GOALI: Atomistic Understanding of Non-Newtonian Flow and Related Phenomena in Chalcogenide Glass-Forming Liquids

非技术描述：硫系玻璃是一类重要的材料，在光子学、通信、光存储、光电子学和环境遥感等领域有着广泛的应用。然而，令人惊讶的是，关于衍生这些玻璃的母体熔体或液体的流动响应知之甚少，特别是当这些熔体在各种工业成形工艺（包括但不限于模塑、挤出、压花和纤维拉伸）期间经受大的变形速率时。该项目旨在首次使用各种尖端表征技术，在原子尺度上研究各种硫系玻璃和液体中变形速率与流动行为之间的机械关系。这种基本的理解可能使硫属玻璃适合低温聚合物形成过程的识别，从而使其广泛应用于具有强大的社会影响的变革性技术。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在各个领域之间转移知识，并为学生提供了智力发展的独特机会。这项研究在教育和推广方面的影响主要体现在三个方面：（1）学生的参与，（2）与工业界的积极合作，以及（3）向更广泛的科学界传播知识，特别是玻璃科学和技术。研究活动提供了为材料科学、化学和其他相关领域的学生提供的专题课程的核心;为妇女和少数民族学生的校园计划做出贡献;并从代表性不足和经济弱势群体中招募有前途的学生。过冷玻璃形成液体的非牛顿流动响应，当其通过机械变形被驱离平衡时，与其在各种加工技术中的可行性密切相关，并且在控制和优化相应的加工参数方面在工业中具有关键意义。这个GOALI项目汇集了来自加州大学戴维斯分校（Sen）和康宁的研究人员，他们具有互补的专业知识和共同的兴趣，Incorporated（Aitken），以解决Ge-As-Se和Ge-P-Se系统中硫属化物玻璃形成液体中非牛顿流动和相关现象的原子和宏观方面之间的联系，使用了强有力的通过高分辨率核磁共振（NMR）和拉曼光谱、差示扫描量热法和小角X射线散射进行流变测量和结构及动力学表征。预测原子模型的结构-变形-粘性流动的关系，建立在该项目中获得的结果的基础上，最终可能使硫系玻璃在低温连续成型过程中的广泛使用，从而使这些材料在现代技术中的广泛应用，从光子学和电信遥感可行。该项目的重点，即如何以及为什么，应变诱导的原子结构重排的动力学和热力学方面控制硫系玻璃形成液体中的剪切稀化行为和相关现象本身就是横切材料研究。该项目的广度，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，这可能会为他们未来的职业生涯开辟许多机会。该项目还通过合作科学家和参与学生之间的众多科学对话和互动丰富了研究生教育和培训经验。

NON-TECHNICAL DESCRIPTION: Chalcogenide glasses are an important class of materials that have found wide-ranging applications in the areas of photonics, telecommunication, optical memory storage, photovoltaics and environmental remote sensing. However, surprisingly, little is known regarding the flow response of the parent melts or liquids from which these glasses are derived, especially when these melts are subjected to large deformation rates during various industrial forming processes, including but not limited to molding, extrusion, embossing and fiber drawing. This project aims to investigate the mechanistic relationships between deformation rate and the flow behavior at the atomic scale in a variety of chalcogenide glasses and liquids for the first time, using a variety of cutting-edge characterization techniques. This fundamental understanding may enable the identification of chalcogenide glasses suitable for low-temperature polymer-forming processes, thereby permitting their widespread application in 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 the students with unique opportunities for intellectual growth. The impact of this research in education and outreach is in three major areas: (1) participation by students, (2) active collaboration with industry, and (3) dissemination of knowledge, especially of glass science and technology, to the broader scientific community. The research activities provide the core of special topics courses that are offered to students in materials science, chemistry and other related fields; contribute to campus programs for women and minority students; and to recruiting promising students from underrepresented and economically disadvantaged groups.TECHNICAL DETAILS: The non-Newtonian flow response of a supercooled glass-forming liquid, when it is driven out of equilibrium via mechanical deformation, is intimately linked to its viability for various processing techniques and is of key significance in industry in controlling and optimizing the corresponding processing parameters. This GOALI project brings together investigators with complementary expertise and common interests from the University of California at Davis (Sen) and from Corning, Incorporated (Aitken) to address the connections between the atomistic and the macroscopic aspects of the non-Newtonian flow and related phenomena in chalcogenide glass-forming liquids in the systems Ge-As-Se and Ge-P-Se using a powerful combination of state-of-the-art rheometric measurements and structural and dynamical characterization with high-resolution nuclear magnetic resonance (NMR) and Raman spectroscopy, differential scanning calorimetry and small-angle X-ray scattering. Predictive atomistic models of structure-deformation-viscous flow relationships, built on the basis of the results obtained in this project, may ultimately enable the use of chalcogenide glasses in a wide range of low-temperature continuous forming processes, thereby making these materials viable for widespread applications in modern technologies ranging from photonics and telecommunication to remote sensing. The focus of this project, namely how and why, the dynamic and thermodynamic aspects of strain-induced rearrangements of the atomic structure control the shear thinning behavior and related phenomena in chalcogenide glass-forming liquids is in itself crosscutting materials research. The breadth, flexibility and interdisciplinary nature of this project prepares students with powerful experimental skills and research experience in both academic and industrial settings that may open up many opportunities for their future careers. This project also enriches the graduate education and training experience through numerous scientific dialogues and interactions between the collaborating scientists and participating students.