固体中的离子扩散行为对材料的导电能力、界面反应速度等有着决定性的作用。对离子扩散迁移能力的测试有助于研究电解质材料的导电行为，控制界面反应， 建立材料结构性能之间的微观联系。本论文利用激光共聚焦显微拉曼，通过不同的实验设计，提出了测试固体电解质中离子扩散系数和迁移率的方法。以氧化铈基电解质为代表，测试了氧离子的扩散迁移性能和多层陶瓷合成过程中铈离子的迁移情况。成功制备了不同 La3+掺杂浓度的氧化铈 Ce1-xLaxO2-x/2（ x=0.05~0.35） 。对其进行拉曼测试后发现， 氧空位对应峰峰强同总峰强之比（ I570/I 总） 与掺杂浓度之间存在线性对应关系。 通过在样品表面逐点测试拉曼光谱， 得到了不同电场强度下样品中氧空位浓度的分布情况。氧空位浓度在电场下呈线性分布，并且浓度梯度随着电场强度增强而增大。 根据空位浓度的分布计算得到了不同温度下的氧离子扩散系数。首先在电解质材料两端施加电场，引起材料中氧空位浓度非均匀分布。然后撤去电场，用拉曼光谱测试不同时刻材料中氧空位浓度的分布情况。结果表明，撤去电场后靠近电极附近空位浓度变化剧烈，而远离电极位置浓度变化较小。推导了氧空位浓度随测试位置和时间的关系，用 Matlab 拟合得到了不同温度下的氧离子扩散系数。通过在电解质材料两端施加周期性改变方向的电场，用拉曼光谱测试固定位置氧空位浓度随时间变化。 统计了空位浓度在两个平衡状态之间的过渡时间， 发现该时长同施加电压呈反比。根据实验结果提出了强电场下固态电解质中离子迁移过程，并通过物理模型计算得到了氧离子在不同温度下的迁移率。合成了 YSZ/SNDC 复合电解质材料， XRD 结果表明在界面处存在微量CeZrO4 杂相。 复合电解质电导率介于纯 SNDC 和 YSZ 之间。利用拉曼面扫可以直观观察界面区域的扩散情况。 利用 SNDC 与 YSZ 的特征峰峰强比（ I465/I630） 表征了界面区域的扩散层位置及厚度，该结果同 EDS 测试结果一致。 复合电解质烧结温度越高，保温时间越长，扩散层厚度越厚。 Ce 离子在两层电解质之间的扩散遵循菲克定律。
Diffusion in solids plays an essential role in the conduction behavior of electrolyte,the determination of interface reaction. The detection of ion migration is benefit forunderstanding the conduction behavior in electrolyte materials and control the processof interface diffusion. Moreover, it is important to establish the relationship between thematerial properties with their micro structure. In the present thesis, we have put forwardnew methods for the determination of ion diffusivity and mobility in solid electrolytesbased on different experimental design using a laser confocal micro Ramanspectrometer. Ceria based electrolyte as the representative, the diffusion coefficient ofoxygen ions and the migration of ceria cation during fabrication of multi-layerelectrolyte has been investigated.A series of ceria based electrolyte with various dopant concentrationCe1-xLaxO2-x/2 (x=0.05~0.35) has been synthesized successfully. Raman spectroscopyhas been measured for all compositions. The intensity ratio of peak for oxygen vacancyto the total intensity (I570/ITotal) increase linearly with the dopant concentration. Thedistribution of oxygen vacancies has been obtained by measuring the Ramanspectroscopy point by point along sample surface. The concentration of oxygenvacancies exhibit linear distribution under electric field and the concentration gradientincrease with the electric field. The diffusion coefficient of oxygen ions has beenacquired through analyzing the distribution of oxygen vacancies under electric field.An electric field was applied on the electrolyte to induce the inhomogeneity ofoxygen vacancies. Then the electric field was removed and the distribution of oxygenvacancies at different time was recorded using Raman spectroscopy. The concentrationof oxygen vacancies near electrode part changed obviously while the side away fromelectrode changed slowly. The concentration change of oxygen vacancies with testpositions and measured time was derived. The diffusion coefficient of oxygen ions wasacquired by fitting with the experiment data using Matlab.An electric field which change the direction periodically was applied on theelectrolyte. The change of oxygen vacancies at test position was recorded by Ramanspectroscopy. The time interval between two steady state of oxygen vacancies has beenAbstractIIImeasured and it is inversely proportional to the value of applied electric field. Apossible migration process of oxygen ions in solid electrolyte under strong electric fieldhas been put forward based on the experiment discovery. The mobility of oxygen ionshas been acquired with a physical model.YSZ/SNDC bilayer electrolyte has been fabricated successfully. XRD resultindicates the existence of tiny impurity phase of CeZrO4. The conductivity ofcomposite electrolyte is between pure YSZ and SNDC. The diffusion region canbe observed visually using Raman mapping. The diffusion thickness at interfaceregion can be measured using Raman intensity ratio of characteristic peaks ofYSZ and SNDC (I465/I630). The diffusion thickness acquired using Rmanspectroscopy is consistant with the one measured by EDS. The thickness ofdiffusion region increase with the sintering temperature and holding time. Themigration of Ce cations follow Fick’s law.
