Nanotechnology Now

Our NanoNews Digest Sponsors


Heifer International

Wikipedia Affiliate Button


DHgate

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

Personal cooling units on the horizon April 29th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Arrowhead Pharmaceuticals Files for Regulatory Clearance to Begin Phase 1/2 Study of ARC-521 April 28th, 2016

The Translational Research Center at the University Hospital of Erlangen in Germany uses the ZetaView from Particle Metrix to quantify extracellular vesicles such as exosomes April 28th, 2016

Chemistry

Adding some salt to the recipe for energy storage materials: Researchers use common table salt as growth template April 22nd, 2016

NRL reveals novel uniform coating process of p-ALD April 21st, 2016

Team builds first quantum cascade laser on silicon: Eliminates the need for an external light source for mid-infrared silicon photonic devices or photonic circuits April 21st, 2016

McMaster researchers achieve a first by coaxing molecules into assembling themselves: Major advance creates the potential for useful new materials April 21st, 2016

Govt.-Legislation/Regulation/Funding/Policy

Personal cooling units on the horizon April 29th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Nanoparticles hold promise as double-edged sword against genital herpes April 28th, 2016

Arrowhead Pharmaceuticals Files for Regulatory Clearance to Begin Phase 1/2 Study of ARC-521 April 28th, 2016

Possible Futures

Personal cooling units on the horizon April 29th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Researchers create a first frequency comb of time-bin entangled qubits: Discovery is a significant step toward multi-channel quantum communication and higher capacity quantum computers April 28th, 2016

Hybrid nanoantennas -- next-generation platform for ultradense data recording April 28th, 2016

Academic/Education

JPK reports on the use of a NanoWizard AFM system at the University of Kaiserslautern to study the interaction of bacteria with microstructured surfaces April 28th, 2016

The Ottawa Hospital Research Institute uses the ZetaView from Particle Metrix to study membrane microparticles as potential biomarkers for underlying diseases April 12th, 2016

FEI Partners with Five Pharmaceutical Companies, the Medical Research Council and the University of Cambridge to form Cryo-EM Research Consortium April 5th, 2016

SUNY Poly, in Collaboration with the George Washington School of Medicine and Health Sciences and Stony Brook University, Demonstrates Pioneering Method to Visualize and Identify Engineered Nanoparticles in Tissue March 25th, 2016

Nanoelectronics

Exploring phosphorene, a promising new material April 29th, 2016

Physicists build 'electronic synapses' for neural networks April 21st, 2016

With simple process, UW-Madison engineers fabricate fastest flexible silicon transistor April 21st, 2016

All powered up: UCI chemists create battery technology with off-the-charts charging capacity April 21st, 2016

Discoveries

Personal cooling units on the horizon April 29th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Nanoparticles hold promise as double-edged sword against genital herpes April 28th, 2016

Researchers create a first frequency comb of time-bin entangled qubits: Discovery is a significant step toward multi-channel quantum communication and higher capacity quantum computers April 28th, 2016

Announcements

Personal cooling units on the horizon April 29th, 2016

Exploring phosphorene, a promising new material April 29th, 2016

Arrowhead Pharmaceuticals Files for Regulatory Clearance to Begin Phase 1/2 Study of ARC-521 April 28th, 2016

The Translational Research Center at the University Hospital of Erlangen in Germany uses the ZetaView from Particle Metrix to quantify extracellular vesicles such as exosomes April 28th, 2016

Energy

NREL finds nanotube semiconductors well-suited for PV systems April 27th, 2016

Researchers create artificial protein to control assembly of buckyballs April 27th, 2016

Flipping a chemical switch helps perovskite solar cells beat the heat April 26th, 2016

New spin Seebeck thermoelectric device with higher conversion efficiency created April 26th, 2016

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







Car Brands
Buy website traffic