Controlling Internal Crystallization of Li2Si2O5 Glass-Ceramics Using SnO2

The impact of adding SnO2 on the nucleation and crystallization of glasses within the SiO2-Li2O-Al2O3-K2O glass system is investigated. Minor amounts of SnO2 (0.01 mol%) yield significant differences in the crystallization sequence and microstructure of these glass-ceramics. Adding SnO2 instigates the formation of Li2SiO3 as the primary crystal phase along with Li2Si2O5 at temperatures below 600 °C. Annealing at 950 °C for 10 minutes yields glass-ceramics with Li2Si2O5 as the sole crystalline phase. However, SnO2 cannot be empirically deduced as having a direct role in nucleation. Further, the study explores the effect of SnO2 concerning crystal formation, yet its exact role and effects remain somewhat ambiguous, necessitating continued investigations. Notably, the research results in a glass-ceramic with an unique microstructure comprising up to 70 wt% comparable large Li2Si2O5 crystals yielding a fracture toughness of up to 3 MPa*m1/2 and a biaxial fracture strength significantly above 300 MPa. These characteristics warrant exploring potential applications in areas demanding materials with a robust combination of toughness and strength, such as dental prosthetics.