| AVS 57th International Symposium & Exhibition | |
| Surface Science | Wednesday Sessions |
| Session SS2-WeM |
| Session: | Electron, Photon and Ion Beam Induced Surface Modification |
| Presenter: | S. Seal, University of Central Florida |
| Authors: | A. Kumar, University of Central Florida V. Shutthanandan, Pacific Northwest National Laboratory R. Devanathan, Pacific Northwest National Laboratory S. Kuchibhatla, Pacific Northwest National Laboratory S. Thevuthasan, Pacific Northwest National Laboratory S. Seal, University of Central Florida |
| Correspondent: | Click to Email |
The damaging effect of radiation in applications such as immobilization of toxic radionuclides, fission and fusion reactors, and radiation therapy has attracted considerable scientific interest. The search for radiation tolerant materials has revealed that fluorite structural derivatives, such as zirconia and cerium oxide, have the ability to accommodate high energy radiation induced defects. Particularly for biomedical applications, cerium oxide is of more interest because not only it can prevent the damage from radiation but also it has the ability to quench free radicals and reactive oxygen species produced as the result of high energy radiation by regenerative switching between the +3 and +4 valence states of cerium. However the underlying mechanisms of radiation interaction and the resulting physicochemical and structural changes of cerium oxide are not well understood. In order to gain a fundamental understanding of radiation tolerance of cerium oxide nanostructures, we explored the behavior of single and polycrystalline ceria under radiation. High quality single and poly crystalline nanoceria thin films were grown on YSZ and sapphire respectively by using oxygen plasma assisted molecular beam epitaxy and exposed to 2 MeV He+ radiation at fluences extending over three order of magnitude (1014 to 1017 ions/cm-2) using the ion beam accelerator at EMSL, in Pacific Northwest National Laboratory. The chemical changes occurring in the thin films due to radiation exposure were characterized in situ by x-ray photoelectron spectroscopy (XPS). The experimentally observed changes in valence state were correlated by simulating the nanoceria thin film by molecular dynamics and studying the displacement cascades produced by cerium and oxygen as primary knock on atom. The structural evolution of nanoceria thin films due to radiation exposure will be discussed in detail with implications for the use of cerium oxide as a radiation tolerant material.