CHTHODE FOR ELECTRON TUBE

摘要

PURPOSE:To prevent the peeling of an electron emissive material by coating a substrate with the electron emissive material layer which has barium- containing alkaline earth metal oxide as a principal component and contains the predetermined weight percentage of rare earth metal oxide with predermined mean particle size. CONSTITUTION:The upper face of the bottom part of a substrate 1 is coated with an electron emissive material layer 2 which has alkaline earth metal oxide 11 as a principal component containing barium at least and besides strontium or/and calcium and contains 0.1-20 weight percentage of rare earth metal oxide with mean particle size of 4.5 mum or less such as scandium oxide, yttrium oxide, etc.. Thereby it is prevented that interlayer composed of compound oxide is concentrated and formed in the neighborhood of the interface between the conductor and the electron emissive material layer 2 under high density current. Stable emission characteristics can be obtained for many hours and besides the peeling of the electron emissive material can be prevented.