Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Argon is not the 'dope' for metallic hydrogen


Hydrogen is both the simplest and the most-abundant element in the universe, so studying it can teach scientists about the essence of matter. And yet there are still many hydrogen secrets to unlock, including how best to force it into a superconductive, metallic state with no electrical resistance.

"Although theoretically ideal for energy transfer or storage, metallic hydrogen is extremely challenging to produce experimentally," said Ho-kwang "Dave" Mao, who led a team of physicists in researching the effect of the noble gas argon on pressurized hydrogen.

This is an illustration of Ar(H2)2 in the diamond anvil cell. The arrows represent different ways that spectroscopic tools study the effect of extreme pressures on the crystal structure and molecular structure of the compound. (For experts, the red arrow represents Raman spectroscopy, the black arrow represents synchrotron x-ray diffraction, and the gray arrow represents optical absorption spectroscopy.)

Image courtesy of Cheng Ji

It has long been proposed that introducing impurities into a sample of molecular hydrogen, H2, could help ease the transition to a metallic state. So Mao and his team set out to study the intermolecular interactions of hydrogen that's weakly-bound, or "doped," with argon, Ar(H2)2, under extreme pressures. The idea is that the impurity could change the nature of the bonds between the hydrogen molecules, reducing the pressure necessary to induce the nonmetal-to-metal transition. Previous research had indicated that Ar(H2)2 might be a good candidate.

Surprisingly, they discovered that the addition of argon did not facilitate the molecular changes needed to initiate a metallic state in hydrogen. Their findings are published by the Proceedings of the National Academy of Sciences.

The team brought the argon-doped hydrogen up to 3.5 million times normal atmospheric pressure--or 358 gigapascals--inside a diamond anvil cell and observed its structural changes using advanced spectroscopic tools.

What they found was that hydrogen stayed in its molecular form even up to the highest pressures, indicating that argon is not the facilitator many had hoped it would be.

"Counter to predictions, the addition of argon did not create a kind of 'chemical pressure' on the hydrogen, pushing its molecules closer together. Rather, it had the opposite effect," said lead author Cheng Ji.


The study's other co-authors are: Carnegie's Alexander Goncharov, Dmitry Popov, Bing Li, Junyue Wang, Yue Meng, Jesse Smith, and Wenge Yang; as well as Vivekanand Shukla, Naresh Jena, and Rajeev Ahuja of Uppsala University; and Vitali Prakpenka of the University of Chicago.

This work was supported by the U.S. National Science Foundation, the U.S. Department of Energy, the Chinese Academy of Sciences Visiting Professorship for Senior International Scientists and Recruitment of Foreign Experts, the European Erasmus Fellowship program, and the Swedish Research Council.

The Carnegie Institution for Science ( is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

Cheng Ji | EurekAlert!

More articles from Materials Sciences:

nachricht Sensitive grip
23.03.2018 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA

nachricht Keeping a tight hold on things: Robot-mounted vacuum grippers flex their artificial muscles
23.03.2018 | Universität des Saarlandes

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Space observation with radar to secure Germany's space infrastructure

Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.

The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...

Im Focus: Researchers Discover New Anti-Cancer Protein

An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.

The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...

Im Focus: Researchers at Fraunhofer monitor re-entry of Chinese space station Tiangong-1

In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.

Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...

Im Focus: Alliance „OLED Licht Forum“ – Key partner for OLED lighting solutions

Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.

They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...

Im Focus: Mars' oceans formed early, possibly aided by massive volcanic eruptions

Oceans formed before Tharsis and evolved together, shaping climate history of Mars

A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

New solar solutions for sustainable buildings and cities

23.03.2018 | Event News

Virtual reality conference comes to Reutlingen

19.03.2018 | Event News

Ultrafast Wireless and Chip Design at the DATE Conference in Dresden

16.03.2018 | Event News

Latest News

Don't Give the Slightest Chance to Toxic Elements in Medicinal Products

23.03.2018 | Life Sciences

Sensitive grip

23.03.2018 | Materials Sciences

No compromises: Combining the benefits of 3D printing and casting

23.03.2018 | Process Engineering

Science & Research
Overview of more VideoLinks >>>