Al 掺杂对Mg2Ni 合金的电子结构及贮氢性能的影响  

Effect of Doping with Aluminium on the Electronic Structure and Hydrogen Storage Properties of Mg_2Ni Alloy

作　　者：蓝志强[1] 肖潇[1] 苏鑫[1] 陈捷狮[1] 郭进[1] 

机构地区：[1]广西大学物理科学与工程技术学院,有色金属及材料加工新技术教育部重点实验室,南宁530004

出　　处：《物理化学学报》2012年第8期1877-1884,共8页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(50861003,51071054);广西科学基金重点项目(2010GXNSFD013004);广西大学拔尖创新团队建设计划项目资助~~

摘　　要：采用基于密度泛函理论(DFT)的平面波赝势(PW-PP)方法,计算Mg2-xAlxNiH4(x=0,0.125,0.25)合金的晶胞体积、电子态密度、键序、电荷布居、生成焓,分析原子间成键和结构的稳定性,研究Al部分替代Mg对Mg2Ni合金及其氢化物的结构和储氢性能的影响.结果表明:随着Al含量的增加,Mg2Ni合金晶胞体积减小,不利于氢原子进入合金中,导致合金的储氢容量降低.在Mg2-xAlxNiH4(x=0,0.125,0.25)中,Mg-H和Al-H相互作用远小于Ni-H的相互作用,随着Al含量的增加,氢化物生成焓减少以及Ni-H的相互作用减弱,氢化物的结构稳定性降低,Al部分替代Mg能有效改善Mg2Ni合金释氢动力学性能.Using plane wave pseudopotential methods based on density functional theory, the unit cell volumes, the electronic densities of states, the bond orders, the charge populations, and the formation enthalpies of Mg2-xAlxNiH4 （x=0, 0.125, 0.25） alloys were calculated. By analyzing atom bonding and structural stability, the effects of partially substituting Al for Mg on the structure and hydrogen storage property of the alloys and their hydrides were investigated. It was shown that the unit cell volume of the Mg2Ni alloy decreases with the increase of Al content; the decreased unit cell volume hinders the incorporation of hydrogen atoms, thus reducing the hydrogen storage capacity. For Mg2-xAlxNiH4 （x=0, 0.125, 0.25） hydrides, the Mg-H and Al-H interactions are much weaker than the Ni-H interaction. However, the Ni-H interaction is weakened and the hydride enthalpy of formation decreases with increased Al content. Although the stability of the hydride structure is weakened, hydrogen desorption kinetics for the Mg2Ni hydride can be improved with the partial substitution of Al for Mg.

关 键 词：第一性原理: Mg2Ni合金:贮氢性能: 电子结构:态密度 

分 类 号：TG139.7[一般工业技术—材料科学与工程]