NaZn_(13)型Fe基化合物的结构和热力学性质研究

Structural and thermodynamic properties of Fe based compounds with NaZn_(13)-type

利用Chen-Mbius晶格反演获得的原子间相互作用势,对NaZn13型Fe基金属间化合物进行原子级模拟研究.计算结果表明,Si原子和Co原子均优先占据96i晶位,Si原子和Co原子替代Fe原子后晶体平均结合能降低.随着Co含量的增加,LaFe13-x-yCoySix和NdFe13-x-yCoySix的晶格参数逐渐降低.声子态密度中,稀土原子主要激发低频模,Si原子主要激发高频模.LaFe11.5-yCoySi1.5化合物的德拜温度随Co含量的增加而增高.

A series of Fe based compounds with NaZn13-type structure is studied by using inversed interatomic potentials. Calculated results show that Si atoms and Co atoms are preferentially substituted for Fe atoms at 96 i site. The addition of Si or Co makes the cohesive energy decrease. It is found that the lattice constants of LaFe13-x-yCoySix and NdFe13-x-yCoySix decrease with the increase of Co content. The investigation on the phonon density of states indicates that the lower frequency modes are mostly excited by the rare-earth atoms, and the higher frequency modes are mostly excited by Si atoms. Moreover, the addition of Co atoms makes the Debye temperature of LaFe11.5-x-yCo,Si1.5 compounds increase.