Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

For future superconductors, a little bit of lithium may do hydrogen a lot of good

08.10.2009
Study suggests strategies for converting hydrogen to metal at significantly lower pressures

Scientists have a long and unsuccessful history of attempting to convert hydrogen to a metal by squeezing it under incredibly high and steady pressures.

Metallic hydrogen is predicted to be a high-temperature superconductor. A superconductor is a state of matter where electrons, and thus electricity, can flow indefinitely and without resistance.

In a paper published this week in the online edition of the Proceedings of the National Academy of Sciences, a team of scientists from Cornell University and the State University of New York at Stony Brook announce a theoretical study that predicts the metallization of hydrogen-rich mixtures at significantly lower pressures.

By adding small amounts of lithium to hydrogen, the study calculates that the resulting system may be metalized at around one-fourth the pressure required to metalize pure hydrogen. Funding for the project was provided by the National Science Foundation (NSF).

Hydrogen and lithium are the first and third lightest elements in the universe, respectively. Under the temperature and pressures found on Earth, hydrogen is a gas and lithium is a metal. In hydrogen gas, the atoms are robustly bonded together in pairs and each hydrogen atom contributes one electron to the bonding. In chemistry shorthand, hydrogen is called H2.

Hydrogen and lithium normally react with each other to form a stable compound. This lithium-hydrogen compound, or LiH, is not metallic.

Metallic hydrogen is thought to be present in the interiors of planets like Jupiter and Saturn because of the intense gravitational forces and pressures that are found there.

On Earth, researchers have tried to pry loose hydrogen's electron by squeezing it between the facets of a diamond anvil cell under pressures up to 3.4 million atmospheres. The pressure at sea level is one atmosphere. The pressure at the center of the Earth is around 3.5 million atmospheres. Scientists have not been successful with this method of steady pressures. They have been, however, with shock-wave methods.

To get around hydrogen's decidedly fixed stance of not becoming a metal under currently accessible laboratory pressures, the research team used sophisticated computer programs.

The programs theoretically calculate if hydrogen can be metalized by combining a lithium atom with varying numbers of hydrogen atoms. The programs also compute if metallic hydrogen can be made under pressures achievable in a laboratory.

The lithium and hydrogen combinations predicted by the study currently do not exist on Earth.

One of the combinations predicted by the team contains one lithium atom for every six hydrogen atoms or LiH6 (see top right image). The complex calculations predict that in the hypothetical compound the Li atom is triggered to release its lone outer electron, which is then distributed over the three H2 molecules.

Under pressure, the hypothetical reaction forms a stable and metallic hydrogen compound.

The calculations also predict that LiH6 could be a metal at normal pressures. However, under these conditions it is not stable and would decompose to form LiH and H2.

"The stable and metallic LiH6 compound is predicted to form around 1 million atmospheres, which is around 25 percent of the pressure required to metalize hydrogen by itself," said Eva Zurek, lead author of the paper and an assistant professor of chemistry at The State University of New York, Buffalo.

"Interestingly, between approximately 1 and 1.6 million atmospheres, all the LiH combinations studied were stable or metastable and all were metallic," said Roald Hoffmann, co-author, recipient of the 1981 Nobel Prize in chemistry and Cornell's Frank H.T. Rhodes Professor of Humane Letters, Emeritus.

Another one of the hypothetical compounds studied by the team was composed of one lithium atom and two hydrogen atoms or LiH2 (see bottom right image).

"The theoretical study opens the exciting possibility that non-traditional combinations of light elements under high pressure can produce metallic hydrogen under experimentally accessible pressures and lead to the discovery of new materials and new states of matter," said Daryl Hess, a program director in the NSF Division of Materials Research.

"Once again, these researchers have taken chemistry to a new frontier," said Carol Bessel, a program director in the NSF Division of Chemistry. "They have described, through their theories and calculations, molecules that test our fundamental assumptions about atoms, molecules and structures. In doing so, they challenge the experimentalists to make what they have imagined in their minds a reality to be held in the hand."

The team members believe the information gleaned from the study suggests that one may combine large amounts of hydrogen with other elements. The information may also some day assist with the design of a metallic hydrogen-based superconductor.

"We have already been in touch with laboratory experimentalists about how LiH6 might be fabricated, starting perhaps with very finely divided forms of the common LiH compound along with extra hydrogen," said Neil W. Ashcroft, co-author, and Cornell's Horace White Professor of Physics, Emeritus.

Additional authors include Artem R. Oganov, an associate professor, and Andriy O. Lyakhov, a post doctoral research associate, of the State University of New York at Stony Brook, Department of GeoSciences. Zurek was a postdoctoral associate in Hoffmann's research group when the studies were completed.

Funding for the study was provided by the NSF Divisions of Chemistry and Materials Research. The research was also supported in part by NSF through TeraGrid resources provided by the National Center for Supercomputing Applications.

Jennifer A. Grasswick | EurekAlert!
Further information:
http://www.nsf.gov

More articles from Power and Electrical Engineering:

nachricht Multicrystalline Silicon Solar Cell with 21.9 % Efficiency: Fraunhofer ISE Again Holds World Record
20.02.2017 | Fraunhofer-Institut für Solare Energiesysteme ISE

nachricht Six-legged robots faster than nature-inspired gait
17.02.2017 | Ecole Polytechnique Fédérale de Lausanne

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Switched-on DNA

20.02.2017 | Materials Sciences

Second cause of hidden hearing loss identified

20.02.2017 | Health and Medicine

Prospect for more effective treatment of nerve pain

20.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>