Structural Transformations in Actinide Oxides under Extreme Conditions

摘要

Relativistic heavy ions provide a unique opportunity to access a physical regime quite far from the conditions of thermodynamic equilibrium. These projectiles deposit exceptional amounts of kinetic energy (MeV-GeV) within an exceedingly short interaction time (sub-fs) into nanometer-sized volumes of a material, resulting in extremely high energy densities (up to tens of eV/atom). The coupling of these extreme energy depositions with high pressure and high temperature (Fig. 1) can dramatically modify phase transformation pathways leading to important applications at the interfaces of materials research, nuclear science, and geoscience. This innovative experimental approach can be used to study the behavior of materials under extreme conditions, to form and stabilize novel phases, to manipulate the physical and chemical properties of solids at the nanoscale, and to investigate the effects of radioactive decay events in compressed and heated minerals of Earth's interior. This presentation focuses on the application of this approach to actinide oxides. The coupling of extreme conditions allows one to investigate entirely unexplored areas of phase space.