A thermionic energy converter with a molybdenum-alumina cermet emitter
- Centre for Technical Ceramics, Eindhoven University of Technology, P. O. Box 513, 5600 MB Eindhoven, The Netherlands (NL)
A study is made of the properties of cermets as electrode materials for thermionic energy converters. For thermodynamic reasons it is expected that all cermets composed of pure Mo and refractory oxides have the same bare work function. From data on the work function of Mo in an oxygen atmosphere this bare work function is estimated to be {Phi}=4.9 eV (at {ital T}=1400 {degree}C). Experimentally, the bare work function of Al{sub 2}O{sub 3}-Mo cermets was found to be {Phi}=4.5 eV, independent of the relative amounts of Al{sub 2}O{sub 3} and Mo. The cesiated work function of the Al{sub 2}O{sub 3}-Mo cermets was found to be 0.15 eV lower than the cesiated work function of pure Mo. The bare work function of Mo{sub 3}Al was found to be {Phi}=4.0 eV. The cesiated work function of Mo{sub 3}Al at collector temperature conditions was 0.3 eV lower than the cesiated work function of pure Mo. The electrical power density of a diode with an Al{sub 2}O{sub 3}-Mo cermet emitter was 0.4 W/cm{sup 2} at 1300 {degree}C. The barrier index at this temperature was 2.36 V. The high barrier index is attributed to a high plasma voltage drop {ital V}{sub {ital d}}=0.91 V.
- OSTI ID:
- 6262621
- Journal Information:
- Journal of Applied Physics; (USA), Journal Name: Journal of Applied Physics; (USA) Journal Issue: 11 Vol. 68:11; ISSN 0021-8979; ISSN JAPIA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
300401* -- Thermionic Converters-- Design & Development
300403 -- Thermionic Converters-- Materials
Components
& Auxiliaries
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CERMETS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
COMPOSITE MATERIALS
DESIGN
DIRECT ENERGY CONVERTERS
EFFICIENCY
ELEMENTS
FUNCTIONS
KINETICS
MATERIALS
METALS
MOLYBDENUM
NESDPS Office of Nuclear Energy Space and Defense Power Systems
OXIDES
OXYGEN COMPOUNDS
REACTION KINETICS
THERMIONIC CONVERTERS
THERMIONIC EMITTERS
TRANSITION ELEMENTS
WORK FUNCTIONS