There is a central relationship between material composition, structure, and function that can be leveraged to produce high performing, chemically relevant materials. Using well-defined surfaces under ultra-high vacuum (UHV) conditions, representative systems interrogated with surface science techniques can elucidate the atomistic mechanisms for complex surface-mediated processes. Studies such as these have broadened the understanding of, and are integral to, developing accurate models for many interfacial phenomena. In this presentation, I will discuss two fields that benefit greatly from such studies: particle accelerator technology and heterogeneous catalysis. Niobium (Nb) is the current standard material for superconducting radio frequency (SRF) cavities while Nb3Sn is a promising next-generation material for SRF cavities. Nb3Sn SRF cavities, currently grown via Sn vapor deposition on preexisting Nb cavities, perform far below anticipated performance metrics. This is understood to be due to structural and compositional inhomogeneities in the Nb3Sn film. There is not, however, an understanding of the Nb3Sn growth mechanism resulting in optimal Nb3Sn films. We have used a combination of in situ UHV techniques to visualize Sn adsorption and diffusion behavior on (3×1)-O Nb(100). Scanning tunneling microscopy (STM) data revealed preferential adsorption of Sn along the (3×1)-O unit cell with Sn diffusion guided by the underlying oxide surface. Genetic algorithm calculations and DFT based descriptors identified energetically preferred Sn binding sites on the (3×1)-O surface and calculated STM images corroborated experimentally determined Sn adsorption structures. This spatially resolved, mechanistic information of Sn adsorption and diffusion on an oxidized Nb surface guides the development of predictive Nb3Sn growth models needed for the optimization of Nb3Sn growth procedures. The final portion of this presentation will discuss ongoing efforts at The University of Kansas to identify the chemical and structural features driving selective product formation on oxide-supported metal nanoparticles. These studies aim to determine the atomistic mechanism(s) driving selective product formation on complex catalyst surfaces.

Leveraging surface science to investigate materials growth and performance: From particle accelerator technology to heterogeneous catalysis

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