Featured Research

from universities, journals, and other organizations

Diamond film possible without the pressure: Rules for ultrathin 'diamane' devised

Date:
February 3, 2014
Source:
Rice University
Summary:
Theoreticians map a phase diagram for diamane, an atomically thin film of perfect diamond that might be created through chemical means with little or no pressure.

The phase diagram developed by scientists at Rice University and in Moscow describes the conditions necessary for the chemical creation of thin films of diamond from stacks of single-atomic-layer graphene.
Credit: Pavel Sorokin/Technological Institute for Superhard and Novel Carbon Materials

Perfect sheets of diamond a few atoms thick appear to be possible even without the big squeeze that makes natural gems.

Scientists have speculated about it and a few labs have even seen signs of what they call diamane, an extremely thin film of diamond that has all of diamond's superior semiconducting and thermal properties.

Now researchers at Rice University and in Russia have calculated a "phase diagram" for the creation of diamane. The diagram is a road map. It lays out the conditions -- temperature, pressure and other factors -- that would be necessary to turn stacked sheets of graphene into a flawless diamond lattice.

In the process, the researchers determined diamane could be made completely chemically, with no pressure at all, under some circumstances.

The team led by Rice theoretical physicist Boris Yakobson and Pavel Sorokin, a former postdoctoral associate at Rice and now a senior researcher at the Technological Institute for Superhard and Novel Carbon Materials in Moscow, reported results in the American Chemical Society journal Nano Letters.

"Diamanes have a wide potential range of application," Sorokin said. "They can be applied as very thin, dielectric hard films in nanocapacitors or mechanically stiff, nanothick elements in nanoelectronics. Also, diamanes have potential for application in nano-optics.

"The possibility of obtaining such a quasi-two-dimensional object is intriguing, but available experimental data prevents the expectation of its fabrication using traditional methods. However, the 'bottom-up' approach proposed by Richard Feynman allows the fabrication of diamanes from smaller objects, such as graphene."

The researchers built computer models to simulate the forces applied by every atom involved in the process. That includes the graphene, the single-atom-thick form of carbon and one of the strongest substances in the universe, as well as the hydrogen (or, alternately, a halogen) that promotes the reaction.

Conditions, they learned, need to be just right for a short stack of graphene pancakes to collapse into a diamond matrix -- or vice versa -- via chemistry.

"A phase diagram shows you which phase dominates the ground state for each pressure and temperature," Yakobson said. "In the case of diamane, the diagram is unusual because the result also depends on thickness, the number of layers of graphene. So we have a new parameter."

Hydrogen isn't the only possible catalyst, he said, but it's the one they used in their calculations. "When the hydrogen attacks, it takes one electron from a carbon atom in graphene. As a result, a bond is broken and another electron is left hanging on the other side of the graphene layer. It's now free to connect to a carbon atom on the adjacent sheet with little or no pressure.

"If you have several layers, you get a domino effect, where hydrogen starts a reaction on top and it propagates through the bonded carbon system," he said. "Once it zips all the way through, the phase transition is complete and the crystal structure is that of diamond."

Yakobson said the paper doesn't cover a possible deal-breaker. "The conversion from one phase to another starts from a small seed, a nucleation site, and in this process there's always what is called a nucleation barrier. We don't calculate that here." He said carbon normally prefers to be graphite (the bulk form of carbon used as pencil lead) rather than diamond, but a high nucleation barrier prevents diamond from making the transition.

"Thermodynamically, an existing diamond should become graphite, but it doesn't happen for exactly this reason," Yakobson said. "So sometimes it's a good thing. But if we want to make flat diamond, we need to find ways to circumvent this barrier."

He said the manufacture of synthetic diamond, which was first reliably made in the 1950s, requires very high pressures of about 725,000 pounds per square inch. Manufactured diamonds are used in hardened tools for cutting, as abrasives and even as high-quality gemstones grown via techniques that simulate the temperatures and pressures found deep in Earth, where natural diamond is forged.

Diamond films are also routinely made via chemical vapor deposition, "but they're always very poor quality because they're polycrystalline," Yakobson said. "For mechanical purposes, like very expensive sandpaper, they're perfect. But for electronics, you would need high quality for it to serve as a wide-band gap semiconductor."

The paper's lead author is Alexander Kvashnin, a former visiting student at Rice and a graduate student at the Moscow Institute of Physics and Technology (MIPT). Co-author Leonid Chernozatonskii is a researcher at the Emanuel Institute of Biochemical Physics at the Russian Academy of Sciences, Moscow. Sorokin holds appointments at MIPT and the National University of Science and Technology, Moscow. Yakobson is Rice's Karl F. Hasselmann Professor of Mechanical Engineering and Materials Science, a professor of chemistry and a member of the Richard E. Smalley Institute for Nanoscale Science and Technology.

The U.S. Air Force Office of Scientific Research, the U.S. Office of Naval Research, the Ministry of Education and Science of the Russian Federation and the Russian Foundation for Basic Research supported the study.


Story Source:

The above story is based on materials provided by Rice University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Alexander G. Kvashnin, Leonid A. Chernozatonskii, Boris I. Yakobson, Pavel B. Sorokin. Phase Diagram of Quasi-Two-Dimensional Carbon, From Graphene to Diamond. Nano Letters, 2014; 140127153947007 DOI: 10.1021/nl403938g#sthash.0qydf5Rx.dpuf

Cite This Page:

Rice University. "Diamond film possible without the pressure: Rules for ultrathin 'diamane' devised." ScienceDaily. ScienceDaily, 3 February 2014. <www.sciencedaily.com/releases/2014/02/140203155201.htm>.
Rice University. (2014, February 3). Diamond film possible without the pressure: Rules for ultrathin 'diamane' devised. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/2014/02/140203155201.htm
Rice University. "Diamond film possible without the pressure: Rules for ultrathin 'diamane' devised." ScienceDaily. www.sciencedaily.com/releases/2014/02/140203155201.htm (accessed July 22, 2014).

Share This




More Matter & Energy News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Government Approves East Coast Oil Exploration

Government Approves East Coast Oil Exploration

AP (July 18, 2014) The Obama administration approved the use of sonic cannons to discover deposits under the ocean floor by shooting sound waves 100 times louder than a jet engine through waters shared by endangered whales and turtles. (July 18) Video provided by AP
Powered by NewsLook.com
Sunken German U-Boat Clearly Visible For First Time

Sunken German U-Boat Clearly Visible For First Time

Newsy (July 18, 2014) The wreckage of the German submarine U-166 has become clearly visible for the first time since it was discovered in 2001. Video provided by Newsy
Powered by NewsLook.com
Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Obama: U.S. Must Have "smartest Airports, Best Power Grid"

Reuters - US Online Video (July 17, 2014) President Barak Obama stopped by at a lunch counter in Delaware before making remarks about boosting the nation's infrastructure. Mana Rabiee reports. Video provided by Reuters
Powered by NewsLook.com
Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

Crude Oil Prices Bounce Back After Falling Below $100 a Barrel

TheStreet (July 16, 2014) Oil Futures are bouncing back after tumbling below $100 a barrel for the first time since May yesterday. Jeff Grossman is the president of BRG Brokerage and trades at the NYMEX. Grossman tells TheStreet the Middle East is always a concern for oil traders. Oil prices were pushed down in recent weeks on Libya increasing its production. Supply disruptions in Iraq fading also contributed to prices falling. News from China's economic front showing a growth for the second quarter also calmed fears on its slowdown. Jeff Grossman talks to TheStreet's Susannah Lee on this and more on the Energy Department's Energy Information Administration (EIA) report. Video provided by TheStreet
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins