喷雾热解合成An2Zr2O7(An=La、Nd)烧绿石及结构分析

    Preparation and Characterization of Pyrochlore An2Zr2O7(An=La, Nd) by Spray Pyrolysis

    • 摘要: 锆基烧绿石An2Zr2O7以优异抗辐照性能和化学稳定性成为高放废物中锕系核素的理想固化基材。镧系核素常作为替代核素进行锕系核素的固化研究,实验以硝酸盐为原料,以三价的镧系元素(La、Nd)模拟锕系元素,采用sol-喷雾热解方法在1200℃、6 h内合成了(La、Nd)2Zr2O7烧绿石。采用粉末X射线衍射(XRD)、扫描电镜(SEM)、拉曼光谱分析方法对合成的样品进行了结构表征,结果表明:利用该方法合成了单一物相的烧绿石立方结构An2Zr2O7;相对于La2Zr2O7的烧绿石结构,Nd2Zr2O7烧绿石具有向萤石结构转变的趋势。该合成方法为目前的高放废液人造岩石固化提供了一定的技术基础。

       

      Abstract: Zirconate pyrochlore (An2Zr2O7) is a well known host material for actinide immobilization because of the chemical durability and radiation stability. Lanthanide (La, Nd) are surrogate elements for actinide that is widely used in experiments, pyrochlore structured La2Zr2O7and Nd2Zr2O7 are prepared at relative low temperature and short time via sol-spray pyrolysis method. X-ray diffraction (XRD), SEM and Raman are employed to investigate the structure characterization. Results show that the compositions are single pyrochlore phase; the Nd2Zr2O7 pyrochlore drives structure phase transition from pyrochlore to defect fluorite. This synthetic method provides a potential pathway to immobilize high-level nuclear waste.

       

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