intermediate-range order. Nevertheless, understanding and controlling structural features that determine intermediate-range order in amorphous materials remain fundamental, yet presently unresolved, issues. The most characteristic signature of such order is the first peak in the total structure factor, referred to as the first sharp diffraction peak or 'low Q' structure. These features correspond to large real-space distances in the materials, and understanding their origin is key to unravelling details of intermediate-range order. Here we employ principles of crystal engineering to design specific patterns of intermediate-range order within amorphous zinc-chloride networks. Using crystalline models, we demonstrate the impact of various structural features on diffraction at low values of Q. Such amorphous network engineering is anticipated to provide the structure/property relationships necessary to tailor specific optical, electronic and mechanical properties.
非晶态材料通常被理解为由分子型结构单元的随机组织构成。然而，长期以来人们都知道，即使在液体中也存在介于离散化学键和周期性晶格之间的结构组织。为了解释这种中程有序现象，人们提出了许多模型，包括随机网络以及由团簇和空隙组成网络的晶体型结构。尽管如此，理解和控制决定非晶态材料中程有序的结构特征仍然是基本问题，但目前尚未得到解决。这种有序的最典型特征是总结构因子中的第一个峰，称为第一尖锐衍射峰或“低Q”结构。这些特征对应于材料中较大的实空间距离，理解它们的起源是解开中程有序细节的关键。在这里，我们运用晶体工程原理在非晶态氯化锌网络中设计特定的中程有序模式。利用晶体模型，我们展示了各种结构特征对低Q值衍射的影响。这种非晶网络工程有望提供定制特定光学、电子和机械性能所需的结构/性能关系。
