元素替代对Mg_2NiH_4释氢性能影响的第一性原理研究  

First-principles study on the effect of component element substitution on the dehydrogenation ability of Mg_2NiH_4

作　　者：黄彬彬[1] 张星辉[1] 贾焕玉[1] 

机构地区：[1]西南交通大学现代物理研究所,成都610031

出　　处：《原子与分子物理学报》2011年第3期563-569,共7页Journal of Atomic and Molecular Physics

基　　金：国家自然科学基金(10874142;10974161);中央高校基本科研业务费专项资金(SWJTU09CX0792010ZT06)

摘　　要：采用基于密度泛函理论(DFT)的平面波赝势(PWP)方法,研究了元素替代对Mg_2NiH_4释氢性能的影响.计算给出了晶胞参数、电子态密度、原子间的键序和生成焓,分析了氢化物的结构稳定性和原子间成键作用之间的关系.计算结果表明,生成焓的计算值随替代元素M(Ti,V,Cr)的变化趋势和实验测定的结果一致,且Ti的替代较好地降低了Mg_2NiH_4的结构稳定性,提高了Mg_2NiH_4的释氢性能.分析电子结构可得,Ni(h)-H和M-H间的相互作用是影响Mg_2NiH_4结构稳定性的主要因素,替代元素正是通过改变M-H的相互作用来提高Mg_2NiH_4的释氢性能.The influence mechanism of element substitution on the dehydrogenation ability of Mg2NiH4 was investigated by using plane - wave pseudo - potential method based on density functional theory. The cell parameters, the density of states, the bond order between atoms and the formation enthalpies were obtained by the calculation. The structural stability of the hydride and the binding nature between atoms were analyzed. With M （M=Ti, V, Cr） substitution, the tendency of the formation enthalpies was consistent with the experiment. The best effect is got by the Ti substitution, which can reduce the structural stability and improve the hydride desorption kinetics of Mg2NiH4. Further analysis of the electronic structures, the interactions of Ni - H and M - H play a dominant role in the structural stability of Mg2NiH4. The substitute element just tries to improve the dehydrogenation ability of Mg2NiH4 by the interactions of M - H.

关 键 词：MG2NIH4 第一性原理 结构稳定性 电子结构 

分 类 号：TG139.7[一般工业技术—材料科学与工程]