Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Oxygen molecule survives to enormously high pressures: RUB publication in Physical Review Letters

30.01.2012
RUB researcher calculates stability thresholds and structures of solid oxygen / Physical Review Letters: Oxygen as insulator, semiconductor, and metal

Using computer simulations, a RUB researcher has shown that the oxygen molecule (O2) is stable up to pressures of 1.9 terapascal, which is about nineteen million times higher than atmosphere pressure. Above that, it polymerizes, i.e. builds larger molecules or structures.


Structures of solid oxygen under high pressure: At 1.9 TPa, oxygen polymerizes and assumes a square spiral-like structure, which is semi-conducting (top). With increasing pressure, the polymer exhibits metallic properties (zig-zag chain-like phase, mid). Then, the structure changes into a metallic layer phase (bottom). The coloured areas represent the charge density in one layer of the structure. Figure: Jian Sun

“This is very surprising” says Dr. Jian Sun from the Department of Theoretical Chemistry. “Other simple molecules like nitrogen or hydrogen do not survive such high pressures.” In cooperation with colleagues from University College London, the University of Cambridge, and the National Research Council of Canada, the researcher also reports that the behaviour of oxygen with increasing pressure is very complicated. It's electrical conductivity first increases, then decreases, and finally increases again. The results are published in Physical Review Letters.

Weaker bonds, greater stability

The oxygen atoms in the O2 molecule are held together by a double covalent bond. Nitrogen (N2), on the other hand, possesses a triple bond. “You would think that the weaker double bond is easier to break than the triple bond and that oxygen would therefore polymerize at lower pressures than nitrogen” says Sun. “We found the opposite, which is astonishing at first sight.”

Coming together when pressure increases

However, in the condensed phase when pressure increases, the molecules become closer to each other. The research team suggests that, under these conditions, the electron lone pairs on different molecules repel one another strongly, thus hindering the molecules from approaching each other. Since oxygen has more lone pairs than nitrogen, the repulsive force between these molecules is stronger, which makes polymerization more difficult. However, the number of lone pairs cannot be the only determinant of the polymerization pressure. “We believe that it is a combination of the number of lone pairs and the strength of the bonds between the atoms”, says Sun.

The many structures of oxygen

At high pressures, gaseous molecules such as hydrogen, carbon monoxide, or nitrogen polymerize into chains, layers, or framework structures. At the same time they usually change from insulators to metals, i.e. they become more conductive with increasing pressure. The research team, however, showed that things are more complicated with oxygen. Under standard conditions, the molecule has insulating properties. If the pressure increases, oxygen metallises and becomes a superconductor. With further pressure increase, its structure changes into a polymer and it becomes semi-conducting. If the pressure rises even more, oxygen once more assumes metallic properties, meaning that the conductivity goes up again. The metallic polymer structure finally changes into a metallic layered structure.

Inside planets

“The polymerization of small molecules under high pressure has attracted much attention because it helps to understand the fundamental physics and chemistry of geological and planetary processes” explains Sun. “For instance, the pressure at the centre of Jupiter is estimated to be about seven terapascal. It was also found that polymerized molecules, like N2 and CO2, have intriguing properties, such as high energy densities and super-hardness.” Dr. Jian Sun joined the RUB-research group of Prof. Dr. Dominik Marx as a Humboldt Research Fellow in 2008 to work on vibrational spectroscopy of aqueous solutions. In parallel to this joint work in "Solvation Science" he developed independent research interests into high pressure chemical physics as an Early Career Researcher.

Bibliographic record

J. Sun, M. Martinez-Canales, D.D. Klug, C.J. Pickard, R.J. Needs (2012): Persistence and eventual demise of oxygen molecules at terapascal pressures, Physical Review Letters, doi: 10.1103/PhysRevLett.108.045503

Further information

Dr. Jian Sun, Department of Theoretical Chemistry, Faculty of Chemistry and Biochemistry at the Ruhr-Universität, 44780 Bochum, Tel.: +49/234/32-22121
jian.sun@theochem.rub.de

Click for more

Department of Theoretical Chemistry
http://www.theochem.rub.de/home.en.html

Editorial journalist
Dr. Julia Weiler

Dr. Josef König | idw
Further information:
http://www.theochem.rub.de/home.en.html
http://www.ruhr-uni-bochum.de

More articles from Physics and Astronomy:

nachricht One-way roads for spin currents
23.05.2018 | Singapore University of Technology and Design

nachricht Tunable diamond string may hold key to quantum memory
23.05.2018 | Harvard John A. Paulson School of Engineering and Applied 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: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Research reveals how order first appears in liquid crystals

23.05.2018 | Life Sciences

Space-like gravity weakens biochemical signals in muscle formation

23.05.2018 | Life Sciences

NIST puts the optical microscope under the microscope to achieve atomic accuracy

23.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>