RUI: examining the discrepancy between stress and enthalpy relaxation in borosilicate glasses: an experimental and numerical study

This National Science Foundation (NSF) Mathematical and Physical Sciences grant, under CFDA 47.049, provides $480,000 to Alfred University to conduct a comprehensive study on stress and enthalpy relaxation in borosilicate glasses. The project aims to: 1) develop a database of stress and enthalpy relaxation data for high-homogeneity borosilicate glasses, 2) compare existing relaxation models, and 3) elucidate the atomic mechanisms behind glass relaxation through experiments and simulations. The research team, which includes undergraduate and graduate students, will leverage Alfred University's expertise in high-temperature measurements and atomistic simulations to advance the fundamental understanding of glass relaxation, a critical phenomenon for high-tech applications like optical fibers and solid-state electrolytes. The award, which runs from August 2024 to July 2028, provides research opportunities for students and supports Alfred University's efforts to train the next generation of glass and ceramics scientists.

Abstract

Non-technical summary. Glass relaxation is the process of glass (an unstable material) trying to reach stability. This process has been investigated for a long time but remains largely a mystery and a challenge, as advanced glasses that make up the backbone of our digital infrastructure are strongly influenced by relaxation. To uncover the origins of glass relaxation, a joint experimental and simulation approach is pursued. The experiments will leverage alfred university?s unique expertise in high-temperature measurements to systematically evaluate the rate of relaxation. The findings made via experiments will be reinforced by atomistic simulations to elucidate the structural origins. A key part of this work is to focus on developing undergraduate students who will work in a technical capacity on the project. Recently, the PI created the undergraduate summer research program at alfred university and this work will help expand the program by providing additional research positions for more students. Undergraduate students in the program also participate in weekly professional development seminars, take tours of large-scale manufacturing sites with our industry partnerships, and present their research at the end-of summer poster competition. Ultimately, this work will create new knowledge about glass relaxation and propel the field of technical glass design while training undergraduate and graduate students for careers in ceramics and glass science. Technical summary. Glass relaxation is challenging to model and understand due to a wide range of chemistries and thermal hysteresis. The volume contraction associated with relaxation occurs with the same functional form in commercial silicate glasses as in small-scale chalcogenide samples. In all glasses, however, relaxation becomes a limiting factor on density fluctuations and volume which in turn influence the mechanical strength, the optical transparency, and the density. These properties are critical for high-tech applications such as optical fiber, display materials, and emerging solid-state electrolytes. The criticality and universality of relaxation have motivated the development of a myriad of theories, with very few quantitative comparisons offered in the literature. Recently, understanding the physics of relaxation has become more complicated, since relaxation has been shown to occur at different rates for the evolution of enthalpy versus the mitigation of stress. This project, supported by the ceramics program in the division of materials research at NSF, addresses three major objectives in furthering the understanding of relaxation in glasses. These include: 1) development of a comprehensive self-consistent relaxation database for both stress and enthalpy relaxation in high-homogeneity borosilicate glasses, as well as the structures thereof; 2) use this database to compare all quantitative models for relaxation proposed in the literature and to quantify the precision and differences between said models; 3) use the collected data in parallel with classical simulations, to elucidate the atomic mechanisms associated with relaxation. The work will be carried out by a team of undergraduate and graduate students, with undergraduates participating in alfred university?s summer research program. Students will gain first-hand experience with spectroscopy equipment, material fabrication, and data analysis. In the PI?s group, undergraduate students work on individual research projects with the goal of publishing their own first-authored research articles. Additionally, the PI organizes the annual alfred university end-of-summer poster contest so that students can interact directly with industry professionals. The cumulative effort of these goals will result in undergraduate and graduate students gaining first-hand experience in developing insights into glass relaxation. 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.- subawards are not planned for this award.