Featured Research

from universities, journals, and other organizations

Oxygen molecule survives to enormously high pressures

Date:
January 30, 2012
Source:
Ruhr-Universitaet-Bochum
Summary:
Using computer simulations, researchers have 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.
Credit: Jian Sun

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.

"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.


Story Source:

The above story is based on materials provided by Ruhr-Universitaet-Bochum. Note: Materials may be edited for content and length.


Journal Reference:

  1. Jian Sun, Miguel Martinez-Canales, Dennis Klug, Chris Pickard, Richard Needs. Persistence and Eventual Demise of Oxygen Molecules at Terapascal Pressures. Physical Review Letters, 2012; 108 (4) DOI: 10.1103/PhysRevLett.108.045503

Cite This Page:

Ruhr-Universitaet-Bochum. "Oxygen molecule survives to enormously high pressures." ScienceDaily. ScienceDaily, 30 January 2012. <www.sciencedaily.com/releases/2012/01/120130093911.htm>.
Ruhr-Universitaet-Bochum. (2012, January 30). Oxygen molecule survives to enormously high pressures. ScienceDaily. Retrieved October 21, 2014 from www.sciencedaily.com/releases/2012/01/120130093911.htm
Ruhr-Universitaet-Bochum. "Oxygen molecule survives to enormously high pressures." ScienceDaily. www.sciencedaily.com/releases/2012/01/120130093911.htm (accessed October 21, 2014).

Share This



More Matter & Energy News

Tuesday, October 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Thanks, Marty McFly! Hoverboards Could Be Coming In 2015

Newsy (Oct. 21, 2014) If you've ever watched "Back to the Future Part II" and wanted to get your hands on a hoverboard, well, you might soon be in luck. Video provided by Newsy
Powered by NewsLook.com
Robots to Fly Planes Where Humans Can't

Robots to Fly Planes Where Humans Can't

Reuters - Innovations Video Online (Oct. 21, 2014) Researchers in South Korea are developing a robotic pilot that could potentially replace humans in the cockpit. Unlike drones and autopilot programs which are configured for specific aircraft, the robots' humanoid design will allow it to fly any type of plane with no additional sensors. Ben Gruber reports. Video provided by Reuters
Powered by NewsLook.com
Graphene Paint Offers Rust-Free Future

Graphene Paint Offers Rust-Free Future

Reuters - Innovations Video Online (Oct. 21, 2014) British scientists have developed a prototype graphene paint that can make coatings which are resistant to liquids, gases, and chemicals. The team says the paint could have a variety of uses, from stopping ships rusting to keeping food fresher for longer. Jim Drury reports. Video provided by Reuters
Powered by NewsLook.com
Portable Breathalyzer Gets You Home Safely

Portable Breathalyzer Gets You Home Safely

Buzz60 (Oct. 21, 2014) Breeze, a portable breathalyzer, gets you home safely by instantly showing your blood alcohol content, and with one tap, lets you call an Uber, a cab or a friend from your contact list to pick you up. Sean Dowling (@SeanDowlingTV) has the details. Video provided by Buzz60
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:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

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