Natural Abundance Si-29 and O-17 NMR Methods for Measuring Silicate Glass Structure

通过该奖项，化学部门的化学测量和成像项目支持俄亥俄州立大学的Philip Grandinetti教授开发高通量方法，利用核磁共振（NMR）光谱来表征玻璃的原子水平结构。眼镜已经被人类使用了几千年。人造玻璃的第一个历史记录出现在4500年前，玻璃在窗户上的使用始于2000多年前。今天，玻璃材料对技术和经济的影响是巨大而多样的。尽管它在技术上取得了成功，玻璃科学家和工程师仍然经常求助于爱迪生的方法，试图了解具有所需性能的玻璃的化学成分。这是因为对玻璃性质和玻璃化转变负责的物理和化学过程还不完全了解。Grandinetti教授和他的同事们的目标是通过优化整合两种核磁共振灵敏度增强策略，回声序列采集和顺磁弛豫增强，在这些样品上实现显着更高的通量核磁共振测量。在硅酸盐玻璃中进行这种高通量核磁共振测量将大大扩大可研究的化学成分范围，并消除制备同位素富集样品的负担和成本。这对研究玻璃的物理、化学和材料科学特性的科学家来说是有好处的。该项目还将为本科生、研究生和研究生提供跨学科的培训机会。PI与法国奥尔良CEMHTI-CNRS实验室的科学家们的持续合作将为学生提供跨越国界合作的机会。格兰迪内蒂教授和伯里亚学院之间的合作伙伴关系将为本科生提供夏季研究机会。在这个多层次的项目中，Grandinetti小组将把氧化玻璃的天然丰度Si-29和O-17的二维核磁共振测量带入常规测量领域。为了为该项目奠定基础，该小组将与Revolution NMR， LLC合作开发下一代动态角度旋转（DAS）探针。然后，该小组将在一套互补的2D NMR测量中使用DAS探针来探索一系列30种基本感兴趣的二元玻璃成分。在这些研究中，Grandinetti实验室将量化Si-O距离的分布、Si-O- si角度和形成网络的阴离子种类分布。他们还将把Si-29的化学位移各向异性和O-17的四极性耦合发展成网络改性剂阳离子聚类的定性和定量探测，并把Si-29的J耦合发展成Si-O-Si键上的Si-O-Si角和网络连通性的更可靠的探测。综上所述，这些研究旨在提供玻璃结构有序和无序的定性和定量细节的新水平。通过这些研究阐明的玻璃的结构细节也将有利于科学家寻求发展玻璃和熔体的热力学模型，并寻求改进用于玻璃分子动力学模拟的势。玻璃中改性剂阳离子聚类行为的细节将有助于科学家开发改进的离子传输、混合碱效应和化学强化玻璃微观结构的结构模型。

With this award, the Chemical Measurement and Imaging Program in the Division of Chemistry is supporting Professor Philip Grandinetti at Ohio State University to develop high-throughput methods for characterizing the atomic level structure of glasses using nuclear magnetic resonance (NMR) spectroscopy. Glasses have been used by mankind for millennia. The first historical record of man-made glasses appears as far back as 4500 years ago and the use of glass in windows began over 2000 years ago. Today the technological and economical impact of glassy materials is both immense and diverse. Despite its technological success, glass scientists and engineers still often resort to Edisonian approaches in attempts to understand the chemical compositions of glasses with desired properties. This is because the physical and chemical processes responsible for the properties of glasses and for glass transition are incompletely understood. Professor Grandinetti and his coworkers aim to achieve significantly higher throughput NMR measurements on such samples by optimally integrating two NMR sensitivity enhancement strategies, echo train acquisition and paramagnetic relaxation enhancement. Such high throughput NMR measurements in silicate glasses would considerably expand the range of chemical compositions that could be studied and eliminate the burden and cost of preparing isotopically enriched samples. This would have benefits for scientists studying the physics, chemistry, and materials science properties of glasses. The project will also provides interdisciplinary training opportunities to undergraduate, graduate and post-graduate students. The PI's ongoing partnership with scientists at the CEMHTI-CNRS lab in Orleans, France, will provide students the opportunity to collaborate across national boundaries. A partnership between Professor Grandinetti and Berea College will provide undergraduate students with summer research opportunities.In this multi-tiered project, the Grandinetti group will bring natural abundance Si-29 and O-17 2D NMR measurements of oxide glasses into the realm of routine measurements. In an effort to lay the groundwork for this project, the group will develop a next generation dynamic-angle spinning (DAS) probe in partnership with Revolution NMR, LLC. The group will then employ the DAS probe in a suite of complementary 2D NMR measurements to explore a series of thirty binary glass compositions of fundamental interest. In these studies, the Grandinetti lab will quantify the distributions of Si-O distances, Si-O-Si angles, and network-forming anionic species distributions. They will also develop the chemical shift anisotropy of Si-29 and the quadrupolar coupling of O-17 into a qualitative and quantitative probe of network modifier cation clustering, and develop the Si-29 J coupling across a Si-O-Si linkage into a more reliable probe of Si-O-Si angles and network connectivities. Taken together, these studies aim to provide a new level of qualitative and quantitative detail about structural order and disorder in glass. The structural details of glass to be elucidated through these studies would also benefit scientists seeking to develop thermodynamic models of glasses and melts, and seeking to refine potentials used in molecular dynamics simulations of glasses. Details on modifier cation clustering behavior in glasses will be useful to scientists developing improved structural models of ionic transport, of the mixed alkali effect, and of the microscopic structure of chemically strengthened glass.