LAMP: laser-assisted melt printing for direct silica glass 3D printing with in situ nanoparticle synthesis

• Hybrid Additive Manufacturing Method: The study presents laser-assisted melt printing (LAMP) as a novel additive manufacturing technique for silica glass, eliminating the need for extensive post-processing like sintering. • Direct Laser Melting: A CO 2 laser in LAMP melts deposited material layer-by-layer, producing a fully fused glass structure with high surface smoothness and reduced porosity compared to traditional sintering. • Gas-Phase Properties Control: By adjusting laser power and atmospheric conditions (oxygen/nitrogen), the transparency and bubble content of printed glass can be tuned. • In Situ Metal Nanoparticle Synthesis: Gold and silver nanoparticles are made during printing, which enables color tuning (red, yellow, orange) and gradient effects. Additive manufacturing of silica glass has become a highly investigated research field. Current methods can produce objects with good optical transparency in resolutions ranging from the millimeter to the micrometer scale depending on the printing approach. Direct printing methods require complex setups, often involving lasers, and exhibit a low versatility for example with regard to material choice. Indirect printing methods are unable to process the glass without the necessity of post-processing in form of sintering. In this study, we present a novel 3D printing approach for silica glass, we call laser assisted melt printing (LAMP), which combines the technique of direct ink writing (DIW) with a laser melting approach. This enables combining the versatility of DIW with the benefits of a direct printing approach. We show how inks made from a mixture of nano- and microparticles can be utilized to produce 3D objects from silica glass. Additionally, the properties of the glass were tailored during the printing process and the optical transparency could be adjusted by the gas atmosphere during the laser melt process. By adding metal ions to the ink, nanoparticles were synthesized in situ , staining the glass in various colors. The synthesis could be controlled by the applied laser power, enabling us to produce sharp transitions and also gradients within the optical properties of the glass.