GOALI: Structural and Topological Controls on Viscoelasticity and Relaxation Processes in Chalcogenide Glass-Forming Liquids

非技术描述：硫属化物（非氧化物合金或含硫、硒或碲的化合物） 玻璃是一类重要的材料，在光子学、电信、存储器存储、光电子学和环境遥感领域具有广泛的应用。基本了解与温度和成分相关的母体流动行为相关的动力学过程 这些玻璃的熔体或液体在其工业生产的所有阶段都是至关重要的。这个计画的目的是提供独特的知识，关于硫属化物液体的动力学行为的“微观（原子）”和“宏观”方面之间的联系 这是第一次使用尖端的表征技术。这些知识是优化这些材料的化学和加工参数以实现改进和新颖功能的关键，从而使其能够应用于具有强大社会影响的现代变革技术。科学上，这项工作影响了材料科学，物理化学和固态物理学。这项工作的跨学科性质转移领域之间的知识，并为学生提供了智力发展的独特机会。毕业生通常会在学术界以及玻璃和半导体行业找到工作。该项目在教育和推广方面的影响主要体现在三个方面：（1）学生参与研究，（2）与工业界积极紧密合作（康宁公司）。在那里，学生得到指导，并获得对行业优先事项的理解，以及（3）向更广泛的科学界传播玻璃科学和技术知识。这些研究成果被嵌入到为材料科学、化学和其他相关领域的学生提供的专题课程中;它们有助于为女性和少数民族学生提供校园课程，并有助于从代表性不足和经济弱势群体中招募有前途的学生。研究了过冷玻璃形成液体中的动力学过程，包括其粘性流动、结构弛豫和玻璃转变附近的退火，控制所得玻璃和玻璃陶瓷的加工和技术应用的所有方面。然而，令人惊讶的是，很少有人知道的原子结构之间的连接，其连接性和拓扑结构和温度依赖性的硫属化物液体的流动行为。因此，从历史上看，用于设计新的硫属化物玻璃的许多方法在很大程度上是经验性的，并且缺乏其组成优化和加工方法所需的预测能力。这个GOALI项目汇集了来自加州大学戴维斯分校（Sen，PI）和康宁公司（Corning Incorporated）的具有互补专业知识和共同兴趣的研究人员（Aitken，co-PI），研究了结构连接性和拓扑结构对过冷硫属化物中粘弹性行为和弛豫过程的温度依赖性的影响使用最先进的振荡平行板流变仪、动态核磁共振（NMR）光谱和差示扫描量热法测量的独特组合，对（硫化物和硒化物）液体进行了分析。预测原子模型的结构-松弛-粘性流的关系，建立在该项目中获得的结果的基础上，可以使这些复杂材料的化学，合成和加工参数的优化，为广泛的现代技术应用。该项目的重点，即如何以及为什么，原子结构的各个方面控制硫系玻璃形成液体中的温度依赖性粘弹性，弛豫行为和相关现象本身就是交叉材料研究。该项目的广泛性，灵活性和跨学科性质为学生提供了强大的实验技能和学术和工业环境中的研究经验，这些经验可能会为未来的职业机会打开大门。它还通过众多的科学互动丰富了研究生教育和培训经验 该奖项反映了NSF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。

NON-TECHNICAL DESCRIPTION: Chalcogenide (non-oxide alloys or compounds containing sulfur, selenium or tellurium) glasses are an important class of materials with wide-ranging applications in the areas of photonics, telecommunication, memory storage, photovoltaics and environmental remote sensing. A fundamental understanding of the dynamical processes associated with the temperature- and composition- dependent flow behavior of the parent melts or liquids from which these glasses are derived, is crucial in all stages of their industrial production. This project aims to provide unique knowledge regarding the connection between the "microscopic (atomistic)" and the "macroscopic" aspects of the dynamical behavior of chalcogenide liquids for the very first time, using a combination of cutting-edge characterization techniques. This knowledge is key to the optimization of the chemistry and processing parameters of these materials for improved and novel functionality, thereby enabling their application in modern transformative technologies with strong societal impact. Scientifically, this work impacts materials science, physical chemistry, and solid-state physics. The interdisciplinary nature of this work transfers knowledge between fields and provides students with unique opportunities for intellectual growth. Graduates typically find employment in both academia and in glass and semiconductor industry. The impact of this project in terms of education and outreach is in three major areas: (1) participation by students in research, (2) active and tight-knit collaboration with industry (Corning, Inc.) where students are mentored and gain understanding of industry priorities, and (3) dissemination of knowledge about glass science and technology to the broader scientific community. The research findings are embedded into special topics courses that are offered to students in materials science, chemistry, and other related fields; and they contribute to campus programs for women and minority students and to the recruitment of promising students from underrepresented and economically-disadvantaged groups.TECHNICAL DETAILS: The dynamical processes in supercooled glass-forming liquids, associated with their viscous flow, structural relaxation and annealing near the glass transition, control all aspects of the processing and technological utility of the resulting glasses and glass-ceramics. However, surprisingly enough, little is known regarding the connection between the atomic structure, its connectivity and topology and the temperature dependence of the flow behavior of chalcogenide liquids. Historically, therefore, much of the approach for designing new chalcogenide glasses has been largely empirical and lacked the predictive power needed for their compositional optimization and processing methods. This GOALI project brings together investigators with complementary expertise and common interests from UC Davis (Sen, PI) and from Corning Incorporated (Aitken, co-PI), to investigate the effects of structural connectivity and topology on the temperature dependence of the viscoelastic behavior and relaxation processes in supercooled chalcogenide (sulfide and selenide) liquids, using a unique combination of state-of-the-art oscillatory parallel-plate rheometry, dynamical nuclear magnetic resonance (NMR) spectroscopy and differential scanning calorimetry measurements. Predictive atomistic models of structure-relaxation-viscous flow relationships, built on the basis of the results obtained in this project, may enable the optimization of the chemistry, synthesis, and processing parameters of these complex materials for a wide range of modern technological applications. The focus of this project, namely how and why, the various aspects of the atomic structure control the temperature dependent viscoelasticity, relaxational behavior and related phenomena in chalcogenide glass-forming liquids is in itself crosscutting materials research. The breadth, flexibility and interdisciplinary nature of this project prepare the students with powerful experimental skills and research experience in both academic and industrial settings that may open many future career opportunities. It also enriches the graduate education and training experience through numerous scientific interactions between the collaborating scientists and participating students.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.