Most people do not think about the mysteries of the crystallization process when they freeze water for drinks, but for the chemist Takayuki Nakamuro of the University of Tokyo, this has become a lifelong affair. After 15 years of work, he was able to see firsthand how this most complex process occurs at a basic, atomic level. Graduate student Masaya Sakakibara was able to record a video of this process.
It was based on atomic resolution real-time electron microscopy technology, or SMART-EM. Much attention was paid to sample preparation – Japanese scientists constructed a frame of carbon one atom thick. It is needed to suppress molecular diffusion so that the studied atoms do not leave the specified area. A solution of sodium chloride, common salt, was placed inside the frame.
The video, recorded at 25 frames per second, demonstrates how a crystal lattice emerges from liquid chaos. It has the dimensions of four by six atoms and is not stable, but this is just logical, because we are not yet a full-fledged crystal, but its embryo. Nakamuro’s team conducted dozens of experiments and in practice proved that the average crystal formation time corresponds to the calculated one – 5.07 seconds.
Experiments with salt crystallization are just the tip of the iceberg, because this substance forms crystals of only one simple form. But the same carbon crystallizes in very different ways, due to which the same set of atoms can turn into soft graphite or ultra-strong diamond. At the next stage, Japanese scientists want to find out whether it is possible to influence the crystallization process at the atomic level and how to use this technology in practice.