Physical Chemistry Seminar – Shinhyo Bang, Chemistry Graduate Student

About the event

Speaker:  Shinhyo Bang, chemistry graduate student

               Moreau Group

Talk title: The structural and electronic attributes of doped Ce (IV) and U (IV) nanomaterials

Abstract: Nuclear energy is not only a reliable energy source replacing traditional fossil fuels, but also a future energy source that expands mankind’s frontiers. Unfortunately, nuclear energy is challenged by the production of highly radioactive waste and potential for environmental contamination. These challenges can be overcome by materials innovations that lead to isolation and immobilization of radioactive nuclides. Designing these new nuclear materials requires fundamental understanding of the material properties, which include the chemical processes to produce the materials and the relationships between their structure and properties.

The chemistry of doped nuclear materials, mainly UO2, is gaining increased attention with spent nuclear fuel being inherently a doped material due to its constituent fission products and the promise for doped-UO2 to display oxidation-resistant behavior. The expected outcomes of this work are 1) to answer the question of how doping affects the structural and electronic attributes of U (IV) nanomaterials and 2) to gain insight into the nature of the bond between U (IV) and the binding ligand atoms. Initially, a relevant U-surrogate system has been explored. Specifically, the synthesis and characterization of Gd-doped CeO2 nanoparticles has been conducted. Different levels of Gd incorporation into CeO2 nanoparticles were achieved with two-phase solvothermal synthesis. The solubility limit and lattice constant evolution of Gd-doped CeO2 nanoparticles were different from their bulk counterparts, which were evidenced by the emergence of a new diffraction peak and compressive strain confirmed by XRD. The evolution of electronic structure probed by in-house XAFS suggests the possibility of tuning the f-orbital contributions to the bond between Ce (IV) and O atoms in the nanoparticle. More exciting discoveries will be enabled by upcoming synchrotron HERFD-XAS measurements at the Cornell High Energy Synchrotron Source (CHESS).