Advanced tools for unveiling nucleation in nanostructured glass-ceramics

Nucleation is of great interest to materials scientists, physicists, and chemists studying fundamental scientific aspects of this phenomenon, as well as engineers working to develop glass-ceramics. Fundamental research in this field is indispensable for understanding the nature of the glassy state and the development of new products such as nanostructured glass-ceramics. However, experimental results on nucleation in inorganic oxide (mostly silicate) glasses and their theoretical interpretation in the framework of various mathematical models are still the subjects of significant debate. Difficulties during the early studies of nucleation partly arose from restrictions in experimental tools employed to study micron-sized or larger crystals, which cannot be directly applied to study nuclei of critical sizes or medium-range order in the parent glass, which are on a length scale of a few nanometers. Advanced tools, e.g., transmission electron microscopy, anomalous small-angle X-ray scattering, small-angle neutron scattering, X-ray absorption spectroscopy, Raman spectroscopy, nuclear magnetic resonance, advanced optical spectroscopy, together with computational modelings provide critical insight into the complicated and rapidly changing environments in which nucleation happens. The new findings from these sophisticated techniques and modeling approaches helps us evaluate hypotheses, modify available models, and develop new nanostructured glass-ceramics. Therefore, this paper reviews state-of-the-art solutions in instrumental and modeling analyses to measure and ultimately control nucleation. We propose adopting these tools and future impactful research in this exciting and challenging open field.