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The surface segregation of La 2O 3 in Mo La 2O 3 cathode was carried out by Auger electron spectroscopy. Lanthanum and oxygen ions (La 3+ and O 2- ) diffuse from the grain boundaries to the surface respectively, and these ions recombine into La 2O 3 molecules on the surface. The results were analyzed by kinetics of grain boundary diffusion. In the temperature range of 1 123～1 423 K, the diffusion coefficients of La 3+ and O 2- ions were found to fit with the following equations: D La =3.670 3×10 -16 exp(-1.016 39×10 5/ RT ) D O=1.512 2×10 -16 exp(-8.130 66×10 4/ RT ). [
The surface segregation of La 2 O 3 in Mo La 2 O 3 cathode was carried out by Auger electron spectroscopy. Lanthanum and oxygen ions (La 3+ and O 2-) diffuse from the grain boundaries to the surface respectively, and these ions recombine into La 2O 3 molecules on the surface. The results were analyzed by kinetics of grain boundary diffusion. In the temperature range of 1 123 ~ 1 423 K, the diffusion coefficients of La 3+ and O 2- ions were found to fit with the following equations : D La = 3.670 3 × 10 -16 exp (-1.016 39 × 10 5 / RT) DO = 1.512 2 × 10 -16 exp (-8.130 66 × 10 4 / RT)