Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Lou's clues lead to nano revelation

Credit: Jun Lou, Rice University
Credit: Jun Lou, Rice University

Abstract:
Gold and silver nanowires bond naturally, stay strong

Lou's clues lead to nano revelation

Houston, TX | Posted on February 15th, 2010

Welding uses heat to join pieces of metal in everything from circuits to skyscrapers. But Rice University researchers have found a way to beat the heat on the nanoscale.

Jun Lou, an assistant professor in mechanical engineering and materials science, and his group have discovered that gold wires between three-billionths and 10-billionths of a meter wide weld themselves together quite nicely - without heat.

They report in today's online edition of the journal Nature Nanotechnology that clean gold nanowires with identical atomic structures will merge into a single wire that loses none of its electrical and mechanical properties. The process works just as well with silver nanowires, which bond with each other or with gold.

This cold-welding process has been observed on the macro scale for decades, Lou said. Clean, flat pieces of similar metals can be made to bond under high pressure and in a vacuum. But only Lou and his colleagues have seen the process happen on the nanoscale, under an electron microscope.

As so often happens in basic research, that's not what they were looking for at all. Lou and Rice graduate student Yang Lu, with collaborators at Sandia National Laboratories and Brown University, were trying to determine the tensile strength of gold nanowires by attaching one end of a wire to a probe in a transmission electron microscope (TEM) and the other to a tiny cantilever spring called an atomic force microscopy (AFM) probe.

Pulling the wire apart gave the team a measurement of its strength. What they didn't expect to see was the broken wire mending itself when its ends or sides touched. Measurements showed the reconnected wire was as strong as before.

"Before you can actually stretch something, you need to clamp it well," said Lou, who received a Young Investigators Research Program grant from the Air Force Office of Sponsored Research last year. "During the manipulation process, we observed this type of welding behavior all the time.

"Initially, we didn't pay attention to it because it didn't seem significant. But after doing a little research on the field, I realized we discovered something that may be useful."

In testing, Lou found the nanowires could be snapped and welded many times. Mended wires never broke again at the same spot; this attests to the strength of the new bond.

The wire's electrical properties also seemed unaffected by repeated breaking and welding. "We'd break a wire and reweld it 11 times and check the electrical properties every time. All the numbers were very close," he said.

The keys to a successful weld are the nanowire's single crystalline structure and matching orientation. "There are a lot of surface atoms, very active, that participate in the diffusion at the nanoscale," Lou said. "We tried gold and silver, and they weld in the same way as long as you satisfy the crystalline-orientation requirement."

Lou sees the discovery opening new paths for researchers looking at molecular-scale electronics. He said teams at Harvard and Northwestern are working on ways to pattern arrays of nanowires, and incorporating cold welding could simplify their processes. "If you're building high-density electronic devices, these kinds of phenomena will be very useful," he said, noting that heat-induced welds on the nanoscale run the risk of damaging the materials' strength or conductivity.

Lou said the discovery has caused a stir among the few he's told. "Different people see different aspects: Electrical engineers see the application side. Theory people see some interesting physics behind this behavior. We hope this paper will encourage more fundamental study."

The paper's co-authors include Jian Yu Huang, a scientist at the Center for Integrated Nanotechnologies at Sandia National Laboratories; and Professor Shouheng Sun and former graduate student Chao Wang of Brown University.

The National Science Foundation and the Air Force Office of Sponsored Research supported the project.

Related materials:

Read the paper here: www.nature.com/nnano/journal/vaop/ncurrent/abs/nnano.2010.4.html.

Video:

This shows two gold nanowires merging in a side-by-side cold welding process, and then separating at a different spot when pulled apart. www.youtube.com/watch?v=cgsuxEHxFjY

Video:

This shows two gold nanowires welding when their tips touch. www.youtube.com/watch?v=7tMEf1WzUbw

Both videos credited to Jun Lou/Rice University.


