The current rapid development of cathode electronics has led fanned by their widespread use as cathode materials. A whole new section on the thermionic properties of aluminides has to extensive investigations of the emission properties of chemical el­ ements and their compounds. This expansion of research is aimed at been introduced. The list of pertinent literature has been aug­ the continual refinement of data already available and the steady widen­ mented by new contributions published in the years 1963-1965, ing of the circle of materials under investigation. These events have as well as some earlier publications that had escaped notice in the necessitated a whole series of additions and changes in this handbook, Russian edition. even though the original Russian edition was published only in 1964. It is the author's hope that the handbook will prove of great val­ Every effort has been made to include all available information ue to American readers interested in the emission properties of the on each element or compound. Particular attention has been given to elements and compounds, and that it will contribute to the further bringing the sections on borides and carbides of the transition and rare development of research in this promising and most timely field of metals up to date, since interest in these compounds has recently been electronics.