The university is Tokyo Metropolitan University.
The mechanism behind the rapid growth of ultra-thin nanowires has been discovered by scientists. Understanding how nanowires grow is important for applications, as they are both a desirable technological innovation and a hazard. Control over crystal structure can be achieved with trace impurities.
New applications in electronics, catalysis, and energy generation are possible with the use of nanowires. They may grow spontaneously where they don't want to. An important technological problem is getting a handle on how they grow.
The crystal growth of o-terphenyl and salol, two typical organic compounds that exhibit whisker crystals, has been looked at by a group of people from Tokyo Metropolitan University. They found a small bubble at the tip of each Filament. They were able to show that the bubble was a small capsule of gas of the same compound. Instead of being deposited onto a growing front like in normal crystal growth, it was transferred to the gas inside the bubble before being attached to the tip of the filament, a vastly different picture from the standard picture of freezing in liquids. It was possible to reproduce fast growth inside thin glass capillaries for a more controlled growth of nanowires.
The large density difference between crystal and liquid in these compounds had a role to play in the bubble formation. They found no whisker growth when they repeated the experiment in other liquids. The tendency of the front to be home to large density inhomogeneities led to the formation of bubbles of gas which went on to give birth to whiskers.
The team decided to suppress bubble formation to get some control over the phenomenon. The material was added to suppress the sound of waves. As bubbles vanished, the whiskers allowed for the slower but whisker-free growth of large chunks of uniform material.
With an understanding of the physics behind the process, the team's work promises new approaches to grownanofilaments for technological applications, and different strategies to safeguard electronics and batteries from potentially dangerous shorts triggered by whisker crystals. Scientific Reports contains the research.
More information: Takumi Yashima et al, Filamentous crystal growth in organic liquids and selection of crystal morphology, Scientific Reports (2022). DOI: 10.1038/s41598-022-13851-5 Journal information: Scientific Reports Provided by Tokyo Metropolitan University
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