Mg-Ce化合物相结构稳定性的赝势平面波方法研究

Study on Structural Stability of Mg-Ce Intermetallic Compounds Based on the Pseudopotential Plane-Wave Method

摘要:

采用基于密度泛函理论的第一原理赝势平面波方法,计算了Mg-Ce二元合金系中不同Ce原子浓度与结构类型金属间化合物的几何、能态与电子结构,并从合金形成热和结合能两方面调查了这些金属间化合物不同结构类型的相结构稳定性.结果表明：Mg3Ce,Mg2Ce,MgCe,MgCe2和MgCe3金属间化合物具有最强合金化形成能力和最高结构稳定性的结构类型分别为DO3,C15,Ba,C15和DO3.电子态密度（DOS）的分析结果表明：不同Ce含量Mg-Ce金属间化合物相结构稳定性的差异源于其费米能级处电子数的不同,高稳定性的相结构类型可归因于其费米能级处较少的Mg（3s）,Mg（2p）,Ce（5d）和Ce（4f）成键电子.

Abstract:

The energy and electronic structure of several Mg-Ce intermetallic compounds with different structure types were investigated using the first-principle pseudopotential plane-wave method. Based on the calculations of formation heat of and cohesive energies, their structural stability was analyzed. The results show that the structure types with the strongest alloying ability and the highest structural stability are DO3, C15, Ba, C15 and DO3, respectively, for the Mg3Ce, Mg2Ce, MgCe, MgCe2, MgCe3 intermetallic compounds. After compared the DOS (density of state) of these phases with different structure types, the results show that the discrepancy in structural stability of Mg-Ce intermetallic compounds can be attributed to the difference in the bonding electron numbers at Feimi level, which mainly originates from the contribution of valence electrons of Mg(3s), Mg(2p), Ce(5d) and Ce(4f) orbits. The less the valence electrons at Feimi level, the better the structural stability of Mg-Ce intermetallic compounds.