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Nanocrystals are so useful that they formed the basis of the 2023 Nobel Prize in Chemistry. But despite their usefulness, scientists have so far been able to make these microscopic crystals from only a limited palette of materials. A group of chemists at the University of Chicago and Argonne National Laboratory has announced a way to make nanocrystals from a useful class of materials known as metal nitrides—a previously impossible task.
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Their study, published July 15 in Nature, opens new doors for electronics and other technologies, such as flexible lighting or medical implants.
"We were able to show how to make a series of nearly a dozen materials that could not be synthesized by traditional methods," said Ruiming Lin, a graduate student at UChicago and first author on the new paper.
Metal nitrides are widely used in technology and manufacturing today. For example, gallium nitride is used in nearly all modern lighting, from LED bulbs to laptop screens. The ability to make nanocrystals from such materials fundamentally increases what can be done with them. Beyond rigid films, they could someday be blended into polymers, inkjet-printed and integrated into fabrics or other flexible devices.
"This expands the boundaries of the field beyond what were previously fundamental constraints and lays the foundation for the use of nitrides as nanomaterials," said Dmitri Talapin, the Ernest DeWitt Burton Distinguished Service Professor of Chemistry and Molecular Engineering at UChicago, a scientist at Argonne and the senior author on the paper.
The right solution
Nanocrystals are just what they sound like—very tiny crystals, so small that millions to billions of them could fit on your fingernail. At this scale, materials can often have surprising and useful properties, such as creating bright light or boosting chemical reactions.
In theory, nanocrystals can be made from almost anything. But in practice, that versatility has been elusive. Lin and other scientists in Talapin's laboratory wanted to see if they could change that. In particular, the group focused on metal nitrides. These are made when metals mix with nitrogen, and as a class, they are tough, biocompatible, and heat- and corrosion-resistant.
The resilience of metal nitrides makes them well suited for uses such as consumer electronics. But that same stability presented a problem for chemists trying to make nanocrystals from them. When crystals form, their ions must swap around a bit before settling into their final configurations, like dance partners switching during a square dance. Metal nitrides, though, form extremely strong bonds—like tango dancers—so they are reluctant to change partners.
"If bonds cannot break during this process, that's a death sentence for nanocrystals," said Talapin. "Once you make an incorrect bond, everything goes south."
The solution to the problem came in two parts, the team said.
First, the Talapin lab built on a previous discovery that using molten salts as the liquid in the recipe could stabilize the formation of nanocrystals. Then, experimenting further, they found a "sweet spot" of temperature and ammonia pressure that allowed the metal-nitrogen bonds to detach and reattach more readily.
"This process is very unusual—it goes against every bit of common sense in the field," said Talapin. "We had to entirely rethink the approach."
Crystals with many uses
The team showed how to make nanocrystals not only from gallium nitride but also from a range of other related nitrides. These included titanium nitride, which is used in medical implants; niobium nitride, an industrially important superconductor; and molybdenum nitride, a common catalyst.
These materials are not only useful but also relatively inexpensive. The team hopes the ability to make them into nanocrystals could expand their utility even further.
"I remember the first time I looked through the electron microscope and saw those crystals," said Lin. "You always hope something you discovered will wind up in applications. I think there will be many uses."
Other authors from UChicago included Ningxin Jiang, Wooje Cho, Zirui Zhou, Di Wang, Justin Ondry, Zehan Mi, James Cassidy, Alex Hinckle, Alexander Filatov and John S. Anderson. The scientists used resources at the UChicago-based National Science Foundation Materials Research Science and Engineering Center; the UChicago Soft Matter Characterization Facility; and Argonne's Center for Nanoscale Materials.
More information: Ruiming Lin et al, Ammonia pressure controls colloidal metal nitride synthesis in molten salts, Nature (2026). DOI: 10.1038/s41586-026-10801-3
Provided by University of Chicago
This story was originally published on Phys.org.
