Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Experimental explanation of supercooling : why water does not freeze in the clouds

Droplet of a gold-silicon liquid alloy on a silicon (111) surface. Pentagonal clusters formed at the interface exhibit a denser structure compared to solid gold and prevent the liquid from crystallization at temperatures as low as 300 Kelvin below the solidification temperature. Graphics: M.Collignon
Droplet of a gold-silicon liquid alloy on a silicon (111) surface. Pentagonal clusters formed at the interface exhibit a denser structure compared to solid gold and prevent the liquid from crystallization at temperatures as low as 300 Kelvin below the solidification temperature. Graphics: M.Collignon

Abstract:
Supercooling, a state where liquids do not solidify even below their normal freezing point, still puzzles scientists today. A good example of this phenomenon is found everyday in meteorology: clouds in high altitude are an accumulation of supercooled droplets of water below their freezing point. Scientists from the Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), the Centre National de Recherche Scientifique (CNRS) and the ESRF have found an experimental explanation of the phenomenon of supercooling. Their research is published this week in Nature.

Experimental explanation of supercooling : why water does not freeze in the clouds

Grenoble, France | Posted on April 24th, 2010

Supercooled liquids are trapped in a metastable state even well below their freezing point, which can only be achieved in liquids that do not contain seeds that may trigger crystallization. Clouds at high altitude are a good example for this: they contain tiny droplets of water that, in the absence of seed crystals do not form ice despite the low temperatures. In everyday life, though, there is usually some crystalline impurity in contact with the liquid that will trigger the crystallization process, and therefore the freezing. Controlling solidification behaviour is important for applications ranging from hail prevention up to technological processes such as welding and casting or even the growth of semiconductor nanostructures.

Supercooling was discovered already in 1724 by Fahrenheit, but even today the phenomenon remains a subject for intense discussions. Over the last 60 years the very existence of deep supercooling has led to speculations that the internal structure of liquids could be incompatible with crystallization. Models propose that a significant fraction of the atoms in liquids arrange in five-fold coordinated clusters. To form a crystal however, one needs a structure that can be repeated periodically, filling the entire space. This is not possible with five-fold coordinated clusters. In the two-dimensional analogue, a plane cannot be filled by pentagons only, whereas triangles, rectangles or hexagons can fill a plane perfectly. In this example, pentagons are an obstacle to crystallization.

Until today there was no experimental proof that this five-fold coordinated structures are at the origin of supercooling. The researchers from the CEA, CNRS and ESRF studied the structure of a particular liquid, a gold-silicon alloy, in contact with a specially decorated silicon (111) surface, where the outermost layer of the solid featured pentagonal atomic arrangements. Their findings confirmed that a strong supercooling effect took place. "We studied what happened to the liquid in contact with a five-fold coordinated surface", explains Tobias Schülli, first author of the paper. The team performed the control experiment with the same liquid exposed to three-fold and four-fold coordinated surfaces, which reduced the supercooling effect dramatically. "This constitutes the first experimental proof that pentagonal order is at the origin of supercooling", explains Tobias Schülli.

It was during their studies, originally focusing on the growth of semiconducting nanowires, that the scientists discovered the unusual properties of these liquids. As they were observing the first stage of growth of nanowires, they could see that the metal-semiconductor alloy they used remained liquid at a much lower temperature than its crystallization point and so they decided to investigate this phenomenon. These liquid alloys are popular in applied research as they enable the growth of sophisticated semiconductor nanostructures at low growth temperatures. Most of these nanowire structures are grown on silicon (111), the same surface used by the team. Semiconducting nanowires are promising candidates for future electronic devices. Prominent examples are solar cells, where scientists are working on the integration of silicon nanowires in order to increase their performance.

(with video)

####

About European Synchrotron Radiation Facility (ESRF)
The ESRF operates the most powerful synchrotron radiation source in Europe. Each year several thousand researchers travel to Grenoble where they work in a first-class scientific environment to conduct exciting experiments at the cutting edge of modern science.

At the ESRF, physicists work side by side with chemists and materials scientists. Biologists, medical doctors, meteorologists, geophysicists and archaeologists have become regular users. Industrial applications are also growing, notably in the fields of pharmaceuticals, cosmetics, petrochemicals and microelectronics.

For more information, please click here

Contacts:
Communication Unit
04 76 88 20 56

Copyright © European Synchrotron Radiation Facility (ESRF)

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

‘Oxford Instruments Young Nanoscientist India Award 2015’ to Prof. Arindam Ghosh April 20th, 2015

Nondestructive 3-D Imaging of Biological Cells with Sound April 20th, 2015

Advances in molecular electronics: Lights on -- molecule on: Researchers from Dresden and Konstanz succeed in light-controlled molecule switching April 20th, 2015

Yale-NUS, NUS and UT Austin researchers establish theoretical framework for graphene physics: Making strides towards using graphene to create new electronic devices April 20th, 2015

Videos/Movies

Light in a spin: Researchers demonstrate angular accelerating light April 15th, 2015

Deben reports on the research of Dr Sunita Ho from UCSF using a CCT500 tensile stage to study the behaviour of dental materials April 14th, 2015

Promising future of quantum dots explored in conference: ‘20 Years of Quantum Dots at Los Alamos’ runs April 12-16 April 13th, 2015

A KAIST research team develops a hyper-stretchable elastic-composite energy harvester April 13th, 2015

Possible Futures

A glass fiber that brings light to a standstill: By coupling photons to atoms, light in a glass fiber can be slowed down to the speed of an express train; for a short while it can even be brought to a complete stop April 9th, 2015

Nanotechnology in Medical Devices Market is expected to reach $8.5 Billion by 2019 March 25th, 2015

Nanotechnology Enabled Drug Delivery to Influence Future Diagnosis and Treatments of Diseases March 21st, 2015

Nanocomposites Market Growth, Industry Outlook To 2020 by Grand View Research, Inc. March 21st, 2015

Nanoelectronics

‘Oxford Instruments Young Nanoscientist India Award 2015’ to Prof. Arindam Ghosh April 20th, 2015

Advances in molecular electronics: Lights on -- molecule on: Researchers from Dresden and Konstanz succeed in light-controlled molecule switching April 20th, 2015

Nanotubes with two walls have singular qualities: Rice University lab calculates unique electronic qualities of double-walled carbon nanotubes April 16th, 2015

Solution-grown nanowires make the best lasers April 14th, 2015

Discoveries

Ethylene Nanosorbent, a Novel Product to Decrease Agricultural Waste April 20th, 2015

Quantum model reveals surface structure of water: National Physical Laboratory, IBM and Edinburgh University have used a new quantum model to reveal the molecular structure of water's liquid surface April 20th, 2015

Happily ever after: Scientists arrange protein-nanoparticle marriage: New biotech method could lead to development of HIV vaccine, targeted cancer treatment April 20th, 2015

Advances in molecular electronics: Lights on -- molecule on: Researchers from Dresden and Konstanz succeed in light-controlled molecule switching April 20th, 2015

Announcements

Happily ever after: Scientists arrange protein-nanoparticle marriage: New biotech method could lead to development of HIV vaccine, targeted cancer treatment April 20th, 2015

Nondestructive 3-D Imaging of Biological Cells with Sound April 20th, 2015

Advances in molecular electronics: Lights on -- molecule on: Researchers from Dresden and Konstanz succeed in light-controlled molecule switching April 20th, 2015

Yale-NUS, NUS and UT Austin researchers establish theoretical framework for graphene physics: Making strides towards using graphene to create new electronic devices April 20th, 2015

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