Glassy materials are everywhere in our lives and have contributed to humanity for many years. Today, they play an essential role in various technologies, including optical fibers. Although we believe that glass is very stable, it sometimes crystallizes causing loss of transparency and isotropy, essential characteristics of glass, which has been a significant problem in industrial applications. Why crystallization occurs in the solid state with almost no molecular movement has been a big mystery. Understanding it can help prevent or optimize crystal growth during deep supercooling.
In a study recently published in Materials from nature, researchers from the Institute of Industrial Sciences, the University of Tokyo, Fudan University, Peking University and collaborating institutions conducted experimental and computer studies on the rapid growth of crystals under supercooled deep. Their work provides critical insight into the mechanism of rapid crystal growth at ultra-low temperatures, contributing to many technological applications by improving the stability of glass or producing high-quality crystals.
“The growth of crystals in glasses is a complex problem that has been around for decades. How precursor structures overcome disorder in the liquid phase to organize into crystals remains controversial, ”says Peng Tan, co-lead author.
A key to the rapid crystal growth revealed by simulations and experiments is that the solid-liquid interfaces in supercooled liquids are thick and rough. The large contact area between the ordered islands and the surrounding messy liquid helps to break up the mess and facilitates the rapid growth of the crystals.
“Another key finding is that the disordered state is inherently mechanically unstable, leading to a domino-like chain reaction of crystal growth,” says Hajime Tanaka, co-lead author. “This is facilitated by the ability of the newly formed imperfectly ordered regions of the crystal to rearrange themselves and, in so doing, prevent the build-up of disorder.”
How can researchers use this knowledge? Crystal growth can be promoted by enhancing the ability of a supercooled liquid to develop precursor structures and reorganize from a suboptimized order. Tanaka, Tan, Xu and their colleagues are optimistic that the researchers will use this information to determine which materials exhibit the properties necessary for increased glass stability or high-quality crystal formation. With further development, there are clear applications to ultrastable glasses and nearly perfect crystals.
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Material provided by Institute of Industrial Sciences, University of Tokyo. Note: Content can be changed for style and length.