Preshaping clear glass at low temperatures

Room-Temperature Molding of Complex-Shaped Transparent Fused Silica Lenses

The high hardness, brittleness, and thermal resistance impose significant challenges in the scalable manufacturing of fused silica lenses, which are widely used in numerous applications. Taking advantage of the nanocomposites by stirring silica nanopowders with photocurable resins, the newly emerged low-temperature pre-shaping technique provides a paradigm shift in fabricating transparent fused silica components. However, preparing the silica slurry and carefully evaporating the organics may significantly increase the process complexity and decrease the manufacturing efficiency for the nanocomposite-based technique. By directly pressing pure silica nanopowders against the complex-shaped metal molds in minutes, this work reports an entirely different room-temperature molding method capable of mass replication of complex-shaped silica lenses without organic additives. After sintering the replicated lenses, fully transparent fused silica lenses with spherical, arrayed, and freeform patterns are generated with nanometric surface roughness and well-reserved mold shapes, demonstrating a scalable and cost-effective route surpassing the current techniques for the manufacturing of high-quality fused silica lenses.

Silica-Encapsulated Germania Colloids as 3D-Printable Glass Precursors

Core-shell colloids make attractive feedstocks for three-dimensional (3D) printing mixed oxide glass materials because they enable synthetic control of precursor dimensions and compositions, improving glass fabrication precision. Toward that end, we report the design and use of core-shell germania-silica (GeO₂-SiO₂) colloids and their use as precursors to fabricate GeO₂-SiO₂ glass monoliths by direct ink write (DIW) 3D printing. By this method, GeO₂ colloids were prepared in solution using sol-gel chemistry and formed oblong, raspberry-like agglomerates with ∼15 nm diameter primary particles that were predominantly amorphous but contained polycrystalline domains. An ∼15 nm encapsulating SiO₂ shell layer was formed directly on the GeO₂ core agglomerates to form core-shell GeO₂-SiO₂ colloids. For glass 3D printing, GeO₂-SiO₂ colloidal sols were formulated into a viscous ink by solvent exchange, printed into monoliths by DIW additive manufacturing, and sintered to transparent glasses. Characterization of the glass components demonstrates that the core-shell GeO₂-SiO₂ presents a feasible route to prepare quality, optically transparent low wt % GeO₂-SiO₂ glasses by DIW printing. Additionally, the results offer a novel, hybrid colloid approach to fabricating 3D-printed Ge-doped silica glass.