大气环境中铀表面结构XRD研究

Study on Surface Structure of Uranium Under Atmosphere Using X-ray Diffraction

摘要: 利用X射线衍射仪和Rietveld方法研究了金属铀在大气环境中经长时间氧化后表面结构与成分的变化。结果表明,铀表面UO2含量随时间分为两个增长阶段:1)扩散控制阶段,在金属铀表面快速形成一层氧化膜,UO2含量增加较快;2)线性增长阶段,出现在反应后期,UO2含量增长缓慢。在氧化过程中,金属铀晶体结构中的原子坐标y值不稳定,随时间呈现一定的上升趋势。

Abstract: The surface structure of uranium under atmosphere is studied by Xray diffraction(XRD)and Rietveld method. The twostep process, a fast step followed by a much slower step, of the UO2 growth kinetics is observed in the present experiment. The fast step is assumed to be a diffusioncontrolled oxidation reaction, and the UO2 growth in the slower step is linear. The atomic coordination, y, in the metal uranium is unstable, and increase gradually during oxidation.