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 (GeO-SiO) colloids and their use as precursors to fabricate GeO-SiO glass monoliths by direct ink write (DIW) 3D printing. By this method, GeO 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.