| 摘要 |
PURPOSE:To suppress deterioration in an electron emitting property during a lifetime by incorporating a specific ratio of Ba scandate powder dispersed into an alkaline earth metallic oxide layer. CONSTITUTION:The metallic face of a Ni substrate 2 is coated with an alkaline earth oxide including 20-50wt.% of Ba scandate powder dispersed thereinto, thereby forming an electron emitting material layer 3. The Ba scandate preferably consists chiefly of Ba2Sc2O5. This enables less deterioration in an electron emitting property during a lifetime so as to obtain an electronic tube cathode with a constantly stable and preferable property. In a composite operation of Ba scandate, a trace quantity of platinum or the like, which is included from a platinum (indium or rhodium) container used for being unaffect by a high temperature, acts as activator to scandium. Therefore, use of the container made of the above mentioned platinum container can restrain any variation in an electron emitting property. |
