Fabrication and Analysis of Glasses with High-Refractive Index using Multicomponent Silica Nanocomposites

• Applicant: Dr.-Ing. Frederik Kotz-Helmer
• Subject Area: Glass, Ceramics and Derived Composites ; Synthesis and Properties of Functional Materials ; Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 455798326

Glass is one of the most important materials for science, technology and industry. In optics and photonics, multi-component glasses with adjustable refractive index and dispersion play a central role. In particular, silicate-based multicomponent glasses, composed of silicon dioxide and added oxide components, can be precisely tailored in properties such as melting temperature, thermal expansion and refractive index. However, shaping of such glass, especially into complex components, has long been a significant limitation.With the Glassomer process I have developed, it is now possible to shape glass at room temperature using established polymer processing techniques such as 3D printing or molding. This is achieved through nanocomposites composed of silicon dioxide nanoparticles embedded in an organic binder matrix, which after shaping, are converted intro transparent glass via debinding and sintering. The process not only enables the fabrication of complex geometries but also offers precise control over composition. Initially, the method was limited to pure fused silica glasses. In the first phase of the project, the process was successfully extended to binary silicate glasses. However, the integration strategies investigated so far do not allow the fabrication of multi-component glasses with tunable refractive index as required for optical applications.The goal of this research project is the development, analysis and shaping of multi-component silicate glasses with adjustable refractive index based on the Glassomer technology. For this purpose, amorphous, multi-component nanoparticles will be synthesized via flame spray pyrolysis (FSP), directly incorporating the desired high-refractive index oxides (e.g. TiO2, ZrO2 or GeO2) along with stabilizing network components (e.g. B2O3, Al2O3). This direct integration into the particles overcomes the limitations of oxide incorporation strategies identified in the first project phase and enable higher concentrations without phase separation or crystallization. The project addresses the entire process chain, from targeted nanoparticle synthesis through the formulation of photocurable nanocomposites, to sintered and detailed analysis of the optical, thermal and structural properties of the resulting glasses. In addition, three-dimensional structuring of the nanocomposites will be investigated. By combining FSP synthesis with the Glassomer technology, the project aims to establish a platform for the rapid, reproducible and geometrically complex production of novel optical glasses. This will open up new application opportunities in optics, photonics and microstructuring technologies.

• DFG Programme: Research Grants