Surface studies of Os/Re/W alloy‐coated impregnated tungsten cathodes
| Autor: | C. S. Ares Fang, C. E. Maloney |
|---|---|
| Rok vydání: | 1990 |
| Předmět: |
Materials science
Metallurgy Alloy technology industry and agriculture Analytical chemistry chemistry.chemical_element Barium Thermionic emission Surfaces and Interfaces Tungsten engineering.material equipment and supplies Condensed Matter Physics Cathode Surfaces Coatings and Films law.invention Metal chemistry law visual_art visual_art.visual_art_medium engineering Work function Stoichiometry |
| Zdroj: | Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films. 8:2329-2332 |
| ISSN: | 1520-8559 0734-2101 |
| DOI: | 10.1116/1.576758 |
| Popis: | Impregnated tungsten cathodes half‐coated with Re/W (or Os/W) alloy and Os/Re/W alloy at right angles were studied to compare the effects of Os/Re/W alloy coatings on the electron emission and emission mechanisms. Constant surface metal compositions of 32% Os–29% Re–39% W and 35% Os–26% Re–39% W were obtained from the activated surfaces initially coated with 40% Os–40% Re–20% W and 35% Os–45% Re–20% W alloys, respectively. Thermionic emission microscopy measurements showed that the Os/Re/W alloy‐coated surface gives an average effective work function of 0.29, 0.08, and 0.03 eV lower than the uncoated, Re/W and Os/W alloy‐coated surfaces. An effective work function of 1.73 eV was obtained from an activated Os/Re/W alloy surface. Auger studies exhibited a smaller BaO coverage and a higher barium coverage in excess of BaO stoichiometry on the Os/Re/W alloy‐coated surface compared to the uncoated, Re/W and Os/W alloy‐coated surfaces. |
| Databáze: | OpenAIRE |
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