替代元素对ZrMn2合金及其氢化物电子结构的影晌

Influence of Substitute Elements on ZrMn2 Alloy and Electronic Structures of Its Hydrides

关键词:  合金  电子结构  替代元素

Key words:  alloy  electronic structure  substitute elements

摘要:

采用基于密度泛函的赝势平面波方法,计算Zr₄Mn₆M₂(M=V,Co,Fe,Al,Mn)及其氢化物的电子结构,并分析了成键特性。结果、表明,Zr₄Mn₆M₂(M=Al,Co,Fe,Mn,V)中晶胞参数值(a、c值),及其相应氢化物的稳定性都随替代元素M的3d轨道电荷占据数的增加而减小。加Co后Zr₄Mn₆Co₂H₁₂中H分别与Co,Mn的相互作用增强,成键更加稳定,可延长合金的循环寿命,并使平台氢压更趋平坦.加V可使合金氧化物中Mn (2)-H间相互作用减弱,因而加V可以减小吸放氢滞后效应,并有效降低平台氢压。

Abstract:

Electron structures of Zr₄Mn₆M₂(M=V,Co,Fe,Al,Mn)and their hydrides are calculated by the plane wave pseudo-potential method which is based on density functional theory. It is found that both the lattice parameters of the alloys and their stability decrease with the increase of 3d electrons of the element M. After Co is added, the chemical bonds of the atom H in Zr₄Mn₆M₂ to Mn(2) and Co become stronger and stable. So, Zr₄Mn₆Co₂H₁₂ has good hydrogen storage, such as longer cycle life and smoother equilibrium plateau pressure. The substitution of the atom V makes the interaction between Mn(2) and H weak and the peak of V 3d band decreased obviously in the electron density of states. As a result, the equilibrium plateau pressure and hysteresis of Zr₄Mn₆V₂H₁₂ is less than that of ZrMn₂H₃.