Breakthrough in Nanocrystals’ Growth

OCTOBER 22, 2010

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Silver nanoplates decorated with silver oxy salt nanoparticles along the edges. These nanostructures were grown under irradiation of high-energy x-rays from the APS, which allowed scientists to “watch’ them grow in real time. The image is from a scanning electron microscope at the Argonne EMC.

Research at the U.S. Department of Energy’s Advanced Photon Source (APS), Center for Nanoscale Materials (CNM), and Electron Microscopy Center (EMC) at Argonne National Laboratory has provided an unprecedented view of nanoparticles growing from the earliest stages of their formation. Nanoparticles are the foundation of nanotechnology and their performance depends on their structure, composition, and size. Researchers will now be able to develop ways to control conditions under which they are grown. The breakthrough will affect a wide range of applications including solar-cell technology and chemical and biological sensors. The research was published in NANOLetters.

As coauthor Wenge Yang of the Carnegie Institution’s Geophysical Laboratory explained: “It’s been very difficult to watch these tiny particles being born and grow in the past because traditional techniques require that the sample be in a vacuum and many nanoparticles are grown in a metal-conducting liquid. So we have not been able to see how different conditions affect the particles, much less understand how we can tweak the conditions to get a desired effect.”

The researchers in this study are from the CNM and APS and the High Pressure Synergetic Consortium (HPSynC) at Argonne, a program jointly run by the Geophysical Laboratory and Argonne.

The scientists used high-energy x-rays from the APS at the X-ray Science Division beamline 1-ID to carry out diffraction studies that enabled them to gain information on the crystal structure of the materials. Thanks to the high brightness and high penetration of the x-rays from the APS, the researchers were able to watch the crystals grow to reveal the structure of these unusual particles. Quite often the chemical reaction occurs in a very short time and then evolves. The scientists used highly focused high-energy x-rays and a fast area detector, the key components to make this investigation possible. This is the first time-resolved study of the evolution of nanoparticles from the time they are born. Scanning electron microscopy at the EMC at Argonne was used to confirm that the x-ray irradiation did affect the growth of nanoparticles at the GaAs-wafer/AgNO3-solution interface

“This study shows the promise of new techniques for probing crystal growth in real time. Our ultimate goal is to use these new methods to track chemical reactions as they occur under a variety of conditions, including variable pressures and temperatures, and to use that knowledge to design and make new materials for energy applications. This is a major thrust area of the HPSynC program that we have launched in partnership with Argonne National Laboratory,” remarked Russell Hemley, the director of Geophysical Laboratory.

"Accurately controlling nanoparticles is very difficult," said lead researcher Yugang Sun, an Argonne chemist. "It's even harder to reproduce the same nanoparticles from batch to batch, because we still don't know all the conditions for the recipe. Temperature, pressure, humidity, impurities—they all affect growth, and we keep discovering more factors. The key to this breakthrough was the unique ability for us to work with scientists from the Advanced Photon Source, the Center for Nanoscale Materials, and the Electron Microscopy Center—all in one place.“

See: Yugang Sun1*, Yang Ren1, Dean R. Haeffner1, Jonathan D. Almer1, Lin Wang2, Wenge Yang2 and Tu T. Truong1, “Nanophase Evolution at Semiconductor/Electrolyte Interface in situ Probed by Time-Resolved High-Energy Synchrotron X-ray Diffraction,” Nano Lett. 10, 3747 (2010). DOI: 10.1021/nl102458k

Author affiliations: 1Argonne National Laboratory, 2Carnegie Institute of Washington

Correspondence: *ygsun@anl.gov

The original Carnegie Institution of Washington press release can be read here.

An Argonne press release on this subject can be read here.

Use of the Center for Nanoscale Materials, Advanced Photon Source, and the Electron Microscopy Center for Materials Research at Argonne was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DEAC02-06CH11357.

HPSynC, is also a part of the Energy Frontier for Research in Extreme Environments (EFree) Center, an Energy Frontier Research Center supported at Carnegie by DOE-BES. One of the missions of this center is to harness new synchrotron radiation techniques for in situ studies of materials structure and dynamics in extreme conditions and thereby to understand and produce new energy materials.

The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science, Office of Basic Energy Sciences (DOE-BES). The APS is the source of the Western Hemisphere’s brightest high-energy x-ray beams for research in virtually every scientific discipline. More than 3,500 scientists representing universities, industry, and academic institutions from every U.S. state and several foreign nations visit the APS each year to carry out applied and basic research in support of the BES mission to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels in order to provide the foundations for new energy technologies and to support DOE missions in energy, environment, and national security. To learn more about the Office of Basic Energy Sciences and its x-ray user facilities, visit http://www.sc.doe.gov/bes/BES.html.

The Center for Nanoscale Materials at Argonne National Laboratory is one of the five DOE Nanoscale Science Research Centers (NSRCs), premier national user facilities for interdisciplinary research at the nanoscale, supported by the DOE Office of Science. Together the NSRCs comprise a suite of complementary facilities that provide researchers with state-of-the-art capabilities to fabricate, process, characterize and model nanoscale materials, and constitute the largest infrastructure investment of the National Nanotechnology Initiative.  The NSRCs are located at DOE’s Argonne, Brookhaven, Lawrence Berkeley, Oak Ridge and Sandia and Los Alamos national laboratories.  For more information about the DOE NSRCs, please visit http://nano.energy.gov.

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