Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Livermore researchers shed new light on the physical properties of carbon


A team based in Livermore has shed some new light on the phase diagram of carbon at high pressure and temperature.

Graphic simulation of the electronic wave function (MLWF) in liquid carbon at a temperature of 9,000°Kelvin and five million atmospheres of pressure, showing a persistent covalent bonding even under these extreme conditions. At this pressure diamond melts at about 8,000°K.

In particular, the authors determined the solid/liquid and solid/solid phase boundaries for pressures up to 20 million Earth atmospheres and more than 10,000 degrees Kelvin. The simulations provide results on the physical properties of carbon, which are of great importance for devising models of Neptune, Uranus and white dwarf stars, as well as of extrasolar carbon-rich planets.

In its elemental form, carbon is found in coal, graphite, diamond, bucky balls and nanotubes. These are materials with very different properties, yet at the microscopic level they only differ by the geometrical arrangements of carbon atoms.

Elemental carbon has been known since prehistory, and one of its best known forms, diamond, is thought to have been first mined in India more than 2,000 years ago. The properties of diamond and its practical and technological applications have been extensively investigated for many centuries.

Despite important experimental work over the last few decades aimed at studying compressed diamond, the phase boundaries and melting properties of elemental carbon are poorly known, and its electronic properties under extreme conditions are not well understood. Experimental data are scarce because of difficulties in reaching megabar (one million atmospheres) pressures and temperature regimes of thousands of degrees Kelvin in the laboratory.

The research team is composed of Alfredo Correa, Stanimir Bonev and Giulia Galli, all of whom were at Lawrence Livermore National Laboratory (LLNL) at the time the work began. Galli is now a professor at UC Davis, and Bonev is an assistant professor at Dalhousie University in Canada.

“Our results show a consistent description of elemental carbon in a broad range of temperature and pressures and a description of its electronic properties within the same framework,” said Correa, a Student Employee Graduate Research Fellowship (SEGRF) student from UC Berkeley who works in LLNL’s Quantum Simulations Group in the Physics and Advanced Technology Directorate. Correa is the lead author of a paper on the recent findings that appears in the online version of the Proceedings of the National Academy of Sciences for the week of Jan. 23-27.

The researchers also discovered that the diamond/BC8/liquid triple point (the temperature and pressure at which these three phases coexist in thermodynamic equilibrium) is at a lower pressure than previously thought (BC8 denotes a solid phase of carbon into which diamond transforms above 12 megabar at zero temperature). The conditions at which the triple point is found are close to recent estimates of the core conditions (temperature and pressure) in Neptune and Uranus.

“Our simulation results call for a partial revision of current planetary models, especially for the description of their core regions,” Correa said. “Our computational work also may help us interpret future experimental work.”

Founded in 1952, Lawrence Livermore National Laboratory has a mission to ensure national security and to apply science and technology to the important issues of our time. Lawrence Livermore National Laboratory is managed by the University of California for the U.S. Department of Energy’s National Nuclear Security Administration.

Anne Stark | EurekAlert!
Further information:

More articles from Physics and Astronomy:

nachricht Move over, lasers: Scientists can now create holograms from neutrons, too
21.10.2016 | National Institute of Standards and Technology (NIST)

nachricht Finding the lightest superdeformed triaxial atomic nucleus
20.10.2016 | The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

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

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>