PNNL

Abstract

Pyrochlore materials, A2B2O7, encompass a wide range of compositions and are technological important for energy and environment issues, for example, used as ionic conductor in solid oxide fuel cells and nuclear waste forms for the storage of actinides, particularly Pu. Here, the recent progresses in understanding ion beam irradiation-induced phenomena in pyrochlore compounds are briefly reviewed with the focus of ion beam-induced crystalline-to-amorphous and pyrochlore to fluorite structural transitions. Systematic ion irradiation studies of lanthanide pyrochlores in which B = Ti, Zr, and Sn have suggested that the radiation response of pyrochlore compounds is highly dependent on compositional changes. Both ionic size and the cation electronic configurations (e.g., bond-types) affect the structural distortion from the ideal fluorite structure and the response behavior of pyrochlore-structure types to ion beam irradiation. Ion beam-induced pyrochlore-to-fluorite structural transition occurs in all irradiated pyrochlore compositions, and the independent kinetics of cation and anion disordering processes were discussed. Numerous novel nanostructures have been created by utilizing the ion beam-induced amorphization, order-disorder transition and phase decomposition, such as amorphous and disordered nano-domains, perfectly latticed matched two-dimensional nanolayer, self-organized ripple structure, metallic nanoparticles and nanowires. The potential application of energetic particle irradiation for nano-engineering pyrochlore structured compounds is highlighted.