These electron microscope images show how the crack in a crystal of titanium dioxide begins to ‘heal’ with increasing electron doses. Image: Mkoyan Group, University of Minnesota.In a surprising new study, researchers at the University of Minnesota have found that the electron beam radiation that they previously thought degraded crystals can actually repair cracks in these nanostructures.
This groundbreaking discovery, reported in a paper in Nature Communications, provides a new pathway to creating more perfect crystal nanostructures, a process that is critical to improving the efficiency and cost-effectiveness of materials that are used in virtually all electronic devices we use every day.
“For a long time, researchers studying nanostructures were thinking that when we put the crystals under electron beam radiation to study them that they would degrade,” said Andre Mkhoyan, a chemical engineering and materials science professor at the University of Minnesota and lead researcher of the study. “What we showed in this study is that when we took a crystal of titanium dioxide and irradiate it with an electron beam, the naturally occurring narrow cracks actually filled in and healed themselves.”
The researchers accidentally stumbled upon this discovery when using the University of Minnesota’s state-of-the-art electron microscope to study the crystals for a completely different reason.
“I was studying the cracks in the crystals under the electron microscope and these cracks kept filling in,” said Silu Guo, a chemical engineering and materials science PhD student at the University of Minnesota. “This was unexpected, and our team realized that maybe there was something even bigger that we should be studying.”
In the self-healing process, several atoms of the crystal move together in tandem and meet in the middle to form a sort of bridge that fills the crack. For the first time, the researchers showed that electron beams could be used constructively to engineer novel nanostructures atom-by-atom.
"Whether it's atomically sharp cracks or other types of defects in a crystal, I believe it's inherent in the materials we've grown, but it's truly astonishing to see how Professor Mkhoyan's group can mend these cracks using an electron beam," said Bharat Jalan, a chemical engineering and materials science professor at the University of Minnesota and a collaborator on the research.
The researchers say the next step is to introduce new factors, like changing the electron beam conditions or changing the temperature of the crystal, to find a way to improve or speed up the process. “First we discovered, now we want to find more ways to engineer the process,” Mkhoyan said.
This story is adapted from material from the University of Minnesota, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.