|About this Abstract
||Materials Science & Technology 2009
||Characterization and Modeling of Ceramic-Ceramic and Metal-Ceramic Interfaces
||**Ab Initio Modeling of Ba-O-Sc on W Cathode Materials (Previously scheduled in the Discovery and Optimization of Materials through Computational Design symposium on Wednesday at 10:00 AM)
||Vasilios Vlahos, Dane Morgan, John H. Booske
|On-Site Speaker (Planned)
Microwave, x-ray, and radio frequency radiation sources require a cathode emitting electrons into vacuum. Good electron emitters can be obtained by lowering the work function of materials through dipole surface coatings. Ba-O on W is used in traditional B-type cathodes, and Ba-O-Sc coatings may play a role in the promising new class of scandate cathodes. Ab initio modeling is used to explore the surface structure, stability, and work function of Ba-Sc-O on W coatings. The overall accuracy of the approach is assessed and resolutions to some previous ab initio and experimental discrepancies are proposed. We demonstrate that measured B-type cathode work functions are consistent with a lower coverage than previously expected and a dynamic stabilization of dipole surface structures very far from equilibrium. We also proposed a low work function Ba-Sc-O surface structures that may play a role in new scandate cathode materials.