Featured Research

from universities, journals, and other organizations

Size affects structure of hollow nanoparticles

Date:
April 23, 2010
Source:
North Carolina State University
Summary:
A new study shows that size plays a key role in determining the structure of certain hollow nanoparticles. The researchers focused on nickel nanoparticles, which have interesting magnetic and catalytic properties that may have applications in fields as diverse as energy production and nanoelectronics.

Image of a half-oxidized 26 nanometer nanoparticle. The nickel region is colored red, and the nickel oxide is colored blue and green.
Credit: Image courtesy of ACS Nano

A new study from North Carolina State University shows that size plays a key role in determining the structure of certain hollow nanoparticles. The researchers focused on nickel nanoparticles, which have interesting magnetic and catalytic properties that may have applications in fields as diverse as energy production and nanoelectronics.

"The principles we're uncovering here have great potential for nanofabrication -- the creation of materials that have very small features, with many applications in fields ranging from electronics to medicine," says Dr. Joe Tracy, an assistant professor of materials science and engineering at NC State and co-author of the study. "This study improves our understanding of hollow nanoparticles and is a foundation for future work on applications in ultra-high density magnetic recording and more efficient catalysts, which is useful for chemical production, waste treatment and energy production."

At issue is the oxidation of nickel nanoparticles. If you start with a "core" piece of nickel and oxidize it, exposing it to oxygen at high temperatures, the structure of the material changes. If the material is partially oxidized -- exposed to oxygen and high heat for a limited time -- a solid nickel oxide shell forms around the material.

If the material is exposed to heat and oxygen for a longer period of time, further oxidation occurs. The external shell remains, but nickel is transported out of the core, leaving a void. If the material is fully oxidized, a larger void is created -- leaving the nickel oxide shell effectively hollow. This conversion of solid to hollow nanoparticles is known as the "nanoscale Kirkendall Effect."

But what NC State researchers have found is that the size of the nickel core also plays a key role in the structure of these particles. For example, in smaller nickel nanoparticles -- those with cores having diameters smaller than 30 nanometers (nm) -- a single void is formed inside the shell during oxidation. This results in an asymmetric core of nickel, with a single void growing on one side of the core. The remaining core shrinks as the oxidation process continues. This is significant, in part, because the nickel oxide shell becomes progressively thicker on the side that abuts the core. The larger the core -- within the 30 nm limit -- the thicker that side of the shell becomes. In other words, you end up with a nickel oxide shell that can be significantly thicker on one side than the other.

However, the researchers found that larger nickel nanoparticles do something completely different. The researchers tested nanoparticles with nickel cores that were 96 nm in diameter, and found that the oxidation process in these nanoparticles created multiple voids in the core -- though the core itself remained completely surrounded by the nickel oxide shell. This process effectively resulted in the creation of bubbles throughout the core. The "skeletons" of those bubbles still remained, even after full oxidation, creating an essentially hollow shell that was still criss-crossed with some remnants of the nickel core.

"This tells us a lot about how to create nanoscale structures using the nanoscale Kirkendall Effect," Tracy says. "It's a building block for future research in the field."

The study is published in the journal ACS Nano. The research was funded by the National Science Foundation and NC State, and is co-authored by Tracy, NC State undergraduate Justin Railsback, NC State Ph.D. student Aaron Johnston-Peck and former NC State postdoctoral research associate Dr. Junwei Wang.

The Department of Materials Science and Engineering is part of NC State's College of Engineering.


Story Source:

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


Journal Reference:

  1. Railsback et al. Size-Dependent Nanoscale Kirkendall Effect During the Oxidation of Nickel Nanoparticles. ACS Nano, 2010; 100402131225066 DOI: 10.1021/nn901736y

Cite This Page:

North Carolina State University. "Size affects structure of hollow nanoparticles." ScienceDaily. ScienceDaily, 23 April 2010. <www.sciencedaily.com/releases/2010/04/100412111617.htm>.
North Carolina State University. (2010, April 23). Size affects structure of hollow nanoparticles. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2010/04/100412111617.htm
North Carolina State University. "Size affects structure of hollow nanoparticles." ScienceDaily. www.sciencedaily.com/releases/2010/04/100412111617.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
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:
from the past week

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