Abstract Oxygen ion diffusion determines the performance of materials in energy conversion, energy storage and catalysis. For nominally pure cerium oxide, experiments measure high activation enthalpies while calculations predict low activation enthalpies. Moreover, for doped oxides, e.g. doped ceria, experiments show a high activation enthalpy for both pure ceria and for high dopant fractions, leading to a minimum in activation enthalpy for small dopant fractions. While for high dopant fractions the increase in activation enthalpy is correlated with the association of oxygen vacancies and dopant ions, which are both created by doping, the minimum in activation enthalpy is assumed in the literature to be related to the maximum in ionic conductivity at similar dopant fractions. In this study, density functional theory (DFT) calculations and Kinetic Monte Carlo (KMC) simulations are combined in order to calculate the ionic conductivity and activation enthalpy in doped oxides. We show that the experimental ionic conductivity and activation energy in nominally pure cerium oxide is dominated by impurities. We resolve the discrepancy between activation enthalpies of nominally pure oxides in experiments as opposed to calculations. This will lead to a more comprehensive understanding of the oxygen ion conductivity and its underlying atomistic mechanisms. Moreover, such a focus will be of great benefit to the future development of sustainable and efficient materials.

中文翻译：

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掺杂二氧化铈和高活化能的无限稀释

摘要 氧离子扩散决定了材料在能量转换、储能和催化方面的性能。对于名义上纯的氧化铈，实验测量高活化焓，而计算预测低活化焓。此外，对于掺杂的氧化物，例如掺杂的二氧化铈，实验显示纯二氧化铈和高掺杂剂分数的高活化焓，导致小掺杂剂分数的活化焓最小。虽然对于高掺杂分数，活化焓的增加与氧空位和掺杂离子的缔合有关，这两者都是由掺杂产生的，文献中假设活化焓的最小值与类似的离子电导率的最大值有关掺杂分数。在这项研究中，密度泛函理论 (DFT) 计算和动力学蒙特卡罗 (KMC) 模拟相结合，以计算掺杂氧化物中的离子电导率和活化焓。我们表明，名义上纯氧化铈的实验离子电导率和活化能由杂质主导。我们在实验中解决了名义纯氧化物的活化焓之间的差异，而不是计算。这将有助于更全面地了解氧离子电导率及其潜在的原子机制。而且，这样的关注将对可持续和高效材料的未来发展大有裨益。我们表明，名义上纯氧化铈的实验离子电导率和活化能由杂质主导。我们在实验中解决了名义纯氧化物的活化焓之间的差异，而不是计算。这将有助于更全面地了解氧离子电导率及其潜在的原子机制。而且，这样的关注将对可持续和高效材料的未来发展大有裨益。我们表明，名义上纯氧化铈的实验离子电导率和活化能由杂质主导。我们在实验中解决了名义纯氧化物的活化焓之间的差异，而不是计算。这将有助于更全面地了解氧离子电导率及其潜在的原子机制。而且，这样的关注将对可持续高效材料的未来发展大有裨益。