Abstract
Using (Ba, Sr, Ca)CO3, nickel and Sc2O3 powders as starting materials, an electron emitter pellet for low temperature operating cathodes has been developed by hot isostatic pressing. During the exhaustion process of a cathode ray tube with the new pellet, carbonate (Ba, Sr, Ca)CO3 was thermally decomposed into oxide (Ba, Sr, Ca)O and CO2. In situ observation of the surface of the pellet during this thermal decomposition process and the examination of the microstructu-es of the pellets after decomposition revealed the condition for thermal decomposition; the highest maximum cathode current can be obtained at the heating rate of 3.2K/s. It was also found that when the carbonate was converted into the oxide at this heating rate, the carbonate confined in the pellet erupted, releasing CO2, and an approximately 10μm thick flat emitting layer with pores was formed on the pellet surface. After the decomposition process, thermal aging by external heating, which is applied to the conventional oxide cathode, and current drawing aging by conduction heating, result in the superior emission property of the emitter pellet.
