Disentangling the role of small polarons and oxygen vacancies in CeO2
Disentangling the role of small polarons and oxygen vacancies in CeO2
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DOI：
10.1103/physrevb.95.245101
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发表时间：
2017-06
影响因子：
3.7
通讯作者：
Lu Sun;Xiaowei Huang;Ligen Wang;A. Janotti
中科院分区：
文献类型：
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作者：
Lu Sun;Xiaowei Huang;Ligen Wang;A. Janotti
氧化铈（CeO 2）作为离子导体或催化剂的优异性能在很大程度上取决于Ce参与Ce转化和氧空位形成的难易程度。因此，准确描述Ce和氧空位是在这一领域的进一步进展是必不可少的。利用HSE 06杂化泛函，研究了CeO 2中小极化子（Ce）的形成、迁移及其与氧空位的相互作用，将小极化子和空位视为独立的实体.氧空位是双施主，可以结合两个小的极化子，形成带正电荷或中性的复合物。我们计算电子自陷能（即，形成小极化子时的能量增益）、小极化子迁移势垒、空位形成和迁移能量以及空位-极化子结合能。我们发现，小极化子弱绑定到氧空位，但这种相互作用显着有助于跳跃电子电导率的激活能。结果与以前的计算结果进行了比较，并根据现有的实验数据进行了讨论。* 通讯作者。电子邮件地址：janotti@udel.edu
The outstanding performance of cerium oxide (CeO2) as ion conductor or catalyst strongly depends on the ease of Ce↔Ce conversion and oxygen vacancy formation. An accurate description of Ce and oxygen vacancy is therefore essential to further progress in this area. Using the HSE06 hybrid functional, we investigate the formation and migration of small polarons (Ce) and their interaction with oxygen vacancies in CeO2, considering the small polaron and vacancy as independent entities. Oxygen vacancies are double donors and can bind up to two small polarons, forming a positively charged or neutral complex. We compute the electron self-trapping energy (i.e., energy gain when forming a small polaron), the small-polaron migration barrier, vacancy formation and migration energies, and vacancy-polaron binding energies. We find that small polarons weakly bind to oxygen vacancies, yet this interaction significantly contributes to the activation energy for hopping electronic conductivity. The results are compared with previous calculations and discussed in the light of available experimental data. * Corresponding author. Email: janotti@udel.edu