单分散微米级铀氧化物微粒的制备

铀微粒同位素分析在核保障环境监测中发挥着重要作用。为保证准确测量单个微粒中铀同位素比，需使用丰度已知且尺寸适宜的标准微粒。通过将铀标准物溶解，并将溶液雾化形成液滴，再经蒸发溶剂、热分解一系列步骤，制得所需微粒。建立了1套以振动孔气溶胶发生器为核心的单分散铀氧化物微粒的制备装置。经扫描电子显微镜观测，制备的微粒呈球形；能谱分析表明，微粒为铀氧化物；微粒粒径主要集中在1.1μm左右，由于液滴的分裂与结合，导致了一定数量的较小和较大微粒存在；经二次离子质谱测定，其丰度值与标称值吻合，不同微粒间校正因子波动较小，能够满足实际测量的要求。

Production of Monodisperse Uranium Oxide Particles

Particle analysis of uranium containing particles plays a significant role in nuclear safeguards. Standard particles of known isotopic composition and suitable size are needed to insure the precision and the accuracy of the measurement for uranium isotopic ratios in single particles. These particles can be obtained by dissolving standard reference uranium materials, nebulizing the solution into droplets of proper diameter and collecting the particles after the desolvation and calcination of the droplets. A set of instruments based on a vibrating orifice aerosol generator was set up. It was observed by SEM that the monodisperse uranium oxide particles are nearly spherical. The composition of the particles, measured by energy dispersive X-ray spectrum, is only uranium and oxide. Their diameter distributions evidence the presence of several populations, the major showing a distribution with a maximum centers at 1.1 μm. The other populations are mainly due to the breaking up and aggregation of the droplets. The isotope ratio of uranium measured by SIMS is in good agreement with the reference values. SIMS analysis demonstrates that the abundance of uranium in these particles matches nominal value. The fluctuation of correction factors between different particles are relatively small and the sizes of particles can meet the demand of measurement. Therefore, these particles can satisfy the requirement in our measurement.