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.
