Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Geosciences Professor Establishes Structure Of A New Superhard Form Of Carbon

28.06.2012
An international team led by Artem R. Oganov, PhD, a professor of theoretical crystallography in the Department of Geosciences at Stony Brook University, has established the structure of a new form of carbon. The results of their work, “Understanding the Nature of Superhard Graphite,” were published June 26 in Scientific Reports, a new journal of the Nature Publishing Group.

Dr. Oganov and his team used a novel computational method to demonstrate that the properties of what had previously been thought to be only a hypothetical structure of a superhard form of carbon called “M-carbon” – constructed by Oganov in 2006 – matched perfectly the experimental data on “superhard graphite.”

“Most of the known forms of carbon have a colorful story of their discovery and a multitude of real or potential revolutionary applications,” said Oganov. “Think of diamond, a record-breaking material in more than one way. Think of graphene, destined to become the material of electronics of the future. Or of fullerenes, the discovery of which has started the field of nanoscience.”

The story of yet another form of carbon started in 1963, when Aust and Drickamer compressed graphite at room temperature. High-temperature compression of graphite is known to produce diamond, but at room temperature an unknown form of carbon was produced. This new form, like diamond, was transparent and superhard - but its other properties were inconsistent with diamond or other known forms of carbon.

“The experiment itself is simple and striking: you compress black ultrasoft graphite, and then it suddenly turns into a colorless, transparent, superhard and mysterious new form of carbon – ‘superhard graphite,’” said Oganov. “The experiment was repeated several times since, and the result was the same, but no convincing structural model was produced, due to the low resolution of experimental data.”

Using his breakthrough crystal structure prediction methodology, Oganov in 2006 constructed a new low-energy superhard structure of “M-carbon.” That work resulted in a stream of scientific papers that within two years proposed different “alphabetic” structures, such as F-, O-, P-, R-, S-, T-, W-, X-, Y-, Z-carbons. “The irony was that most of these also had properties compatible with experimental observations on ‘superhard graphite.’ To discriminate between these models, higher-resolution experimental data and additional theoretical insight are required,” he said.

According to Oganov, the reason why diamond is not formed on cold compression of graphite is that the reconstruction needed to transform graphite into diamond is too large and is associated with too great an energy barrier, which can be overcome only at high temperatures, when atoms can jump far. At low temperatures, graphite chooses instead a transformation associated with the lowest activation barrier.

One could establish the structure of ‘superhard graphite’ by finding which structure has the lowest barrier of formation from graphite. To do that, Oganov, his postdoctoral associate Salah Eddine Boulfelfel, and their German colleague, Professor Stefano Leoni, of Dresden University of Technology, used a powerful simulation approach, recently adapted to solid materials, known as transition path sampling. These simulations required some of the world's most powerful supercomputers, and finally proved that "superhard graphite" is indeed identical to M-carbon, earlier predicted by Oganov.

“These calculations are technically extremely challenging, and it took us many months to perform and analyze them. Searching for the truth, you have to be prepared for any outcome, and we were ready to accept if another of the many proposed structures won the contest. But we got lucky, and our own proposal – M-carbon – won,” said Oganov.

Another result of this study is a set of detailed mechanisms of formation of several potential carbon allotropes. These could be used to engineer ways of their synthesis for potential technological applications.

“We don't know yet which applications M-carbon will find, but most forms of carbon did manage to find revolutionary applications, and this amazing material might do so as well,” said Oganov.

Please click here (http://www.youtube.com/watch?v=bm0ZmXpHCk0) for a short video by Salah Eddine Boulfelfel on the “New Carbon Allotrope at High Pressure” from the Artem Oganov Lecture Series.

| Newswise Science News
Further information:
http://www.stonybrook.edu

More articles from Materials Sciences:

nachricht New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University

nachricht Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>