Optical properties, band structures, and phase transition of UO2+x epitaxial films deposited by polymer-assisted deposition
Dongxu Zhang,
Haopeng Dong,
Yuanfu Lou,
Yongqiang Zhong,
Fangfang Li,
Xiaoguo Fu,
Yuxiang Zheng,
Wenwu Li
Affiliations
Dongxu Zhang
China Academy of Engineering and Physics, Mianyang 621900, China
Haopeng Dong
China Academy of Engineering and Physics, Mianyang 621900, China
Yuanfu Lou
China Academy of Engineering and Physics, Mianyang 621900, China
Yongqiang Zhong
China Academy of Engineering and Physics, Mianyang 621900, China
Fangfang Li
China Academy of Engineering and Physics, Mianyang 621900, China
Xiaoguo Fu
China Academy of Engineering and Physics, Mianyang 621900, China
Yuxiang Zheng
Yiwu Research Institute of Fudan University, Chengbei Road, Yiwu 322000, China
Wenwu Li
Shanghai Frontiers Science Research Base of Intelligent Optoelectronics and Perception, Department of Materials Science, Institute of Optoelectronics, Fudan University, Shanghai 200433, China
Optical properties of the UO2+x film deposited by a polymer-assisted deposition method have been investigated by spectroscopic ellipsometry (SE). This epitaxial film contains at least two kinds of uranium oxides of U3O8 and UO3, and the O/U ratio is 2.74, which is confirmed by x-ray diffraction (XRD) and scanning Auger microscopy methods. By investigating the optical constants, the bandgaps of U3O8 and UO3 are determined as 2.3 and 1.0 eV, respectively, and 80% of the epitaxial film is U3O8 and 20% is UO3. The speciation signatures from the XRD and band structures show that the UO2+x epitaxial film reduced to U3O8 with the heating treatment at 480 K in a vacuum while oxidized to UO3 at 650 K. This work demonstrates a useful tool for studying the optical properties, band structures, and phase transition of uranium oxide film by SE.
