Letter | Published:

Identification by X-Rays of Interface Compounds on “Oxide” Cathodes

Nature volume 159, pages 609610 (03 May 1947) | Download Citation



A RECENT paper by Fineman and Eisenstein1 has presented interesting observations concerning the interfacial films formed between coating and metal core material on alkaline earth oxide-coated cathodes. Nickel alloys containing impurity elements such as magnesium, aluminium or silicon (or like elements) are commonly employed for these cathodes, and it has been, accepted for many years that the process of activation is facilitated by the presence of one or other of the above impurities2. Chemical reaction with the alkaline earth oxide at elevated temperatures frees barium ions which are required for the development of the thermionic emission.

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  1. 1.

    , and , J. Appl. Phys., 17, 663 (1946).

  2. 2.

    , Phil. Mag., 20, 1 (1935).

  3. 3.

    , J. Roy. Soc. Arts, 88, 318 (1940).

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  1. Research Laboratories, General Electric Company, Ltd., Wembley.

    • H. P. ROOKSBY


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