The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that ...The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that the valence of lanthanum changes during the activation processes. As the temperature increases, the lattice oxygen in La 2O 3 is dissociated, resulting in partial reduction of the lanthanum to LaO x(x <3/2). In addition, the lanthanum rich phase diffuses from bulk into the surface of the sample. The lack of lattice oxygen in this phase has a favorable effect on emission, which leads to a lower work function for the Mo La 2O 3 cathode.展开更多
文摘The changes of the valence state of lanthanum in the Mo La 2O 3 model cathode specimens were systematically studied by in situ XPS/AES analyses from room temperature to 1550 ℃. The experimental results show that the valence of lanthanum changes during the activation processes. As the temperature increases, the lattice oxygen in La 2O 3 is dissociated, resulting in partial reduction of the lanthanum to LaO x(x <3/2). In addition, the lanthanum rich phase diffuses from bulk into the surface of the sample. The lack of lattice oxygen in this phase has a favorable effect on emission, which leads to a lower work function for the Mo La 2O 3 cathode.
