Electron tube cathode

An indirectly heated electron tube cathode comprising:

• a base including nickel as a main ingredient and further including a reducing agent;
• a metal layer containing either tungsten or molybdenum as a main ingredient, formed on said base;
• and
• an emissive material layer, including an alkali earth metal oxide as a main ingredient and including 0.01 to 9 wt % of at least one of scandium oxide and yttrium oxide, formed on said metal layer, said alkali earth metal oxide including at least barium oxide.

An indirectly heated electron tube cathode comprising:

• a base including nickel as a main ingredient and further including a reducing agent containing at least one of silicon and magnesium;
• a metal layer, of at most 2.0 .mu.m in thickness, including tungsten as a main ingredient, and formed on said base, subjected to heat treatment in a hydrogen atmosphere at 800.degree. C. to 1,100.degree. C.;
• and
• an emissive material layer including an alkali earth metal oxide and 0.01 to 25 wt % of a rare earth metal oxide, said alkali earth metal oxide including at least barium oxide, and being formed on said metal layer.

An indirectly heated electron tube cathode, comprising:

• a base containing nickel as a main ingredient and further containing a reducing agent;
• a metal layer, containing either tungsten or molybdenum, formed on said base;
• and
• an emissive material layer, containing an alkali earth metal oxide as a main ingredient and 0.01 to 9 wt % of scandium oxide, formed on said metal layer, said alkali earth metal oxide containing at least barium oxide.