Crystallization clarified, researchers report

October 28, 2019

CHAMPAIGN, Ill. -- Researchers from the University of Illinois at Urbana-Champaign and Northwestern University have made it possible to observe and simulate the self-assembly of crystalline materials at a much higher resolution than before.

Using computer modeling and an imaging technique called liquid-phase electron microscopy, the team pinpointed the individual motions of tiny nanoscale particles as they orient themselves into crystal lattices. The work confirms that synthetic nanoparticles - the fundamental building blocks of many synthetic and biological materials - can assemble in ways far more complex than larger particles, the researchers said, and paves the way to more general applications for mineralization, pharmaceuticals, optics and electronics.

The new study, led by Qian Chen, a professor of materials science and engineering at the U. of I., and Erik Luijten, a Northwestern professor of materials science and engineering and of engineering sciences and applied mathematics, is published in the journal Nature Materials.

"Imaging and modeling are routinely performed for particles about 1 micrometer in size," said Luijten, who led the computation modeling portion of the study. "Here, we have newly developed techniques that can do this for particles that are 100 nanometers in size - 10 times smaller than before."

Because nanoparticles are very small and interact in liquid solutions, verifying their crystallization pathways through direct observation was not possible before liquid-phase electron microscopy, said Chen, who led the experimental portion of the study.

Chen's team performed laboratory experiments using tiny gold prisms in a fluid, watching closely as the particles began to interact with each other.

"The particles begin to stack together and form columns, but they do so in a misaligned manner before finally packing tightly and crystallizing into ordered crystals," said Zihao Ou, a U. of I. graduate student and study co-author.

"What we have observed is an intermediate amorphous phase that occurs along the crystallization pathway for nanoparticles - something not witnessed before this work," Chen said.

However, there are details about crystallization pathways that cannot be measured by imaging alone, the researchers said.

"Our computer simulations, developed by Northwestern University graduate student Ziwei Wang, allow us to sort out the details of the fundamental driving forces behind nanoparticle motion and crystallization," Luijten said. "It turns out that randomness in the orientation of the particles leads to a different type of crystallization on larger-length scales. That is a notion that was suggested by the experimental data, but it really required simulations to confirm this principle."

The researchers envision a wide range of applications for this development, from understanding how proteins self-assemble to the nanoscale physics behind new battery materials, for example.

"Scientists want to know how to control the synthesis of crystalline materials so that they can engineer new materials," said Binbin Luo, a U. of I. graduate student and study co-author. "Understanding exactly how this process happens is essential to that control."
Chen also is affiliated with the department of chemistry, Beckman Institute for Advanced Science and Technology and the Materials Research Laboratory at the U. of I. Luijten also is affiliated with the departments of chemistry and of physics and astronomy at Northwestern.

The U.S. Department of Energy and the National Science Foundation supported this research.

Editor's notes:

To reach Qian Chen, call 217-300-1137; email

To reach Erik Luijten, email

The paper "Kinetic pathways of crystallization at the nanoscale" is available online and from the U. of I. News Bureau. DOI: 10.1038/s41563-019-0514-1

University of Illinois at Urbana-Champaign, News Bureau

Related Nanoparticles Articles from Brightsurf:

An ionic forcefield for nanoparticles
Nanoparticles are promising drug delivery tools but they struggle to get past the immune system's first line of defense: proteins in the blood serum that tag potential invaders.

Phytoplankton disturbed by nanoparticles
Products derived from nanotechnology are efficient and highly sought-after, yet their effects on the environment are still poorly understood.

How to get more cancer-fighting nanoparticles to where they are needed
University of Toronto Engineering researchers have discovered a dose threshold that greatly increases the delivery of cancer-fighting drugs into a tumour.

Nanoparticles: Acidic alert
Researchers of Ludwig-Maximilians-Universitaet (LMU) in Munich have synthesized nanoparticles that can be induced by a change in pH to release a deadly dose of ionized iron within cells.

3D reconstructions of individual nanoparticles
Want to find out how to design and build materials atom by atom?

Directing nanoparticles straight to tumors
Modern anticancer therapies aim to attack tumor cells while sparing healthy tissue.

Sweet nanoparticles trick kidney
Researchers engineer tiny particles with sugar molecules to prevent side effect in cancer therapy.

A megalibrary of nanoparticles
Using straightforward chemistry and a mix-and-match, modular strategy, researchers have developed a simple approach that could produce over 65,000 different types of complex nanoparticles.

Dialing up the heat on nanoparticles
Rapid progress in the field of metallic nanotechnology is sparking a science revolution that is likely to impact all areas of society, according to professor of physics Ventsislav Valev and his team at the University of Bath in the UK.

Illuminating the world of nanoparticles
Scientists at the Okinawa Institute of Science and Technology Graduate University (OIST) have developed a light-based device that can act as a biosensor, detecting biological substances in materials; for example, harmful pathogens in food samples.

Read More: Nanoparticles News and Nanoparticles Current Events is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to