Time resolved X-ray diffraction studies on the non-equilibrium structural dynamics of silicate glasses at ultrahigh pressures

Laser shock experiments give a unique insight into the behavior of the matter subjected to extremely high temperatures and pressures and are key to modeling material failure and deformation dynamics under ballistic impact. To understand the role of composition in the dynamic response of silicates, we performed laser-driven shock compression experiments on soda-lime glass (SLG) and borosilicate glass (BSG). VISAR and in-situ XRD were used to determine the pressure and structural phases, respectively. Following laser shock compression above 40 GPa, transformation of SLG from its ambient 4-fold coordinated amorphous structure to a 6-fold coordinated high density amorphous structure was observed that persisted up to 100GPa. Above 100 GPa, a very broad diffuse peak was observed potentially due to melting. In contrast, BSG transformed from its ambient 4-fold coordinated amorphous structure to a crystalline structure in 40 to 60 GPa range. Above 65 GPa, BSG was seen to undergo a transformation to a 6-fold coordinated high density amorphous structure like that observed in SLG. Although similar in silica content, SLG with network modifying cations (Na⁺, Ca²⁺) remained amorphous while BSG with the network forming cations (B³⁺, Al³⁺) crystallized at 40 GPa, highlighting the distinct behavior between network modifiers and network formers in silicate glasses. Our in-situ XRD studies were able to directly resolve the structural transformation in silicate glasses and clarify the role of composition.