摘要
基于分子动力学方法,利用Buckingham势描述原子间的相互作用,使用Ziegler-Biersack-Littmark(ZBL)库仑屏蔽势修正近程力,积分过程中采用自适应步长,使用Wigner-Seitz方法判别缺陷,研究了不同种类、方向、能量的初始撞出原子(primary knock-on atom,PKA)作用下,ZrO2中点缺陷的时空演化特性。结果表明,在弹道阶段、离位峰阶段和稳定阶段中,O缺陷数始终大于Zr缺陷数。与Zr-PKA作用相比,原子序数较小的O-PKA作用下缺陷产生速率较小,缺陷数峰值较小,空间分布不集中;PKA以不同方向入射时,在ZrO2中产生的缺陷数峰值不同,损伤呈现出各向异性,但缺陷数稳态值相差不大;PKA能量增大,级联碰撞时间增长,缺陷数增多。在级联碰撞作用下,ZrO2的晶体结构没有改变,仅产生了孤立的点缺陷及尺寸较小的点缺陷簇,表现出优异的抗辐照性能。
The spatio-temporal evolution characteristics of irradiation induced point defects in ZrO2 is studied by molecular dynamics using collision cascade model.To account for the highly non-equilibrium nature of collision cascade,some modifications are made to the classical MD codes.Firstly,the empirical Buckingham potential is employed to describe the interaction between atoms,which is joined to ZBL(Ziegler-Biersack-Littmark)potential at short distances using Fermi function.Then,the dynamic equations are solved numerically with an adaptive time step.Finally,the point defects are determined by Wigner-Seitz analysis.The results show that the number of O defects is always greater than that of Zr defects in ballistic,displacement spike and steady stages.Compared with the results produced by Zr-PKA,the spatial distribution of defects induced by O-PKA is more dispersed,and the generation rate and peak value is smaller.Besides,the incident direction of PKA has a significant effect on the evolution of defect number over time.Specifically,the peak value of defects varies greatly,but the surviving value is almost the same.Moreover,the duration of collision cascade and the number of defects are positively correlated with PKA energy.The results of radial distribution function(RDF)show that displacement damage can hardly change the structural order of ZrO2,which has excellent radiation resistance.The damage mainly exists in the form of isolated point defects and small clusters of point defects.
作者
赵中华
渠广昊
闵道敏
刘杰
李盛涛
ZHAO Zhong-hua;QU Guang-hao;MIN Dao-min;LIU Jie;LI Sheng-tao(State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University,Xi’an 710049,China;Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China)
出处
《现代应用物理》
2020年第4期106-111,共6页
Modern Applied Physics
基金
国家自然科学基金资助项目(11690040,11690041)
强脉冲辐射环境模拟与效应国家重点实验室基金资助项目(SKLIPR1709)。
