Nanotechnology Now

Our NanoNews Digest Sponsors

Heifer International

Wikipedia Affiliate Button

Home > Press > Kinks and curves at the nanoscale: New research shows 'perfect twin boundaries' are not so perfect

Since 2004, materials scientists and nanotechnologists have been excited about a special of arrangement of atoms called a "coherent twin boundary" that can add strength and other advantages to metals like gold and copper. The CTB's are often described as "perfect," appearing like a one-atom-thick perfectly-flat plane in models and images. New research at the University of Vermont and Lawrence Livermore National Laboratory shows that these boundaries are not so perfect after all. Even more surprising, the newly discovered kinks and defects appear to be the cause of the CTB's strength.This image shows a simulation of atoms in a coherent twin boundary (shown in red) in copper. The newly discovered "kink" defects appear as green step-like structures and folds in the red areas. The red twin boundaries extend between columns of green atoms which represent grain boundaries within the copper.

Credit: Frederic Sansoz, University of Vermont
Since 2004, materials scientists and nanotechnologists have been excited about a special of arrangement of atoms called a "coherent twin boundary" that can add strength and other advantages to metals like gold and copper. The CTB's are often described as "perfect," appearing like a one-atom-thick perfectly-flat plane in models and images. New research at the University of Vermont and Lawrence Livermore National Laboratory shows that these boundaries are not so perfect after all. Even more surprising, the newly discovered kinks and defects appear to be the cause of the CTB's strength.This image shows a simulation of atoms in a coherent twin boundary (shown in red) in copper. The newly discovered "kink" defects appear as green step-like structures and folds in the red areas. The red twin boundaries extend between columns of green atoms which represent grain boundaries within the copper.

Credit: Frederic Sansoz, University of Vermont

Abstract:
One of the basic principles of nanotechnology is that when you make things extremely small—one nanometer is about five atoms wide, 100,000 times smaller than the diameter of a human hair—they are going to become more perfect.

Kinks and curves at the nanoscale: New research shows 'perfect twin boundaries' are not so perfect

Burlington, VT | Posted on May 20th, 2013

"Perfect in the sense that their arrangement of atoms in the real world will become more like an idealized model," says University of Vermont engineer Frederic Sansoz, "with smaller crystals—in for example, gold or copper—it's easier to have fewer defects in them."

And eliminating the defects at the interface separating two crystals, or grains, has been shown by nanotechnology experts to be a powerful strategy for making materials stronger, more easily molded, and less electrically resistant—or a host of other qualities sought by designers and manufacturers.

Since 2004, when a seminal paper came out in Science, materials scientists have been excited about one special of arrangement of atoms in metals and other materials called a "coherent twin boundary" or CTB.

Based on theory and experiment, these coherent twin boundaries are often described as "perfect," appearing like a perfectly flat, one-atom-thick plane in computer models and electron microscope images.

Over the last decade, a body of literature has shown these coherent twin boundaries—found at the nanoscale within the crystalline structure of common metals like gold, silver and copper—are highly effective at making materials much stronger while maintaining their ability to undergo permanent change in shape without breaking and still allowing easy transmission of electrons—an important fact for computer manufacturing and other electronics applications.

But new research now shows that coherent twin boundaries are not so perfect after all.

A team of scientists, including Sansoz, a professor in UVM's College of Engineering and Mathematical Sciences, and colleagues from the Lawrence Livermore National Laboratory and elsewhere, write in the May 19 edition of Nature Materials that coherent twin boundaries found in copper "are inherently defective."

With a high-resolution electron microscope, using a more powerful technique than has ever been used to examine these boundaries, they found tiny kink-like steps and curvatures in what had previously been observed as perfect.

Even more surprising, these kinks and other defects appear to be the cause of the coherent twin boundary's strength and other desirable qualities.

"Everything we have learned on these materials in the past 10 years will have to be revisited with this new information," Sansoz says

The experiment, led by Morris Wang at the Lawrence Livermore Lab, applied a newly developed mapping technique to study the crystal orientation of CTBs in so-called nanotwinned copper and "boom—it revealed these defects," says Sansoz.

This real-world discovery conformed to earlier intriguing theoretical findings that Sansoz had been making with "atomistic simulations" on a computer. The lab results sent Sansoz back to his computer models where he introduced the newly discovered "kink" defects into his calculations. Using UVM's Vermont Advanced Computing Center, he theoretically confirmed that the kink defects observed by the Livermore team lead to "rather rich deformation processes at the atomic scale," he says, that do not exist with perfect twin boundaries.

With the computer model, "we found a series of completely new mechanisms," he says, for explaining why coherent twin boundaries simultaneously add strength and yet also allow stretching (what scientists call "tensile ductility")— properties that are usually mutually exclusive in conventional materials.

"We had no idea such defects existed," says Sansoz. "So much for the perfect twin boundary. We now call them defective twin boundaries."

For several decades, scientists have looked for ways to shrink the size of individual crystalline grains within metals and other materials. Like a series of dykes or walls within the larger structure, the boundaries between grains can slow internal slip and help resist failure. Generally, the more of these boundaries—the stronger the material.

Originally, scientists believed that coherent twin boundaries in materials were much more reliable and stable than conventional grain boundaries, which are incoherently full of defects. But the new research shows they could both contain similar types of defects despite very different boundary energies.

