Intense thermal field electron emission from room-temperature stable electride

Thermal field emission (TFE) from a flat surface of 12CaO center dot 7Al(2)O(3) (C12A7) electride was examined at temperatures up to 900 degrees C and applied external voltages of 0-6 kV in a 10(-5) Pa vacuum. TFE started to occur at similar to 650 degrees C and steeply increased at similar to 900 degrees C to reach similar to 80 mu A (similar to 1.5 A cm(-2)) when an extraction field of 10(5) V cm(-1) (an extraction voltage of 6 kV) was applied. The work function estimated from the Richardson-Dushman equation was similar to 2.1 eV, which is rather smaller than that of LaB6 (similar to 2.7 eV). It is experimentally confirmed that the emission with a current of similar to 50 mu A (from a 80 mu m diameter area) was stably sustained for more than 90 h. The efficient and stable emission at relatively low temperature in a moderate vacuum atmosphere strongly suggests that the C12A7 electride has high potential for TFE applications.