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用基于密度泛函理论的第一性原理赝势平面波方法,计算了Cr合金化前后Mg2Ni相及其氢化物的能量与电子结构。合金形成热的计算结果表明:Cr合金化Mg2Ni,形成Mg(I)CrNi的相结构最稳定,其中,Cr原子最易占据Mg(I):(0.5,0,z),z=l/9位置;进一步对其氢化物的解氢反应热进行计算,发现Cr合金化Mg2Ni氢化物后,体系解氢所需吸收的热量与合金化前相比明显降低,体系的解氢能力得到增强;电子态密度(DOS)、密集数与差分电荷密度的计算结果发现:Mg(I)CrNi相结构最稳定的主要原因在于体系在费米能级(EF)处附近的成键电子数最多;而Cr合金化Mg2Ni氢化物体系解氢能力增强的主要原因在于:Cr合金化后导致体系的稳定性降低,削弱了H-Ni和H-Mg间的成键作用。
The energy and electron structures of the Mg2Ni phase and its hydride before and after Cr alloying were calculated using the first principles pseudopotential plane wave method based on the density functional theory. The results show that the most stable phase structure of Mg2Ni and Mg (I) CrNi is Cr, Mg (I) :( 0.5,0, z), z = l / 9 The results show that the amount of heat required for the hydrogen desorption of the system is obviously lower than that before alloying and the hydrogen desorption ability of the system is enhanced. The results of calculation of DOS, DIC, and difference charge density indicate that the most stable structure of Mg (I) CrNi phase is due to the largest number of bonding electrons near the Fermi level (EF) The main reason for the enhanced hydrogen abstraction ability of alloying Mg2Ni hydride system is that the alloying of Cr reduces the stability of the system and weakens the bonding between H-Ni and H-Mg.