Structure and Dynamics in Boron- and Fluoride-Containing Oxide Glasses and Liquids: High-Resolution and High-Temperature Nuclear Magnetic Resonance Studies

含硼和氟化物氧化物玻璃和液体的结构和动力学：高分辨率和高温核磁共振研究

• 批准号: 0100986
• 负责人: Jonathan Stebbins
• 金额: $ 34.58万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-09-01 至 2004-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0100986&HistoricalAwards=false
• 关键词: Structure; Dynamics; Boron; Fluoride; Containing

Solid-state Nuclear Magnetic Resonance will continue to be used to study the structure and dynamics of two classes of oxide glasses that have major technological applications, namely boron-containing glasses and oxyfluoride glasses. We will acquire quantitative microscopic information on borate, borosilicate, aluminoborate, and oxyfluoride glasses at ambient and high temperature, including systems containing diamagnetic analogs of rare earth elements, and will interpret and model existing thermodynamic and transport property data in light of these new findings. We will continue to emphasize temperature effects, with both in situ, high temperature measurements and studies of glasses prepared with varying thermal histories, which record the liquid structure at a range in temperature. We will use a wide range of NMR methods (on nuclides including 11B, 170, 19F, 23Na, 25Mg, 27AI, and 29Si), supplemented where needed by other methods such as Raman and infrared spectroscopy. Instruments available at Stanford include spectrometers with 9.4, 14.1, and 18.8 Tesla magnets (the latter the highest field strength currently commercially obtainable), with sophisticated high-speed magic-angle spinning, double and triple resonance, and high temperature NMR probes. A newly-developed rapid quench apparatus that will allow thermal history studies of small, valuable, isotopically enriched samples to be done. Applications of new NMR methods, in particular multiple quantum NMR, will continue to play a major role, as will the empirical calibration of NMR observables with structure of known crystalline model compounds. Models linking the microscopic and macroscopic will continue to be developed and tested and a new program of ab initio energy calculations, based on density functional theory, will be used to complement experimental results. Boron-containing oxide glasses are widely used in corrosion- and temperature-resistant containers, pipes and tanks, in "fiberglass" composites, in optical components, computer display screens, etc. Borosilicate glasses are also likely to play a major role in sequestering radioactive wastes. The ease with which the boron cation changes its local structural environment as a function of composition and temperature not only contributes to the useful properties of these materials but makes them a unique and intriguing subject scientifically. In oxyfluoride glasses, some oxygen ion is replaced by fluoride, again giving the resulting glasses and glass-forming liquids unique properties, and again posing a wealth of fundamental scientific issues concerning the structure and dynamics of mixed-anion systems. Fluoride has long been used to lower viscosities and melting temperatures of glass-forming liquids without clear understanding of mechanism; in recent high-tech innovations, oxyfluoride glasses are becoming interesting as hosts for rare earth elements in laser and optical amplifier materials. In all of these materials, the ability to tailor their properties to specific technological applications requires quantitative knowledge of their structure at the atomic scale, and the dynamics with which that structure changes in the precursor high-temperature glass melts. Nuclear magnetic resonance "sees" the local atomic structure and dynamics, often in a highly quantitative way, around selected isotopes of many of the most important constituents of oxide glasses. NMR has thus proven to be a near-ideal tool for studying such non-crystalline materials, and has increased our understanding of them enormously. This project should have direct interest to the Materials Science community, but its results will also have real significance to physicists working on the dynamics of glass- forming and other complex liquids, to physical chemists developing new applications of solid-state NMR, and to geochemists trying to model and predict the behavior of silicate magmas in nature. In the past, and hopefully in the future, the discipline-crossing nature of this type of study has broadened the perspectives of students in our group, with backgrounds in spectroscopy or geochemistry, into the fascinating and technologically important world of glass and ceramic sciences.

固态核磁共振将继续用于研究具有主要技术应用的两类氧化物玻璃的结构和动力学，即含硼玻璃和氟氧化物玻璃。我们将获得定量的微观信息硼酸盐，硼硅酸盐，铝硼酸盐，氟氧化物玻璃在环境温度和高温下，包括含有稀土元素的抗磁性类似物的系统，并将解释和模拟现有的热力学和传输特性数据，根据这些新的发现。我们将继续强调温度的影响，在现场，高温测量和玻璃制备与不同的热历史，记录在一定温度范围内的液体结构的研究。我们将使用广泛的NMR方法（包括11 B，170，19 F，23 Na，25 Mg，27 Al和29 Si等核素），并在需要时辅以其他方法，如拉曼和红外光谱。斯坦福大学提供的仪器包括具有9.4、14.1和18.8特斯拉磁体的光谱仪（后者是目前商业上可获得的最高场强），具有复杂的高速魔角旋转、双重和三重共振以及高温NMR探针。一种新开发的快速淬火装置，将允许进行小的、有价值的、同位素富集的样品的热历史研究。新的核磁共振方法的应用，特别是多量子核磁共振，将继续发挥重要作用，将与已知的结晶模型化合物的结构的核磁共振观测的经验校准。将继续开发和测试连接微观和宏观的模型，并将使用基于密度泛函理论的从头算能量计算的新程序来补充实验结果。含硼氧化物玻璃广泛用于耐腐蚀和耐高温的容器、管道和储罐、“玻璃纤维”复合材料、光学元件、计算机显示屏等。硼阳离子改变其局部结构环境的容易程度作为组成和温度的函数，不仅有助于这些材料的有用特性，而且使它们成为科学上独特而有趣的主题。在氟氧化物玻璃中，一些氧离子被氟化物取代，再次赋予所得玻璃和玻璃形成液体独特的性质，并再次提出了关于混合阴离子系统的结构和动力学的大量基础科学问题。长期以来，氟化物一直被用来降低玻璃形成液体的粘度和熔化温度，但对其机理没有明确的了解;在最近的高科技创新中，氟氧化物玻璃作为激光和光学放大器材料中稀土元素的基质变得越来越有趣。 在所有这些材料中，将其特性定制为特定技术应用的能力需要在原子尺度上对其结构的定量知识，以及在前体高温玻璃熔体中结构变化的动力学。 核磁共振“看到”了氧化物玻璃中许多最重要成分的选定同位素周围的局部原子结构和动力学，通常是以高度定量的方式。因此，NMR已被证明是研究此类非晶体材料的理想工具，并极大地增加了我们对它们的理解。这个项目应该有直接的兴趣，材料科学界，但其结果也将有真实的意义的物理学家工作的动力学玻璃形成和其他复杂的液体，物理化学家开发新的应用固态核磁共振，地球化学家试图模拟和预测的行为硅酸盐岩浆在自然界中。在过去，希望在未来，这种类型的研究的学科交叉性质已经扩大了学生在我们组的观点，在光谱学或地球化学的背景，进入玻璃和陶瓷科学的迷人和技术上重要的世界。