Nuclear magnetic resonance studies of disordered materials

材料科学的进步依赖于可靠的结构表征方法。许多种类的固体材料的无序性质使得很难获得对原子级结构的详细理解。核磁共振（NMR）理论和仪器的最新发展极大地扩展了这种技术可以研究的元素范围。事实上，NMR正迅速成为各种先进材料（包括玻璃、陶瓷、水泥、聚合物和多孔材料）结构表征的常规方法。这项建议的广泛目标是建立在新开发的核磁共振技术，旨在确定无序固体中的长程结构。这些努力的核心是利用两个原子核之间的相互作用作为距离的直接探针的方法。这种方法提供了更直接的信息，中程秩序比化学位移，这只是间接相关的相邻原子。没有其他实验技术能够像NMR那样直接映射原子连接性。这项工作将导致更详细的原子级组织和散装性能之间的相关性，从而打开大门，更全面地描述玻璃结构，并提供结构和功能之间的关键联系。 虽然普遍适用的技术寻求，最初的应用将针对不同复杂性的硼酸盐玻璃，和顺磁性有机金属材料，这两个代表了充分研究，但不完全理解的系统，在商业生产和新材料的开发具有深远的影响。除了技术开发和探索，这些研究将产生独特的和基本的洞察玻璃态的性质，提供结构信息的合理设计的高性能玻璃的应用范围从光学透镜到核废料固定。

Advancement in materials science depends on reliable methods of structural characterization. The disordered nature of many classes of solid materials makes it difficult to obtain a detailed understanding of the atomic-level structure. Recent developments in nuclear magnetic resonance (NMR) theory and instrumentation have greatly expanded the range of elements that can be studied by this technique. Indeed, NMR is rapidly becoming a routine approach for the structural characterization of a wide variety of advanced materials, including glasses, ceramics, cements, polymers and porous materials. The broad objective of this proposal is to build on newly developed techniques in NMR designed to identify longer-range structure in disordered solids. Central to these efforts are methods which exploit interactions between two nuclei as a direct probe of distance. This approach provides more direct information on medium-range order than chemical shifts, which are only indirectly related to neighbouring atoms. No other experimental technique is able to map atomic connectivities as directly as NMR. This work will lead to more detailed correlations between atomic-level organization and bulk properties, thus opening the door to a more comprehensive description of glass structure and providing a critical link between structure and function.  Although generally applicable techniques are sought, initial applications will target borate-based glasses of varying complexity, and paramagnetic organometallic materials, both of which represent well-studied but incompletely understood systems with far-reaching implications in commercial production and the development of new materials. In addition to technique development and exploration, these studies will yield unique and fundamental insight into the nature of the glassy state, providing structural information essential to the rational design of high-performance glasses for applications ranging from optical lenses to nuclear waste immobilization.