Scalable fabrication of transparent sodium calcium silicate glass-ceramics by structural engineering overcoming anisotropy barriers

Abstract

Abstract Transparent glass-ceramics with high crystallinity offer many attractive optical, mechanical, and biomedical properties. However, for glass-ceramics containing crystals with thermal expansion anisotropy, excessive crystallization induces severe microcracking and consequent loss of transparency. Here, we employ structural engineering in the sodium calcium silicate system to mitigate thermal expansion anisotropy through Zr 4+ substitution at Ca 2+ sites in Na 4 Ca 4 Si 6 O 18 crystal and stabilize the crystallized high-temperature polymorph. This strategy overcomes microcrack barriers, enabling large-sized glass-ceramics with high crystallinity ( ~ 93 wt%) and >84% visible transmittance. Validated for biomedical implants (100% cell viability and bioactivity) and fire-resistant windows, the work expands the application scope of the traditional alkali-silicate system towards highly crystalline transparent glass-ceramics for advanced functional uses.