The researchers used a laser-heated two-stage diamond anvil cell to synthesize materials in the terapascal range (1000 gigapascals). Image: Timofey Fedotenko.
The researchers used a laser-heated two-stage diamond anvil cell to synthesize materials in the terapascal range (1000 gigapascals). Image: Timofey Fedotenko.

A research team from the University of Bayreuth in Germany, together with international partners, has pushed the boundaries of high-pressure and high-temperature research into cosmic dimensions. For the first time, they have succeeded in simultaneously synthesizing and analyzing materials under compression pressures of more than one terapascal (1000 gigapascals).

Such extremely high pressures prevail, for example, at the center of the planet Uranus, and are more than three times higher than the pressure at the center of the Earth. In a paper in Nature, the researchers describe the method they have developed for the synthesis and structural analysis of novel materials at these high pressures.

Theoretical models predict very unusual structures and properties of materials under extreme pressure-temperature conditions. Up to now, however, researchers have not been able to verify these predictions experimentally at compression pressures of more than 200 gigapascals. On the one hand, this is because complex technical requirements are required to expose material samples to such extreme pressures, and, on the other hand, because sophisticated methods for simultaneous structural analyses were lacking.

The experiments reported in the Nature paper therefore open up completely new dimensions for high-pressure crystallography: materials can now be created and studied in the laboratory that exist – if at all – only under extremely high pressures in the vastness of the universe.

“The method we have developed enables us for the first time to synthesize new material structures in the terapascal range and to analyze them in situ – that is: while the experiment is still running,” explains first author Leonid Dubrovinsky of the Bavarian Geoinstitute (BGI) at the University of Bayreuth. “In this way, we learn about previously unknown states, properties and structures of crystals, and can significantly deepen our understanding of matter in general. Valuable insights can be gained for the exploration of terrestrial planets and the synthesis of functional materials used in innovative technologies.”

In the paper, the researchers show how they have generated and visualized in situ novel rhenium compounds using the new method. The compounds in question are a novel rhenium nitride (Re7N3) and a rhenium-nitrogen alloy. These materials were synthesized under extreme pressures in a two-stage diamond anvil cell heated by laser beams, while synchrotron single-crystal X-ray diffraction provided full chemical and structural characterization.

“Two and a half years ago, we were very surprised in Bayreuth when we were able to produce a super-hard metallic conductor based on rhenium and nitrogen that could withstand even extremely high pressures,” says lead author Natalia Dubrovinskaia from the Laboratory of Crystallography at the University of Bayreuth. “If we apply high-pressure crystallography in the terapascal range in the future, we may make further surprising discoveries in this direction. The doors are now wide open for creative materials research that generates and visualizes unexpected structures under extreme pressures.”

This story is adapted from material from the University of Bayreuth, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.