Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Not all diamonds are forever

23.05.2014

Rice University researchers see nanodiamonds created in coal fade away in seconds

Images taken by Rice University scientists show that some diamonds are not forever.


The dark spots in these images are nanodiamonds formed in hydrogenated anthracite coal when hit by beams from an electron microscope, according to researchers at Rice University. (Credit: Billups Lab/Rice University)

The Rice researchers behind a new study that explains the creation of nanodiamonds in treated coal also show that some microscopic diamonds only last seconds before fading back into less-structured forms of carbon under the impact of an electron beam. The research by Rice chemist Ed Billups and his colleagues appears in the American Chemical Society’s Journal of Physical Chemistry Letters.

Billups and Yanqiu Sun, a former postdoctoral researcher in his lab, witnessed the interesting effect while working on ways to chemically reduce carbon from anthracite coal and make it soluble. First they noticed nanodiamonds forming amid the amorphous, hydrogen-infused layers of graphite.

... more about:
»diamonds »energy »experiments »macroscale »reaction

It happened, they discovered, when they took close-ups of the coal with an electron microscope, which fires an electron beam at the point of interest. Unexpectedly, the energy input congealed clusters of hydrogenated carbon atoms, some of which took on the lattice-like structure of nanodiamonds.

“The beam is very powerful,” Billups said. “To knock hydrogen atoms off of something takes a tremendous amount of energy.”

Even without the kind of pressure needed to make macroscale diamonds, the energy knocked loose hydrogen atoms to prompt a chain reaction between layers of graphite in the coal that resulted in diamonds between 2 and 10 nanometers wide.

But the most “nano” of the nanodiamonds were seen to fade away under the power of the electron beam in a succession of images taken over 30 seconds.

“The small diamonds are not stable and they revert to the starting material, the anthracite,” Billups said.

Billups turned to Rice theoretical physicist Boris Yakobson and his colleagues at the Technological Institute for Superhard and Novel Carbon Materials in Moscow to explain what the chemists saw. Yakobson, Pavel Sorokin and Alexander Kvashnin had already come up with a chart — called a phase diagram — that demonstrated how thin diamond films might be made without massive pressure.

They used similar calculations to show how nanodiamonds could form in treated anthracite and subbituminous coal. In this case, the electron microscope’s beam knocks hydrogen atoms loose from carbon layers. Then the dangling bonds compensate by connecting to an adjacent carbon layer, which is prompted to connect to the next layer. The reaction zips the atoms into a matrix characteristic of diamond until pressure forces the process to halt.

Natural, macroscale diamonds require extreme pressures and temperatures to form, but the phase diagram should be reconsidered for nanodiamonds, the researchers said.

“There is a window of stability for diamonds within the range of 19-52 angstroms (tenths of a nanometer), beyond which graphite is more stable,” Billups said. Stable nanodiamonds up to 20 nanometers in size can be formed in hydrogenated anthracite, they found, though the smallest nanodiamonds were unstable under continued electron-beam radiation.

Billups noted subsequent electron-beam experiments with pristine anthracite formed no diamonds, while tests with less-robust infusions of hydrogen led to regions with “onion-like fringes” of graphitic carbon, but no fully formed diamonds. Both experiments lent support to the need for sufficient hydrogen to form nanodiamonds.

Kvashnin is a former visiting student at Rice and a graduate student at the Moscow Institute of Physics and Technology (MIPT). 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. Billups is a professor of chemistry at Rice.

The Robert A. Welch Foundation, the Ministry of Education and Science of the Russian Federation and the Russian Foundation for Basic Research supported the research.

David Ruth | Eurek Alert!
Further information:
http://www.rice.edu

Further reports about: diamonds energy experiments macroscale reaction

More articles from Life Sciences:

nachricht Velcro for human cells
16.01.2019 | Albert-Ludwigs-Universität Freiburg im Breisgau

nachricht More efficient solar cells imitate photosynthesis
16.01.2019 | Friedrich-Alexander-Universität Erlangen-Nürnberg

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Flying Optical Cats for Quantum Communication

Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.

In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...

Im Focus: Nanocellulose for novel implants: Ears from the 3D-printer

Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.

It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:

Im Focus: Elucidating the Atomic Mechanism of Superlubricity

The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.

One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...

Im Focus: Mission completed – EU partners successfully test new technologies for space robots in Morocco

Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.

Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...

Im Focus: Programming light on a chip

Research opens doors in photonic quantum information processing, optical signal processing and microwave photonics

Researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed a new integrated photonics platform that can...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Our digital society in 2040

16.01.2019 | Event News

11th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Aachen, 3-4 April 2019

14.01.2019 | Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

 
Latest News

Velcro for human cells

16.01.2019 | Life Sciences

Kiel physicists discover new effect in the interaction of plasmas with solids

16.01.2019 | Physics and Astronomy

The pace at which the world’s permafrost soils are warming

16.01.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>