ICSM, UMR 5257 CEA/CNRS/UM2/ENSCM, Site de Marcoule-Bât. 426, BP 17171, 30207 Bagnols/Cèze, Cedex, France.
Inorg Chem. 2012 Mar 19;51(6):3868-78. doi: 10.1021/ic300071c. Epub 2012 Feb 29.
The dissolution of Ce(1-x)Ln(x)O(2-x/2) solid solutions was undertaken in various acid media in order to evaluate the effects of several physicochemical parameters such as chemical composition, temperature, and acidity on the reaction kinetics. The normalized dissolution rates (R(L,0)) were found to be strongly modified by the trivalent lanthanide incorporation rate, due to the presence of oxygen vacancies decreasing the samples cohesion. Conversely, the nature of the trivalent cation considered only weakly impacted the R(L,0) values. The dependence of the normalized dissolution rates on the temperature then appeared to be of the same order of magnitude than that of chemical composition. Moreover, it allowed determining the corresponding activation energy (E(A) ≈ 60-85 kJ·mol(-1)) which accounts for a dissolution driven by surface-controlled reactions. A similar conclusion was made regarding the acidity of the solution: the partial order related to (H(3)O(+)) reaching about 0.7. Finally, the prevailing effect of the incorporation of aliovalent cations in the fluorite-type CeO(2) matrix on the dissolution kinetics precluded the observation of slight effects such as those linked to the complexing agents or to the crystal structure of the samples.
为了评估化学组成、温度和酸度等多种物理化学参数对反应动力学的影响，将 Ce(1-x)Ln(x)O(2-x/2)固溶体在各种酸介质中进行溶解。归一化溶解速率（R(L,0)）强烈受到三价镧系元素掺入速率的影响，这是由于氧空位的存在降低了样品的内聚强度。相反，所考虑的三价阳离子的性质仅对 R(L,0)值产生微弱影响。归一化溶解速率对温度的依赖性似乎与化学组成的依赖性处于同一数量级。此外，它允许确定相应的活化能（E(A) ≈ 60-85 kJ·mol(-1)），这表明溶解过程是由表面控制的反应驱动的。对于溶液的酸度也得出了类似的结论：与（H(3)O(+））相关的部分阶数约为 0.7。最后，在萤石型 CeO(2)基质中掺入同价阳离子对溶解动力学的主要影响使得难以观察到轻微的影响，例如与配位剂或样品晶体结构相关的影响。
