Ti掺杂对Li-Mg-N-H材料储氢性能影响的第一性原理研究  

First-Principles Study on the Effect of Ti Doping on Hydrogen Storage Performance of Li-Mg-N-H Materials

作　　者：闫敏艳 宫长伟[1] 张鹤 张敏刚[1] YAN Minyan;GONG Changwei;ZHANG He;ZHANG Mingang(College of Materials Science and Engineering,Taiyuan University of Science and Technology,Taiyuan 030024,China)

机构地区：[1]太原科技大学材料科学与工程学院,太原030024

出　　处：《人工晶体学报》2022年第2期297-303,共7页Journal of Synthetic Crystals

基　　金：山西省高等学校科技创新项目(2020L0367);太原科技大学科研启动基金(20152028)。

摘　　要：采用基于密度泛函理论的第一性原理赝势平面波方法,研究了Ti掺杂对Li_(2)MgN_(2)H_(2)材料储氢性能的影响及作用机理,计算给出了杂质替换能、生成焓、能带结构、态密度、差分电荷密度及布居等。研究表明,Ti掺杂Li_(2)MgN_(2)H_(2)体系时,其倾向于替换其中的Mg原子,且当替换8c位置的Mg时,杂质替换能最低,晶体结构最为稳定。生成焓计算结果表明,Ti掺杂能够有效降低Li_(2)MgN_(2)H_(2)的结构稳定性,有利于其吸氢反应的进行。进一步结合电子结构分析发现,Ti掺杂使得Li_(2)MgN_(2)H_(2)材料的晶胞体积增大,能隙降低,同时Ti与N原子之间较强的相互作用使得Li—N和N—H键的成键峰峰值降低,键强减弱,这些因素均有利于Li_(2)MgN_(2)H_(2)材料吸氢动力学性能的提高。The effect of Ti doping on the hydrogen storage performance of Li_(2)MgN_(2)H_(2)materials and its mechanism were investigated by the first-principles plane-wave pseudopotential method based on the density functional theory.The impurity replacement energy,formation enthalpy,energy band structure,density of states,differential charge density and population were calculated.The results show that when Ti atom is doped with Li_(2)MgN_(2)H_(2)system,it tends to occupy the Mg lattice sites,and when replacing Mg at position 8c,the impurity replacement energy is the lowest and the crystal structure is the most stable.The calculation results of the formation enthalpy indicate that Ti doping can effectively reduce the structural stability of Li_(2)MgN_(2)H_(2),which is beneficial to its hydrogen absorption reaction.Further combined with the analysis of the electronic structure,it is found that for the Li_(2)MgN_(2)H_(2)materials after Ti doping,the unit cell volume increases and the energy gap reduces.At the same time,because of the strong interaction between Ti and N atoms,the peak value of the Li—N and N—H bonds reduces,and the bond strength weakens.These factors are all conducive to the improvement of the hydrogen absorption kinetic performance of the Li_(2)MgN_(2)H_(2)material.

关 键 词：第一性原理 Li-Mg-N-H Ti掺杂 生成焓 电子结构 储氢 

分 类 号：O469[理学—凝聚态物理] TB34[理学—电子物理学]