Thermionic emission and work function of U and UO/sub 2/

Journal Article · Sat Dec 14 23:00:00 EST 1985 · J. Appl. Phys.; (United States)

DOI:https://doi.org/10.1063/1.336242· OSTI ID:5042770

McLean, W; Chen, H

Thermionic emission measurements have been used to determine the work function (phi) of pure and oxidized uranium samples between 1100 and 1300 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 Schottky curves obtained at various temperatures. A combination of ion-sputtering and ultrahigh vacuum (UHV) annealing at high temperatures was successful in reducing the total impurity level on the hot surfaces to 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 Schottky coefficients for clean U approached their ideal values at fields >400 V/cm.

• Research Organization: University of California, Lawrence Livermore National Laboratory, Livermore, California 94550
• OSTI ID: 5042770
• Journal Information: J. Appl. Phys.; (United States), Journal Name: J. Appl. Phys.; (United States) Vol. 58:12; ISSN JAPIA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
360204 -- Ceramics
Cermets
& Refractories-- Physical Properties
ACTINIDE COMPOUNDS
ACTINIDES
ANNEALING
ATOM TRANSPORT
AUGER ELECTRON SPECTROSCOPY
CHALCOGENIDES
DATA
DIFFUSION
ELECTRON SPECTROSCOPY
ELEMENTS
EMISSION
EXPERIMENTAL DATA
FUNCTIONS
HEAT TREATMENTS
HEATING
IMPURITIES
INFORMATION
METALS
NEUTRAL-PARTICLE TRANSPORT
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
RADIATION TRANSPORT
SEGREGATION
SPECTROSCOPY
SPUTTERING
THERMIONIC EMISSION
ULTRAHIGH VACUUM
URANIUM
URANIUM COMPOUNDS
URANIUM OXIDES
VERY HIGH TEMPERATURE
WORK FUNCTIONS