The paper, entitled "A little bit of lithium does a lot for hydrogen," presents the first prediction of stable LiHn hydrides (LiH2, LiH6, LiH8). These hypothetical materials demonstrate that nontraditional stoichiometries can considerably expand the view of chemical bonding already under moderate pressure.
Metallic hydrogen, believed to be stable at high pressures, is theorized to be a superconductor at record high temperatures of at least a few hundred Kelvin (room temperature or higher). Due to its high (100%) hydrogen content and high density it is the ultimate energy storage material – if it can be synthesized in large quantities and subsequently brought to ambient conditions in the same metallic form.
For decades, researchers at the top research institutions around the world have predicted exotic properties for metallic hydrogen, but no credible reports of experimental synthesis of solid metallic hydrogen ever appeared because of two primary obstacles. First, metallization of hydrogen requires pressures of about four million atmospheres, which was out of reach of static compression techniques. Extreme pressures, even if they could be reached, imply that only tiny amounts of the material can be prepared, which would be of little practical use. Second, the recovery of this high pressure material to ambient pressure will be almost certainly problematic.
Work of Eva Zurek, assistant professor at the University at Buffalo, her former Cornell University colleagues Roald Hoffmann and Neil W. Ashcroft, in collaboration with Professor Artem R. Oganov and his colleague Andiry O. Lyakhov at Stony Brook University, offers surprising new optimism.
"Synthesis of metallic hydrogen has long been a dream of physicists. A dream that is now one big step closer, thanks to this theoretical work," says Professor Oganov.
"There are fundamental reasons to be excited about this form of metallic hydrogen. Light nucleus of hydrogen behaves like a quantum particle-wave, making it possible that there will be altogether new states of matter, simultaneously superconducting and superfluid."
To uncover these findings, Zurek tapped the powerful computational methods developed by Oganov and Lyakhov – methods which allow one to predict the structure and composition of new stable compounds before they are synthesized in the lab. What Zurek found was that, while LiH is a simple and well-known material at normal conditions, very unusual chemistry appears at pressures above one million atmospheres.
Unexpected hydrogen-rich metallic compounds, such as LiH2, LiH6 and LiH8 become stable. Many of their properties would be similar to those of the long-sought metallic hydrogen, but conditions of synthesis can be readily achieved in the lab. The study also shows a way to prepare metallic almost-hydrogen for possible practical use.
"Finding elements that would form such compounds at still lower pressures is now the most realistic solution to the metallic hydrogen problem and opens the door to a world of new chemistry, where little can be anticipated with traditional chemical concepts – no one would have expected LiH8 , LiH6 or LiH2 to be stable compounds," says Oganov. "It is possible that new important chemical rules will be found along this exploratory path. And who knows, maybe one day this will lead us to room-temperature superconductivity and new twists in the search for hydrogen storage materials."
Greg Filiano | Newswise Science News
Rainbow colors reveal cell history: Uncovering β-cell heterogeneity
22.09.2017 | DFG-Forschungszentrum für Regenerative Therapien TU Dresden
The pyrenoid is a carbon-fixing liquid droplet
22.09.2017 | Max-Planck-Institut für Biochemie
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
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