Artini Cristina, Pani Marcella, Carnasciali Maria Maddalena, Buscaglia Maria Teresa, Plaisier Jasper Rikkert, Costa Giorgio Andrea
†DCCI, Department of Chemistry and Industrial Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova, Italy.
‡CNR-IENI, Via De Marini 6, 16149 Genova, Italy.
Inorg Chem. 2015 Apr 20;54(8):4126-37. doi: 10.1021/acs.inorgchem.5b00395. Epub 2015 Apr 7.
A structural study of Sm- and Gd-doped ceria was performed with the aim to clarify some unexplained structural features. (Ce1-xREx)O2-x/2 samples (RE ≡ Sm, Gd; x = 0, 0.1, ..., 1) were prepared by coprecipitation of mixed oxalates and subsequent thermal treatment at 1473, 1173, or 1073 K in air; they were then analyzed at room temperature both by synchrotron X-ray diffraction and μ-Raman spectroscopy. Two structural models were adopted to fit the experimental data, namely, a fluoritic one, resembling the CeO2 structure at low RE content, and a hybrid one at higher RE content, intermediate between the CeO2 and the RE2O3 structures. Two main transitions were detected along the compositional range: (a) an RE-dependent transition at the boundary between the fluoritic and the hybrid regions, of a chemical nature; (b) an RE-independent transition within the hybrid region at ∼0.5, having a purely geometrical nature. The presence of two finely interlaced F- and C-based structures within the hybrid region was confirmed, and hints of their composition were obtained by μ-Raman spectroscopy. The obtained results indicate a possible explanation for the non-Vegard behavioral trend of the cell parameters.
对掺钐和钆的二氧化铈进行了结构研究，旨在阐明一些尚未解释清楚的结构特征。通过混合草酸盐的共沉淀以及随后在空气中于1473、1173或1073 K下进行热处理，制备了（Ce1-xREx）O2-x/2样品（RE≡Sm、Gd；x = 0、0.1、……、1）；然后在室温下通过同步加速器X射线衍射和μ拉曼光谱对其进行分析。采用了两种结构模型来拟合实验数据，即一种萤石型结构，在低稀土含量时类似于CeO2结构，以及一种混合型结构，在较高稀土含量时介于CeO2和RE2O3结构之间。沿着组成范围检测到两个主要转变：（a）在萤石型和混合型区域边界处的一个依赖于稀土的转变，具有化学性质；（b）在混合型区域内约0.5处的一个不依赖于稀土的转变，具有纯几何性质。证实了混合型区域内存在两种精细交织的基于F和C的结构，并通过μ拉曼光谱获得了它们组成的线索。所获得的结果为晶胞参数的非维加德行为趋势提供了一种可能的解释。
