Fabrication and Analysis of special property glasses using silica nanocomposites

• Applicant: Dr.-Ing. Frederik Kotz
• Subject Area: Synthesis and Properties of Functional Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 455798326

Glass is one of the most important material class for research and industry. The most widely used glasses, silicate glasses, consist of silicon dioxide as a network former and dopants, which can induce favorable glass properties, such as reduced melting temperatures and adjustable thermal expansion or refractive index. Such doped glasses are called special property glasses. The biggest challenges in the field of special property glasses are the homogeneous distribution of dopants and the shaping process, especially on the microscale. The systematic analysis of novel glass mixtures is difficult, since every mixture has to be individually mixed, melted, and cooled down in a controlled manner - the influence of dopants on glass formation is therefore still difficult to investigate. In the field of glass research, I have developed the Glassomer process which is based on the fabrication of silicon dioxide nanocomposites, which can be shaped by polymerization. The nanocomposites can be converted to brown parts (porous powder components) by debinding and sintered to high purity fused silica glass. However, this process has been so far limited to fused silica glass. Due to the extensive analytical possibilities in each of the individual processing steps, the possibility of shaping (e.g. by means of high-resolution 3D printing) and the lower temperatures during sintering, this process is further interesting for the production of special property glasses.In this project the behavior of dopants during sintering of glasses is studied, whereby the distribution of the dopants before and after sintering is of particular interest. Based on the Glassomer process, new methods for the introduction of the dopants (Al2O3, B2O3, TiO2) into the glass are being developed: by producing modified nanoparticles, by doping porous brown parts or by modifying the binder matrix. The analysis of the ion distribution in the brown part and in the sintered glass as well as the optical, thermal and mechanical properties of the special glasses are analyzed and compared in order to examine the distribution of the dopants and the associated effects on the glass properties. The data gained will further be compared with data from established glass manufacturing processes. The project will make an important contribution to understanding the influence of dopants on glass properties and will enable the optimization of glass mixtures with regard to doping concentration and sintering behavior. The diverse possibilities for shaping enabled by the binder matrix will be studied during the course of this project to manufacture microstructures in special glasses.

• DFG Programme: Research Grants