Until now, atoms in physical matter were understood to exist typically in one of three states — solid, liquid or gas. An international team of physicists led by the University of Edinburgh has found, however, that some elements can, when subjected to extreme conditions, take on the properties of both solid and liquid states.
Potassium pearls under paraffin oil. Image credit: Images of Elements / CC BY 3.0.
Applying high pressures and temperatures to potassium creates a state in which most of the element’s atoms form a solid lattice structure.
However, the structure also contains a second set of potassium atoms that are in a fluid arrangement.
“Potassium is one of the simplest metals we know, yet if you squeeze it, it forms very complicated structures,” said lead author Dr. Andreas Hermann, from the School of Physics and Astronomy at the University of Edinburgh.
Until now, it was unclear if these structures represented a distinct state of matter — named the chain-melted state — or existed as transition stages between two distinct states.
Dr. Hermann and colleagues used powerful computer simulations to study the existence of the new state.
Simulating how up to 20,000 potassium atoms behave under extreme conditions revealed that the structures formed represent the stable chain-melted state.
“Applying pressure to the atoms leads to the formation of two interlinked solid lattice structures,” the researchers said.
“Chemical interactions between atoms in one lattice are strong, meaning they stay in a solid form when the structure is heated, while the other atoms melt into a liquid state.”
“Over half a dozen elements — including sodium and bismuth — are thought to be capable of existing in the newly-discovered state.”
The team’s work will be published in the Proceedings of the National Academy of Sciences.
_____
Andreas Hermann et al. 2019. On the chain-melted phase of matter. PNAS, in press; doi: 10.1073/pnas.1900985116
