CAREER: Investigation of Sol-gel-derived Hybrid Colloids for New Silica-Germania Glasses

该奖项全部或部分由《2021年美国救援计划法案》（公法117-2）资助。无机玻璃光学材料在许多改善日常生活的技术中发挥着关键作用。然而，传统的玻璃加工方法（即熔融淬火制造）从根本上限制了许多玻璃系统，并阻碍了新应用的研究发展。该研究项目由材料研究部的陶瓷和固态与材料化学项目支持，研究纳米级锗和锗硅颗粒（即胶体）及其作为构建块的用途，通过适合3D打印的非常规化学方法制造非晶体（即玻璃）材料。通过综合控制胶体组成和形态，探索了制备非晶体混合氧化物材料的新途径。这为利用该方法定制玻璃材料提供了新的设计规则，在玻璃科学和光学材料设计中具有广泛的意义。综合教育计划通过将现代材料科学和发现带入课堂并提供研究培训机会，提供无缝的学习社区。本科院校（PUI）的本科生和来自不同背景的当地高中生研究人员学习基本的研究技能，使用最先进的设备，并通过合作和研究相关的旅行接触到更广泛的研究人员群体。奥马哈公立学校招募了高中科学教师参加一个暑期项目。该项目将教师与当地教师导师联系起来，提供动手材料和化学研究经验，并开展课堂活动，让高中生参与研究概念，提高对STEM机会的认识。虽然熔融淬火方法代表了对无序非结晶固体的传统理解，但它限制了玻璃的设计。杂化胶体是制备具有传统工艺无法实现的成分和性能的非晶体材料的有吸引力的前体。通过合成调整胶体化学和形态，新型的溶胶-凝胶衍生玻璃可以使用尖端技术，如增材制造，自下而上地制造出来。在材料研究部陶瓷和固态和材料化学项目的支持下，首席研究员研究了驱动胶体生长和随后硅锗玻璃中玻璃网络形成的基础化学和材料科学。本研究计划的两个目的是探索(1)驱动非晶溶胶-凝胶锗胶体生长的化学机制和(2)杂化锗-硅胶体结构与形成玻璃性质之间的关系。潜在的中心假设是：(1)通过探测溶胶-凝胶水解，可以发现导致稳定的非晶锗胶体生长的合成化学机制，从而减轻随后的溶液中结晶动力学；(2)混合胶体设计可以用于形成新的二元组合的硅锗玻璃。利用核磁共振、FTIR和拉曼光谱、TGA/DSC和XRD对溶液和固态中的体/系综和微观尺度的时间和温度依赖分析进行化学和结构测定，电子和扫描探针显微镜用于阐明互补的物理信息，包括胶体大小和结构，以及从纳米到微观尺度的形态变化。系统地绘制控制锗胶体生长的动力学和热力学过程、杂化胶体形成二氧化硅-锗玻璃、二氧化硅-锗玻璃网络结构及其对玻璃光学性质的影响是本研究的潜在成果。此外，该项目还为高中和本科研究人员提供了现代材料研究的培训机会，他们将学习与玻璃和陶瓷材料的合成、制造和分析相关的方法和技术。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2).PART 1: NON-TECHNICAL SUMMARYInorganic glass optical materials play a critical role in many technologies that improve everyday life. Nevertheless, conventional glass processing methods (i.e., melt quench fabrication) fundamentally limit many glass systems and hinder research development of novel applications. This research project, supported by the Ceramics and the Solid State and Materials Chemistry programs in the Division of Materials Research, investigates nanoscale germania and germania-silica particles (i.e., colloids) and their use as building blocks for fabricating non-crystalline (i.e., glass) materials by unconventional chemical methods, amenable to 3D printing. The principal investigator explores new routes for preparing non-crystalline mixed oxide materials by synthetically controlling colloid composition and morphology. This provides new design rules for tailored fabrication of glass materials by the method, with broad implications in glass science and optical material design. An integrated educational plan offers a seamless learning community by bringing modern materials science and discovery into the classroom and providing research training opportunities. Undergraduate students at a primarily undergraduate institution (PUI) and local high school student researchers from diverse backgrounds learn essential research skills, use state-of-the-art equipment, and gain exposure to a broader community of researchers through collaboration and research-relevant travel. High school science teachers are recruited from Omaha public schools to participate in a summer program. The program connects teachers with local faculty mentors, provides hands-on materials and chemistry research experiences, and results in classroom activities to engage high school students in research concepts and increase awareness of STEM opportunities.PART 2: TECHNICAL SUMMARYWhile the melt-quench approach typifies the traditional understanding of disordered, non-crystalline solids, it limits glass design. Hybrid colloids are attractive precursors for preparing non-crystalline materials with compositions and properties unachievable by conventional processes. By synthetically tuning colloid chemistry and morphology, novel, sol-gel-derived glasses can be made from the bottom up using cutting-edge technologies, such as additive manufacturing. With support from the Ceramics and the Solid State and Materials Chemistry programs in the Division of Materials Research, the principal investigator studies the fundamental chemistry and materials science driving colloid growth and subsequent glass network formation in silica-germania glasses. The two aims of this research plan are to explore the (1) chemical mechanisms that drive amorphous sol-gel germania colloid growth and (2) the relationships between hybrid germania-silica colloid structure and resulting glass-forming properties. The underlying central hypotheses are that (1) by probing sol-gel hydrolysis, synthetic chemical mechanisms leading to stable amorphous germania colloid growth can be discovered, mitigating subsequent in-solution crystallization kinetics, and (2) that hybrid colloid design can be used to form silica-germania glasses in new binary compositions. Bulk/ensemble and microscale time- and temperature-dependent analyses in solution and solid-state utilizing NMR, FTIR, and Raman spectroscopies, TGA/DSC, and XRD enable chemical and structural determination, and electron and scanning probe microscopies are used to elucidate complementary physical information including colloid size and structure, as well as morphological changes from the nano- to micro-scales. Systematic mapping of the kinetic and thermodynamic processes that govern germania colloid growth, the formation of silica-germania glass from hybrid colloids, silica-germania glass network structure, and its impact on glass optical properties are potential outcomes of the research. Additionally, this project provides high school and undergraduate researchers with training opportunities in modern materials research, and they learn methods and techniques related to the synthesis, fabrication, and analysis of glass and ceramic materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.