Environmental Stability of 612-aluminate with Different Phase Structures

The 612-aluminate is widely applied as the active substance for thermionic cathodes in high-power vacuum electronic devices. Two different structures with different component phases, Ba
3
CaAl
2
O
7
, and Ba
3
Al
2
O
6
+ BaCO
3
, are acquired by sintering the precursor synthesized by the liquid-phase co-precipitation method. It is found that when exposed to moist air, the total weight gain and the gain rate of the dual-phase sample are smaller than the single-phase one. Better environmental stability favors the storage and fabrication of cathodes. This dual-phase 612-aluminate is worth being popularized for the thermionic cathodes.