Ab Initio Study of the UO₂→U₃O₈ Transition

Uranium Dioxide (UO₂) is the most common and used compound for nuclear energy reactors; it is important to gain a deep understanding of the system. Previous work done at the University of Texas at El Paso (UTEP) highlighted the path of deformity that UO₂ undergoes when exposed to extreme environments. Density Functional Theory (DFT) calculations were implemented not only to investigate any structural and chemical changes, but to also highlight any possible pathways that may occur. We investigated various types of defects (i.e. Frenkel, Interstitial, Schottky, Vacancy, etc.). Oxidation of a UO₂ crystal structure was found to be the most likely to occur, confirming the formation of U₄O₉, which in turn plays a vital role in the UO₂→U₃O₈ transformation. We tested various pathways that have been proposed in literature for validation to the work done at UTEP.