Core structure and dissociation energetics of basal edge dislocation inalpha-A1203 : A combined atomistic simulation and transmission electron microscopy analysis
Core structure and dissociation energetics of basal edge dislocation inalpha-A1203 : A combined atomistic simulation and transmission electron microscopy analysis
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α-A1203 基底边缘位错的核心结构和解离能量：原子模拟和透射电子显微镜分析相结合
DOI：
10.1016/j.actamat.2013.11.035
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发表时间：
2013
期刊：
影响因子：
9.4
通讯作者：
Y. Ikuhara
中科院分区：
文献类型：
--
作者：
K. Tsuruta;E. Tochigi;Y. Kezuka;K. Takata;N. Shibata;A. Nakamura;Y. Ikuhara
利用大规模分子动力学(MD)模拟方法，研究了α-Al_2O_3中1/3<；1 1 1‘0>；和1/3<；1 1 1’0>；1/3<；1 1 2>；1/3<；1 1 2>；1/3<；1 1 1‘0>；1/3<；1 1 2>；1/3<；1 1 2>；1/3<；1 1 1’0>；1/3<；1 1 2>；1/3<；1 1 1‘0>；1/3<；1 1 2 0>；1/3<；1 1 2 0>；1/3部分位错对具有稳定的核间距(∼2 nm)，这也是在高分辨电子显微镜实验中观察到的现象。分部之间的距离可以用弹性芯-芯排斥力和对层错扩展的有效引力(SFS)之间的平衡来定量解释。比较了部分位错的两种核心结构：一对具有Al/O端面的偏位错和一对具有Al/Al端面的偏位错。在两种情况下，核间相互作用和平衡距离的总体趋势是相同的，而Al-O端基对在平衡距离处的能量略有有利。在分子动力学结果中观察到了SF平面上的残余剪应力，这可以归因于SF中的局域原子结构。
Using large-scale molecular dynamics (MD) simulations, we investigate the energetics and local structures/stresses of partial dislocations, 1/3< 0 1 1¯ 0> and 1/3< 1 0 1¯ 0>, dissociated from the 1/3< 1 1 2¯ 0> perfect basal edge dislocation in α-Al 2 O 3. The validity of the model adopted in the simulation is confirmed by comparing with theoretical stress/strain distributions and with those experimentally obtained from a high-resolution transmission electron microscopy (HRTEM) observation. Partial dislocation pairs have a stable inter-core distance (∼ 2 nm), which is also a phenomenon that is observed in the HRTEM experiments. The distance between the partials can be explained quantitatively by the balance between an elastic core–core repulsion and an effective attractive force against the extension of stacking faults (SFs). A comparison is made for two types of core structures of partial dislocations: a pair of partials with Al-terminated/O-terminated extra-half planes and that with Al-/Al-terminated ones. The overall tendency of the inter-core interaction and the equilibrium distances are the same in both cases, whereas the Al–O-terminated pair is slightly favourable in energy at the equilibrium distance. A residual shear stress on the SF plane is observed in the MD results, which can be attributed to local atomic structure in the SF.