Theoretical study of cathode surfaces and high-temperature superconductors. Final report

Technical Report · Tue Aug 01 04:00:00 EDT 1995

OSTI ID:135434

Mueller, W

Calculations are presented for the work functions of BaO on W, Os, Pt, and alloys of Re-W, Os-W, and Ir-W that are in excellent agreement with experiment. The observed emission enhancement for alloy relative to tungsten dispenser cathodes is attributed to properties of the substrate crystal structure and explained by the smaller depolarization of the surface dipole on hexagonal as compared to cubic substrates. For Ba and BaO on W(100), the geometry of the adsorbates has been determined by a comparison of inverse photoemission spectra with calculated densities of unoccupied states based on the fully relativistic embedded cluster approach. Results are also discussed for models of scandate cathodes and the electronic structure of oxygen on W(100) at room and elevated temperatures. A detailed comparison is made for the surface electronic structure of the high-temperature superconductor YBa2Cu3O7 as obtained with non-, quasi-, and fully relativistic cluster calculations.

• Research Organization: National Aeronautics and Space Administration, Greenbelt, MD (United States). Goddard Space Flight Center
• OSTI ID: 135434
• Report Number(s): N--96-11972; NASA-CR--198379; E--9839; NAS--1.26:198379; CNN: NAS3-25940; RTOP 235-01-03-0A
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
BARIUM OXIDES
CATHODES
COPPER OXIDES
ELECTRONIC STRUCTURE
HIGH-TC SUPERCONDUCTORS
PROGRESS REPORT
SURFACE PROPERTIES
WORK FUNCTIONS
YTTRIUM OXIDES