Liu Xiang-Yang, Martinez Enrique, Uberuaga Blas P
Materials Science and Technology Division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545, USA.
Sci Rep. 2019 Apr 24;9(1):6499. doi: 10.1038/s41598-019-42926-z.
Understanding the effect of dislocations on the mass transport in ionic ceramics is important for understanding the behavior of these materials in a variety of contexts. In particular, the dissociated nature of vacancies at screw dislocations, or more generally, at a wide range of low-angle twist grain-boundaries, has ramifications for the mechanism of defect migration and thus mass transport at these microstructural features. In this paper, a systematic study of the dissociated vacancies at screw dislocations in MgO is carried out. The important role of stress migration in the atomistic modeling study is identified. Another aspect of the current work is a rigorous treatment of the linear elasticity model. As a result, good agreement between the atomistic modeling results and the linear elasticity model is obtained. Furthermore, we demonstrate that the proposed vacancy dissociation mechanism can also be extended to more complicated ionic ceramics such as UO, highlighting the generality of the mechanism.
了解位错对离子陶瓷中质量传输的影响对于理解这些材料在各种情况下的行为至关重要。特别是，螺旋位错处空位的解离性质，或者更一般地说，在各种小角度扭转晶界处空位的解离性质，对缺陷迁移机制以及因此在这些微观结构特征处的质量传输有影响。本文对MgO中螺旋位错处的解离空位进行了系统研究。确定了应力迁移在原子模型研究中的重要作用。当前工作的另一个方面是对线性弹性模型的严格处理。结果，原子模型结果与线性弹性模型之间取得了良好的一致性。此外，我们证明所提出的空位解离机制也可以扩展到更复杂的离子陶瓷，如UO，突出了该机制的普遍性。
