Al辐照损伤初期的第一性原理研究

发布时间：2018-02-23 01:05

本文关键词： Al 辐照损伤点缺陷第一性原理　出处：《物理学报》2017年05期 　论文类型：期刊论文

【摘要】：采用密度泛函理论框架下的第一性原理平面波赝势方法,对Al辐照损伤初期产生的本征点缺陷和He缺陷进行了研究.通过晶体结构、缺陷形成能和结合能,分析比较了缺陷形成的难易程度及对晶体稳定性的影响,并从态密度、差分电荷密度和电荷布居的角度,分析了其电子机理.结果表明:对于同类型的缺陷,其造成的晶格畸变越大,体系稳定性越低,缺陷形成的难度越大.同类型缺陷形成的难易程度由易到难依次为空位(置换位原子)、八面体间隙原子和四面体间隙原子,但相同位置的本征缺陷的形成难度小于He缺陷.间隙原子容易与空位结合,且Al原子与空位结合的能力强于He原子.间隙Al原子和He原子主要存在于八面体,且缺陷原子引起部分电子向更高能级转移,并导致与其最邻近的Al原子之间的共价作用减弱,从而降低了体系稳定性.间隙Al原子与最邻近的Al原子之间产生了强烈的共价作用,而He原子和最邻近Al原子之间主要为范德瓦耳斯力和较弱的离子键,这是含He缺陷的体系稳定性更低的重要原因.
[Abstract]:Based on the first-principle plane-wave pseudopotential method under the framework of density functional theory (DFT), the intrinsic point defects and he defects produced in the initial stage of Al irradiation damage are studied. The formation energy and binding energy of the defects are obtained by means of the crystal structure. The degree of difficulty in forming defects and their effects on crystal stability are analyzed and compared. The electronic mechanism of the defects is analyzed from the angles of density of states, differential charge density and charge distribution. The results show that: for the same type of defects, The greater the lattice distortion, the lower the stability of the system and the more difficult the formation of defects. The easy degree of formation of the same type of defects is vacancy (substitution atom, octahedron interstitial atom and tetrahedron gap atom). However, the formation of intrinsic defects in the same position is less difficult than that of he defects. Interstitial atoms are easy to bind to vacancies, and Al atoms have stronger ability to bind to vacancies than he atoms, and interstitial Al atoms and he atoms mainly exist in octahedrons. The defect atom causes partial electron transfer to higher energy order and weakens the covalent interaction with its nearest Al atom. Thus, the stability of the system is reduced. There is a strong covalent interaction between the interstitial Al atoms and the nearest Al atoms, while between he atoms and the nearest Al atoms, the van der Waals force and the weaker ionic bonds are the main ones. This is an important reason for the lower stability of He-containing systems.
【作者单位】：火箭军工程大学核工程系;中国科学院力学研究所高温气体动力学国家重点实验室;
【基金】：国家自然科学基金(批准号:11472280,51272298)资助的课题~~
【分类号】：O469

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