Enhanced thermionic emission performance of LaB 6 by Ce doping

Motivated by enhanced thermionic emission performance resulting from low work function, the work function of CexLa1−xB6 is studied by first-principles calculation based on density functional theory. By calculation, the optimal Ce doping concentration is determined to be 0.25, and a very low work function Φ = 2.04 eV is predicted on the (001) surface of Ce0.25La0.75B6. High-quality Ce0.25La0.75B6 single crystal was fabricated by optical floating zone technique. By the experimental measurement on the thermionic emission performance, the average work function of Ce0.25La0.75B6 is about 2.61 eV, which is lower than the work function of both CeB6 and LaB6. By the combination of calculation and experiment, we concluded that Ce doping can reduce the work function of LaB6 and enhance its thermionic emission performance.