Thermionic emission and work function of U and UO/sub 2/
Thermionic emission measurements have been used to determine the work function (phi) of pure and oxidized uranium samples between 1100 and 1300/sup 0/K; Auger electron spectroscopy (AES) was used to verify the cleanliness and compositions of the samples. It was found that impurities present in ppM amounts in the bulk U segregated to the surface upon heating and had an appreciable effect on the zero-field emission currents as well as the slopes of the Schottkey curves obtained at various temperatures. A combination of ion-sputtering and ultra-high vacuum (UHV) annealing at high temperatures was successful in reducing the total impurity level on the hot surfaces to approx.5%. At this low concentration of impurities, well-behaved Richardson line plots were obtained with A = 135 A cm/sup -2/ K/sup -2/ and phi = 3.54 eV for pure U, and A = 128 A cm/sup -2/ K/sup -2/ and phi = 3.19 eV for UO/sub 2/. The Schottkey coefficients for clean U approached their ideal values at fields > 400 V/cm.
- Research Organization:
- Lawrence Livermore National Lab., CA (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6408579
- Report Number(s):
- UCRL-90427; CONF-8406187-3; ON: DE86002626
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360104* -- Metals & Alloys-- Physical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ACTINIDE COMPOUNDS
ACTINIDES
CHALCOGENIDES
DATA
ELEMENTS
EMISSION
EXPERIMENTAL DATA
FUNCTIONS
INFORMATION
METALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
THERMIONIC EMISSION
URANIUM
URANIUM COMPOUNDS
URANIUM DIOXIDE
URANIUM OXIDES
VERY HIGH TEMPERATURE
WORK FUNCTIONS