Selection of the powdery metal hydride best for producing H− by thermal desorption
| Autor: | Hiroyuki Kawano, S. Sugimoto, Y. Zhu, Akihide Tanaka, T. Iseki, Motoi Wada, M. Sasao |
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| Rok vydání: | 2000 |
| Předmět: | |
| Zdroj: | Review of Scientific Instruments. 71:853-855 |
| ISSN: | 1089-7623 0034-6748 |
| DOI: | 10.1063/1.1150311 |
| Popis: | To find the metal hydride best for producing H− by thermal desorption, the desorption rates of H−, H2 and electron (e−) directly emitted from a powdery sample (∼1 mg) of NaH, LiH, MgH2, CaH2, SrH2, TiH2, ZrH2, KBH4, LiAlH4, or NaAlH4 heated up to ∼1000 K were determined simultaneously with a special system. Theoretical analysis of the experimental data thus achieved yields the following results. (1) Both H− and e− are emitted from those active spots (mainly consisting of alkali or alkali earth metal) created by thermal decomposition (e.g., LiH→Li+H2/2). (2) The active spots are readily destroyed and reconstructed by admission of H2 and by stopping the admission, respectively. (3) The work function (φ) of activated NaH is very low (∼2 eV), but NaH is rapidly depleted owing to its thermal instability. (4) Among the ten hydrides, CaH2 is concluded to be the best as a source material for thermal desorption of H− because activated CaH2 (φ≃5 eV) is most stable and strongest in H− (∼10−12 A or 10−10 A/cm2 after ... |
| Databáze: | OpenAIRE |
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