Americium occupies a pivotal position in the actinide series with regard to the behavior of 5f electrons. High-pressure techniques together with synchrotron radiation have been used to determine the structural behavior up to 100 GPa. We have resolved earlier controversial findings regarding americium and find that our experimental results are in discord with recent theoretical predictions. We have two new findings: (1) that there exists a critical, new structural link between americium under pressure and its near neighbor, plutonium; and (2) that the 5f electron delocalization in americium occurs in two rather than one step.

No abstract

A new set-up for collecting high-quality data suitable for structural re®nement at high pressure and high temperature has been developed on beamline ID30 at the ESRF. The possibility of using high X-ray energies, high brilliance of third-generation sources and a new fast imaging-plate detector interfaced to the Paris±Edinburgh large-volume press has lead to a signi®cant reduction of acquisition time and improvement of the quality of the data. The feasibility of angle-dispersive X-ray diffraction experiments at high pressure and high temperature, even on light elements, has been demonstrated.

No abstract

No abstract