烧绿石型富氧相Ce_2Zr_2O_8的Rietveld结构精修及其Raman光谱研究  

Rietveld Structure Refinement and Raman Spectroscopy of Pyrochlore-type Oxygen-rich Ce_2Zr_2O_8 Phase

作　　者：谢华[1,2] 王烈林[1] 罗德礼[2] 

机构地区：[1]西南科技大学核废物与环境安全国防重点学科实验室,绵阳621010 [2]表面物理与化学重点实验室,绵阳621907

出　　处：《无机材料学报》2014年第5期539-544,共6页Journal of Inorganic Materials

基　　金：国家自然科学基金(21101129);核废物与环境安全国防重点科学实验室开放基金(11zxnk08)~~

摘　　要：采用石墨还原法成功制备了烧绿石型富氧相Ce2Zr2O8,选用缺氧型烧绿石Nd2Zr2O7作为Ce2Zr2O8相前驱体CeZrO3.5的替代物与之进行结构对比分析。实验结果表明:Ce2Zr2O8相中富余氧主要占据前驱体中的氧空位,且氧离子扩散不会破坏原本有序排列的阳离子(Ce/Zr)亚点阵;同时,Ce2Zr2O8相中Zr-O配位体由前驱体中共顶联接的八面体转变为共棱联接的立方体,其反相畴界密度和振动光谱谱带亦较前驱体明显提高。以上结果说明Ce2Zr2O8相结构处于亚稳态,该结构特征有利于氧离子的快速吸附或释放,这为其成为汽车尾气净化剂提供了结构上的可行性,但也说明当An2Zr2O7烧绿石在自辐照条件下向富氧相An2Zr2O8发生转变时,其抗辐照和化学稳定等性能有下降趋势。Pyrochlore-type oxygen-rich Ce2Zr2O8 phase was prepared successfully by graphite reduction method. In order to compare the structure between Ce2Zr2O8 and Nd2Zr2O7, the pyrochlore Nd2Zr2O7 was selected as the substitute of CeZrO3.5＋δ, the oxide precursor of Ce2Zr2O8. Experimental results show that excessive oxygen in the Ce2Zr2O8 structure mainly occupies the oxygen vacancies from the precursor structure. Oxygen ions diffusion in the precursor CeZrO3.5 structure does not destroy the ordering cation sublattice. Meanwhile, Zr-O ligands are transformed from octahedrons of co-top connection in the precursor to cubes of co-edge connection in the Ce2Zr2O8. The antiphase boundary density and Raman bands in comparison with the precursor are improved significantly, suggesting the structure of Ce2Zr2O8 phase is in a metastable state. The characteristic structure facililates rapid adsorption or release of oxygen ions, providing structural feasibility for ideal candidate materials for automobile exhaust purification. However, the structure of Ce2Zr2O8 indicated that the radiation resistance and chemical stability may be downward when An2Zr2O7 pyrochlore under self irradiation condition transforms to the oxygen-rich phase Ce2Zr2O8.

关 键 词：Ce2Zr2O8 有序阳离子 反相畴界 配位体 

分 类 号：O731[理学—晶体学] TL93[核科学技术—辐射防护及环境保护]