Beiträge zur Elektronenemission von Metalloxyden, Legierungen und Metallkarbiden
Contributions are given concerning thermionic emission of metal oxides, alloys and metal carbides. It seems to be more convenient to characterize the emission power of such substances by a temperature of optimal electron emission and an emission image instead of giving merely an average value of the work function. On account of the formula for thermionic electron emission a linear relation can be expected between the average value of the work function and the temperature of optimal thermionic emission. Alloys of Cr especially with Fe and Ni show a decomposition for higher temperatures caused by evaporation and migration of Cr on the emitting surface. The thermionic emission of the measured metal carbides is much smaller than that of the alkaline earth oxides and is diminished too by oxidizing processes during the heating of the cathodes.