Thermal field emission (TFE) from a flat surface of 12CaO·7 Al2 O3 (C12A7) electride was examined at temperatures up to 900 °C and applied external voltages of 0-6 kV in a 10-5 Pa vacuum. TFE started to occur at ∼650 °C and steeply increased at ∼900 °C to reach ∼80 μA (∼1.5 A cm-2) when an extraction field of 105 V cm-1 (an extraction voltage of 6 kV) was applied. The work function estimated from the Richardson-Dushman equation was ∼2.1 eV, which is rather smaller than that of La B6 (∼2.7 eV). It is experimentally confirmed that the emission with a current of ∼50 μA (from a 80 μm 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.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)