Additive\nManufacturing of Optical Quality Germania–Silica\nGlasses

Abstract

Direct\nink writing (DIW) three-dimensional (3D) printing provides\na revolutionary approach to fabricating components with gradients\nin material properties. Herein, we report a method for generating\ncolloidal germania feedstock and germania–silica inks for the\nproduction of optical quality germania–silica (GeO₂–SiO₂) glasses by DIW, making available a new material\ncomposition for the development of multimaterial and functionally\ngraded optical quality glasses and ceramics by additive manufacturing.\nColloidal germania and silica particles are prepared by a base-catalyzed\nsol–gel method and converted to printable shear-thinning suspensions\nwith desired viscoelastic properties for DIW. The volatile solvents\nare then evaporated, and the green bodies are calcined and sintered\nto produce transparent, crack-free glasses. Chemical and structural\nevolution of GeO₂–SiO₂ glasses is confirmed\nby nuclear magnetic resonance, X-ray diffraction, and Raman spectroscopy.\nUV–vis transmission and optical homogeneity measurements reveal\ncomparable performance of the 3D printed GeO₂–SiO₂ glasses to glasses produced using conventional approaches\nand improved performance over 3D printed TiO₂–SiO₂ inks. Moreover, because GeO₂–SiO₂ inks are compatible with DIW technology, they offer exciting options\nfor forming new materials with patterned compositions such as gradients\nin the refractive index that cannot be achieved with conventional\nmanufacturing approaches.