Researchers from Sweden’s Linköping University, along with colleagues from Europe and the US, have for the first time witnessed interactions between the innermost electrons in the atomic nuclei of the metal osmium (Os) in experiments conducted at extremely high pressures.
The findings, which have been published in the journal Nature, represent a “giant leap” in the understanding of how matter functions, lead investigator and theoretical physics professor Igor Abrikosov said in a statement. This knowledge will help researchers develop materials that are better able to withstand extreme conditions, he added.
At ambient pressure, metallic osmium is the densest known element, and also has one of the highest cohesive energies and melting temperatures, the study authors wrote. It is also highly incompressible. How it behaves at higher pressures, however, has been poorly understood as osmium had only previously been studied at pressures of less than 75 gigapascals.
Findings may result in discovery of new states of matter
As pressure increases, the properties of a material changes, they explained. For instance, the distance between the atoms decrease, and the highly-mobile outer electrons (also called valence electrons) begin to interact with one another. However, in most cases, the inner electrons still move steadily around their atomic nuclei and do not interact with each other.
Previously, the highest pressure achieved by scientists was 400 gigapascals, or approximately the same pressure as the center of the Earth. Using a new method, though, Abrikosov and his fellow researchers were able to achieve a pressure twice that level. They compressed osmium, a metal nearly as incompressible as diamond, to these elevated levels to see what happened.
While they found no significant changes to the valence electrons, supercomputer calculations at the National Supercomputer Centre (NSC) in Linköping ultimately found that the innermost electrons began interacting with one another as a result of the extreme pressure. This was the first time this behavior had been observed, and could lead to even bigger discoveries.
“The ability to affect the core electrons under static high-pressure experimental conditions,” the authors wrote, “even for incompressible metals such as Os, opens up opportunities to search for new states of matter under extreme compression.” Abrikosov called the findings “exciting” and added that it “opens up a whole box of new questions for future research.”
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(Image credit: Elena Bykova/University of Bayreuth)
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