Collaborative Research: Elucidating the Atomic Origin and Mechanism of Relaxation in Silicate Glasses

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NON-TECHNICAL DESCRIPTION: A glass is continually relaxing toward more stable states, which can result in undesirable aging effects in the high-tech glasses used as protective cover screens, flat panel display substrates, or the glass optical fibers that form the backbone of the Internet. Despite recent progress in describing glass relaxation at the macroscale, the atomic scale nature of glass relaxation remains poorly understood. To address this gap in knowledge, this project aims to elucidate the atomic origin and mechanisms of glass relaxation. Such fundamental insights would facilitate the rational, non-empirical design of novel glasses with improved stability against aging effects. By seamlessly integrating experiments, simulations, and theory, this collaborative project aims to train students to be well-versed in both experimental and modeling approaches relevant to materials science and engineering, with particular focus on industrial glasses. This project places a special focus on attracting, engaging, developing, and retaining female students in engineering careers to rectify the gender imbalance. In addition, this project seeks to expose students from local middle and high school in rural areas in Pennsylvania to the crucial role of materials in our society. TECHNICAL DETAILS: The objective of this research is to investigate the nature of glass relaxation at the atomic scale. This project aims to: (i) explore the linkages between distinct modes of relaxation under different regimes of temperature, (ii) decode the role of the atomic topology in controlling the propensity for relaxation, and (iii) reveal the structural mechanisms of glass relaxation. This research relies on a strategic combination of carefully-controlled experiments and atomistic simulations -wherein experimental and simulation activities mutually inform and feed into each other. This project is timely as it relies on a new accelerated simulation technique to access long-term relaxation effects through modeling, as well as powerful experimental techniques (e.g., X-ray photon correlation spectroscopy and vertical scanning interferometry) to investigate the nature of glass relaxation at low-temperature and train students in cutting-edge materials characterization and modeling research techniques. The synergy between experimental and computational approaches is key to assess the existence of relaxation deep within the glassy state, thereby questioning the conception of the very nature of the glassy state. This project also interrogates the concept of "intermediate phase" in silicate glasses, wherein relaxation is expected to be minimized. Overall, this project addresses broad, fundamental, yet unanswered questions in glass science, with important implications both at the fundamental and practical levels, as relaxation is one of the most critical problems at the intersection between glass physics and chemistry.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.