One of the heaviest known elements can be modified more than scientists thought — possibly opening the door to new ways of recycling nuclear fuel and enhanced long-term storage of radioactive elements — according to a recent study published in the journal Nature.
Heavy elements squeezed with diamonds
The international research team behind the discovery showed how curium — element 96 in the periodic table and one of the last ones physically visible to human eyes — reacts to high pressure created when it's squeezed between two diamonds.
Florida State University Professor Thomas Albrecht-Schmitt led the research, joined by collaborators at Aachen University and the University of Buffalo. Their powers combined, they found curium's outer electrons displayed some shifty behavior — changing the element's ability to bond with other elements — are altered when the distance to surrounding lighter atoms is reduced.
"This was not anticipated because the chemistry of curium makes it resistant to these types of changes," said Albrecht-Schmitt, Gregory R. Choppin Professor of Chemistry at Florida State University. "In short, it is quite inert."
Atypical resistance to alteration via diamond squeeze
While only specific curium compounds displayed changes, the discovery fascinated scientists because curium's properties are typically totally resistant to modification, according to phys.org.
The new study was also carried forward by the leadership of University of Buffalo chemistry professor Eva Zurek and Jochen Autschbach, and Manfred Speldrich — an Aachen University, Germany researcher.
Albrecht-Schmitt's contribution in this study is connected to his lab's wider mission to enhance our understanding of heavier, or actinide, elements — resting hauntingly at the bottom of the periodic table.
$10 million for new ways to mitigate nuclear waste
In 2016, the Department of Energy (DoE) gave him $10 million to found the Center for Actinide Science and Technology — to concentrate on accelerating scientific advancements toward better managing nuclear waste.
Despite being on the periodic table for decades, the heavier elements are still largely a mystery to scientists — especially compared to lighter elements like nitrogen and oxygen. "It's an exciting experiment that showed that we have much greater control of the chemistry of these difficult to control elements than previously thought," said Albrecht-Schmitt, according to phys.org.
"The curium (3+) ion we studied has a half-filled outer electron shell that is very difficult to engage in chemical bonding," said Larkin Professor of Chemistry Autschbach, from the University of Buffalo. "An integrated experimental and theoretical approach showed that the application of high pressure to a crystal contained curium (3+), along with sulfur-organic and ammonium ions, causes the outer shell of curium to participate in covalent chemical bonding with sulfur. This may help guide new ways of studying the mysterious behavior of chemically resistant actinide shells."
As we learn more about the heavier side of the periodic table, scientists are opening doors to new strategies to control processes of chemical separation — used to design resilient materials for long-term storage of radioactive elements and nuclear recycling — according to Albrecht-Schmitt. And new knowledge revealed by squeezing heavy elements between diamonds could also apply to other elements.