Heterogeneous-surface-mediated crystallization control

The crystallization of matter at interfaces has long been a significant issue in science and technology, but surface-directed crystallization with controlled kinetics remains a matter of challenge. Here, we demonstrate a conceptual novel mechanism to steer liquid–solid phase transformation at interfaces by tailoring the chemical and structural inhomogeneity of a glass substrate through self-limited nanocrystallization of the glassy phase. Importantly, this approach enables large-scale development of metastable crystallization products, such as nanowire membranes. The thorough studies of the intermediate stages of crystallization reveal a unique cooperative mechanism in which the intricate interplays between inherent nanoscale forces and unique heterogeneous surfaces contribute to the mesoscale structural transformation from isolated units to superstructures. We further show that the constructed superstructures offer unprecedented opportuntities for the development of functional membrane systems possessing the combination of robust trace-detection performance and molecular trapping function. These findings not only present clear technological implications, but also provide an improved understanding of the fundamental mechanisms of surface-induced geological and biological processes. A glassy surface embedded with zones of crystalline order can spur materials to form nanowires and molecule-trapping membranes on demand. Surface-induced crystallization plays important roles in processes ranging from bone biomineralization to transistor fabrication. Shifeng Zhou from South China University of Technology in Guangzhou and co-workers have reported a great discovery that glass-ceramics surface can help to control liquid-to-solid transformations at interfaces without resorting to chemical treatments or specialized templates. Using thermal treatments, the team precipitated titanium dioxide nanocrystals into an otherwise homogenous inorganic oxide glass. The resulting non-uniform interface created periodic potential field that enabled strict control over crystal nucleation and aggregation. Additional charge imbalances between tiny aggregations guided materials to grow into remarkable superstructures. As a practical example, microporous silver membranes that detect trace amounts of hazardous aromatic vapours were demonstrated. A new surface-directed crystallization mechanism enabled by the chemical and structural inhomogeneity of the glass substrate through self-limited nanocrystallization of glassy phase was proposed and demonstrated. Benefiting from the intricate interplays between nanoscale force and heterogeneous surface, the strategy offers new opportunities in the large-scale development of various metastable crystallization products and also serves practical purpose.