Cesium adsorption on the Zr/O/W(100) surface
Interest in zirconium covered tungsten as an electrode material has been stimulated by recent work on the model surface Zr/O/W(100). This surface has been shown to have an effective thermionic work function of approx.2.6 eV, when properly prepared, with very low volatility and excellent thermal stability. For advanced thermionic converter applications and for proposed future nuclear electric propulsion systems, the emitter requirement is phi/sub eff/ less than or equal to 2.4 eV at 1600 K. The corresponding collector must have a work function < 1.4 eV at approx. 600 K. For any electrode materials yet studied, these requirements dictate the presence of an equilibrium pressure of cesium vapor. The adsorption/desorption characteristics of cesium in the Zr/O/W(100) surface and the effect of cesium coverage on the surface work function were studied, using Auger electron spectrometry (AES), field-emission retarding potential work function measurements (FERP) and thermal desorption mass spectrometry (TDS). The minimum work function attained for cesium adsorption on the Zr/O/W(100) surface was 2.12 eV. The desorption spectrum of cesium from this surface shows major binding states at 1.1 and 1.3 eV, with desorption complete at T less than or equal to 900 K.
- Research Organization:
- Oregon Graduate Center, Beaverton (USA)
- OSTI ID:
- 5431454
- Country of Publication:
- United States
- Language:
- English
Similar Records
Electronic properties of cesium oxide thin films
DOE/JPL Advanced Thermionic Technology Program. Progress report No. 45, October-November-December 1980
Related Subjects
300403* -- Thermionic Converters-- Materials
Components
& Auxiliaries
36 MATERIALS SCIENCE
360104 -- Metals & Alloys-- Physical Properties
ADSORPTION
ALKALI METALS
CATHODES
CESIUM
CHALCOGENIDES
COATINGS
DIRECT ENERGY CONVERTERS
ELECTRODES
ELEMENTS
FUNCTIONS
HIGH TEMPERATURE
METALS
NESDPS Office of Nuclear Energy Space and Defense Power Systems
OXIDES
OXYGEN COMPOUNDS
SORPTION
SORPTIVE PROPERTIES
SURFACE PROPERTIES
SURFACES
THERMIONIC CONVERTERS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TUNGSTEN
WORK FUNCTIONS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES