Plutonium plays a key role in the nuclear industry but its peculiar structural behaviour has baffled physicists for 30 years. Conventional tests of crystal structure are unsuitable for radioactive elements such as plutonium, and current theoretical models fail to predict the surprising jump in its atomic volume that occurs when it is heated. But the theory typically used to explain crystal structure, known as density functional theory, cannot account for this increase. Moreover, density functional theory also predicts magnetic effects that have never been observed. The jump in volume is closely linked to the position of plutonium in the periodic table, according to Savrasov and colleagues.
Plutonium is one of a series of heavy elements known as the actinides.
The electrostatic attraction between the nucleus and the orbiting electrons grows stronger throughout the series because each successive element has an extra electron and proton. Savrasov's group suggests that the 'delta' crystal structure of plutonium is the missing link between plutonium and americium - they believe it combines both localized and delocalized electrons. They found that by incorporating the effects of electron interactions in plutonium, the theory could accurately predict its unusual structural behaviour. Contact us .