Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第15卷    第9期    总第78期    2005年9月

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文章编号: 1004-0609(2005)09-1403-08
MgH2-Ti体系解氢能力的第一原理计算
周惦武, 彭 平, 刘金水

(湖南大学材料科学与工程学院, 长沙 410082)

摘 要:  采用基于密度泛函理论的第一原理赝势平面波方法, 计算了不同含量的Ti固溶于镁氢化合物(MgH2)中形成(MgTi)H2, 析出TiH2相形成TiH2/ MgH2相界的能量与电子结构。 负合金形成热的计算结果表明: 对MgH2进行Ti合金化, 体系相结构的稳定性变差, Ti在MgH2中固溶以及TiH2/ MgH2相界的存在均有利于MgH2解氢能力的增强。 电子态密度(DOS)与电子密度的进一步分析发现: 合金化体系解氢能力增强的主要原因在于Mg—H之间的成键作用较弱, 以及Ti诱导费米能级EF处电子密度N(EF)的增加和EF附近HOMO-LUMO能隙ΔEH-L的变窄甚至消失。

 

关键字:  MgH2; 赝势平面波; 解氢能力; 电子结构

First-principles calculation of dehydrogenating properties of MgH2-Ti systems
ZHOU Dian-wu, PENG Ping, LIU Jin-shui

School of Materials Science and Engineering, Hunan University,
Changsha 410082, China

Abstract: Using a first-principles plane-wave pseudopotential method, the energetics and electronic structure of (MgTi)H2 formed by titanium dissolving into magnesium hydride and TiH2/MgH2 interface model were investigated. The heats of formation of considered systems were estimated from the electronic structure calculations, a reduction of the absolute value of the negative heat of formation of titanium alloying systems was found as compared with that of MgH2. This indicates that titanium alloying befits the improvement of the dehydrogenating properties of MgH2. After compared the densities of states (DOS) and the charge distribution of MgH2 with and without titanium addition, it is found that the improvement of dehydrogenating properties of MgH2 caused by titanium alloying originates from the weakened bonding between magnesium and hydrogen, and the increasing of the valence electrons at Fermi level and decreasing of the HOMO-LUMO gap (ΔEH-L) near Fermi level.

 

Key words: MgH2; plane-wave pseudopotential theory; dehydrogenating properties; electronic structure

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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