Hinterberg J, Zacherle T, De Souza R A
Institute of Physical Chemistry, RWTH Aachen University and JARA-FIT, 52056 Aachen, Germany.
Phys Rev Lett. 2013 May 17;110(20):205901. doi: 10.1103/PhysRevLett.110.205901. Epub 2013 May 13.
We examine the effect of mechanical strain on the migration of oxygen vacancies in fluorite-structured ceria by means of density functional theory calculations. Different strain states (uniaxial, biaxial and isotropic) and strain magnitudes (up to ± 7%) are considered. From the calculations we extract the complete activation volume tensor for oxygen-vacancy migration in CeO(2), that is, all diagonal ΔV(mig,kk) and off-diagonal ΔV(mig,kl) tensor elements. These individual tensor elements are found, crucially, to be independent of strain state; they do, however, depend on stress (ΔV(mig,kk)) or effective pressure (ΔV(mig,kl)). Armed with knowledge of all tensor elements we predict strain states for which oxygen-ion transport in ceria is maximized. In general, with our approach the effect of an arbitrary strain state on the migration barrier for mass transport in a solid can be calculated quantitatively.
我们通过密度泛函理论计算研究了机械应变对萤石结构二氧化铈中氧空位迁移的影响。考虑了不同的应变状态（单轴、双轴和各向同性）以及应变幅度（高达±7%）。通过计算，我们提取了CeO₂中氧空位迁移的完整激活体积张量，即所有对角ΔV(mig,kk)和非对角ΔV(mig,kl)张量元素。至关重要的是，发现这些单个张量元素与应变状态无关；然而，它们确实取决于应力（ΔV(mig,kk)）或有效压力（ΔV(mig,kl)）。基于对所有张量元素的了解，我们预测了二氧化铈中氧离子传输最大化的应变状态。一般来说，采用我们的方法可以定量计算任意应变状态对固体中质量传输迁移势垒的影响。
