| Numéro |
J. Phys. Colloques
Volume 47, Numéro C2, Mars 1986
32 nd International Field Emission Symposium / 32ème Symposium International d'Emission de Champ
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| Page(s) | C2-353 - C2-357 | |
| DOI | https://doi.org/10.1051/jphyscol:1986254 | |
J. Phys. Colloques 47 (1986) C2-353-C2-357
DOI: 10.1051/jphyscol:1986254
OXIDE FORMATION ON Rh FIELD EMITTER SURFACES AND ITS REDUCTION BY CO
G.L. KELLOGGSandia National Laboratories, Albuquerque, New Mexico 87185, U.S.A.
Abstract
The growth of oxide films on Rh surfaces and their reduction by CO has been systematically studied by imaging atom-probe mass spectroscopy and field ion microscopy. The tips were oxidized and reduced in a "high-pressure" reaction chamber at pressures of 1 Torr and subsequently transferred under ultrahigh vacuum to an imaging atom-probe for analysis. The total uptake of oxygen and the chemical form of the oxide were measured as a function of time and temperature. The time dependence suggested that oxide formation on Rh follows a logarithmic growth law and the temperature dependence yielded an activation energy of 3.1 kcal/mole. Field ion microscopy of oxidized tips indicated that the oxide layers were non-uniform. Rhodium oxides were reduced in 1 Torr CO at temperatures slightly above 400 K.