Ce1-xGdxO2-δ固溶体中缺陷物种的拉曼光谱研究

Defect Sites in the Ce_(1-x)Gd_xO_(2-δ) Solid Solutions by Raman Spectroscopy

采用溶胶-凝胶法制备一系列Ce1-xGdxO2-δ固溶体。利用紫外(325 nm)和可见(514 nm)Raman光谱,X射线粉末衍射(XRD),透射电子显微镜(TEM)和紫外可见漫反射光谱(UV-Vis DRS),考察了Ce1-xGdxO2-δ固溶体的缺陷物种的分布以及Gd含量对缺陷浓度的影响。结果表明:Ce1-xGdxO2-δ固溶体中存在氧缺位(～560 cm-1)和GdO8型缺陷结构(～600 cm-1)。根据样品对Raman激发光的吸收,紫外Raman光谱反映样品的表层信息,可见Raman光谱反映样品的整体信息。Ce1-xGdxO2-δ固溶体表层氧缺位(να)和GdO8型缺陷物种的浓度(νβ)均高于固溶体体相,这归因于缺陷物种的表面富集。然而,相比于GdO8型缺陷物种,体相中氧缺位浓度增加较表层中的更显著。

A series of Ce1-xGdxO2-δ solid solutions were prepared using a sol-gel method, Raman spectroscopy with325 and 514 nm excitation wavelengths, X-ray diffraction （XRD）, transmission electron microscopy images （TEM）and UV-Vis diffuse reflectance spectra （UV-Vis DRS） were used to analyze the distributions of defect sites inCe1-xGdxO2-δ solid solutions and the effect of Gd content on their concentration. There were two defect sites ofoxygen vacancies and GdOs-type complex corresponding to the Raman peaks at 560 cm^-1 and 600 cm^-1respectively. The UV Raman spectroscopy could provide the surface information, while the Visible Ramanspectroscopy could get the whole information of the sample. The concentration of oxygen vacancies and GdO8-typecomplex were higher on the surface than in the bulk due to the surface enrichment. However, comparing with theconcentration of GdOs-type complex, the increase in the concentration of oxygen vacancies in the bulk was moreobvious than that of in the surface.