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

Abstract

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.