Relationship between nano scale defect structure and composition of cerium oxide solid solutions

对氧化铈固溶体进行了研究，重点研究了（1）薄膜的制备，（2）固溶体的纳米级缺陷结构，（3）退火时间对结构的影响。（1）研究了几种制备氧化铈薄膜的方法。如果需要很薄的氧化铈薄膜，则采用均匀沉淀法。对于较厚的氧化铈膜，水热技术是更好的。（2）用X射线衍射和拉曼光谱对烧结态氧化铈固溶体进行了研究。在所有三种不同的掺杂剂（NdO_3、GdO_3和YO_4）中，X射线衍射表明，在这些掺杂剂的浓度为约0 - 40摩尔%时，固溶体为萤石结构。<1.5><1.5><1.5>在较高浓度下，存在许多卫星峰，但很难区分具有卫星峰的萤石结构和稀土C型结构。拉曼光谱表明，NdO_2-CeO_2体系<1.5> ...更多信息 在较高的NdO_3浓度下，仍保持基本的萤石结构。<1.5>对于GdO_2-CeO_2体系，在0 - 30 mol % GdO_2时，由于Ce和O相互作用产生的拉曼谱带与萤石结构相同，但当GdO_2含量达到70 mol %时，拉曼谱带发生变化并保持在一个新的位置。<1.5><1.5><1.5>对于YO_2-CeO_2体系，随着YO_2浓度从30增加到70 mol %，Ce与O相互作用的拉曼谱带连续变化，表明该体系结构连续变化。<1.5><1.5>（3）研究了退火对氧化铈固溶体晶体结构的影响。在900 ℃和1400 ℃下进行退火，最长时间为336天。YO_2-CeO_2系统样品在退火过程中出现了晶格常数的变化。<1.5>这是由于晶体结构从萤石结构转变为具有不同晶格参数的稀土C型结构。而NdO_2-CeO_2和GdO_2-CeO_2系统的样品在退火过程中很稳定。<1.5><1.5>少

Research on cerium oxide solid solution, especially on (1)fabrication of thin films, (2)nano scale defect structure of the solid solution, and (3)the effect of annealing time on the structure was performed. (1)Several methods were tested to fabricate cerium oxide thin films. Homogeneous precipitation method was useful if very thin film of cerium oxide was needed. For thicker films of cerium oxide, the hydrothermal technique was better. (2)As-sintered cerium oxide solid solution was investigated by x-ray diffraction and Raman spectroscopy. In all three different dopants (NdO_<1.5>,GdO_<1.5>, and YO_<1.5>), x-ray diffraction indicated that at the concentration of about 0-40 mol % of these dopants, the solid solution was in fluorite structure. At higher concentrations, many satellite peaks were present but it was very difficult to distinguish between fluorite structure with satellite peaks and rare earth C-type structure. The Raman spectroscopy revealed that the system of NdO_<1.5>-CeO_2 … More maintained the basic fluorite structure even at higher concentration of NdO_<1.5>. For the system of GdO_<1.5>-CeO_2, the Raman band due to interaction between Ce and O remained the same as the fluorite structure at 0-30 mol % GdO_<1.5>, but the Raman band changed to a new position and stayed there up to 70 mol % GdO_<1.5>. For the system of YO_<1.5>-CeO_2, the Raman band due to the interaction between Ce and O changed continuously as the concentration of YO_<1.5> increased from 30 to 70 mol %, indicating continuous structural change in this system. (3)The effect of annealing on the crystal structure of these cerium oxide solid solutions was investigated. The annealing was performed at 900℃ and 1400℃ for the maximum period of 336 days. The samples of the system of YO_<1.5>-CeO_2 showed the change in lattice parameter during the annealing. This was due to the crystal structure change from fluorite structure to rare earth C-type structure with different lattice parameters. On the other hand the specimens of the systems of NdO_<1.5>-CeO_2 and GdO_<1.5>-CeO_2 were found to be very stable during the annealing. Less