Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Study Shows That Size Affects Structure of Hollow Nanoparticles

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

Abstract:
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.

By Matt Shipman, News Services

Study Shows That Size Affects Structure of Hollow Nanoparticles

Raleigh, NC | Posted on April 13th, 2010

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, "Size-Dependent Nanoscale Kirkendall Effect During the Oxidation of Nickel Nanoparticles," 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.


Note to editors: The study abstract follows.

"Size-Dependent Nanoscale Kirkendall Effect During the Oxidation of Nickel Nanoparticles"

Authors: Justin. G. Railsback, Aaron C. Johnston-Peck, Junwei Wang, Joseph B. Tracy, North Carolina State University

Published: April 2, 2010, ACS Nano

Abstract: The transformation of Ni nanoparticles (NPs) of different sizes (average diameters of 9 nm, 26 nm, and 96 nm) during oxidation to hollow (single void) or porous (multiple voids) NiO through the nanoscale Kirkendall effect was observed by transmission electron microscopy. Samples treated for 1-4 hours at 200-500 C show that the structures of the completely oxidized NPs do not depend on the temperature, but oxidation proceeds more quickly at elevated temperatures. For the Ni/NiO system, after formation of an initial NiO shell (of thickness ~3 nm), single or multiple voids nucleate on the inner surface of the NiO shell, and the voids grow until conversion to NiO is complete. Differences in the void formation and growth processes cause size-dependent nanostructural evolution: For 9 nm and 26 nm NPs, a single void forms beneath the NiO shell, and the void grows by moving across the NP while conversion to NiO occurs opposite the site where the void initially formed. Due to differences in the Ni/NiO volume ratios for the 9 nm and 26 nm NPs when the void first forms, they have distinct nanostructures: The 9 nm NPs form NiO shells that are nearly radially symmetric, while there is a pronounced asymmetry in the NiO shells for 26 nm NPs. By choosing an intermediate oxidation temperature and varying the reaction time, partially oxidized Ni(core)/NiO(shell) NPs can be synthesized with good control. For 96 nm NPs, multiple voids form and grow, which results in porous NiO NPs.

####

About North Carolina State University
With more than 31,000 students and nearly 8,000 faculty and staff, North Carolina State University is a comprehensive university known for its leadership in education and research, and globally recognized for its science, technology, engineering and mathematics leadership.

NC State students, faculty and staff are focused. As one of the leading land-grant institutions in the nation, NC State is committed to playing an active and vital role in improving the quality of life for the citizens of North Carolina, the nation and the world.

For more information, please click here

Contacts:
Matt Shipman
News Services
919.515.6386

Dr. Joe Tracy
919.513.2623

Copyright © North Carolina State University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

Tiny nanoclusters could solve big problems for lithium-ion batteries February 21st, 2017

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Nominations Invited for $250,000 Kabiller Prize in Nanoscience: Major international prize recognizes a visionary nanotechnology researcher February 20th, 2017

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

Chemistry

In-cell molecular sieve from protein crystal February 14th, 2017

Nano-level lubricant tuning improves material for electronic devices and surface coatings February 11th, 2017

Scientists determine precise 3-D location, identity of all 23,000 atoms in a nanoparticle: Berkeley Lab researchers help to map iron-platinum particle in unprecedented detail February 6th, 2017

UCLA physicists map the atomic structure of an alloy: Researchers measured the coordinates of more than 23,000 atoms in a technologically important material February 3rd, 2017

Govt.-Legislation/Regulation/Funding/Policy

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

Engineers shrink microscope to dime-sized device February 17th, 2017

Francis Alexander Named Deputy Director of Brookhaven Lab's Computational Science Initiative February 16th, 2017

Good vibrations help reveal molecular details: Rice University scientists combine disciplines to pinpoint small structures in unlabeled molecules February 15th, 2017

Possible Futures

Tiny nanoclusters could solve big problems for lithium-ion batteries February 21st, 2017

Nominations Invited for $250,000 Kabiller Prize in Nanoscience: Major international prize recognizes a visionary nanotechnology researcher February 20th, 2017

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

Academic/Education

Nominations Invited for $250,000 Kabiller Prize in Nanoscience: Major international prize recognizes a visionary nanotechnology researcher February 20th, 2017

Oxford Nanoimaging report on how the Nanoimager, a desktop microscope delivering single molecule, super-resolution performance, is being applied at the MRC Centre for Molecular Bacteriology & Infection November 22nd, 2016

The University of Applied Sciences in Upper Austria uses Deben tensile stages as an integral part of their computed tomography research and testing facility October 18th, 2016

Enterprise In Space Partners with Sketchfab and 3D Hubs for NewSpace Education October 13th, 2016

Nanoelectronics

Particles from outer space are wreaking low-grade havoc on personal electronics February 19th, 2017

Liquid metal nano printing set to revolutionize electronics: Creating integrated circuits just atoms thick February 18th, 2017

1,000 times more efficient nano-LED opens door to faster microchips February 5th, 2017

Boron atoms stretch out, gain new powers: Rice University simulations demonstrate 1-D material's stiffness, electrical versatility January 26th, 2017

Discoveries

Tiny nanoclusters could solve big problems for lithium-ion batteries February 21st, 2017

Oxford Instruments announces Dr Brad Ramshaw of Cornell University, as winner of the 2017 Lee Osheroff Richardson Science Prize February 20th, 2017

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

Announcements

Tiny nanoclusters could solve big problems for lithium-ion batteries February 21st, 2017

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

Oxford Instruments announces Dr Brad Ramshaw of Cornell University, as winner of the 2017 Lee Osheroff Richardson Science Prize February 20th, 2017

Breakthrough with a chain of gold atoms: In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport February 20th, 2017

Energy

Strem Chemicals and Dotz Nano Ltd. Sign Distribution Agreement for Graphene Quantum Dots Collaboration February 21st, 2017

'Lossless' metamaterial could boost efficiency of lasers and other light-based devices February 20th, 2017

In-cell molecular sieve from protein crystal February 14th, 2017

NREL research pinpoints promise of polycrystalline perovskites February 8th, 2017

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project