MgH_2-X(X=Si,Ge,Sn,Pb)体系解氢能力的第一原理计算  

First-Principles Calculation of Dehydrogenating Properties of MgH_2-X(X=Si,Ge,Sn,Pb) Systems

作　　者：周惦武[1] 刘金水[2] 张健[2] 彭平[2] 

机构地区：[1]湖南大学机械与汽车工程学院,湖南长沙410082 [2]湖南大学材料科学与工程学院,湖南长沙410082

出　　处：《湖南大学学报（自然科学版）》2006年第6期85-89,共5页Journal of Hunan University:Natural Sciences

基　　金：教育部高等学校博士学科点专项科研基金资助项目(20020530012)

摘　　要：采用基于密度泛函理论的第一原理赝势平面波方法,研究了MgH2-X(X=Si,Ge,Sn,Pb)合金化体系的能量、几何与电子结构.负形成热的计算发现:合金化元素X在镁氢化合物(MgH2)中少量固溶时,体系相结构稳定性变差,预示着解氢能力得到改善.电子态密度(DOS)与电子密度的进一步分析发现:镁氢化合物X合金化后,X与其周围的H原子相互作用不明显,而Mg-H之间的成键作用减弱.体系Ge合金化解氢能力增强的理论计算与实验结果一致,预测Si,Sn,Pb少量固溶于MgH2能提高体系的解氢能力.A first-principles plane-wave pseudopotential method based on the density functional theory was used to investigate the energy and electronic structure of magnesium hydride （MgH2） alloyed by X（X = Si,Ge, Sn,Pb）. Through calculations of the negative heat of formation of magnesium hydride alloyed by X, it was found that when a little X dissolve into magnesium hydride, the structural stability of alloying systems decreases, which indicates that the dehydrogenation properties of MgH2 can be improved. After comparing the densities of states （DOS） and the charge distribution of MgH2 with and without X alloying, it was found that the improvement of the dehydrogenation properties of MgH2 alloyed by X attributes to the fact that the weakened bonding between magnesium and hydrogen is caused by no stronger interactions between X and hydrogen. The calculation results of the improvement of the dehydrogenation properties of MgH2-X （X= Ge） systems are in agreement with the experimental results. Hence, the dehydrogenation properties of MgH2 are expected to be improved by the addition of Si, Sn, Pb alloying elements.

关 键 词：赝势平面波 镁氢化合物 合金形成热 电子结构 

分 类 号：TG146.2[一般工业技术—材料科学与工程]