Glasses have traditionally been enabling materials in major societal challenges. Significant breakthroughs on many areas of technological progress have been very closely linked to the exploitation of glassy materials. This key role will persist in the global goals for a sustainable future, from living, energy, health and transport to information processing. However, fundamental limitationsmust be overcome on this road.
As a major, ab initio exploitation of disordered materials must be achieved, using highly-adapted processing strategies. Such technologies will not only enable new types of glasses with unprecedented properties, but also novel processing routes that might overcome current limitations of energy efficiency. To this end, fundamental research and in-depth conceptual developments are required which combine the formulation of chemical compositions, knowledge of structural evolution on molecular scale, and the thermo-kinetics of material deposition into holistic design tools. Such tools would significantly contribute to solving some of the most urgent material needs for glass applications, be it in the form of thin films, particles or bulk products.
The UTOPES project challenged today’s engineering concepts towards the conception of such tools. For that, melt deposition, isothermal deposition from liquid phases, and gas-phase deposition of non-crystalline materials were considered in a generalist approach, which was to overcome traditional boundaries between classes of chemically different materials. As a unifying assumption, we started from ideas of structural disorder being determined not only by the chemical constituents present in the material, but also by the way a given glass was processed. In turn, such disorder – non-periodic fluctuations in local material behaviour on very short length scale – is the basis of macroscopic properties, and presents the primary difference to crystalline materials. Our starting point was the lack of quantifiers for disorder in chemically complex glasses: current theory is based on strongly simplified (both in terms of system size and species complexity) computational or physical models, whereas such models cannot cover phenomena known to occur in real-world, industrially relevant glasses. In turn, the latter are described mostly through short-range structural parameters, or through simplistic or empirical approaches which do not allow to connect disorder to macroscopic properties.
Within UTOPES, we demonstrated how the evolution of disorder and structural complexity in glassy materials can be tailored through adequate processing. Providing a topological scheme for the quantification of disorder, we were able to resolve similarities for the broadest range of industrially relevant glass chemistries, from classical silicates to metallic, organic and hybrid materials – with a focus on refractory oxide glasses for future applications in optics and other functional devices. While fabricating such glasses through classical melting procedures leads to rigid trends in material disorder (and, hence, resulting properties), alternative processing can overcome such trends. For example, gas-phase deposition of refractory oxide glasses can achieve optical or mechanical properties outside of what is feasible by regular melting and annealing. UTOPES took us a great step further on the road to deciphering order in disorder, breaking grounds for the third generation of glasses with properties beyond the current limits of engineering.
