Paper TF+AS-TuA12
First Principles Studies of Oxygen Transfer at Buried Metal/Metal Oxide Interfaces

Tuesday, October 30, 2012, 5:40 pm, Room 10

Heterogeneous material interfaces between metals and metal-oxides provide a unique opportunity to create active functional materials. The functionality of these heterostructures can hinge either on limiting or enabling oxygen transfer across the interface. For example, there has been recent research on how to use thin film metal/metal-oxide super-structures to control the power output generated by the exothermic exchange of oxygen across the as-deposited interface. In all of these heterogeneous systems, it is imperative to fundamentally understand the mechanisms that facilitate oxygen exchange, as the dynamics are not currently well understood. In the work presented here, chemically accurate Density Functional Theory calculations have been used to predictively determine likely reaction pathways for oxygen transport in energetic nanocomposite materials and to characterize the stability of novel heterogeneous material interfaces. Our ultimate goal is to tune power output through an understanding of the mechanisms of oxygen transport across heterogeneous interfaces and within the super-structure. Several systems have been investigated, including more traditional thermite materials such as Al and Ti paired with Cu₂O. In these systems, the energy release is large, but there is also a high degree of strain when ideal systems are modeled. Other model systems were chosen based on structural similarity, minimal lattice mismatch, and the degree of exothermicity associated with oxygen transfer. Results on these systems will also be presented. Preliminary calculations simulate systems at various early stages to isolate factors that could influence the reaction, such as strain or initial barrier height. The results presented here show qualitative agreement between calculations and experimental observations. This project has been supported by the Army Research Office through grant # W911NF-10-1-0069 and the NSF Graduate Research Fellowship Grant # DGE0750733.