Alloying effect on stability of MgH2 from a first-principles study

Alloying effect on the stability of MgH2 has been studied by using ab-initio total-energy calculations.Considering two different crystallographic modifications (rutile-type and fluorite-type structures)and the substitution effect from some transitional metals (Sc,Ti,Y),rare earths (La,Ce),and group ⅡA elements (Ca,Sr,Ba),the formation enthalpy and electronic structure of Mg1-xMxH2 have been calculated.The results show that MgH2 with the rutile-type structure becomes unstable and transforms into a fluorite-type structure beyond certain substitutional alloy contents,especially for Ti,Ce and Ba.Further analysis of electronic structure shows that the interactions between the substitutional atoms and H weaken the strength of Mg-H and Mg-Mg bonds,directly lowering the stability of Mg-based hydrides.This work may have predictive value for Mg based hydrogen storage alloy.
Mg-based alloy Alloying effect Structural transformation First-principles
Dian-Hui Wang Zhong-Min Wang Chao-Hao Hu Huai-Ying Zhou
School of Materials Science and Engineering,Guilin University of Electronic Technology,Guilin,Guangxi 541004,PR China
国内会议
常州
英文
294-294
2012-10-19(万方平台首次上网日期,不代表论文的发表时间)