Kenji Shinozaki received a Ph.D. in Engineering at Nagaoka University of Technology in 2013. He was an Assistant Professor at Nagaoka University of Technology from 2013 to 2016. Since 2016, he has worked at National Institute of Advanced Science and Technology (AIST) as a senior researcher. He is also associate professor as principal investigator in Osaka University since 2022. His current research interest includes development of new functional glasses and glass-ceramics for optical and mechanical properties.

Glass Structure Design for Ultrafast Nanocrystallization: Toward Oxyfluoride Glass-Ceramics Devices

In this talk, a new material design is proposed that eliminates the need for heat-treatment processes. The impact of short- to medium-range structures on the crystallization of glasses was investigated to enable nanocrystallization in quenching process via ultrafast nucleation. Herein, short- to medium-range structures of BaF2–ZnO–B2O3 glasses were investigated using 11B- and 19F-magic-angle spinning nuclear magnetic resonance (MAS-NMR), machine learning molecular dynamics (MD) simulation, and high-energy synchrotron X-ray diffraction. Obvious selectivity in the binding was observed: F- preferred Ba2+ and O2- preferred B3+, whereas Zn2+ was bound to both anions. The binding selectivity caused fluoride-rich domain, and the fluoride-related structure factors and bond distance were very similar to the peak positions of precipitated crystals. Our structural investigation suggest the pre-existence of a crystal-like structure with a similar composition, density, and ordering to those of precipitated crystals. Glass with the modified composition was successfully crystallized during the press quenching of the melt and the fiber drawing process. These results can facilitate the production of photonic components such as nanocrystallized glass fibers and microspheres for upconversion lasers, as well as a wide variety of glass-ceramics products.