铀氧化物的氧化还原行为及其价态的X-射线光电子能谱的研究

Study of Redox Behaviour of Uranium Oxides and Their Valence State Ratio by X-Ray Photoelectron Spectrometry

应用X-射线光电子能谱(XPS)对铀氧化物(UO_2、UO_3、U_3O_5)的化学态及其不同价态的相对含量(U^(4+)/U^(5+))进行了研究,结果表明.常温下 UO_2:在空气中可氧化形成 UO_(2+X)UO_3易与水结合形成水合物,在高温和高真空中易脱氧,部分U^(5+)转变成U^(4+)U_3O_2.中存在U^(4+)和U^(+5)两种价态,其相对量之比为1:2.铀氧化物中U^(4+)和U^(5+)的U4f_(7/2);.结合能相差leV左右,借助于曲线拟合技术可以对铀的不同价态的相对含量进行定量分析.

The redox behaviour of uranium oxides (UO2,UO3,U3O8) and their valence state ratios (U4+/U6+)have been studied by XPS. The results indicate that UO2can be oxidized into UO2+x, in air at ambient temperature; UO3 combines with H2O to form hydrous oxide easily , and a fraction of hexavalent uranium on the surface can change into quadrivalent due to its deoxidation in high vacuum chamber at high temperature; U3O8 consists of two kinds of different valence states of uranium oxides, i. e. U4+and U6+,and the relative intensity ratio between them is 1 : 2. Although binding energy difference between U4+and U8+4f7/2 peaks of uranium oxides is about 0. 9-1. 2 eV ,quantitative analysis of relative content of different valence state of uranium can be carried out in terms of the curve fitting technique by computer.