Chemical stability of La 2O 3 in carbonized and uncarbonized La 2O 3 Mo cathodes was studied by in situ XPS analysis. Experimental results show that chemical stability of La 2O 3 is not good enough. In vacuum and at h...Chemical stability of La 2O 3 in carbonized and uncarbonized La 2O 3 Mo cathodes was studied by in situ XPS analysis. Experimental results show that chemical stability of La 2O 3 is not good enough. In vacuum and at high temperature, oxygen can be dissociated from the lattice of La 2O 3 in the uncarbonized La 2O 3 Mo cathode. Binding energy shifts of La?3d5/2 and La?3d3/2 core peaks, and obvious decrease of satellite peak intensity in La?3d doublet with increasing temperature show that metallic La appears at carbonized La 2O 3 Mo cathode surface at high temperature.展开更多
The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in situ X ray Photoelectron Spectroscopy. The theoretical results show that at the ...The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in situ X ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La 2O 3 in the La 2O 3 Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo 2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG DTA were taken. The experimental results show that the chemical state of lanthanum changes during heating. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.展开更多
本文采用高温光电子能谱方法对 L a2 O3- Mo阴极及碳化 L a2 O3- Mo阴极材料表面 L a2 O3 的化学稳定性进行了研究。实验结果表明 ,L a2 O3并不具备文献报道的极好的化学稳定性。材料中的 L a2 O3在高温、真空条件下 ,其部分晶格氧发生...本文采用高温光电子能谱方法对 L a2 O3- Mo阴极及碳化 L a2 O3- Mo阴极材料表面 L a2 O3 的化学稳定性进行了研究。实验结果表明 ,L a2 O3并不具备文献报道的极好的化学稳定性。材料中的 L a2 O3在高温、真空条件下 ,其部分晶格氧发生分离。 L a2 O3可以被 Mo2 C还原成单质 L a。单质 L a的结合能高于 L a2 O3的结合能。实验证实单质 L a3d5 / 2的结合能为 835 .96 e V,并首次给出 L a3d3/ 2的结合能实验数值为 85 2 .2 3e V。展开更多
文摘Chemical stability of La 2O 3 in carbonized and uncarbonized La 2O 3 Mo cathodes was studied by in situ XPS analysis. Experimental results show that chemical stability of La 2O 3 is not good enough. In vacuum and at high temperature, oxygen can be dissociated from the lattice of La 2O 3 in the uncarbonized La 2O 3 Mo cathode. Binding energy shifts of La?3d5/2 and La?3d3/2 core peaks, and obvious decrease of satellite peak intensity in La?3d doublet with increasing temperature show that metallic La appears at carbonized La 2O 3 Mo cathode surface at high temperature.
文摘The chemical reaction between lanthanum oxide and molybdenum carbide was studied by thermodynamic calculation, thermal analysis and in situ X ray Photoelectron Spectroscopy. The theoretical results show that at the environment allowing for the evaporation of lanthanum, such as in high vacuum, La 2O 3 in the La 2O 3 Mo materials can be reduced to metallic lanthanum by molybdenum carbide (Mo 2C). To confirm the conclusion, many analysis methods such as XRD, SPS, and TG DTA were taken. The experimental results show that the chemical state of lanthanum changes during heating. It was proved, for the first time, that reacted metallic lanthanum appears at the surface of this kind of material at high temperature.
文摘本文采用高温光电子能谱方法对 L a2 O3- Mo阴极及碳化 L a2 O3- Mo阴极材料表面 L a2 O3 的化学稳定性进行了研究。实验结果表明 ,L a2 O3并不具备文献报道的极好的化学稳定性。材料中的 L a2 O3在高温、真空条件下 ,其部分晶格氧发生分离。 L a2 O3可以被 Mo2 C还原成单质 L a。单质 L a的结合能高于 L a2 O3的结合能。实验证实单质 L a3d5 / 2的结合能为 835 .96 e V,并首次给出 L a3d3/ 2的结合能实验数值为 85 2 .2 3e V。
