【作者】 黄丹；

【导师】 郭进；

【作者基本信息】 广西大学 ， 理论物理， 2006， 硕士

【摘要】 本论文研究了Mg基贮氢合金的电子结构及贮氢性能。在理论计算方面，采用第一原理平面波赝势方法，对Mg₂Ni及其氢化物LT（low temper-ature phase）相、HT（high temperature phase）相-Mg₂NiH₄电子结构进行研究，对其成键特征进行了分析，并对LT、HT-Mg₂NiH₄的电子结构差异进行了比较；利用同样的方法研究了La₂MgNi₉及LaMg₂Ni₉的电子结构，并对La₂MgNi₉及LaMg₂Ni₉的性能差异提供了微观解释。在实验方面，通过Ar气保护下的高频感应熔炼方法，制备了La_1+xMg_2-xNi₉（x=0，0.5，1.0，1.5）系列合金，研究了不同La、Mg含量对合金的相组成及其贮氢和电化学性能的影响。 在LT、HT-Mg₂NiH₄中，Ni原子轨道H原子轨道在成键区存在较强的s-p-d杂化作用，因而造成了Mg₂NiH₄放氢动力学性能差。可把Ni与周围的四个氢原子视为NiH₄单元，Mg与NiH₄单元的作用存在一定的离子性。在LT→HT的转变中，Mg与NiH₄之间的离子作用减弱，电子在其之间受到的束缚减弱，使得在高温相中电子更具有离域性，LT-Mg₂NiH₄显示为半导体，而HT-Mg₂NiH₄则为导体。 在La₂MgNi₉中，根据La取代LaMg₂Ni₉中Mg位置的不同，建立了分散及近邻模型。在分散取代下，系统具有更低的能量，其生成热也相对更多还原

【Abstract】 In this dissertation, the electronic structures and hydrogen storage properties of Mg-based hydrogen storage alloys have been investigated. For one thing, the electronic structures of Mg₂Ni alloys and its hydride were calculated by first-principle plane-wave pseudopotential method, and the bonding characteristics were analyzed. The difference in electronic structures between LT（low temperature phase）-Mg₂NiH₄ and HT（high temperature phase）-Mg₂NiH₄ were discussed. The electronic structures of La₂MgNi₉ and LaMg₂Ni₉ were studied by the same method. The difference in hydrogen storage properties between La₂MgNi₉ and LaMg₂Ni₉ were explained by the electronic structure analysis. For another, La_1+xMg_2-xNi₉ （x=0, 0.5, 1.0, 1.5） alloys were prepared in high frequency induction furnace under Ar atmosphere, the characteristics of alloy phases and the properties of hydrogen storage and electrochemistry at different contents of La and Mg were studied. In Mg₂NiH₄ compounds, there is strong s-p-d hybridization between Ni and H in Ni-H bonding areas, which is a reason why Mg₂NiH₄ compounds have poor dynamic property. After the LT→HT phase transformation, the更多还原