####

About Rice University
Located in Houston, Rice University is consistently ranked one of America's best teaching and research universities. Known for its "unconventional wisdom," Rice is distinguished by its: size -- 3,102 undergraduates and 2,237 graduate students; selectivity -- 12 applicants for each place in the freshman class; resources -- an undergraduate student-to-faculty ratio of 5-to-1; sixth largest endowment per student among American private research universities; residential college system, which builds communities that are both close-knit and diverse; and collaborative culture, which crosses disciplines, integrates teaching and research, and intermingles undergraduate and graduate work.

For more information, please click here

Contacts:
David Ruth
Associate Director for National Media Relations
Rice University
Direct: 713-348-6327
Cell: 612-702-9473

Copyright © Rice 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

Researchers develop artificial building blocks of life March 8th, 2024

How surface roughness influences the adhesion of soft materials: Research team discovers universal mechanism that leads to adhesion hysteresis in soft materials March 8th, 2024

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

Physics

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024

Scientists use heat to create transformations between skyrmions and antiskyrmions January 12th, 2024

Focused ion beam technology: A single tool for a wide range of applications January 12th, 2024

Possible Futures

Two-dimensional bimetallic selenium-containing metal-organic frameworks and their calcinated derivatives as electrocatalysts for overall water splitting March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Nanoelectronics

Interdisciplinary: Rice team tackles the future of semiconductors Multiferroics could be the key to ultralow-energy computing October 6th, 2023

Key element for a scalable quantum computer: Physicists from Forschungszentrum Jülich and RWTH Aachen University demonstrate electron transport on a quantum chip September 23rd, 2022

Reduced power consumption in semiconductor devices September 23rd, 2022

Atomic level deposition to extend Moore’s law and beyond July 15th, 2022

Announcements

What heat can tell us about battery chemistry: using the Peltier effect to study lithium-ion cells March 8th, 2024

Curcumin nanoemulsion is tested for treatment of intestinal inflammation: A formulation developed by Brazilian researchers proved effective in tests involving mice March 8th, 2024

The Access to Advanced Health Institute receives up to $12.7 million to develop novel nanoalum adjuvant formulation for better protection against tuberculosis and pandemic influenza March 8th, 2024

Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024

Tools

First direct imaging of small noble gas clusters at room temperature: Novel opportunities in quantum technology and condensed matter physics opened by noble gas atoms confined between graphene layers January 12th, 2024

New laser setup probes metamaterial structures with ultrafast pulses: The technique could speed up the development of acoustic lenses, impact-resistant films, and other futuristic materials November 17th, 2023

Ferroelectrically modulate the Fermi level of graphene oxide to enhance SERS response November 3rd, 2023

The USTC realizes In situ electron paramagnetic resonance spectroscopy using single nanodiamond sensors November 3rd, 2023

Grants/Sponsored Research/Awards/Scholarships/Gifts/Contests/Honors/Records

Discovery of new Li ion conductor unlocks new direction for sustainable batteries: University of Liverpool researchers have discovered a new solid material that rapidly conducts lithium ions February 16th, 2024

$900,000 awarded to optimize graphene energy harvesting devices: The WoodNext Foundation's commitment to U of A physicist Paul Thibado will be used to develop sensor systems compatible with six different power sources January 12th, 2024

Catalytic combo converts CO2 to solid carbon nanofibers: Tandem electrocatalytic-thermocatalytic conversion could help offset emissions of potent greenhouse gas by locking carbon away in a useful material January 12th, 2024

'Sudden death' of quantum fluctuations defies current theories of superconductivity: Study challenges the conventional wisdom of superconducting quantum transitions January 12th, 2024

Alliances/Trade associations/Partnerships/Distributorships

Manchester graphene spin-out signs $1billion game-changing deal to help tackle global sustainability challenges: Landmark deal for the commercialisation of graphene April 14th, 2023

Chicago Quantum Exchange welcomes six new partners highlighting quantum technology solutions, from Chicago and beyond September 23rd, 2022

CEA & Partners Present ‘Powerful Step Towards Industrialization’ Of Linear Si Quantum Dot Arrays Using FDSOI Material at VLSI Symposium: Invited paper reports 3-step characterization chain and resulting methodologies and metrics that accelerate learning, provide data on device pe June 17th, 2022

University of Illinois Chicago joins Brookhaven Lab's Quantum Center June 10th, 2022

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