The focus of the research is to develop an understanding of more complicated oxide surfaces which are important for a range of applications such as in ferroelectric devices, catalysts or fuel cells. At present relatively little is known about this class of oxide surfaces. The target is to develop predicted tools by combining theoretical calculations with unique methods of determining how the atoms are arranged at the surfaces. The intent is that in the future we can avoid trial-and-error methods of determining the best oxides for these applications, instead being able to predict and therefore design the best oxides. This has the potential, for instance, to lead to much more efficient water-splitting photocatalysts which would have a large impact on future energy needs and reduce carbon-dioxide production. The research will also help support both local outreach to high-school students in the Evanston area as well as international outreach efforts via workshops in the developing nations.
The primary focus of the proposed work is to study the surfaces of more complicated strongly-correlated electron oxides. The target is to determine how to understand and explain the structure and thermodynamics of the surfaces using a combined experimental-theoretical approach exploiting unique UHV electron microscopy facilities and new DFT methods. The proposed research will be a step towards establishing the scientific underpinnings of the use of strongly correlated oxide surfaces for applications such as in fuel cells or for photocatalytic splitting of water. The research will also help support both local outreach to high-school students in the Evanston area as well as international outreach efforts via workshops in the developing nations.
Oxide surfaces are an important frontier, with numerous applications in areas ranging from catalysis to the emerging field of oxide electronics. Despite this, our understanding of oxide surfaces is relatively primitive and more often than not it is assumed that they are simple. This is not true, and in fact there is growing evidence that they are exceedingly complicated. How the atoms are arranged at the surfaces is in most cases not known. For future commercial applications industry will demand five-sigma controlled growth of oxides which will include quantitative understanding of how the surface structures depends upon conditions, for which a prerequisite is knowing were the atoms are. The main focus of the project was to move beyond simple oxide surfaces to move complicated systems with more direct relevance for a range of potential applications such as ferroelectrics, catalysts or cathodes for fuel cells. In addition to this main theme a few experiments to complete work on the magnesium oxide surface were proposed, as well as a smaller continuation of previous work developing algorithms for density functional theory and related optimization codes. Elements of the work were performed in collaboration with scientists at Oxford University in the UK. For oxide surfaces, we were able to find where the atoms are located for a number of different structures. While doing this we were also able to work out a simpler method of explaining how the surfaces prefer to be arranged which can be taught to undergraduate students. We were also able to develop some new and more efficient methods for calculating the energy associated with different arrangements of the atoms. These new methods are now being widely used by others around the world. In terms of Intellectual Merit, this project has developed new methods and new ways of understanding oxide surfaces. Our efforts to develop more efficient methods of performing quantum-mechanical calculations have led to new algorithms which may see wider applications in other areas of science and engineering. In terms of Broader Impact, the structures we have determined as part of this project are starting to be used by others to improve how they produce oxide films for device applications. As such they have a significant role as enabling science for future technological applications in fields such as low-power electronics. In addition, the new algorithms that have been developed are already being used by about two thousand groups around the world to obtain faster and more accurate results.
