Link between Temperature-Dependent Elasticity and Viscosity of Glass-forming Liquids

非技术描述：尽管在玻璃工业的加工控制和了解地球内部的地质过程等领域具有巨大的重要性，但人们对玻璃形成液体在冷却到玻璃转变过程中粘度急剧上升的原因知之甚少。该项目通过协同结合现场实验和先进的计算方法来解决这一问题，通过与高温弹性的联系来提供对玻璃形成液体粘度的结构理解。了解粘性流动过程中涉及的原子过程对于开发化学成分截然不同的玻璃至关重要，因为个人电子产品、汽车、太阳能电池板、建筑和海底通信电缆等应用对玻璃的需求越来越大。综合教育努力将本科生水平的计算材料科学课程引入材料科学与工程课程。这门课程使学生意识到计算技术对科学和技术未来的重要性，并培训下一代劳动力，使他们能够利用计算工具进行材料设计和测试。通过激发年轻人的好奇心，向女性和代表性不足的少数民族灌输信心，不断努力激励和鼓励K-12学生追求科学和工程作为职业道路。技术细节：玻璃形成液体粘度的非阿累尼乌斯温度依赖性的结构起源仍然难以捉摸，是凝聚态物理学中一个重要但尚未解决的问题。因此，玻璃工业的加工控制在很大程度上是经验的，阻碍了对地球内部地球物理过程的理解。对粘性的结构认识较差，主要是由于缺乏对粘性流动过程中微观事件的现场分析。近年来，越来越清楚的是，玻璃形成液体的高温弹性和粘度具有很强的相关性；然而，由于实验的困难，很难获得过冷液体的温度相关弹性系数，特别是剪切弹性系数。这项研究通过使用原位布里渊光散射技术来测量范围广泛的过冷玻璃形成液体的高温弹性系数，跨越了坚硬和脆弱的玻璃形成物的整个宽度，从而弥补了这一差距。补充性计算研究的目的是阐明玻璃化转变温度以上的结构发展，从而导致玻璃形成液体的温度相关弹性和粘度之间的强相关性。在原子尺度上了解玻璃形成液体的粘性流动将有助于揭示玻璃转变，并有助于揭示岩浆产生、迁移和火成岩演化等岩浆过程。

NON-TECHNICAL DESCRIPTION: Despite the enormous importance in areas such as processing control in the glass industry, and understanding the geological processes in the Earth interior, very little is known why the viscosity of a glass-forming liquid rises dramatically as it is cooled toward the glass transition. This project addresses this issue by synergistically combining in situ experimental and advanced computational approaches to provide a structural understanding of viscosity of glass-forming liquids through the link to the high temperature elasticity. Understanding the atomic processes involved in the viscous flow process is of critical importance for developing glasses with vastly different chemistries that are increasingly demanded for applications such as personal electronics, automobiles, solar panels, buildings, and submarine communications cables. The integrated educational effort introduces an undergraduate level computational materials science course into the Materials Science and Engineering curriculum. This course is making students aware of the importance of computational techniques to the future of science and technology, and is training the next generation of workforce with the capabilities to utilize computational tools for materials design and testing. Continuous efforts are being made to inspire and encourage K-12 students to pursue science and engineering as a career path, by igniting curiosity in young minds and instilling confidence in women and underrepresented minorities.TECHNICAL DETAILS: The structural origin of the non-Arrhenius temperature dependence of viscosity of glass-forming liquids remains elusive and constitutes an important, but unsolved problem in condensed matter physics. Consequently, processing control in glass industry is largely empirical, and understanding the geophysical processes in the interior of the Earth is hindered. The poor structural understanding of viscosity is mainly due to the lack of in situ analysis of the microscopic events during the viscous flow process. It has become increasingly clear in recent years that high temperature elasticity and viscosity of glass-forming liquids are strongly correlated; however, temperature-dependent elastic moduli, especially the shear modulus, of supercooled liquids are scarcely available due to the experimental difficulties. This research bridges this gap by using in situ Brillouin light scattering technique to measure high temperature elastic moduli of a wide range of supercooled glass-forming liquids spanning the full breadth of strong and fragile glass-formers. Complementary computational study aims to illustrate the structural developments above the glass transition temperature that gives rise to the strong correlation between the temperature-dependent elasticity and viscosity of glass-forming liquids. Understanding the viscous flow of glass-forming liquids at the atomic scale will shed light on the glass transition, and help reveal magmatic processes such as magma generation and transport and evolution of igneous rocks.