Featured Research

from universities, journals, and other organizations

Scientists offer new insights on controlling nanoparticle stability

Date:
December 9, 2013
Source:
University of Oregon
Summary:
Chemists studying the structure of ligand-stabilized gold nanoparticles have captured fundamental new insights about their stability.

University of Oregon chemists studying the structure of ligand-stabilized gold nanoparticles have captured fundamental new insights about their stability. The information, they say, could help to maintain a desired, integral property in nanoparticles used in electronic devices, where stability is important, or to design them so they readily condense into thin films for such things as inks or catalysts in electronic or solar devices.

Related Articles


In a project -- detailed in the Nov. 27 issue of the Journal of Physical Chemistry C -- doctoral student Beverly L. Smith and James E. Hutchison, who holds the Lokey-Harrington Chair in Chemistry at the UO, analyzed how nanoparticle size and molecules on their surfaces, called ligands, influence structural integrity under rising temperatures.

They focused on nanoparticles less than two nanometers in diameter -- the smallest studied to date -- to better understand structural stability of these tiny particles being engineered for use in electronics, medicine and other materials. Whether a nanoparticle needs to remain stable or condense depends on how they are being used. Those used as catalysts in industrial chemical processing or quantum dots for lighting need to remain intact; if they are precursors for coatings in solar devices or for printing ink, nanoparticles need to be unstable so they sinter and condense into a thin mass.

For their experiments, Smith and Hutchison produced gold nanoparticles in four well-controlled sizes, ranging from 0.9 nanometers to 1.5 nanometers, and analyzed ligand loss and sintering with thermogravimetric analysis and differential scanning calorimetry, and examined the resulting films by scanning electron microscopy and X-ray photoelectron spectroscopy. As the nanoparticles were heated at 5 degrees Celsius per minute, from room temperature to 600 degrees Celsius, the nanoparticles began to transform near 150 degrees Celsius.

The researchers found that smaller nanoparticles have better structural integrity than larger-sized particles that have been tested. In other words, Hutchison said, they are less likely to lose their ligands and bind together. "If you have unstable particles, then the property you want is fleeting," he said. "Either the light emission degrades over time and you're done, or the metal becomes inactive and you're done. In that case, you want to preserve the function and keep the particles from aggregating."

The opposite is desired for Hutchison and others working in the National Science Foundation-funded Center for Sustainable Materials Chemistry, a multi-universities collaboration led by the UO and Oregon State University. Researchers there are synthesizing nanoparticles as precursors for thin films.

"We want solution precursors that can lead to inorganic thin films for use in electronics and solar industries," said Hutchison, who also is a member of the UO Materials Science Institute. "In this case, we want to know how to keep our nanoparticles or other precursors stable enough in solution so that we can work with them, using just a tiny amount of additional energy to make them unstable so that they condense into a film -- where the property that you want comes from the extended solid that is generated, not from the nanoparticles themselves."

The research, Hutchison said, identified weak sites on nanoparticles where ligands might pop off. If only a small amount do so, he said, separate nanoparticles are more likely to come together and begin the sintering process to create thin films. "That's a really stabilizing effect that, in turn, kicks out all these ligands on the outside," he said. "The surface area decreases quickly and the particles get bigger, but now all the extra ligands gets excluded into the film and then, over time, the ligands vaporize and go away."

The coming apart, however, is a "catastrophic failure" if protecting against sintering is the goal. It may be possible to use the findings, he said, to explore ways to strengthen nanoparticles, such as developing ligands that bind in at least two sites or avoiding volatile ligands.

The process, as studied, produced porous gold films. "A next step might be to study how to manipulate the process to get a more dense film if that is desired," Hutchison said. Understanding how nanoparticles respond to certain conditions, such as changing temperatures, he added, may help researchers reduce waste in the manufacturing process.

"Researchers at the University of Oregon are re-engineering the science, manufacturing and business processes behind critical products," said Kimberly Andrews Espy, vice president for research and innovation and dean of the UO Graduate School. "This research analyzing the structural stability of nanoparticles by Dr. Hutchison and his team has the potential to improve the engineering of electronics, medicine and other materials, helping to foster a sustainable future for our planet and its people."

Smith, the paper's lead author, received a master's degree in chemistry in 2009 from the UO. She now is a doctoral student in Hutchison's lab. During the initial stages of the research, she was supported by the NSF's Integrative Graduate Education and Research Traineeship (IGERT) program. Funding from the Air Force Research Laboratory (grant No. FA8650-05-1-5041) to Hutchison also supported the research. Hutchison also is a member of both the Oregon Nanoscience and Microtechnologies Institute (ONAMI) and Oregon BEST (Oregon Built Environment & Sustainable Technologies Center), which are state signature research initiatives.


Story Source:

The above story is based on materials provided by University of Oregon. Note: Materials may be edited for content and length.


Cite This Page:

University of Oregon. "Scientists offer new insights on controlling nanoparticle stability." ScienceDaily. ScienceDaily, 9 December 2013. <www.sciencedaily.com/releases/2013/12/131209181103.htm>.
University of Oregon. (2013, December 9). Scientists offer new insights on controlling nanoparticle stability. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2013/12/131209181103.htm
University of Oregon. "Scientists offer new insights on controlling nanoparticle stability." ScienceDaily. www.sciencedaily.com/releases/2013/12/131209181103.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Touch-Free Smart Phone Empowers Mobility-Impaired

Touch-Free Smart Phone Empowers Mobility-Impaired

Reuters - Innovations Video Online (Dec. 21, 2014) A touch-free phone developed in Israel enables the mobility-impaired to operate smart phones with just a movement of the head. Suzannah Butcher reports. Video provided by Reuters
Powered by NewsLook.com
Building Google Into Cars

Building Google Into Cars

Reuters - Business Video Online (Dec. 19, 2014) Google's next Android version could become the standard that'll power your vehicle's entertainment and navigation features, Reuters has learned. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
AP Review: Nikon D750 and GoPro Hero 4

AP Review: Nikon D750 and GoPro Hero 4

AP (Dec. 19, 2014) What to buy an experienced photographer or video shooter? There is some strong gear on the market from Nikon and GoPro. The AP's Ron Harris takes a closer look. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins