Measuring, characterizing, and manipulating at the nanoscale are foundational elements of nanotechnology. And this week we’ve seen in news from IBM just how important improving microscopy is to all that.
Now researchers at the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab) have used transmission electron microscopy and advanced liquid cell handling to see if they could gather evidence to support the controversial theory that nanoparticles act as artificial atoms during the growth of crystals.
“We observed that as nanoparticles become attached they initially form winding polycrystalline chains,” says Haimei Zheng, a staff scientist in Berkeley Lab’s Materials Sciences Division in a press release. “These chains eventually align and attach end-to-end to form nanowires that straighten and stretch into single crystal nanorods with length-to-thickness ratios up to 40:1. This nanocrystal growth process, whereby nanoparticle chains as well as nanoparticles serve as the fundamental building blocks for nanorods, is both smart and efficient.”
You can see this process quite clearly in the video:
The research, which was published last week in the journal Science, observed the nanoparticles “undergo continuous rotation and interaction until they find a perfect lattice match. A sudden jump to contact then occurs over less than 1 nanometer, followed by lateral atom-by-atom addition initiated at the contact point.”
This observation and understanding of how nanoparticles make up crystal growth will likely provide important insight into the design of nanomaterials.
“From what we observed only single nanoparticles exist at the beginning of crystal growth, but, as growth proceeds, small chains of nanoparticles become dominant until, ultimately, only long chains of nanoparticles can be seen,” Zheng says. “Our observations provide a link between the world of single molecules and hierarchical nanostructures, paving the way for the rational design of nanomaterials with controlled properties.”
Dexter Johnson is a contributing editor at IEEE Spectrum, with a focus on nanotechnology.