氢原子在过渡金属修饰的Mg(0001)面扩散的第一性原理研究  

First Principle Study on H Atom Diffusion on Mg(0001) Surface Doped with Transition Metal

作　　者：腊明[1] 陈昌东[1] 冯云晓[1] 张志玮[1] 

机构地区：[1]平顶山学院化学化工学院,平顶山467000

出　　处：《人工晶体学报》2015年第1期243-249,共7页Journal of Synthetic Crystals

基　　金：河南省科技攻关项目(KJT142102310462;KJT142192310186);河南省教育厅自然科学基金(12B430018);平顶山学院高层次人才基金

摘　　要：基于密度泛函理论(DFT)的第一性原理计算方法,对氢原子在过渡金属(Sc、Ti、Cr、Mn、Fe、Co、Ni、Cu、V、Zn)修饰的Mg(0001)表面扩散性能进行了研究。研究发现过渡金属元素Sc、Ti、V、Cr、Mn、Fe、Co、Ni和Cu选择替代在镁表面第二层稳定,而Zn则选择替代在第一层稳定。当镁表面掺杂Zn和Cu时,氢原子选择停留在表面稳定;当掺杂Sc、Ti、V、Cr、Mn、Fe、Co和Ni时,氢原子选择进入镁块体内部。值得一提的是氢原子通过从过渡金属顶部通道扩散进入镁块体内部的势垒大大降低,笔者用差分电荷密度分析后发现氢原子与过渡金属原子成键使扩散势垒降低。当氢原子进入镁块体内部后靠近Sc、Ti、V、Cu和Zn原子时,将与这些过渡金属原子成键,从而阻碍了氢原子继续向内部扩散;而氢原子靠近Cr、Mn、Fe、Co、Ni原子时,选择离开过渡金属从而促进了氢原子向块体内扩散,可以大幅改善镁基储氢材料的吸氢动力性能。H atom diffusion on clean and transition metals（Sc,Ti,Cu,Cr,Mn,Fe,Co,Ni,V and Zn） doped Mg（0001） surfaces was studied by first-principles calculations within the density functional theory（DFT）. Firstly,the stability of transition metals atom doped Mg（0001） surface was studied. The results show that transition metal such as Sc,Ti,V,Cr,Mn,Fe,Co,Ni and Cu prefer to substitute in the second layer. On the other hand,Zn tends to substitute in the first layer. Secondly,H atom diffusion on transition metal atoms doped Mg（0001） surfaces were studied. The results show that when Mg（0001）surface doped by Zn and Cu,H atom prefer to place on the surface. Oppositely,when Mg（0001） surface doped by Sc,Ti,V,Cr,Mn,Fe,Co,Ni and Cu,H atom prefer to place inside the Mg bulk. It＇s worth mentioning that the energy barriers of H atom diffusion inside the Mg（0001） surface which doped with transition metal has been significant reduced. Charge density difference distributions point out that theeffect comes from H atom bonding with transition metal atom. H atom binds the transition metal atom such as Sc,Ti,V,Cu and Zn tightly,and prevents H atom continue to diffusion into the Mg bulk.Oppositely,when Mg（0001） surface doped with Cr,Mn,Fe,Co and Ni; the transition metal atoms bind the H atoms loosely,allowing them easily to diffuse. The results will improve the H absorption kinetics of Mg-based materials.

关 键 词：过渡金属 Mg(0001)面 氢原子 扩散 密度泛函理论 

分 类 号：O469[理学—凝聚态物理]