"Understanding these defective structures is the first step to take full use of these CTBs for strengthening and maintaining the ductility and electrical conductivity of many materials," Morris Wang said. "To understand the behavior and mechanisms of these defects will help our engineering design of these materials for high-strength applications."

For Sansoz, this discovery underlines a deep principle, "There are all manner of defects in nature," he says, "with nanotech, you are trying to control the way they are formed and dispersed in matter, and to understand their impact on properties. The point of this paper is that some defects make a material stronger."

####

For more information, please click here

Contacts:
Joshua Brown

802-656-3039

Copyright © University of Vermont

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

Magnetic antiparticles offer new horizons for information technologies: Computer simulations reveal new behavior of antiskyrmions in gradually increased electric currents August 21st, 2018

Energy-efficient spin current can be controlled by magnetic field and temperature: SCMR effect simplifies the design of fundamental spintronic components August 20th, 2018

Color effects from transparent 3D printed nanostructures: New design tool automatically creates nanostructure 3D print templates for user-given colors Scientists present work at prestigious SIGGRAPH conference August 18th, 2018

Smallest transistor worldwide switches current with a single atom in solid electrolyte: Milestone of energy efficiency in information technology -- Publication in Advanced Materials August 17th, 2018

Scientists turn to the quantum realm to improve energy transportation August 17th, 2018

Physics

Energy-efficient spin current can be controlled by magnetic field and temperature: SCMR effect simplifies the design of fundamental spintronic components August 20th, 2018

Scientists create antilaser for ultracold atoms condensate August 16th, 2018

Imaging

Novel nanoparticle-based approach detects and treats oral plaque without drugs August 17th, 2018

Laboratories

UVA multidisciplinary engineering team designs technology for smart materials: The invention could lead to devices and manufactured goods, such as fabrics, that can dynamically regulate between thermally insulating and cooling August 17th, 2018

Govt.-Legislation/Regulation/Funding/Policy

Color effects from transparent 3D printed nanostructures: New design tool automatically creates nanostructure 3D print templates for user-given colors Scientists present work at prestigious SIGGRAPH conference August 18th, 2018

UVA multidisciplinary engineering team designs technology for smart materials: The invention could lead to devices and manufactured goods, such as fabrics, that can dynamically regulate between thermally insulating and cooling August 17th, 2018

Scientists turn to the quantum realm to improve energy transportation August 17th, 2018

Research brief: UMN researchers use green gold to rapidly detect and identify harmful bacteria August 15th, 2018

Discoveries

Magnetic antiparticles offer new horizons for information technologies: Computer simulations reveal new behavior of antiskyrmions in gradually increased electric currents August 21st, 2018

Energy-efficient spin current can be controlled by magnetic field and temperature: SCMR effect simplifies the design of fundamental spintronic components August 20th, 2018

Color effects from transparent 3D printed nanostructures: New design tool automatically creates nanostructure 3D print templates for user-given colors Scientists present work at prestigious SIGGRAPH conference August 18th, 2018

Smallest transistor worldwide switches current with a single atom in solid electrolyte: Milestone of energy efficiency in information technology -- Publication in Advanced Materials August 17th, 2018

Materials/Metamaterials

CTI Materials drives nano commercialization with it's patented surfactant free nanoparticle dispersions August 15th, 2018

Flipping the switch on supramolecular electronics August 14th, 2018

Biomimetic micro/nanoscale fiber reinforced composites August 10th, 2018

Yale-NUS scientist and collaborators solve open theoretical problem on electron interactions August 10th, 2018

Announcements

Magnetic antiparticles offer new horizons for information technologies: Computer simulations reveal new behavior of antiskyrmions in gradually increased electric currents August 21st, 2018

Energy-efficient spin current can be controlled by magnetic field and temperature: SCMR effect simplifies the design of fundamental spintronic components August 20th, 2018

Color effects from transparent 3D printed nanostructures: New design tool automatically creates nanostructure 3D print templates for user-given colors Scientists present work at prestigious SIGGRAPH conference August 18th, 2018

Smallest transistor worldwide switches current with a single atom in solid electrolyte: Milestone of energy efficiency in information technology -- Publication in Advanced Materials August 17th, 2018

Tools

Novel nanoparticle-based approach detects and treats oral plaque without drugs August 17th, 2018

Nanometrics Delivers 100th: Atlas III System for Advanced Process Control Metrology Atlas III: Systems are qualified and in production for advanced devices in DRAM, 3D-NAND and Foundry/Logic August 2nd, 2018

Picosun’s ALD solutions make quality watches tick July 26th, 2018

Nanometrics Announces Participation in Upcoming Investor Conferences July 25th, 2018

Research partnerships

Color effects from transparent 3D printed nanostructures: New design tool automatically creates nanostructure 3D print templates for user-given colors Scientists present work at prestigious SIGGRAPH conference August 18th, 2018

UVA multidisciplinary engineering team designs technology for smart materials: The invention could lead to devices and manufactured goods, such as fabrics, that can dynamically regulate between thermally insulating and cooling August 17th, 2018

Breaking down the Wiedemann-Franz law: In a study exploring the coupling between heat and particle currents in a gas of strongly interacting atoms, physicists at ETH Zurich find puzzling behaviours August 10th, 2018

Yale-NUS scientist and collaborators solve open theoretical problem on electron interactions August 10th, 2018

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



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project