Vallinayagam Muthu, Posselt Matthias, Faßbender Jürgen
Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany. Technische Universität Dresden, 01062 Dresden, Germany.
J Phys Condens Matter. 2019 Dec 4;31(48):485702. doi: 10.1088/1361-648X/ab39a4. Epub 2019 Aug 8.
Calculations based on density functional theory are performed to investigate the interaction of O-Y and O-Y-Ti clusters in bcc Fe with He atoms, vacancies (v) and self-interstitial atoms (SIA). The four different cluster structures studied in our previous work (J. Phys.: Condens. Matter 31 095701) are considered. He, v and SIA are inserted on different positions inside and in the environment of the clusters, the total energy of the corresponding supercell is minimized and the binding and incorporation energy of the three kinds of defects is determined. He in the center of a cage-like (CL) cluster is more stable than on interfacial vacant sites (IVS). In CL O-Y clusters He on an IVS is more stable than in the cluster structure with oxygen in the center, whereas there is no significant difference between the two kinds for clusters with Ti. Up to a distance of 1.5 times the iron lattice constant from the cluster center He is not stable on most of the octahedral and tetrahedral interstitial sites in the Fe matrix near the interface. Instead He is shifted towards positions closer to the cluster. Relaxation occurs to known IVS as well as to previously unknown interfacial interstitial sites. Moreover, two or three He atoms are placed on sites found to be stable after adding a single He. The corresponding binding and incorporation energies obtained after relaxation are nearly equal to the sum of the values for the interaction with a single He atom. However, placing He dimers or trimers in the environment of a vacancy may also lead to relatively low values of the incorporation energy. Also, barriers for jumps of He atoms between interfacial sites and the center of CL clusters are determined. In the CL O-Y cluster the barriers are lower than in the CL O-Y-Ti cluster, i.e. trapping and release of He is easier in the former than in the latter. v and SIA interaction with the clusters is also attractive. The binding energy of v strongly depends on the site where v is inserted while in all studied cases the SIA is annihilated at the cluster-iron interface. Present results clearly demonstrate that the oxide-based nanoclusters are strong traps for irradiation induced defects which is in agreement with experimental findings.
基于密度泛函理论进行计算，以研究体心立方铁中O - Y和O - Y - Ti团簇与氦原子、空位（v）和自间隙原子（SIA）的相互作用。考虑了我们之前工作（《物理学报：凝聚态物质》31 095701）中研究的四种不同团簇结构。将氦、空位和自间隙原子插入团簇内部及其环境中的不同位置，使相应超胞的总能量最小化，并确定三种缺陷的结合能和掺入能。笼状（CL）团簇中心的氦比界面空位处（IVS）的氦更稳定。在CL O - Y团簇中，IVS上的氦比中心有氧的团簇结构中的氦更稳定，而对于含钛团簇，这两种情况之间没有显著差异。在距团簇中心1.5倍铁晶格常数的距离内，氦在界面附近铁基体中的大多数八面体和四面体间隙位置上不稳定。相反，氦会向更靠近团簇的位置移动。弛豫发生在已知的IVS以及先前未知的界面间隙位置。此外，在添加单个氦后发现稳定的位置上放置两个或三个氦原子。弛豫后得到的相应结合能和掺入能几乎等于与单个氦原子相互作用的值之和。然而，在空位环境中放置氦二聚体或三聚体也可能导致掺入能的相对较低值。还确定了氦原子在界面位置和CL团簇中心之间跳跃的势垒。在CL O - Y团簇中，势垒低于CL O - Y - Ti团簇，即前者中氦的捕获和释放比后者更容易。空位和自间隙原子与团簇的相互作用也具有吸引力。空位的结合能强烈依赖于空位插入的位置，而在所有研究的情况下，自间隙原子在团簇 - 铁界面处湮灭。目前的结果清楚地表明，基于氧化物的纳米团簇是辐照诱导缺陷的强陷阱，这与实验结果一致。
