Energetics and structural relaxation of constitutional defects in CoAl and CoTi from first principles
Energetics and structural relaxation of constitutional defects in CoAl and CoTi from first principles
复制标题
根据第一原理研究 CoAl 和 CoTi 组织缺陷的能量学和结构弛豫
DOI：
10.1103/physrevb.68.144103
复制
发表时间：
2003
影响因子：
3.7
通讯作者：
Y. Shirai
中科院分区：
文献类型：
--
作者：
M. Mizuno;H. Araki;Y. Shirai
采用第一性原理电子结构计算方法研究了CoAl和CoTi中本构缺陷的能量和结构弛豫。为了估计结构缺陷的稳定性，通过使用不同尺寸的超原胞进行计算，获得了形成能的组成依赖曲线。键合特性的差异导致CoAl和CoTi之间的缺陷的能量和结构弛豫的差异：共价键合特性在CoAl中比在CoTi中更明显，并且CoTi具有比CoAl更大的离子键合特性。在富Al CoAl中，Co空位比Al反位更有利，而在富Ti CoTi中观察到相反的趋势。反位的Ti-d轨道和过剩电子对Ti反位原子的稳定性起着重要的作用。在CoAl和CoTi中，本构缺陷周围的弛豫不能仅用原子尺寸的差异来解释。由于缺陷周围的电荷重新分布而引起的键合电荷密度的变化在结构弛豫中起着关键作用。这种情况源于金属间化合物中离子键和共价键的混合。离子键的性质导致缺陷周围的有效电荷和共价键的影响，电荷重新分布屏蔽有效电荷。CoTi中的离子成键特性导致Co反位原子周围的相邻原子和CoTi中的Ti空位向外弛豫。
The energetics and structural relaxations of constitutional defects in CoAl and CoTi are investigated using first-principles electronic structure calculations. In order to estimate the stability of the constitutional defects, the compositional dependence curves of the formation energy are obtained from the calculations employing supercells of various sizes. The difference in the bonding character induces the difference in the energetics and structural relaxations of the defects between CoAl and CoTi: A covalent bonding character is more pronounced in CoAl than in CoTi and CoTi has a larger ionic bonding character than CoAl. The Co vacancy is energetically more favorable than the Al antisite in Al-rich CoAl, whereas the opposite trend is observed in Ti-rich CoTi. The Ti-d orbital at the antisite and the excess electrons play an important role for the stability of the Ti antisite atom. The relaxation around the constitutional defects in CoAl and CoTi cannot be explained by only the atomic size difference. The change in the bonding charge density as a result of the charge redistribution around the defects plays a key role in the structural relaxation. This situation originates from the mixture of the ionic and covalent bonding character in intermetallic compounds. The ionic bonding character leads to the effective charge around the defects and the covalent bonding is affected by the charge redistribution screening the effective charge. The ionic bonding character in CoTi brings about the outward relaxations of the neighboring atoms around the Co antisite atom and the Ti vacancy in CoTi.
影响因子：
3.7
作者：
N. Kulikov;A. Postnikov;G. Borstel;J. A. S. S. O. Physics-J.-A.-S.-S.-O.-Physics-1410184010;Troitsk;Russia.;Osnabrueck University
通讯作者：
N. Kulikov;A. Postnikov;G. Borstel;J. A. S. S. O. Physics-J.-A.-S.-S.-O.-Physics-1410184010;Troitsk;Russia.;Osnabrueck University