过渡金属对Mg_2Ni氢化物电子结构和热力学稳定性影响:第一性原理研究  

Effects of transitional metal on electronic structure and thermodynamic stability of Mg_2Ni hydride: A first-principle investigation

作　　者：陈捷狮[1] 曾含[1] 王路[1] 蓝志强[1] 郭进[1] 

机构地区：[1]广西大学物理科学与工程技术学院,南宁530004

出　　处：《中国有色金属学报》2012年第1期216-223,共8页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(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

摘　　要：采用基于密度泛函理论(DFT)的平面波赝势(PW-PP)方法,计算并分析了Mg2Ni1-xMx(M=Mn,Fe,Co,Ni,Cu,x=0.25)合金及其氢化物Mg2Ni1-xMxH4的电子结构和热力学稳定性。计算结果表明:Mg2NiH4和Mg2Ni1-xMx的晶胞参数与实验值吻合较好。对Mg2Ni1-xMxH4的电子结构分析发现:氢化物中的Ni—H和M—H键为共价键、Mg—H键为离子键,且Ni—H与M—H键的相互作用强于Mg—H键的。Mn、Fe和Co的部分替代对Ni—H键的相互作用影响较小,而Cu的替代则减弱了Ni—H键的相互作用,这可能是Cu替代后氢化物结构稳定性降低的一个原因。计算了Mg2Ni0.75M0.25H4(M=Mn,Fe,Co,Ni,Cu)的生成焓,分别为-57.7、-61.5、-61.4、63.4和41.6 kJ/mol,与实验值吻合较好。The electronic structures and thermodynamic stabilities of Mg2Ni1-xMx（M=Mn,Fe,Co,Ni,Cu,x=0.25） alloys and their hydrides Mg2Ni1-xMxH4 were investigated by plane-wave pseudo-potential approach based on the density functional theory.It is found that the calculated cell parameters of Mg2NiH4 and Mg2Ni1-xMx alloy are in good agreement with the experimental results.For Mg2Ni1-xMxH4,the interaction between Mg-H bonds is ionic bond,while the interactions between Ni-H and M-H are covalent bonds,which are stronger than that of Mg-H bonds.The Ni-H bond strength is almost unchanged when Ni is partially replaced by Mn,Fe and Co,and the Ni-H bond strength is weakened when Ni is partially substituted by Cu,which may be one of the reasons for causing the reduced structure stability of Mg2Ni0.75Cu0.25H4.The calculated formation enthalpies of Mg2Ni0.75M0.25H4（M=Mn,Fe,Co,Ni,Cu） are -57.7,-61.5,-61.4,63.4 and 41.6 kJ/mol,respectively,which are in good agreement with the experimental results.

关 键 词：MG2NI 第一性原理 电子结构 热力学稳定性 

分 类 号：O641[理学—物理化学]