柠檬酸溶胶-凝胶法制备的Ce1-xZrxO2: 结构及其氧移动性

采用 XRF、XRD、Raman、XPS、H₂-TPR 以及与氩离子刻蚀相结合的XPS等表征技术对柠檬酸溶胶-凝胶法制备的Ce_1-xZr_xO₂ (0≤x≤1)样品的结构及其氧移动性进行了研究. 结果表明, Ce_1-xZr_xO₂ 样品的晶型结构对其中氧的移动性有明显影响. 当x≤0.15 时, Ce_1-xZr_xO₂ 以立方CeO₂相 Ce-Zr-O 固溶体存在, 随着Zr含量的逐渐增加, CeO₂晶胞体积减小、氧空位浓度增加, 氧移动性逐渐增强; 当x＞0.15时, 形成四方ZrO₂相和立方CeO₂相Ce-Zr-O固溶体的混合物, 随着Zr含量的逐渐增加, 四方ZrO₂相的含量增加、氧空位浓度减小, 氧移动性逐渐减弱. 因此, Ce_0.852Zr_0.152O₂样品具有最高的氧移动性.

Structure and Oxygen Mobility of Ce1-xZrxO2 Prepared by Citric Acid Sol-gel Method

The structure and oxygen mobility of Ce_1-xZr_xO₂ (0 ≤x≤ 1) samples prepared by citric acid sol-gel method were characterized by XRF, XRD, Raman, XPS, Ar+ etching-XPS and H₂-TPR. The data showed that the crystalline structure of Ce_1-xZr_xO₂ can significantly affect the oxygen mobility. When x≤0.15, the samples were found to exist as cubic Ce-Zr-O solid solutions. An increase in x resulted in a shrinking of the crystal unit volume, an increasing in the number of oxygen vacancies, and an increasing in the oxygen mobility as well. When x＞0.15, Ce_1-xZr_xO₂ existed in a mixed phases of tetragonal and cubic Ce-Zr-O solid solutions; the percentage of tetragonal phase increased, oxygen vacancies decreased and oxygen mobility reduced with increasing x in these samples. Therefore, this present work shows that oxygen mobility in the Ce_0.85Zr_0.152O₂ sample is the highest.