Navigation Links
Spiraling nanotrees offer new twist on growth of nanowires
Date:5/1/2008

MADISON Since scientists first learned to make nanowires, the nano-sized wires just a few millionths of a centimeter thick have taken many forms, including nanobelts, nanocoils and nanoflowers.

But when University of Wisconsin-Madison chemistry professor Song Jin and graduate student Matthew Bierman accidentally made some pine tree shapes one day complete with tall trunks and branches that tapered in length as they spiraled upward they knew theyd stumbled upon something peculiar.

At the beginning we saw just a couple of trees, and we said, What the heck is going on here? recalls Jin. They were so curious.

Writing in the May 1 edition of Science Express, Jin and his team reveal just how curious the nanotrees truly are. In fact, theyre evidence of an entirely different way of growing nanowires, one that promises to give scientists a powerful means to create new and better nanomaterials for all sorts of applications, including high-performance integrated circuits, biosensors, solar cells, LEDs and lasers.

Until now, most nanowires have been made with metal catalysts, which promote the growth of nanomaterials along one dimension to form long rods. While the branches on Jins trees also elongate in this way, growth of the trunks is driven by a screw dislocation, or defect, in their crystal structure. At the top of the trunk, the defect provides a spiral step for atoms to settle on an otherwise perfect crystal face, causing them stack together in a spiral parking ramp-type structure that quickly lengthens the tip.

Dislocations are fundamental to the growth and characteristics of all crystalline materials, but this is the first time theyve been shown to aid the growth of one-dimensional nanostructures. Engineering these defects, says Jin, may not only allow scientists to create more elaborate nanostructures, but also to investigate the fundamental mechanical, thermal and electronic properties of dislocations in materials.

His team created its nanotrees specifically by applying a slight variation of a synthesis technique called chemical vapor deposition to the material lead sulfide. But the chemists believe the new mechanism will be applicable to many other materials, as well.

We think these findings will motivate a lot of people to do this purposefully, to design dislocation and try to grow nanowires around it, Jin says. Or perhaps people who have grown a structure and were puzzled by it will read our paper and say, Hey, we see something similar in our system, so maybe now we have the solution.

What initially puzzled Jin and his students about their pine tree structures was the long length of the trunks compared with the branches, a difference that indicated the trunks were growing much faster. The result was surprising because when complex, branching nanostructures are grown with metal catalysts, the branches are usually all of similar length because of similar growth rates, leading to boxy shapes rather than the cone-shapes of the trees.

Another oddity was the twist to the trunks, which sent the branches spiraling.

The long and twisting trunks were telling us we had a new growth mode, says Jin. Suspecting dislocation, the team set about refining their technique for growing the pine trees they soon learned to produce entire forests with ease and then confirmed the presence of dislocations with a special type of transmission electron microscopy.

Upon closer examination, the twisting trunks and spiraling branches also turned out to embody a well-known general theory about the mechanical deformation of crystalline materials caused by screw dislocations. Although this so-called Eshelby twist was first calculated back in 1953 and is discussed in many textbooks, Jins experimental results likely offer the best support yet for the theory.

These are beautiful, truly intriguing structures, but behind them is also a really beautiful, interesting science, says Jin. Once you understand it, you just feel sosatisfied.


'/>"/>

Contact: Song Jin
jin@chem.wisc.edu
608-262-1562
University of Wisconsin-Madison
Source:Eurekalert

Related biology technology :

1. Emisphere Technologies, Inc. Announces Pricing of Registered Direct Offering
2. Roche Extends Tender Offer for Ventana
3. ATS Medical Expands Open Pivot Heart Valve Offerings
4. New 200 mg Vial for Eloxatin(R) (Oxaliplatin Injection) Offers Greater Convenience and Efficiency of Preparation
5. Updated NIH Guidelines Offer Valuable Information on Asthma Diagnosis and Management
6. ARYx Therapeutics, Inc. Files Registration Statement for Initial Public Offering
7. Anacor Files Registration Statement for Initial Public Offering
8. NPS Pharmaceuticals Commences Tender Offer for 3.0% Convertible Notes Due 2008
9. Clinsys Clinical Research, Inc. Announces Key Hires, Rajagopalan Srinivasan, Ph.D, to Strengthen Global Biostatistics Service Offering and Christopher Gregory, Ph.D, to Scientific Affairs
10. Schering-Plough Announces Pricing of Senior Notes Offering
11. Exelixis Announces Closing of Public Offering of Common Stock
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:6/23/2016)... ... , ... Supplyframe, the Industry Network for electronics hardware design ... Located in Pasadena, Calif., the Design Lab’s mission is to bring together inventors ... and brought to market. , The Design Lab is Supplyframe’s physical representation of ...
(Date:6/23/2016)... Calif. , June 23, 2016  Blueprint Bio, ... biological discoveries to the medical community, has closed its ... Matthew Nunez . "We have received ... with the capital we need to meet our current ... essentially provide us the runway to complete validation on ...
(Date:6/23/2016)... ... June 23, 2016 , ... ... regulatory and technical consulting, provides a free webinar on Performing Quality ... 13, 2016 at 12pm CT at no charge. , Incomplete investigations are still ...
(Date:6/22/2016)... DIEGO , June 22, 2016 ... that will allow them to produce up to ... from one lot within one week. These high-quality, ... time laboriously preparing cells and spend more time ... possible through a proprietary, high-volume manufacturing process that ...
Breaking Biology Technology:
(Date:4/15/2016)... 2016 Research and Markets has ... Market 2016-2020,"  report to their offering.  , ... ,The global gait biometrics market is expected to ... period 2016-2020. Gait analysis generates multiple ... used to compute factors that are not or ...
(Date:3/31/2016)... March 31, 2016   ... or the "Company") LegacyXChange is excited to ... its soon to be launched online site for trading ... ) will also provide potential shareholders a sense ... technology to an industry that is notorious for fraud. ...
(Date:3/23/2016)... 2016 Einzigartige ... und Stimmerkennung mit Passwörtern     ... MESG ), ein führender Anbieter digitaler Kommunikationsdienste, ... SpeechPro zusammenarbeitet, um erstmals dessen Biometrietechnologie einzusetzen. ... Möglichkeit angeboten, im Rahmen mobiler Apps neben ...
Breaking Biology News(10 mins):